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1d506c26 | 1 | @c Copyright (C) 2008--2024 Free Software Foundation, Inc. |
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2 | @c Permission is granted to copy, distribute and/or modify this document |
3 | @c under the terms of the GNU Free Documentation License, Version 1.3 or | |
4 | @c any later version published by the Free Software Foundation; with the | |
5 | @c Invariant Sections being ``Free Software'' and ``Free Software Needs | |
6 | @c Free Documentation'', with the Front-Cover Texts being ``A GNU Manual,'' | |
7 | @c and with the Back-Cover Texts as in (a) below. | |
8 | @c | |
9 | @c (a) The FSF's Back-Cover Text is: ``You are free to copy and modify | |
10 | @c this GNU Manual. Buying copies from GNU Press supports the FSF in | |
11 | @c developing GNU and promoting software freedom.'' | |
12 | ||
13 | @node Python | |
14 | @section Extending @value{GDBN} using Python | |
15 | @cindex python scripting | |
16 | @cindex scripting with python | |
17 | ||
18 | You can extend @value{GDBN} using the @uref{http://www.python.org/, | |
19 | Python programming language}. This feature is available only if | |
20 | @value{GDBN} was configured using @option{--with-python}. | |
21 | ||
22 | @cindex python directory | |
23 | Python scripts used by @value{GDBN} should be installed in | |
24 | @file{@var{data-directory}/python}, where @var{data-directory} is | |
25 | the data directory as determined at @value{GDBN} startup (@pxref{Data Files}). | |
26 | This directory, known as the @dfn{python directory}, | |
27 | is automatically added to the Python Search Path in order to allow | |
28 | the Python interpreter to locate all scripts installed at this location. | |
29 | ||
30 | Additionally, @value{GDBN} commands and convenience functions which | |
31 | are written in Python and are located in the | |
32 | @file{@var{data-directory}/python/gdb/command} or | |
33 | @file{@var{data-directory}/python/gdb/function} directories are | |
34 | automatically imported when @value{GDBN} starts. | |
35 | ||
36 | @menu | |
37 | * Python Commands:: Accessing Python from @value{GDBN}. | |
38 | * Python API:: Accessing @value{GDBN} from Python. | |
39 | * Python Auto-loading:: Automatically loading Python code. | |
40 | * Python modules:: Python modules provided by @value{GDBN}. | |
41 | @end menu | |
42 | ||
43 | @node Python Commands | |
44 | @subsection Python Commands | |
45 | @cindex python commands | |
46 | @cindex commands to access python | |
47 | ||
48 | @value{GDBN} provides two commands for accessing the Python interpreter, | |
49 | and one related setting: | |
50 | ||
51 | @table @code | |
52 | @kindex python-interactive | |
53 | @kindex pi | |
54 | @item python-interactive @r{[}@var{command}@r{]} | |
55 | @itemx pi @r{[}@var{command}@r{]} | |
56 | Without an argument, the @code{python-interactive} command can be used | |
57 | to start an interactive Python prompt. To return to @value{GDBN}, | |
58 | type the @code{EOF} character (e.g., @kbd{Ctrl-D} on an empty prompt). | |
59 | ||
60 | Alternatively, a single-line Python command can be given as an | |
61 | argument and evaluated. If the command is an expression, the result | |
62 | will be printed; otherwise, nothing will be printed. For example: | |
63 | ||
64 | @smallexample | |
65 | (@value{GDBP}) python-interactive 2 + 3 | |
66 | 5 | |
67 | @end smallexample | |
68 | ||
69 | @kindex python | |
70 | @kindex py | |
71 | @item python @r{[}@var{command}@r{]} | |
72 | @itemx py @r{[}@var{command}@r{]} | |
73 | The @code{python} command can be used to evaluate Python code. | |
74 | ||
75 | If given an argument, the @code{python} command will evaluate the | |
76 | argument as a Python command. For example: | |
77 | ||
78 | @smallexample | |
79 | (@value{GDBP}) python print 23 | |
80 | 23 | |
81 | @end smallexample | |
82 | ||
83 | If you do not provide an argument to @code{python}, it will act as a | |
84 | multi-line command, like @code{define}. In this case, the Python | |
85 | script is made up of subsequent command lines, given after the | |
86 | @code{python} command. This command list is terminated using a line | |
87 | containing @code{end}. For example: | |
88 | ||
89 | @smallexample | |
90 | (@value{GDBP}) python | |
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91 | >print 23 |
92 | >end | |
93 | 23 | |
94 | @end smallexample | |
95 | ||
740b42ce | 96 | @anchor{set_python_print_stack} |
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97 | @kindex set python print-stack |
98 | @item set python print-stack | |
99 | By default, @value{GDBN} will print only the message component of a | |
100 | Python exception when an error occurs in a Python script. This can be | |
101 | controlled using @code{set python print-stack}: if @code{full}, then | |
102 | full Python stack printing is enabled; if @code{none}, then Python stack | |
103 | and message printing is disabled; if @code{message}, the default, only | |
104 | the message component of the error is printed. | |
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105 | |
106 | @kindex set python ignore-environment | |
107 | @item set python ignore-environment @r{[}on@r{|}off@r{]} | |
108 | By default this option is @samp{off}, and, when @value{GDBN} | |
109 | initializes its internal Python interpreter, the Python interpreter | |
110 | will check the environment for variables that will effect how it | |
111 | behaves, for example @env{PYTHONHOME}, and | |
112 | @env{PYTHONPATH}@footnote{See the ENVIRONMENT VARIABLES section of | |
113 | @command{man 1 python} for a comprehensive list.}. | |
114 | ||
115 | If this option is set to @samp{on} before Python is initialized then | |
116 | Python will ignore all such environment variables. As Python is | |
117 | initialized early during @value{GDBN}'s startup process, then this | |
118 | option must be placed into the early initialization file | |
119 | (@pxref{Initialization Files}) to have the desired effect. | |
120 | ||
121 | This option is equivalent to passing @option{-E} to the real | |
122 | @command{python} executable. | |
123 | ||
124 | @kindex set python dont-write-bytecode | |
125 | @item set python dont-write-bytecode @r{[}auto@r{|}on@r{|}off@r{]} | |
126 | When this option is @samp{off}, then, once @value{GDBN} has | |
127 | initialized the Python interpreter, the interpreter will byte-compile | |
128 | any Python modules that it imports and write the byte code to disk in | |
129 | @file{.pyc} files. | |
130 | ||
131 | If this option is set to @samp{on} before Python is initialized then | |
132 | Python will no longer write the byte code to disk. As Python is | |
133 | initialized early during @value{GDBN}'s startup process, then this | |
134 | option must be placed into the early initialization file | |
135 | (@pxref{Initialization Files}) to have the desired effect. | |
136 | ||
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137 | By default this option is set to @samp{auto}. In this mode, provided |
138 | the @code{python ignore-environment} setting is @samp{off}, the | |
139 | environment variable @env{PYTHONDONTWRITEBYTECODE} is examined to see | |
edeaceda | 140 | if it should write out byte-code or not. |
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141 | @env{PYTHONDONTWRITEBYTECODE} is considered to be off/disabled either |
142 | when set to the empty string or when the environment variable doesn't | |
143 | exist. All other settings, including those which don't seem to make | |
144 | sense, indicate that it's on/enabled. | |
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145 | |
146 | This option is equivalent to passing @option{-B} to the real | |
147 | @command{python} executable. | |
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148 | @end table |
149 | ||
150 | It is also possible to execute a Python script from the @value{GDBN} | |
151 | interpreter: | |
152 | ||
153 | @table @code | |
154 | @item source @file{script-name} | |
155 | The script name must end with @samp{.py} and @value{GDBN} must be configured | |
156 | to recognize the script language based on filename extension using | |
157 | the @code{script-extension} setting. @xref{Extending GDB, ,Extending GDB}. | |
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158 | @end table |
159 | ||
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160 | The following commands are intended to help debug @value{GDBN} itself: |
161 | ||
162 | @table @code | |
163 | @kindex set debug py-breakpoint | |
164 | @kindex show debug py-breakpoint | |
165 | @item set debug py-breakpoint on@r{|}off | |
166 | @itemx show debug py-breakpoint | |
167 | When @samp{on}, @value{GDBN} prints debug messages related to the | |
168 | Python breakpoint API. This is @samp{off} by default. | |
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169 | |
170 | @kindex set debug py-unwind | |
171 | @kindex show debug py-unwind | |
172 | @item set debug py-unwind on@r{|}off | |
173 | @itemx show debug py-unwind | |
174 | When @samp{on}, @value{GDBN} prints debug messages related to the | |
175 | Python unwinder API. This is @samp{off} by default. | |
75140e3b AB |
176 | @end table |
177 | ||
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178 | @node Python API |
179 | @subsection Python API | |
180 | @cindex python api | |
181 | @cindex programming in python | |
182 | ||
183 | You can get quick online help for @value{GDBN}'s Python API by issuing | |
184 | the command @w{@kbd{python help (gdb)}}. | |
185 | ||
186 | Functions and methods which have two or more optional arguments allow | |
187 | them to be specified using keyword syntax. This allows passing some | |
188 | optional arguments while skipping others. Example: | |
189 | @w{@code{gdb.some_function ('foo', bar = 1, baz = 2)}}. | |
190 | ||
191 | @menu | |
192 | * Basic Python:: Basic Python Functions. | |
560c121c | 193 | * Threading in GDB:: Using Python threads in GDB. |
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194 | * Exception Handling:: How Python exceptions are translated. |
195 | * Values From Inferior:: Python representation of values. | |
196 | * Types In Python:: Python representation of types. | |
197 | * Pretty Printing API:: Pretty-printing values. | |
198 | * Selecting Pretty-Printers:: How GDB chooses a pretty-printer. | |
199 | * Writing a Pretty-Printer:: Writing a Pretty-Printer. | |
cc81f07b | 200 | * Type Printing API:: Pretty-printing types. |
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201 | * Frame Filter API:: Filtering Frames. |
202 | * Frame Decorator API:: Decorating Frames. | |
203 | * Writing a Frame Filter:: Writing a Frame Filter. | |
d11916aa | 204 | * Unwinding Frames in Python:: Writing frame unwinder. |
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205 | * Xmethods In Python:: Adding and replacing methods of C++ classes. |
206 | * Xmethod API:: Xmethod types. | |
207 | * Writing an Xmethod:: Writing an xmethod. | |
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208 | * Inferiors In Python:: Python representation of inferiors (processes) |
209 | * Events In Python:: Listening for events from @value{GDBN}. | |
210 | * Threads In Python:: Accessing inferior threads from Python. | |
0a0faf9f | 211 | * Recordings In Python:: Accessing recordings from Python. |
740b42ce | 212 | * CLI Commands In Python:: Implementing new CLI commands in Python. |
c96452ad | 213 | * GDB/MI Commands In Python:: Implementing new @sc{gdb/mi} commands in Python. |
4825fd2d | 214 | * GDB/MI Notifications In Python:: Implementing new @sc{gdb/mi} notifications in Python. |
329baa95 DE |
215 | * Parameters In Python:: Adding new @value{GDBN} parameters. |
216 | * Functions In Python:: Writing new convenience functions. | |
217 | * Progspaces In Python:: Program spaces. | |
218 | * Objfiles In Python:: Object files. | |
219 | * Frames In Python:: Accessing inferior stack frames from Python. | |
220 | * Blocks In Python:: Accessing blocks from Python. | |
221 | * Symbols In Python:: Python representation of symbols. | |
222 | * Symbol Tables In Python:: Python representation of symbol tables. | |
223 | * Line Tables In Python:: Python representation of line tables. | |
224 | * Breakpoints In Python:: Manipulating breakpoints using Python. | |
225 | * Finish Breakpoints in Python:: Setting Breakpoints on function return | |
226 | using Python. | |
227 | * Lazy Strings In Python:: Python representation of lazy strings. | |
228 | * Architectures In Python:: Python representation of architectures. | |
0f767f94 | 229 | * Registers In Python:: Python representation of registers. |
cc81f07b | 230 | * Connections In Python:: Python representation of connections. |
01b1af32 | 231 | * TUI Windows In Python:: Implementing new TUI windows. |
15e15b2d | 232 | * Disassembly In Python:: Instruction Disassembly In Python |
8f6c452b | 233 | * Missing Debug Info In Python:: Handle missing debug info from Python. |
329baa95 DE |
234 | @end menu |
235 | ||
236 | @node Basic Python | |
237 | @subsubsection Basic Python | |
238 | ||
239 | @cindex python stdout | |
240 | @cindex python pagination | |
241 | At startup, @value{GDBN} overrides Python's @code{sys.stdout} and | |
242 | @code{sys.stderr} to print using @value{GDBN}'s output-paging streams. | |
243 | A Python program which outputs to one of these streams may have its | |
244 | output interrupted by the user (@pxref{Screen Size}). In this | |
245 | situation, a Python @code{KeyboardInterrupt} exception is thrown. | |
246 | ||
247 | Some care must be taken when writing Python code to run in | |
248 | @value{GDBN}. Two things worth noting in particular: | |
249 | ||
250 | @itemize @bullet | |
251 | @item | |
14432bde | 252 | @value{GDBN} installs handlers for @code{SIGCHLD} and @code{SIGINT}. |
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253 | Python code must not override these, or even change the options using |
254 | @code{sigaction}. If your program changes the handling of these | |
255 | signals, @value{GDBN} will most likely stop working correctly. Note | |
256 | that it is unfortunately common for GUI toolkits to install a | |
14432bde TT |
257 | @code{SIGCHLD} handler. When creating a new Python thread, you can |
258 | use @code{gdb.block_signals} or @code{gdb.Thread} to handle this | |
259 | correctly; see @ref{Threading in GDB}. | |
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260 | |
261 | @item | |
262 | @value{GDBN} takes care to mark its internal file descriptors as | |
263 | close-on-exec. However, this cannot be done in a thread-safe way on | |
264 | all platforms. Your Python programs should be aware of this and | |
265 | should both create new file descriptors with the close-on-exec flag | |
266 | set and arrange to close unneeded file descriptors before starting a | |
267 | child process. | |
268 | @end itemize | |
269 | ||
270 | @cindex python functions | |
271 | @cindex python module | |
272 | @cindex gdb module | |
273 | @value{GDBN} introduces a new Python module, named @code{gdb}. All | |
274 | methods and classes added by @value{GDBN} are placed in this module. | |
275 | @value{GDBN} automatically @code{import}s the @code{gdb} module for | |
276 | use in all scripts evaluated by the @code{python} command. | |
277 | ||
1256af7d SM |
278 | Some types of the @code{gdb} module come with a textual representation |
279 | (accessible through the @code{repr} or @code{str} functions). These are | |
280 | offered for debugging purposes only, expect them to change over time. | |
281 | ||
329baa95 DE |
282 | @defvar gdb.PYTHONDIR |
283 | A string containing the python directory (@pxref{Python}). | |
284 | @end defvar | |
285 | ||
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286 | @defun gdb.execute (command @r{[}, from_tty @r{[}, to_string@r{]]}) |
287 | Evaluate @var{command}, a string, as a @value{GDBN} CLI command. | |
288 | If a GDB exception happens while @var{command} runs, it is | |
289 | translated as described in @ref{Exception Handling,,Exception Handling}. | |
290 | ||
697aa1b7 | 291 | The @var{from_tty} flag specifies whether @value{GDBN} ought to consider this |
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292 | command as having originated from the user invoking it interactively. |
293 | It must be a boolean value. If omitted, it defaults to @code{False}. | |
294 | ||
295 | By default, any output produced by @var{command} is sent to | |
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296 | @value{GDBN}'s standard output (and to the log output if logging is |
297 | turned on). If the @var{to_string} parameter is | |
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298 | @code{True}, then output will be collected by @code{gdb.execute} and |
299 | returned as a string. The default is @code{False}, in which case the | |
300 | return value is @code{None}. If @var{to_string} is @code{True}, the | |
301 | @value{GDBN} virtual terminal will be temporarily set to unlimited width | |
302 | and height, and its pagination will be disabled; @pxref{Screen Size}. | |
303 | @end defun | |
304 | ||
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305 | @defun gdb.breakpoints () |
306 | Return a sequence holding all of @value{GDBN}'s breakpoints. | |
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307 | @xref{Breakpoints In Python}, for more information. In @value{GDBN} |
308 | version 7.11 and earlier, this function returned @code{None} if there | |
309 | were no breakpoints. This peculiarity was subsequently fixed, and now | |
310 | @code{gdb.breakpoints} returns an empty sequence in this case. | |
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311 | @end defun |
312 | ||
d8ae99a7 PM |
313 | @defun gdb.rbreak (regex @r{[}, minsyms @r{[}, throttle, @r{[}, symtabs @r{]]]}) |
314 | Return a Python list holding a collection of newly set | |
315 | @code{gdb.Breakpoint} objects matching function names defined by the | |
316 | @var{regex} pattern. If the @var{minsyms} keyword is @code{True}, all | |
317 | system functions (those not explicitly defined in the inferior) will | |
318 | also be included in the match. The @var{throttle} keyword takes an | |
319 | integer that defines the maximum number of pattern matches for | |
320 | functions matched by the @var{regex} pattern. If the number of | |
321 | matches exceeds the integer value of @var{throttle}, a | |
322 | @code{RuntimeError} will be raised and no breakpoints will be created. | |
323 | If @var{throttle} is not defined then there is no imposed limit on the | |
324 | maximum number of matches and breakpoints to be created. The | |
325 | @var{symtabs} keyword takes a Python iterable that yields a collection | |
326 | of @code{gdb.Symtab} objects and will restrict the search to those | |
327 | functions only contained within the @code{gdb.Symtab} objects. | |
328 | @end defun | |
329 | ||
329baa95 | 330 | @defun gdb.parameter (parameter) |
697aa1b7 EZ |
331 | Return the value of a @value{GDBN} @var{parameter} given by its name, |
332 | a string; the parameter name string may contain spaces if the parameter has a | |
333 | multi-part name. For example, @samp{print object} is a valid | |
334 | parameter name. | |
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335 | |
336 | If the named parameter does not exist, this function throws a | |
337 | @code{gdb.error} (@pxref{Exception Handling}). Otherwise, the | |
338 | parameter's value is converted to a Python value of the appropriate | |
339 | type, and returned. | |
340 | @end defun | |
341 | ||
b583c328 TT |
342 | @defun gdb.set_parameter (name, value) |
343 | Sets the gdb parameter @var{name} to @var{value}. As with | |
344 | @code{gdb.parameter}, the parameter name string may contain spaces if | |
345 | the parameter has a multi-part name. | |
346 | @end defun | |
347 | ||
b583c328 TT |
348 | @defun gdb.with_parameter (name, value) |
349 | Create a Python context manager (for use with the Python | |
350 | @command{with} statement) that temporarily sets the gdb parameter | |
351 | @var{name} to @var{value}. On exit from the context, the previous | |
352 | value will be restored. | |
353 | ||
354 | This uses @code{gdb.parameter} in its implementation, so it can throw | |
355 | the same exceptions as that function. | |
356 | ||
357 | For example, it's sometimes useful to evaluate some Python code with a | |
358 | particular gdb language: | |
359 | ||
360 | @smallexample | |
361 | with gdb.with_parameter('language', 'pascal'): | |
362 | ... language-specific operations | |
363 | @end smallexample | |
364 | @end defun | |
365 | ||
329baa95 DE |
366 | @defun gdb.history (number) |
367 | Return a value from @value{GDBN}'s value history (@pxref{Value | |
697aa1b7 | 368 | History}). The @var{number} argument indicates which history element to return. |
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369 | If @var{number} is negative, then @value{GDBN} will take its absolute value |
370 | and count backward from the last element (i.e., the most recent element) to | |
371 | find the value to return. If @var{number} is zero, then @value{GDBN} will | |
372 | return the most recent element. If the element specified by @var{number} | |
373 | doesn't exist in the value history, a @code{gdb.error} exception will be | |
374 | raised. | |
375 | ||
376 | If no exception is raised, the return value is always an instance of | |
377 | @code{gdb.Value} (@pxref{Values From Inferior}). | |
378 | @end defun | |
379 | ||
540bf37b AB |
380 | @defun gdb.add_history (value) |
381 | Takes @var{value}, an instance of @code{gdb.Value} (@pxref{Values From | |
382 | Inferior}), and appends the value this object represents to | |
383 | @value{GDBN}'s value history (@pxref{Value History}), and return an | |
384 | integer, its history number. If @var{value} is not a | |
385 | @code{gdb.Value}, it is is converted using the @code{gdb.Value} | |
386 | constructor. If @var{value} can't be converted to a @code{gdb.Value} | |
387 | then a @code{TypeError} is raised. | |
388 | ||
389 | When a command implemented in Python prints a single @code{gdb.Value} | |
390 | as its result, then placing the value into the history will allow the | |
391 | user convenient access to those values via CLI history facilities. | |
392 | @end defun | |
393 | ||
30a87e90 AB |
394 | @defun gdb.history_count () |
395 | Return an integer indicating the number of values in @value{GDBN}'s | |
396 | value history (@pxref{Value History}). | |
397 | @end defun | |
398 | ||
7729052b TT |
399 | @defun gdb.convenience_variable (name) |
400 | Return the value of the convenience variable (@pxref{Convenience | |
401 | Vars}) named @var{name}. @var{name} must be a string. The name | |
402 | should not include the @samp{$} that is used to mark a convenience | |
403 | variable in an expression. If the convenience variable does not | |
404 | exist, then @code{None} is returned. | |
405 | @end defun | |
406 | ||
7729052b TT |
407 | @defun gdb.set_convenience_variable (name, value) |
408 | Set the value of the convenience variable (@pxref{Convenience Vars}) | |
409 | named @var{name}. @var{name} must be a string. The name should not | |
410 | include the @samp{$} that is used to mark a convenience variable in an | |
411 | expression. If @var{value} is @code{None}, then the convenience | |
412 | variable is removed. Otherwise, if @var{value} is not a | |
413 | @code{gdb.Value} (@pxref{Values From Inferior}), it is is converted | |
414 | using the @code{gdb.Value} constructor. | |
415 | @end defun | |
416 | ||
125862f0 | 417 | @defun gdb.parse_and_eval (expression @r{[}, global_context@r{]}) |
697aa1b7 EZ |
418 | Parse @var{expression}, which must be a string, as an expression in |
419 | the current language, evaluate it, and return the result as a | |
420 | @code{gdb.Value}. | |
329baa95 | 421 | |
125862f0 TT |
422 | @var{global_context}, if provided, is a boolean indicating whether the |
423 | parsing should be done in the global context. The default is | |
424 | @samp{False}, meaning that the current frame or current static context | |
425 | should be used. | |
426 | ||
329baa95 | 427 | This function can be useful when implementing a new command |
740b42ce AB |
428 | (@pxref{CLI Commands In Python}, @pxref{GDB/MI Commands In Python}), |
429 | as it provides a way to parse the | |
329baa95 | 430 | command's argument as an expression. It is also useful simply to |
7729052b | 431 | compute values. |
329baa95 DE |
432 | @end defun |
433 | ||
329baa95 DE |
434 | @defun gdb.find_pc_line (pc) |
435 | Return the @code{gdb.Symtab_and_line} object corresponding to the | |
436 | @var{pc} value. @xref{Symbol Tables In Python}. If an invalid | |
437 | value of @var{pc} is passed as an argument, then the @code{symtab} and | |
438 | @code{line} attributes of the returned @code{gdb.Symtab_and_line} object | |
8743a9cd TT |
439 | will be @code{None} and 0 respectively. This is identical to |
440 | @code{gdb.current_progspace().find_pc_line(pc)} and is included for | |
441 | historical compatibility. | |
329baa95 DE |
442 | @end defun |
443 | ||
b13d7831 | 444 | @defun gdb.write (string @r{[}, stream@r{]}) |
329baa95 DE |
445 | Print a string to @value{GDBN}'s paginated output stream. The |
446 | optional @var{stream} determines the stream to print to. The default | |
447 | stream is @value{GDBN}'s standard output stream. Possible stream | |
448 | values are: | |
449 | ||
450 | @table @code | |
451 | @findex STDOUT | |
452 | @findex gdb.STDOUT | |
453 | @item gdb.STDOUT | |
454 | @value{GDBN}'s standard output stream. | |
455 | ||
456 | @findex STDERR | |
457 | @findex gdb.STDERR | |
458 | @item gdb.STDERR | |
459 | @value{GDBN}'s standard error stream. | |
460 | ||
461 | @findex STDLOG | |
462 | @findex gdb.STDLOG | |
463 | @item gdb.STDLOG | |
464 | @value{GDBN}'s log stream (@pxref{Logging Output}). | |
465 | @end table | |
466 | ||
467 | Writing to @code{sys.stdout} or @code{sys.stderr} will automatically | |
468 | call this function and will automatically direct the output to the | |
469 | relevant stream. | |
470 | @end defun | |
471 | ||
dd083c65 | 472 | @defun gdb.flush (@r{[}, stream@r{]}) |
329baa95 DE |
473 | Flush the buffer of a @value{GDBN} paginated stream so that the |
474 | contents are displayed immediately. @value{GDBN} will flush the | |
475 | contents of a stream automatically when it encounters a newline in the | |
476 | buffer. The optional @var{stream} determines the stream to flush. The | |
477 | default stream is @value{GDBN}'s standard output stream. Possible | |
478 | stream values are: | |
479 | ||
480 | @table @code | |
481 | @findex STDOUT | |
482 | @findex gdb.STDOUT | |
483 | @item gdb.STDOUT | |
484 | @value{GDBN}'s standard output stream. | |
485 | ||
486 | @findex STDERR | |
487 | @findex gdb.STDERR | |
488 | @item gdb.STDERR | |
489 | @value{GDBN}'s standard error stream. | |
490 | ||
491 | @findex STDLOG | |
492 | @findex gdb.STDLOG | |
493 | @item gdb.STDLOG | |
494 | @value{GDBN}'s log stream (@pxref{Logging Output}). | |
495 | ||
496 | @end table | |
497 | ||
498 | Flushing @code{sys.stdout} or @code{sys.stderr} will automatically | |
499 | call this function for the relevant stream. | |
500 | @end defun | |
501 | ||
329baa95 DE |
502 | @defun gdb.target_charset () |
503 | Return the name of the current target character set (@pxref{Character | |
504 | Sets}). This differs from @code{gdb.parameter('target-charset')} in | |
505 | that @samp{auto} is never returned. | |
506 | @end defun | |
507 | ||
329baa95 DE |
508 | @defun gdb.target_wide_charset () |
509 | Return the name of the current target wide character set | |
510 | (@pxref{Character Sets}). This differs from | |
511 | @code{gdb.parameter('target-wide-charset')} in that @samp{auto} is | |
512 | never returned. | |
513 | @end defun | |
514 | ||
61671e97 AB |
515 | @defun gdb.host_charset () |
516 | Return a string, the name of the current host character set | |
517 | (@pxref{Character Sets}). This differs from | |
518 | @code{gdb.parameter('host-charset')} in that @samp{auto} is never | |
519 | returned. | |
520 | @end defun | |
521 | ||
329baa95 DE |
522 | @defun gdb.solib_name (address) |
523 | Return the name of the shared library holding the given @var{address} | |
8743a9cd TT |
524 | as a string, or @code{None}. This is identical to |
525 | @code{gdb.current_progspace().solib_name(address)} and is included for | |
526 | historical compatibility. | |
329baa95 DE |
527 | @end defun |
528 | ||
0d2a5839 | 529 | @defun gdb.decode_line (@r{[}expression@r{]}) |
329baa95 DE |
530 | Return locations of the line specified by @var{expression}, or of the |
531 | current line if no argument was given. This function returns a Python | |
532 | tuple containing two elements. The first element contains a string | |
533 | holding any unparsed section of @var{expression} (or @code{None} if | |
534 | the expression has been fully parsed). The second element contains | |
535 | either @code{None} or another tuple that contains all the locations | |
536 | that match the expression represented as @code{gdb.Symtab_and_line} | |
537 | objects (@pxref{Symbol Tables In Python}). If @var{expression} is | |
538 | provided, it is decoded the way that @value{GDBN}'s inbuilt | |
5541bfdc PA |
539 | @code{break} or @code{edit} commands do (@pxref{Location |
540 | Specifications}). | |
329baa95 DE |
541 | @end defun |
542 | ||
543 | @defun gdb.prompt_hook (current_prompt) | |
544 | @anchor{prompt_hook} | |
545 | ||
546 | If @var{prompt_hook} is callable, @value{GDBN} will call the method | |
547 | assigned to this operation before a prompt is displayed by | |
548 | @value{GDBN}. | |
549 | ||
550 | The parameter @code{current_prompt} contains the current @value{GDBN} | |
551 | prompt. This method must return a Python string, or @code{None}. If | |
552 | a string is returned, the @value{GDBN} prompt will be set to that | |
553 | string. If @code{None} is returned, @value{GDBN} will continue to use | |
554 | the current prompt. | |
555 | ||
556 | Some prompts cannot be substituted in @value{GDBN}. Secondary prompts | |
557 | such as those used by readline for command input, and annotation | |
558 | related prompts are prohibited from being changed. | |
559 | @end defun | |
560 | ||
15e15b2d | 561 | @anchor{gdb_architecture_names} |
8b87fbe6 AB |
562 | @defun gdb.architecture_names () |
563 | Return a list containing all of the architecture names that the | |
564 | current build of @value{GDBN} supports. Each architecture name is a | |
565 | string. The names returned in this list are the same names as are | |
566 | returned from @code{gdb.Architecture.name} | |
567 | (@pxref{gdbpy_architecture_name,,Architecture.name}). | |
568 | @end defun | |
569 | ||
0e3b7c25 AB |
570 | @anchor{gdbpy_connections} |
571 | @defun gdb.connections | |
572 | Return a list of @code{gdb.TargetConnection} objects, one for each | |
573 | currently active connection (@pxref{Connections In Python}). The | |
574 | connection objects are in no particular order in the returned list. | |
575 | @end defun | |
576 | ||
ebb83b77 | 577 | @defun gdb.format_address (address @r{[}, progspace, architecture@r{]}) |
25209e2c AB |
578 | Return a string in the format @samp{@var{addr} |
579 | <@var{symbol}+@var{offset}>}, where @var{addr} is @var{address} | |
580 | formatted in hexadecimal, @var{symbol} is the symbol whose address is | |
581 | the nearest to @var{address} and below it in memory, and @var{offset} | |
582 | is the offset from @var{symbol} to @var{address} in decimal. | |
583 | ||
584 | If no suitable @var{symbol} was found, then the | |
585 | <@var{symbol}+@var{offset}> part is not included in the returned | |
586 | string, instead the returned string will just contain the | |
587 | @var{address} formatted as hexadecimal. How far @value{GDBN} looks | |
588 | back for a suitable symbol can be controlled with @kbd{set print | |
589 | max-symbolic-offset} (@pxref{Print Settings}). | |
590 | ||
591 | Additionally, the returned string can include file name and line | |
592 | number information when @kbd{set print symbol-filename on} | |
593 | (@pxref{Print Settings}), in this case the format of the returned | |
594 | string is @samp{@var{addr} <@var{symbol}+@var{offset}> at | |
595 | @var{filename}:@var{line-number}}. | |
596 | ||
597 | ||
598 | The @var{progspace} is the gdb.Progspace in which @var{symbol} is | |
599 | looked up, and @var{architecture} is used when formatting @var{addr}, | |
600 | e.g.@: in order to determine the size of an address in bytes. | |
601 | ||
602 | If neither @var{progspace} or @var{architecture} are passed, then by | |
603 | default @value{GDBN} will use the program space and architecture of | |
604 | the currently selected inferior, thus, the following two calls are | |
605 | equivalent: | |
606 | ||
607 | @smallexample | |
608 | gdb.format_address(address) | |
609 | gdb.format_address(address, | |
610 | gdb.selected_inferior().progspace, | |
611 | gdb.selected_inferior().architecture()) | |
612 | @end smallexample | |
613 | ||
614 | It is not valid to only pass one of @var{progspace} or | |
615 | @var{architecture}, either they must both be provided, or neither must | |
616 | be provided (and the defaults will be used). | |
617 | ||
618 | This method uses the same mechanism for formatting address, symbol, | |
619 | and offset information as core @value{GDBN} does in commands such as | |
620 | @kbd{disassemble}. | |
621 | ||
622 | Here are some examples of the possible string formats: | |
623 | ||
624 | @smallexample | |
625 | 0x00001042 | |
626 | 0x00001042 <symbol+16> | |
627 | 0x00001042 <symbol+16 at file.c:123> | |
628 | @end smallexample | |
629 | @end defun | |
630 | ||
80fa4b2a TT |
631 | @defun gdb.current_language () |
632 | Return the name of the current language as a string. Unlike | |
633 | @code{gdb.parameter('language')}, this function will never return | |
634 | @samp{auto}. If a @code{gdb.Frame} object is available (@pxref{Frames | |
635 | In Python}), the @code{language} method might be preferable in some | |
636 | cases, as that is not affected by the user's language setting. | |
637 | @end defun | |
638 | ||
560c121c TT |
639 | @node Threading in GDB |
640 | @subsubsection Threading in GDB | |
641 | ||
642 | @value{GDBN} is not thread-safe. If your Python program uses multiple | |
643 | threads, you must be careful to only call @value{GDBN}-specific | |
644 | functions in the @value{GDBN} thread. @value{GDBN} provides some | |
645 | functions to help with this. | |
646 | ||
647 | @defun gdb.block_signals () | |
648 | As mentioned earlier (@pxref{Basic Python}), certain signals must be | |
649 | delivered to the @value{GDBN} main thread. The @code{block_signals} | |
650 | function returns a context manager that will block these signals on | |
651 | entry. This can be used when starting a new thread to ensure that the | |
652 | signals are blocked there, like: | |
653 | ||
654 | @smallexample | |
655 | with gdb.block_signals(): | |
656 | start_new_thread() | |
657 | @end smallexample | |
658 | @end defun | |
659 | ||
660 | @deftp {class} gdb.Thread | |
661 | This is a subclass of Python's @code{threading.Thread} class. It | |
662 | overrides the @code{start} method to call @code{block_signals}, making | |
663 | this an easy-to-use drop-in replacement for creating threads that will | |
664 | work well in @value{GDBN}. | |
665 | @end deftp | |
666 | ||
3a12e74e TT |
667 | @defun gdb.interrupt () |
668 | This causes @value{GDBN} to react as if the user had typed a control-C | |
669 | character at the terminal. That is, if the inferior is running, it is | |
670 | interrupted; if a @value{GDBN} command is executing, it is stopped; | |
671 | and if a Python command is running, @code{KeyboardInterrupt} will be | |
672 | raised. | |
673 | ||
674 | Unlike most Python APIs in @value{GDBN}, @code{interrupt} is | |
675 | thread-safe. | |
676 | @end defun | |
677 | ||
560c121c TT |
678 | @defun gdb.post_event (event) |
679 | Put @var{event}, a callable object taking no arguments, into | |
680 | @value{GDBN}'s internal event queue. This callable will be invoked at | |
681 | some later point, during @value{GDBN}'s event processing. Events | |
682 | posted using @code{post_event} will be run in the order in which they | |
683 | were posted; however, there is no way to know when they will be | |
684 | processed relative to other events inside @value{GDBN}. | |
685 | ||
686 | Unlike most Python APIs in @value{GDBN}, @code{post_event} is | |
687 | thread-safe. For example: | |
688 | ||
689 | @smallexample | |
690 | (@value{GDBP}) python | |
691 | >import threading | |
692 | > | |
693 | >class Writer(): | |
694 | > def __init__(self, message): | |
695 | > self.message = message; | |
696 | > def __call__(self): | |
697 | > gdb.write(self.message) | |
698 | > | |
699 | >class MyThread1 (threading.Thread): | |
700 | > def run (self): | |
701 | > gdb.post_event(Writer("Hello ")) | |
702 | > | |
703 | >class MyThread2 (threading.Thread): | |
704 | > def run (self): | |
705 | > gdb.post_event(Writer("World\n")) | |
706 | > | |
707 | >MyThread1().start() | |
708 | >MyThread2().start() | |
709 | >end | |
710 | (@value{GDBP}) Hello World | |
711 | @end smallexample | |
712 | @end defun | |
713 | ||
714 | ||
329baa95 DE |
715 | @node Exception Handling |
716 | @subsubsection Exception Handling | |
717 | @cindex python exceptions | |
718 | @cindex exceptions, python | |
719 | ||
720 | When executing the @code{python} command, Python exceptions | |
721 | uncaught within the Python code are translated to calls to | |
722 | @value{GDBN} error-reporting mechanism. If the command that called | |
723 | @code{python} does not handle the error, @value{GDBN} will | |
724 | terminate it and print an error message containing the Python | |
725 | exception name, the associated value, and the Python call stack | |
726 | backtrace at the point where the exception was raised. Example: | |
727 | ||
728 | @smallexample | |
729 | (@value{GDBP}) python print foo | |
730 | Traceback (most recent call last): | |
731 | File "<string>", line 1, in <module> | |
732 | NameError: name 'foo' is not defined | |
733 | @end smallexample | |
734 | ||
735 | @value{GDBN} errors that happen in @value{GDBN} commands invoked by | |
736 | Python code are converted to Python exceptions. The type of the | |
737 | Python exception depends on the error. | |
738 | ||
739 | @ftable @code | |
740 | @item gdb.error | |
741 | This is the base class for most exceptions generated by @value{GDBN}. | |
742 | It is derived from @code{RuntimeError}, for compatibility with earlier | |
743 | versions of @value{GDBN}. | |
744 | ||
745 | If an error occurring in @value{GDBN} does not fit into some more | |
746 | specific category, then the generated exception will have this type. | |
747 | ||
748 | @item gdb.MemoryError | |
749 | This is a subclass of @code{gdb.error} which is thrown when an | |
750 | operation tried to access invalid memory in the inferior. | |
751 | ||
752 | @item KeyboardInterrupt | |
753 | User interrupt (via @kbd{C-c} or by typing @kbd{q} at a pagination | |
754 | prompt) is translated to a Python @code{KeyboardInterrupt} exception. | |
755 | @end ftable | |
756 | ||
757 | In all cases, your exception handler will see the @value{GDBN} error | |
758 | message as its value and the Python call stack backtrace at the Python | |
33b5899f | 759 | statement closest to where the @value{GDBN} error occurred as the |
329baa95 DE |
760 | traceback. |
761 | ||
4a5a194a TT |
762 | |
763 | When implementing @value{GDBN} commands in Python via | |
764 | @code{gdb.Command}, or functions via @code{gdb.Function}, it is useful | |
765 | to be able to throw an exception that doesn't cause a traceback to be | |
766 | printed. For example, the user may have invoked the command | |
767 | incorrectly. @value{GDBN} provides a special exception class that can | |
768 | be used for this purpose. | |
769 | ||
770 | @ftable @code | |
771 | @item gdb.GdbError | |
772 | When thrown from a command or function, this exception will cause the | |
773 | command or function to fail, but the Python stack will not be | |
774 | displayed. @value{GDBN} does not throw this exception itself, but | |
775 | rather recognizes it when thrown from user Python code. Example: | |
329baa95 DE |
776 | |
777 | @smallexample | |
778 | (gdb) python | |
779 | >class HelloWorld (gdb.Command): | |
780 | > """Greet the whole world.""" | |
781 | > def __init__ (self): | |
782 | > super (HelloWorld, self).__init__ ("hello-world", gdb.COMMAND_USER) | |
783 | > def invoke (self, args, from_tty): | |
784 | > argv = gdb.string_to_argv (args) | |
785 | > if len (argv) != 0: | |
786 | > raise gdb.GdbError ("hello-world takes no arguments") | |
f3bdc2db | 787 | > print ("Hello, World!") |
329baa95 DE |
788 | >HelloWorld () |
789 | >end | |
790 | (gdb) hello-world 42 | |
791 | hello-world takes no arguments | |
792 | @end smallexample | |
4a5a194a | 793 | @end ftable |
329baa95 DE |
794 | |
795 | @node Values From Inferior | |
796 | @subsubsection Values From Inferior | |
797 | @cindex values from inferior, with Python | |
798 | @cindex python, working with values from inferior | |
799 | ||
800 | @cindex @code{gdb.Value} | |
801 | @value{GDBN} provides values it obtains from the inferior program in | |
802 | an object of type @code{gdb.Value}. @value{GDBN} uses this object | |
803 | for its internal bookkeeping of the inferior's values, and for | |
804 | fetching values when necessary. | |
805 | ||
806 | Inferior values that are simple scalars can be used directly in | |
807 | Python expressions that are valid for the value's data type. Here's | |
808 | an example for an integer or floating-point value @code{some_val}: | |
809 | ||
810 | @smallexample | |
811 | bar = some_val + 2 | |
812 | @end smallexample | |
813 | ||
814 | @noindent | |
815 | As result of this, @code{bar} will also be a @code{gdb.Value} object | |
f7bd0f78 SC |
816 | whose values are of the same type as those of @code{some_val}. Valid |
817 | Python operations can also be performed on @code{gdb.Value} objects | |
818 | representing a @code{struct} or @code{class} object. For such cases, | |
819 | the overloaded operator (if present), is used to perform the operation. | |
820 | For example, if @code{val1} and @code{val2} are @code{gdb.Value} objects | |
821 | representing instances of a @code{class} which overloads the @code{+} | |
822 | operator, then one can use the @code{+} operator in their Python script | |
823 | as follows: | |
824 | ||
825 | @smallexample | |
826 | val3 = val1 + val2 | |
827 | @end smallexample | |
828 | ||
829 | @noindent | |
830 | The result of the operation @code{val3} is also a @code{gdb.Value} | |
831 | object corresponding to the value returned by the overloaded @code{+} | |
832 | operator. In general, overloaded operators are invoked for the | |
833 | following operations: @code{+} (binary addition), @code{-} (binary | |
834 | subtraction), @code{*} (multiplication), @code{/}, @code{%}, @code{<<}, | |
835 | @code{>>}, @code{|}, @code{&}, @code{^}. | |
329baa95 DE |
836 | |
837 | Inferior values that are structures or instances of some class can | |
838 | be accessed using the Python @dfn{dictionary syntax}. For example, if | |
839 | @code{some_val} is a @code{gdb.Value} instance holding a structure, you | |
840 | can access its @code{foo} element with: | |
841 | ||
842 | @smallexample | |
843 | bar = some_val['foo'] | |
844 | @end smallexample | |
845 | ||
846 | @cindex getting structure elements using gdb.Field objects as subscripts | |
847 | Again, @code{bar} will also be a @code{gdb.Value} object. Structure | |
848 | elements can also be accessed by using @code{gdb.Field} objects as | |
849 | subscripts (@pxref{Types In Python}, for more information on | |
850 | @code{gdb.Field} objects). For example, if @code{foo_field} is a | |
851 | @code{gdb.Field} object corresponding to element @code{foo} of the above | |
852 | structure, then @code{bar} can also be accessed as follows: | |
853 | ||
854 | @smallexample | |
855 | bar = some_val[foo_field] | |
856 | @end smallexample | |
857 | ||
4f7d9afb TT |
858 | If a @code{gdb.Value} has array or pointer type, an integer index can |
859 | be used to access elements. | |
860 | ||
861 | @smallexample | |
862 | result = some_array[23] | |
863 | @end smallexample | |
864 | ||
329baa95 DE |
865 | A @code{gdb.Value} that represents a function can be executed via |
866 | inferior function call. Any arguments provided to the call must match | |
867 | the function's prototype, and must be provided in the order specified | |
868 | by that prototype. | |
869 | ||
870 | For example, @code{some_val} is a @code{gdb.Value} instance | |
871 | representing a function that takes two integers as arguments. To | |
872 | execute this function, call it like so: | |
873 | ||
874 | @smallexample | |
875 | result = some_val (10,20) | |
876 | @end smallexample | |
877 | ||
878 | Any values returned from a function call will be stored as a | |
879 | @code{gdb.Value}. | |
880 | ||
881 | The following attributes are provided: | |
882 | ||
883 | @defvar Value.address | |
884 | If this object is addressable, this read-only attribute holds a | |
885 | @code{gdb.Value} object representing the address. Otherwise, | |
886 | this attribute holds @code{None}. | |
887 | @end defvar | |
888 | ||
889 | @cindex optimized out value in Python | |
890 | @defvar Value.is_optimized_out | |
891 | This read-only boolean attribute is true if the compiler optimized out | |
892 | this value, thus it is not available for fetching from the inferior. | |
893 | @end defvar | |
894 | ||
895 | @defvar Value.type | |
896 | The type of this @code{gdb.Value}. The value of this attribute is a | |
897 | @code{gdb.Type} object (@pxref{Types In Python}). | |
898 | @end defvar | |
899 | ||
900 | @defvar Value.dynamic_type | |
9da10427 TT |
901 | The dynamic type of this @code{gdb.Value}. This uses the object's |
902 | virtual table and the C@t{++} run-time type information | |
903 | (@acronym{RTTI}) to determine the dynamic type of the value. If this | |
904 | value is of class type, it will return the class in which the value is | |
905 | embedded, if any. If this value is of pointer or reference to a class | |
906 | type, it will compute the dynamic type of the referenced object, and | |
907 | return a pointer or reference to that type, respectively. In all | |
908 | other cases, it will return the value's static type. | |
329baa95 DE |
909 | |
910 | Note that this feature will only work when debugging a C@t{++} program | |
911 | that includes @acronym{RTTI} for the object in question. Otherwise, | |
912 | it will just return the static type of the value as in @kbd{ptype foo} | |
913 | (@pxref{Symbols, ptype}). | |
914 | @end defvar | |
915 | ||
916 | @defvar Value.is_lazy | |
917 | The value of this read-only boolean attribute is @code{True} if this | |
918 | @code{gdb.Value} has not yet been fetched from the inferior. | |
919 | @value{GDBN} does not fetch values until necessary, for efficiency. | |
920 | For example: | |
921 | ||
922 | @smallexample | |
923 | myval = gdb.parse_and_eval ('somevar') | |
924 | @end smallexample | |
925 | ||
926 | The value of @code{somevar} is not fetched at this time. It will be | |
927 | fetched when the value is needed, or when the @code{fetch_lazy} | |
928 | method is invoked. | |
929 | @end defvar | |
930 | ||
ef8cf909 AB |
931 | @defvar Value.bytes |
932 | The value of this attribute is a @code{bytes} object containing the | |
933 | bytes that make up this @code{Value}'s complete value in little endian | |
934 | order. If the complete contents of this value are not available then | |
935 | accessing this attribute will raise an exception. | |
936 | ||
937 | This attribute can also be assigned to. The new value should be a | |
938 | buffer object (e.g.@: a @code{bytes} object), the length of the new | |
939 | buffer must exactly match the length of this @code{Value}'s type. The | |
940 | bytes values in the new buffer should be in little endian order. | |
941 | ||
942 | As with @code{Value.assign} (@pxref{Value.assign}), if this value | |
943 | cannot be assigned to, then an exception will be thrown. | |
944 | @end defvar | |
945 | ||
329baa95 DE |
946 | The following methods are provided: |
947 | ||
ebb83b77 | 948 | @defun Value.__init__ (val) |
329baa95 DE |
949 | Many Python values can be converted directly to a @code{gdb.Value} via |
950 | this object initializer. Specifically: | |
951 | ||
952 | @table @asis | |
953 | @item Python boolean | |
954 | A Python boolean is converted to the boolean type from the current | |
955 | language. | |
956 | ||
957 | @item Python integer | |
958 | A Python integer is converted to the C @code{long} type for the | |
959 | current architecture. | |
960 | ||
961 | @item Python long | |
962 | A Python long is converted to the C @code{long long} type for the | |
963 | current architecture. | |
964 | ||
965 | @item Python float | |
966 | A Python float is converted to the C @code{double} type for the | |
967 | current architecture. | |
968 | ||
969 | @item Python string | |
b3ce5e5f DE |
970 | A Python string is converted to a target string in the current target |
971 | language using the current target encoding. | |
972 | If a character cannot be represented in the current target encoding, | |
973 | then an exception is thrown. | |
329baa95 DE |
974 | |
975 | @item @code{gdb.Value} | |
976 | If @code{val} is a @code{gdb.Value}, then a copy of the value is made. | |
977 | ||
978 | @item @code{gdb.LazyString} | |
979 | If @code{val} is a @code{gdb.LazyString} (@pxref{Lazy Strings In | |
980 | Python}), then the lazy string's @code{value} method is called, and | |
981 | its result is used. | |
982 | @end table | |
983 | @end defun | |
984 | ||
ebb83b77 | 985 | @defun Value.__init__ (val, type) |
af54ade9 KB |
986 | This second form of the @code{gdb.Value} constructor returns a |
987 | @code{gdb.Value} of type @var{type} where the value contents are taken | |
988 | from the Python buffer object specified by @var{val}. The number of | |
989 | bytes in the Python buffer object must be greater than or equal to the | |
990 | size of @var{type}. | |
2988a360 AB |
991 | |
992 | If @var{type} is @code{None} then this version of @code{__init__} | |
993 | behaves as though @var{type} was not passed at all. | |
af54ade9 KB |
994 | @end defun |
995 | ||
ef8cf909 | 996 | @anchor{Value.assign} |
ed801569 TT |
997 | @defun Value.assign (rhs) |
998 | Assign @var{rhs} to this value, and return @code{None}. If this value | |
999 | cannot be assigned to, or if the assignment is invalid for some reason | |
1000 | (for example a type-checking failure), an exception will be thrown. | |
1001 | @end defun | |
1002 | ||
329baa95 DE |
1003 | @defun Value.cast (type) |
1004 | Return a new instance of @code{gdb.Value} that is the result of | |
1005 | casting this instance to the type described by @var{type}, which must | |
1006 | be a @code{gdb.Type} object. If the cast cannot be performed for some | |
1007 | reason, this method throws an exception. | |
1008 | @end defun | |
1009 | ||
1010 | @defun Value.dereference () | |
1011 | For pointer data types, this method returns a new @code{gdb.Value} object | |
1012 | whose contents is the object pointed to by the pointer. For example, if | |
1013 | @code{foo} is a C pointer to an @code{int}, declared in your C program as | |
1014 | ||
1015 | @smallexample | |
1016 | int *foo; | |
1017 | @end smallexample | |
1018 | ||
1019 | @noindent | |
1020 | then you can use the corresponding @code{gdb.Value} to access what | |
1021 | @code{foo} points to like this: | |
1022 | ||
1023 | @smallexample | |
1024 | bar = foo.dereference () | |
1025 | @end smallexample | |
1026 | ||
1027 | The result @code{bar} will be a @code{gdb.Value} object holding the | |
1028 | value pointed to by @code{foo}. | |
1029 | ||
1030 | A similar function @code{Value.referenced_value} exists which also | |
760f7560 | 1031 | returns @code{gdb.Value} objects corresponding to the values pointed to |
329baa95 DE |
1032 | by pointer values (and additionally, values referenced by reference |
1033 | values). However, the behavior of @code{Value.dereference} | |
1034 | differs from @code{Value.referenced_value} by the fact that the | |
1035 | behavior of @code{Value.dereference} is identical to applying the C | |
1036 | unary operator @code{*} on a given value. For example, consider a | |
1037 | reference to a pointer @code{ptrref}, declared in your C@t{++} program | |
1038 | as | |
1039 | ||
1040 | @smallexample | |
1041 | typedef int *intptr; | |
1042 | ... | |
1043 | int val = 10; | |
1044 | intptr ptr = &val; | |
1045 | intptr &ptrref = ptr; | |
1046 | @end smallexample | |
1047 | ||
1048 | Though @code{ptrref} is a reference value, one can apply the method | |
1049 | @code{Value.dereference} to the @code{gdb.Value} object corresponding | |
1050 | to it and obtain a @code{gdb.Value} which is identical to that | |
1051 | corresponding to @code{val}. However, if you apply the method | |
1052 | @code{Value.referenced_value}, the result would be a @code{gdb.Value} | |
1053 | object identical to that corresponding to @code{ptr}. | |
1054 | ||
1055 | @smallexample | |
1056 | py_ptrref = gdb.parse_and_eval ("ptrref") | |
1057 | py_val = py_ptrref.dereference () | |
1058 | py_ptr = py_ptrref.referenced_value () | |
1059 | @end smallexample | |
1060 | ||
1061 | The @code{gdb.Value} object @code{py_val} is identical to that | |
1062 | corresponding to @code{val}, and @code{py_ptr} is identical to that | |
1063 | corresponding to @code{ptr}. In general, @code{Value.dereference} can | |
1064 | be applied whenever the C unary operator @code{*} can be applied | |
1065 | to the corresponding C value. For those cases where applying both | |
1066 | @code{Value.dereference} and @code{Value.referenced_value} is allowed, | |
1067 | the results obtained need not be identical (as we have seen in the above | |
1068 | example). The results are however identical when applied on | |
1069 | @code{gdb.Value} objects corresponding to pointers (@code{gdb.Value} | |
1070 | objects with type code @code{TYPE_CODE_PTR}) in a C/C@t{++} program. | |
1071 | @end defun | |
1072 | ||
1073 | @defun Value.referenced_value () | |
1074 | For pointer or reference data types, this method returns a new | |
1075 | @code{gdb.Value} object corresponding to the value referenced by the | |
1076 | pointer/reference value. For pointer data types, | |
1077 | @code{Value.dereference} and @code{Value.referenced_value} produce | |
1078 | identical results. The difference between these methods is that | |
1079 | @code{Value.dereference} cannot get the values referenced by reference | |
1080 | values. For example, consider a reference to an @code{int}, declared | |
1081 | in your C@t{++} program as | |
1082 | ||
1083 | @smallexample | |
1084 | int val = 10; | |
1085 | int &ref = val; | |
1086 | @end smallexample | |
1087 | ||
1088 | @noindent | |
1089 | then applying @code{Value.dereference} to the @code{gdb.Value} object | |
1090 | corresponding to @code{ref} will result in an error, while applying | |
1091 | @code{Value.referenced_value} will result in a @code{gdb.Value} object | |
1092 | identical to that corresponding to @code{val}. | |
1093 | ||
1094 | @smallexample | |
1095 | py_ref = gdb.parse_and_eval ("ref") | |
1096 | er_ref = py_ref.dereference () # Results in error | |
1097 | py_val = py_ref.referenced_value () # Returns the referenced value | |
1098 | @end smallexample | |
1099 | ||
1100 | The @code{gdb.Value} object @code{py_val} is identical to that | |
1101 | corresponding to @code{val}. | |
1102 | @end defun | |
1103 | ||
4c082a81 SC |
1104 | @defun Value.reference_value () |
1105 | Return a @code{gdb.Value} object which is a reference to the value | |
1106 | encapsulated by this instance. | |
1107 | @end defun | |
1108 | ||
1109 | @defun Value.const_value () | |
1110 | Return a @code{gdb.Value} object which is a @code{const} version of the | |
1111 | value encapsulated by this instance. | |
1112 | @end defun | |
1113 | ||
329baa95 DE |
1114 | @defun Value.dynamic_cast (type) |
1115 | Like @code{Value.cast}, but works as if the C@t{++} @code{dynamic_cast} | |
1116 | operator were used. Consult a C@t{++} reference for details. | |
1117 | @end defun | |
1118 | ||
1119 | @defun Value.reinterpret_cast (type) | |
1120 | Like @code{Value.cast}, but works as if the C@t{++} @code{reinterpret_cast} | |
1121 | operator were used. Consult a C@t{++} reference for details. | |
1122 | @end defun | |
1123 | ||
52093e1b MB |
1124 | @defun Value.format_string (...) |
1125 | Convert a @code{gdb.Value} to a string, similarly to what the @code{print} | |
1126 | command does. Invoked with no arguments, this is equivalent to calling | |
1127 | the @code{str} function on the @code{gdb.Value}. The representation of | |
1128 | the same value may change across different versions of @value{GDBN}, so | |
1129 | you shouldn't, for instance, parse the strings returned by this method. | |
1130 | ||
1131 | All the arguments are keyword only. If an argument is not specified, the | |
1132 | current global default setting is used. | |
1133 | ||
1134 | @table @code | |
1135 | @item raw | |
1136 | @code{True} if pretty-printers (@pxref{Pretty Printing}) should not be | |
1137 | used to format the value. @code{False} if enabled pretty-printers | |
1138 | matching the type represented by the @code{gdb.Value} should be used to | |
1139 | format it. | |
1140 | ||
1141 | @item pretty_arrays | |
1142 | @code{True} if arrays should be pretty printed to be more convenient to | |
1143 | read, @code{False} if they shouldn't (see @code{set print array} in | |
1144 | @ref{Print Settings}). | |
1145 | ||
1146 | @item pretty_structs | |
1147 | @code{True} if structs should be pretty printed to be more convenient to | |
1148 | read, @code{False} if they shouldn't (see @code{set print pretty} in | |
1149 | @ref{Print Settings}). | |
1150 | ||
1151 | @item array_indexes | |
1152 | @code{True} if array indexes should be included in the string | |
1153 | representation of arrays, @code{False} if they shouldn't (see @code{set | |
1154 | print array-indexes} in @ref{Print Settings}). | |
1155 | ||
1156 | @item symbols | |
1157 | @code{True} if the string representation of a pointer should include the | |
1158 | corresponding symbol name (if one exists), @code{False} if it shouldn't | |
1159 | (see @code{set print symbol} in @ref{Print Settings}). | |
1160 | ||
1161 | @item unions | |
1162 | @code{True} if unions which are contained in other structures or unions | |
1163 | should be expanded, @code{False} if they shouldn't (see @code{set print | |
1164 | union} in @ref{Print Settings}). | |
1165 | ||
4aea001f HD |
1166 | @item address |
1167 | @code{True} if the string representation of a pointer should include the | |
1168 | address, @code{False} if it shouldn't (see @code{set print address} in | |
1169 | @ref{Print Settings}). | |
1170 | ||
3f52a090 EL |
1171 | @item nibbles |
1172 | @code{True} if binary values should be displayed in groups of four bits, | |
1173 | known as nibbles. @code{False} if it shouldn't (@pxref{Print Settings, | |
1174 | set print nibbles}). | |
1175 | ||
52093e1b MB |
1176 | @item deref_refs |
1177 | @code{True} if C@t{++} references should be resolved to the value they | |
1178 | refer to, @code{False} (the default) if they shouldn't. Note that, unlike | |
1179 | for the @code{print} command, references are not automatically expanded | |
1180 | when using the @code{format_string} method or the @code{str} | |
1181 | function. There is no global @code{print} setting to change the default | |
1182 | behaviour. | |
1183 | ||
1184 | @item actual_objects | |
1185 | @code{True} if the representation of a pointer to an object should | |
1186 | identify the @emph{actual} (derived) type of the object rather than the | |
1187 | @emph{declared} type, using the virtual function table. @code{False} if | |
1188 | the @emph{declared} type should be used. (See @code{set print object} in | |
1189 | @ref{Print Settings}). | |
1190 | ||
9f121239 | 1191 | @item static_members |
52093e1b MB |
1192 | @code{True} if static members should be included in the string |
1193 | representation of a C@t{++} object, @code{False} if they shouldn't (see | |
1194 | @code{set print static-members} in @ref{Print Settings}). | |
1195 | ||
76b58849 AB |
1196 | @item max_characters |
1197 | Number of string characters to print, @code{0} to follow | |
1198 | @code{max_elements}, or @code{UINT_MAX} to print an unlimited number | |
1199 | of characters (see @code{set print characters} in @ref{Print Settings}). | |
1200 | ||
52093e1b MB |
1201 | @item max_elements |
1202 | Number of array elements to print, or @code{0} to print an unlimited | |
1203 | number of elements (see @code{set print elements} in @ref{Print | |
1204 | Settings}). | |
1205 | ||
2e62ab40 AB |
1206 | @item max_depth |
1207 | The maximum depth to print for nested structs and unions, or @code{-1} | |
1208 | to print an unlimited number of elements (see @code{set print | |
1209 | max-depth} in @ref{Print Settings}). | |
1210 | ||
52093e1b MB |
1211 | @item repeat_threshold |
1212 | Set the threshold for suppressing display of repeated array elements, or | |
1213 | @code{0} to represent all elements, even if repeated. (See @code{set | |
1214 | print repeats} in @ref{Print Settings}). | |
1215 | ||
1216 | @item format | |
1217 | A string containing a single character representing the format to use for | |
1218 | the returned string. For instance, @code{'x'} is equivalent to using the | |
1219 | @value{GDBN} command @code{print} with the @code{/x} option and formats | |
1220 | the value as a hexadecimal number. | |
0642912e AB |
1221 | |
1222 | @item styling | |
1223 | @code{True} if @value{GDBN} should apply styling to the returned | |
1224 | string. When styling is applied, the returned string might contain | |
1225 | ANSI terminal escape sequences. Escape sequences will only be | |
1226 | included if styling is turned on, see @ref{Output Styling}. | |
1227 | Additionally, @value{GDBN} only styles some value contents, so not | |
1228 | every output string will contain escape sequences. | |
1229 | ||
1230 | When @code{False}, which is the default, no output styling is applied. | |
72be9d6b TT |
1231 | |
1232 | @item summary | |
1233 | @code{True} when just a summary should be printed. In this mode, | |
1234 | scalar values are printed in their entirety, but aggregates such as | |
1235 | structures or unions are omitted. This mode is used by @code{set | |
1236 | print frame-arguments scalars} (@pxref{Print Settings}). | |
52093e1b MB |
1237 | @end table |
1238 | @end defun | |
1239 | ||
59668c9d TT |
1240 | @defun Value.to_array () |
1241 | If this value is array-like (@pxref{Type.is_array_like}), then this | |
1242 | method converts it to an array, which is returned. If this value is | |
1243 | already an array, it is simply returned. Otherwise, an exception is | |
1244 | throw. | |
1245 | @end defun | |
1246 | ||
329baa95 DE |
1247 | @defun Value.string (@r{[}encoding@r{[}, errors@r{[}, length@r{]]]}) |
1248 | If this @code{gdb.Value} represents a string, then this method | |
1249 | converts the contents to a Python string. Otherwise, this method will | |
1250 | throw an exception. | |
1251 | ||
b3ce5e5f DE |
1252 | Values are interpreted as strings according to the rules of the |
1253 | current language. If the optional length argument is given, the | |
1254 | string will be converted to that length, and will include any embedded | |
1255 | zeroes that the string may contain. Otherwise, for languages | |
1256 | where the string is zero-terminated, the entire string will be | |
1257 | converted. | |
329baa95 | 1258 | |
b3ce5e5f DE |
1259 | For example, in C-like languages, a value is a string if it is a pointer |
1260 | to or an array of characters or ints of type @code{wchar_t}, @code{char16_t}, | |
1261 | or @code{char32_t}. | |
329baa95 DE |
1262 | |
1263 | If the optional @var{encoding} argument is given, it must be a string | |
1264 | naming the encoding of the string in the @code{gdb.Value}, such as | |
1265 | @code{"ascii"}, @code{"iso-8859-6"} or @code{"utf-8"}. It accepts | |
1266 | the same encodings as the corresponding argument to Python's | |
1267 | @code{string.decode} method, and the Python codec machinery will be used | |
1268 | to convert the string. If @var{encoding} is not given, or if | |
1269 | @var{encoding} is the empty string, then either the @code{target-charset} | |
1270 | (@pxref{Character Sets}) will be used, or a language-specific encoding | |
1271 | will be used, if the current language is able to supply one. | |
1272 | ||
1273 | The optional @var{errors} argument is the same as the corresponding | |
1274 | argument to Python's @code{string.decode} method. | |
1275 | ||
1276 | If the optional @var{length} argument is given, the string will be | |
1277 | fetched and converted to the given length. | |
1278 | @end defun | |
1279 | ||
1280 | @defun Value.lazy_string (@r{[}encoding @r{[}, length@r{]]}) | |
1281 | If this @code{gdb.Value} represents a string, then this method | |
1282 | converts the contents to a @code{gdb.LazyString} (@pxref{Lazy Strings | |
1283 | In Python}). Otherwise, this method will throw an exception. | |
1284 | ||
1285 | If the optional @var{encoding} argument is given, it must be a string | |
1286 | naming the encoding of the @code{gdb.LazyString}. Some examples are: | |
1287 | @samp{ascii}, @samp{iso-8859-6} or @samp{utf-8}. If the | |
1288 | @var{encoding} argument is an encoding that @value{GDBN} does | |
1289 | recognize, @value{GDBN} will raise an error. | |
1290 | ||
1291 | When a lazy string is printed, the @value{GDBN} encoding machinery is | |
1292 | used to convert the string during printing. If the optional | |
1293 | @var{encoding} argument is not provided, or is an empty string, | |
1294 | @value{GDBN} will automatically select the encoding most suitable for | |
1295 | the string type. For further information on encoding in @value{GDBN} | |
1296 | please see @ref{Character Sets}. | |
1297 | ||
1298 | If the optional @var{length} argument is given, the string will be | |
1299 | fetched and encoded to the length of characters specified. If | |
1300 | the @var{length} argument is not provided, the string will be fetched | |
1301 | and encoded until a null of appropriate width is found. | |
1302 | @end defun | |
1303 | ||
1304 | @defun Value.fetch_lazy () | |
1305 | If the @code{gdb.Value} object is currently a lazy value | |
1306 | (@code{gdb.Value.is_lazy} is @code{True}), then the value is | |
1307 | fetched from the inferior. Any errors that occur in the process | |
1308 | will produce a Python exception. | |
1309 | ||
1310 | If the @code{gdb.Value} object is not a lazy value, this method | |
1311 | has no effect. | |
1312 | ||
1313 | This method does not return a value. | |
1314 | @end defun | |
1315 | ||
1316 | ||
1317 | @node Types In Python | |
1318 | @subsubsection Types In Python | |
1319 | @cindex types in Python | |
1320 | @cindex Python, working with types | |
1321 | ||
1322 | @tindex gdb.Type | |
1323 | @value{GDBN} represents types from the inferior using the class | |
1324 | @code{gdb.Type}. | |
1325 | ||
1326 | The following type-related functions are available in the @code{gdb} | |
1327 | module: | |
1328 | ||
329baa95 | 1329 | @defun gdb.lookup_type (name @r{[}, block@r{]}) |
697aa1b7 | 1330 | This function looks up a type by its @var{name}, which must be a string. |
329baa95 DE |
1331 | |
1332 | If @var{block} is given, then @var{name} is looked up in that scope. | |
1333 | Otherwise, it is searched for globally. | |
1334 | ||
1335 | Ordinarily, this function will return an instance of @code{gdb.Type}. | |
1336 | If the named type cannot be found, it will throw an exception. | |
1337 | @end defun | |
1338 | ||
d3771fe2 TT |
1339 | Integer types can be found without looking them up by name. |
1340 | @xref{Architectures In Python}, for the @code{integer_type} method. | |
1341 | ||
329baa95 DE |
1342 | If the type is a structure or class type, or an enum type, the fields |
1343 | of that type can be accessed using the Python @dfn{dictionary syntax}. | |
1344 | For example, if @code{some_type} is a @code{gdb.Type} instance holding | |
1345 | a structure type, you can access its @code{foo} field with: | |
1346 | ||
1347 | @smallexample | |
1348 | bar = some_type['foo'] | |
1349 | @end smallexample | |
1350 | ||
1351 | @code{bar} will be a @code{gdb.Field} object; see below under the | |
1352 | description of the @code{Type.fields} method for a description of the | |
1353 | @code{gdb.Field} class. | |
1354 | ||
1355 | An instance of @code{Type} has the following attributes: | |
1356 | ||
6d7bb824 TT |
1357 | @defvar Type.alignof |
1358 | The alignment of this type, in bytes. Type alignment comes from the | |
1359 | debugging information; if it was not specified, then @value{GDBN} will | |
1360 | use the relevant ABI to try to determine the alignment. In some | |
1361 | cases, even this is not possible, and zero will be returned. | |
1362 | @end defvar | |
1363 | ||
329baa95 DE |
1364 | @defvar Type.code |
1365 | The type code for this type. The type code will be one of the | |
1366 | @code{TYPE_CODE_} constants defined below. | |
1367 | @end defvar | |
1368 | ||
1acda803 TT |
1369 | @defvar Type.dynamic |
1370 | A boolean indicating whether this type is dynamic. In some | |
1371 | situations, such as Rust @code{enum} types or Ada variant records, the | |
45fc7c99 TT |
1372 | concrete type of a value may vary depending on its contents. That is, |
1373 | the declared type of a variable, or the type returned by | |
1374 | @code{gdb.lookup_type} may be dynamic; while the type of the | |
1375 | variable's value will be a concrete instance of that dynamic type. | |
1376 | ||
1377 | For example, consider this code: | |
1378 | @smallexample | |
1379 | int n; | |
1380 | int array[n]; | |
1381 | @end smallexample | |
1382 | ||
1383 | Here, at least conceptually (whether your compiler actually does this | |
1384 | is a separate issue), examining @w{@code{gdb.lookup_symbol("array", ...).type}} | |
1385 | could yield a @code{gdb.Type} which reports a size of @code{None}. | |
1386 | This is the dynamic type. | |
1387 | ||
1388 | However, examining @code{gdb.parse_and_eval("array").type} would yield | |
1389 | a concrete type, whose length would be known. | |
1acda803 TT |
1390 | @end defvar |
1391 | ||
329baa95 DE |
1392 | @defvar Type.name |
1393 | The name of this type. If this type has no name, then @code{None} | |
1394 | is returned. | |
1395 | @end defvar | |
1396 | ||
1397 | @defvar Type.sizeof | |
1398 | The size of this type, in target @code{char} units. Usually, a | |
1399 | target's @code{char} type will be an 8-bit byte. However, on some | |
1acda803 TT |
1400 | unusual platforms, this type may have a different size. A dynamic |
1401 | type may not have a fixed size; in this case, this attribute's value | |
1402 | will be @code{None}. | |
329baa95 DE |
1403 | @end defvar |
1404 | ||
1405 | @defvar Type.tag | |
1406 | The tag name for this type. The tag name is the name after | |
1407 | @code{struct}, @code{union}, or @code{enum} in C and C@t{++}; not all | |
1408 | languages have this concept. If this type has no tag name, then | |
1409 | @code{None} is returned. | |
1410 | @end defvar | |
1411 | ||
e1f2e1a2 CB |
1412 | @defvar Type.objfile |
1413 | The @code{gdb.Objfile} that this type was defined in, or @code{None} if | |
1414 | there is no associated objfile. | |
1415 | @end defvar | |
1416 | ||
ee6a3d9e AB |
1417 | @defvar Type.is_scalar |
1418 | This property is @code{True} if the type is a scalar type, otherwise, | |
1419 | this property is @code{False}. Examples of non-scalar types include | |
1420 | structures, unions, and classes. | |
1421 | @end defvar | |
1422 | ||
551b380f AB |
1423 | @defvar Type.is_signed |
1424 | For scalar types (those for which @code{Type.is_scalar} is | |
1425 | @code{True}), this property is @code{True} if the type is signed, | |
1426 | otherwise this property is @code{False}. | |
1427 | ||
1428 | Attempting to read this property for a non-scalar type (a type for | |
1429 | which @code{Type.is_scalar} is @code{False}), will raise a | |
1430 | @code{ValueError}. | |
1431 | @end defvar | |
1432 | ||
59668c9d TT |
1433 | @defvar Type.is_array_like |
1434 | @anchor{Type.is_array_like} | |
1435 | A boolean indicating whether this type is array-like. | |
1436 | ||
1437 | Some languages have array-like objects that are represented internally | |
1438 | as structures. For example, this is true for a Rust slice type, or | |
1439 | for an Ada unconstrained array. @value{GDBN} may know about these | |
1440 | types. This determination is done based on the language from which | |
1441 | the type originated. | |
1442 | @end defvar | |
1443 | ||
1444 | @defvar Type.is_string_like | |
1445 | A boolean indicating whether this type is string-like. Like | |
1446 | @code{Type.is_array_like}, this is determined based on the originating | |
1447 | language of the type. | |
1448 | @end defvar | |
1449 | ||
329baa95 DE |
1450 | The following methods are provided: |
1451 | ||
1452 | @defun Type.fields () | |
fa94b3a7 SM |
1453 | |
1454 | Return the fields of this type. The behavior depends on the type code: | |
1455 | ||
1456 | @itemize @bullet | |
1457 | ||
1458 | @item | |
1459 | For structure and union types, this method returns the fields. | |
1460 | ||
fa94b3a7 SM |
1461 | @item |
1462 | Enum types have one field per enum constant. | |
1463 | ||
1464 | @item | |
1465 | Function and method types have one field per parameter. The base types of | |
1466 | C@t{++} classes are also represented as fields. | |
1467 | ||
1468 | @item | |
1469 | Array types have one field representing the array's range. | |
1470 | ||
1471 | @item | |
1472 | If the type does not fit into one of these categories, a @code{TypeError} | |
1473 | is raised. | |
1474 | ||
1475 | @end itemize | |
329baa95 DE |
1476 | |
1477 | Each field is a @code{gdb.Field} object, with some pre-defined attributes: | |
1478 | @table @code | |
1479 | @item bitpos | |
1480 | This attribute is not available for @code{enum} or @code{static} | |
9c37b5ae | 1481 | (as in C@t{++}) fields. The value is the position, counting |
1acda803 TT |
1482 | in bits, from the start of the containing type. Note that, in a |
1483 | dynamic type, the position of a field may not be constant. In this | |
45fc7c99 TT |
1484 | case, the value will be @code{None}. Also, a dynamic type may have |
1485 | fields that do not appear in a corresponding concrete type. | |
329baa95 DE |
1486 | |
1487 | @item enumval | |
1488 | This attribute is only available for @code{enum} fields, and its value | |
1489 | is the enumeration member's integer representation. | |
1490 | ||
1491 | @item name | |
1492 | The name of the field, or @code{None} for anonymous fields. | |
1493 | ||
1494 | @item artificial | |
1495 | This is @code{True} if the field is artificial, usually meaning that | |
1496 | it was provided by the compiler and not the user. This attribute is | |
1497 | always provided, and is @code{False} if the field is not artificial. | |
1498 | ||
1499 | @item is_base_class | |
1500 | This is @code{True} if the field represents a base class of a C@t{++} | |
1501 | structure. This attribute is always provided, and is @code{False} | |
1502 | if the field is not a base class of the type that is the argument of | |
1503 | @code{fields}, or if that type was not a C@t{++} class. | |
1504 | ||
1505 | @item bitsize | |
1506 | If the field is packed, or is a bitfield, then this will have a | |
1507 | non-zero value, which is the size of the field in bits. Otherwise, | |
1508 | this will be zero; in this case the field's size is given by its type. | |
1509 | ||
1510 | @item type | |
1511 | The type of the field. This is usually an instance of @code{Type}, | |
1512 | but it can be @code{None} in some situations. | |
1513 | ||
1514 | @item parent_type | |
1515 | The type which contains this field. This is an instance of | |
1516 | @code{gdb.Type}. | |
1517 | @end table | |
1518 | @end defun | |
1519 | ||
ebb83b77 | 1520 | @defun Type.array (n1 @r{[}, n2@r{]}) |
329baa95 DE |
1521 | Return a new @code{gdb.Type} object which represents an array of this |
1522 | type. If one argument is given, it is the inclusive upper bound of | |
1523 | the array; in this case the lower bound is zero. If two arguments are | |
1524 | given, the first argument is the lower bound of the array, and the | |
1525 | second argument is the upper bound of the array. An array's length | |
1526 | must not be negative, but the bounds can be. | |
1527 | @end defun | |
1528 | ||
ebb83b77 | 1529 | @defun Type.vector (n1 @r{[}, n2@r{]}) |
329baa95 DE |
1530 | Return a new @code{gdb.Type} object which represents a vector of this |
1531 | type. If one argument is given, it is the inclusive upper bound of | |
1532 | the vector; in this case the lower bound is zero. If two arguments are | |
1533 | given, the first argument is the lower bound of the vector, and the | |
1534 | second argument is the upper bound of the vector. A vector's length | |
1535 | must not be negative, but the bounds can be. | |
1536 | ||
1537 | The difference between an @code{array} and a @code{vector} is that | |
1538 | arrays behave like in C: when used in expressions they decay to a pointer | |
1539 | to the first element whereas vectors are treated as first class values. | |
1540 | @end defun | |
1541 | ||
1542 | @defun Type.const () | |
1543 | Return a new @code{gdb.Type} object which represents a | |
1544 | @code{const}-qualified variant of this type. | |
1545 | @end defun | |
1546 | ||
1547 | @defun Type.volatile () | |
1548 | Return a new @code{gdb.Type} object which represents a | |
1549 | @code{volatile}-qualified variant of this type. | |
1550 | @end defun | |
1551 | ||
1552 | @defun Type.unqualified () | |
1553 | Return a new @code{gdb.Type} object which represents an unqualified | |
1554 | variant of this type. That is, the result is neither @code{const} nor | |
1555 | @code{volatile}. | |
1556 | @end defun | |
1557 | ||
1558 | @defun Type.range () | |
1559 | Return a Python @code{Tuple} object that contains two elements: the | |
1560 | low bound of the argument type and the high bound of that type. If | |
1561 | the type does not have a range, @value{GDBN} will raise a | |
1562 | @code{gdb.error} exception (@pxref{Exception Handling}). | |
1563 | @end defun | |
1564 | ||
1565 | @defun Type.reference () | |
1566 | Return a new @code{gdb.Type} object which represents a reference to this | |
1567 | type. | |
1568 | @end defun | |
1569 | ||
1570 | @defun Type.pointer () | |
1571 | Return a new @code{gdb.Type} object which represents a pointer to this | |
1572 | type. | |
1573 | @end defun | |
1574 | ||
1575 | @defun Type.strip_typedefs () | |
1576 | Return a new @code{gdb.Type} that represents the real type, | |
1577 | after removing all layers of typedefs. | |
1578 | @end defun | |
1579 | ||
1580 | @defun Type.target () | |
1581 | Return a new @code{gdb.Type} object which represents the target type | |
1582 | of this type. | |
1583 | ||
1584 | For a pointer type, the target type is the type of the pointed-to | |
1585 | object. For an array type (meaning C-like arrays), the target type is | |
1586 | the type of the elements of the array. For a function or method type, | |
1587 | the target type is the type of the return value. For a complex type, | |
1588 | the target type is the type of the elements. For a typedef, the | |
1589 | target type is the aliased type. | |
1590 | ||
1591 | If the type does not have a target, this method will throw an | |
1592 | exception. | |
1593 | @end defun | |
1594 | ||
1595 | @defun Type.template_argument (n @r{[}, block@r{]}) | |
1596 | If this @code{gdb.Type} is an instantiation of a template, this will | |
1a6a384b JL |
1597 | return a new @code{gdb.Value} or @code{gdb.Type} which represents the |
1598 | value of the @var{n}th template argument (indexed starting at 0). | |
329baa95 | 1599 | |
1a6a384b JL |
1600 | If this @code{gdb.Type} is not a template type, or if the type has fewer |
1601 | than @var{n} template arguments, this will throw an exception. | |
1602 | Ordinarily, only C@t{++} code will have template types. | |
329baa95 DE |
1603 | |
1604 | If @var{block} is given, then @var{name} is looked up in that scope. | |
1605 | Otherwise, it is searched for globally. | |
1606 | @end defun | |
1607 | ||
59fb7612 SS |
1608 | @defun Type.optimized_out () |
1609 | Return @code{gdb.Value} instance of this type whose value is optimized | |
1610 | out. This allows a frame decorator to indicate that the value of an | |
1611 | argument or a local variable is not known. | |
1612 | @end defun | |
329baa95 DE |
1613 | |
1614 | Each type has a code, which indicates what category this type falls | |
1615 | into. The available type categories are represented by constants | |
1616 | defined in the @code{gdb} module: | |
1617 | ||
b3ce5e5f DE |
1618 | @vtable @code |
1619 | @vindex TYPE_CODE_PTR | |
329baa95 DE |
1620 | @item gdb.TYPE_CODE_PTR |
1621 | The type is a pointer. | |
1622 | ||
b3ce5e5f | 1623 | @vindex TYPE_CODE_ARRAY |
329baa95 DE |
1624 | @item gdb.TYPE_CODE_ARRAY |
1625 | The type is an array. | |
1626 | ||
b3ce5e5f | 1627 | @vindex TYPE_CODE_STRUCT |
329baa95 DE |
1628 | @item gdb.TYPE_CODE_STRUCT |
1629 | The type is a structure. | |
1630 | ||
b3ce5e5f | 1631 | @vindex TYPE_CODE_UNION |
329baa95 DE |
1632 | @item gdb.TYPE_CODE_UNION |
1633 | The type is a union. | |
1634 | ||
b3ce5e5f | 1635 | @vindex TYPE_CODE_ENUM |
329baa95 DE |
1636 | @item gdb.TYPE_CODE_ENUM |
1637 | The type is an enum. | |
1638 | ||
b3ce5e5f | 1639 | @vindex TYPE_CODE_FLAGS |
329baa95 DE |
1640 | @item gdb.TYPE_CODE_FLAGS |
1641 | A bit flags type, used for things such as status registers. | |
1642 | ||
b3ce5e5f | 1643 | @vindex TYPE_CODE_FUNC |
329baa95 DE |
1644 | @item gdb.TYPE_CODE_FUNC |
1645 | The type is a function. | |
1646 | ||
b3ce5e5f | 1647 | @vindex TYPE_CODE_INT |
329baa95 DE |
1648 | @item gdb.TYPE_CODE_INT |
1649 | The type is an integer type. | |
1650 | ||
b3ce5e5f | 1651 | @vindex TYPE_CODE_FLT |
329baa95 DE |
1652 | @item gdb.TYPE_CODE_FLT |
1653 | A floating point type. | |
1654 | ||
b3ce5e5f | 1655 | @vindex TYPE_CODE_VOID |
329baa95 DE |
1656 | @item gdb.TYPE_CODE_VOID |
1657 | The special type @code{void}. | |
1658 | ||
b3ce5e5f | 1659 | @vindex TYPE_CODE_SET |
329baa95 DE |
1660 | @item gdb.TYPE_CODE_SET |
1661 | A Pascal set type. | |
1662 | ||
b3ce5e5f | 1663 | @vindex TYPE_CODE_RANGE |
329baa95 DE |
1664 | @item gdb.TYPE_CODE_RANGE |
1665 | A range type, that is, an integer type with bounds. | |
1666 | ||
b3ce5e5f | 1667 | @vindex TYPE_CODE_STRING |
329baa95 DE |
1668 | @item gdb.TYPE_CODE_STRING |
1669 | A string type. Note that this is only used for certain languages with | |
1670 | language-defined string types; C strings are not represented this way. | |
1671 | ||
b3ce5e5f | 1672 | @vindex TYPE_CODE_BITSTRING |
329baa95 DE |
1673 | @item gdb.TYPE_CODE_BITSTRING |
1674 | A string of bits. It is deprecated. | |
1675 | ||
b3ce5e5f | 1676 | @vindex TYPE_CODE_ERROR |
329baa95 DE |
1677 | @item gdb.TYPE_CODE_ERROR |
1678 | An unknown or erroneous type. | |
1679 | ||
b3ce5e5f | 1680 | @vindex TYPE_CODE_METHOD |
329baa95 | 1681 | @item gdb.TYPE_CODE_METHOD |
9c37b5ae | 1682 | A method type, as found in C@t{++}. |
329baa95 | 1683 | |
b3ce5e5f | 1684 | @vindex TYPE_CODE_METHODPTR |
329baa95 DE |
1685 | @item gdb.TYPE_CODE_METHODPTR |
1686 | A pointer-to-member-function. | |
1687 | ||
b3ce5e5f | 1688 | @vindex TYPE_CODE_MEMBERPTR |
329baa95 DE |
1689 | @item gdb.TYPE_CODE_MEMBERPTR |
1690 | A pointer-to-member. | |
1691 | ||
b3ce5e5f | 1692 | @vindex TYPE_CODE_REF |
329baa95 DE |
1693 | @item gdb.TYPE_CODE_REF |
1694 | A reference type. | |
1695 | ||
3fcf899d AV |
1696 | @vindex TYPE_CODE_RVALUE_REF |
1697 | @item gdb.TYPE_CODE_RVALUE_REF | |
1698 | A C@t{++}11 rvalue reference type. | |
1699 | ||
b3ce5e5f | 1700 | @vindex TYPE_CODE_CHAR |
329baa95 DE |
1701 | @item gdb.TYPE_CODE_CHAR |
1702 | A character type. | |
1703 | ||
b3ce5e5f | 1704 | @vindex TYPE_CODE_BOOL |
329baa95 DE |
1705 | @item gdb.TYPE_CODE_BOOL |
1706 | A boolean type. | |
1707 | ||
b3ce5e5f | 1708 | @vindex TYPE_CODE_COMPLEX |
329baa95 DE |
1709 | @item gdb.TYPE_CODE_COMPLEX |
1710 | A complex float type. | |
1711 | ||
b3ce5e5f | 1712 | @vindex TYPE_CODE_TYPEDEF |
329baa95 DE |
1713 | @item gdb.TYPE_CODE_TYPEDEF |
1714 | A typedef to some other type. | |
1715 | ||
b3ce5e5f | 1716 | @vindex TYPE_CODE_NAMESPACE |
329baa95 DE |
1717 | @item gdb.TYPE_CODE_NAMESPACE |
1718 | A C@t{++} namespace. | |
1719 | ||
b3ce5e5f | 1720 | @vindex TYPE_CODE_DECFLOAT |
329baa95 DE |
1721 | @item gdb.TYPE_CODE_DECFLOAT |
1722 | A decimal floating point type. | |
1723 | ||
b3ce5e5f | 1724 | @vindex TYPE_CODE_INTERNAL_FUNCTION |
329baa95 DE |
1725 | @item gdb.TYPE_CODE_INTERNAL_FUNCTION |
1726 | A function internal to @value{GDBN}. This is the type used to represent | |
1727 | convenience functions. | |
4881fcd7 TT |
1728 | |
1729 | @vindex TYPE_CODE_XMETHOD | |
1730 | @item gdb.TYPE_CODE_XMETHOD | |
1731 | A method internal to @value{GDBN}. This is the type used to represent | |
1732 | xmethods (@pxref{Writing an Xmethod}). | |
1733 | ||
1734 | @vindex TYPE_CODE_FIXED_POINT | |
1735 | @item gdb.TYPE_CODE_FIXED_POINT | |
1736 | A fixed-point number. | |
1737 | ||
1738 | @vindex TYPE_CODE_NAMESPACE | |
1739 | @item gdb.TYPE_CODE_NAMESPACE | |
1740 | A Fortran namelist. | |
b3ce5e5f | 1741 | @end vtable |
329baa95 DE |
1742 | |
1743 | Further support for types is provided in the @code{gdb.types} | |
1744 | Python module (@pxref{gdb.types}). | |
1745 | ||
1746 | @node Pretty Printing API | |
1747 | @subsubsection Pretty Printing API | |
b3ce5e5f | 1748 | @cindex python pretty printing api |
329baa95 | 1749 | |
329baa95 | 1750 | A pretty-printer is just an object that holds a value and implements a |
27a9fec6 TT |
1751 | specific interface, defined here. An example output is provided |
1752 | (@pxref{Pretty Printing}). | |
329baa95 | 1753 | |
fb282576 TT |
1754 | Because @value{GDBN} did not document extensibility for |
1755 | pretty-printers, by default @value{GDBN} will assume that only the | |
1756 | basic pretty-printer methods may be available. The basic methods are | |
1757 | marked as such, below. | |
1758 | ||
1759 | To allow extensibility, @value{GDBN} provides the | |
1760 | @code{gdb.ValuePrinter} base class. This class does not provide any | |
1761 | attributes or behavior, but instead serves as a tag that can be | |
1762 | recognized by @value{GDBN}. For such printers, @value{GDBN} reserves | |
1763 | all attributes starting with a lower-case letter. That is, in the | |
1764 | future, @value{GDBN} may add a new method or attribute to the | |
1765 | pretty-printer protocol, and @code{gdb.ValuePrinter}-based printers | |
1766 | are expected to handle this gracefully. A simple way to do this would | |
1767 | be to use a leading underscore (or two, following the Python | |
1768 | name-mangling scheme) to any attributes local to the implementation. | |
1769 | ||
329baa95 DE |
1770 | @defun pretty_printer.children (self) |
1771 | @value{GDBN} will call this method on a pretty-printer to compute the | |
1772 | children of the pretty-printer's value. | |
1773 | ||
1774 | This method must return an object conforming to the Python iterator | |
1775 | protocol. Each item returned by the iterator must be a tuple holding | |
1776 | two elements. The first element is the ``name'' of the child; the | |
1777 | second element is the child's value. The value can be any Python | |
1778 | object which is convertible to a @value{GDBN} value. | |
1779 | ||
fb282576 TT |
1780 | This is a basic method, and is optional. If it does not exist, |
1781 | @value{GDBN} will act as though the value has no children. | |
2e62ab40 | 1782 | |
a97c8e56 TT |
1783 | For efficiency, the @code{children} method should lazily compute its |
1784 | results. This will let @value{GDBN} read as few elements as | |
1785 | necessary, for example when various print settings (@pxref{Print | |
1786 | Settings}) or @code{-var-list-children} (@pxref{GDB/MI Variable | |
1787 | Objects}) limit the number of elements to be displayed. | |
1788 | ||
2e62ab40 AB |
1789 | Children may be hidden from display based on the value of @samp{set |
1790 | print max-depth} (@pxref{Print Settings}). | |
329baa95 DE |
1791 | @end defun |
1792 | ||
1793 | @defun pretty_printer.display_hint (self) | |
1794 | The CLI may call this method and use its result to change the | |
1795 | formatting of a value. The result will also be supplied to an MI | |
1796 | consumer as a @samp{displayhint} attribute of the variable being | |
1797 | printed. | |
1798 | ||
fb282576 TT |
1799 | This is a basic method, and is optional. If it does exist, this |
1800 | method must return a string or the special value @code{None}. | |
329baa95 DE |
1801 | |
1802 | Some display hints are predefined by @value{GDBN}: | |
1803 | ||
1804 | @table @samp | |
1805 | @item array | |
1806 | Indicate that the object being printed is ``array-like''. The CLI | |
1807 | uses this to respect parameters such as @code{set print elements} and | |
1808 | @code{set print array}. | |
1809 | ||
1810 | @item map | |
1811 | Indicate that the object being printed is ``map-like'', and that the | |
1812 | children of this value can be assumed to alternate between keys and | |
1813 | values. | |
1814 | ||
1815 | @item string | |
1816 | Indicate that the object being printed is ``string-like''. If the | |
1817 | printer's @code{to_string} method returns a Python string of some | |
1818 | kind, then @value{GDBN} will call its internal language-specific | |
1819 | string-printing function to format the string. For the CLI this means | |
1820 | adding quotation marks, possibly escaping some characters, respecting | |
1821 | @code{set print elements}, and the like. | |
1822 | @end table | |
9f9aa852 AB |
1823 | |
1824 | The special value @code{None} causes @value{GDBN} to apply the default | |
1825 | display rules. | |
329baa95 DE |
1826 | @end defun |
1827 | ||
1828 | @defun pretty_printer.to_string (self) | |
1829 | @value{GDBN} will call this method to display the string | |
1830 | representation of the value passed to the object's constructor. | |
1831 | ||
fb282576 TT |
1832 | This is a basic method, and is optional. |
1833 | ||
329baa95 DE |
1834 | When printing from the CLI, if the @code{to_string} method exists, |
1835 | then @value{GDBN} will prepend its result to the values returned by | |
1836 | @code{children}. Exactly how this formatting is done is dependent on | |
1837 | the display hint, and may change as more hints are added. Also, | |
1838 | depending on the print settings (@pxref{Print Settings}), the CLI may | |
1839 | print just the result of @code{to_string} in a stack trace, omitting | |
1840 | the result of @code{children}. | |
1841 | ||
1842 | If this method returns a string, it is printed verbatim. | |
1843 | ||
1844 | Otherwise, if this method returns an instance of @code{gdb.Value}, | |
1845 | then @value{GDBN} prints this value. This may result in a call to | |
1846 | another pretty-printer. | |
1847 | ||
1848 | If instead the method returns a Python value which is convertible to a | |
1849 | @code{gdb.Value}, then @value{GDBN} performs the conversion and prints | |
1850 | the resulting value. Again, this may result in a call to another | |
1851 | pretty-printer. Python scalars (integers, floats, and booleans) and | |
1852 | strings are convertible to @code{gdb.Value}; other types are not. | |
1853 | ||
1854 | Finally, if this method returns @code{None} then no further operations | |
1855 | are peformed in this method and nothing is printed. | |
1856 | ||
1857 | If the result is not one of these types, an exception is raised. | |
1858 | @end defun | |
1859 | ||
f35baff3 TT |
1860 | @defun pretty_printer.num_children () |
1861 | This is not a basic method, so @value{GDBN} will only ever call it for | |
1862 | objects derived from @code{gdb.ValuePrinter}. | |
1863 | ||
1864 | If available, this method should return the number of children. | |
1865 | @code{None} may be returned if the number can't readily be computed. | |
1866 | @end defun | |
1867 | ||
1868 | @defun pretty_printer.child (n) | |
1869 | This is not a basic method, so @value{GDBN} will only ever call it for | |
1870 | objects derived from @code{gdb.ValuePrinter}. | |
1871 | ||
1872 | If available, this method should return the child value indicated by | |
1873 | @var{n}. Indices start at zero. | |
1874 | @end defun | |
1875 | ||
329baa95 DE |
1876 | @value{GDBN} provides a function which can be used to look up the |
1877 | default pretty-printer for a @code{gdb.Value}: | |
1878 | ||
329baa95 DE |
1879 | @defun gdb.default_visualizer (value) |
1880 | This function takes a @code{gdb.Value} object as an argument. If a | |
1881 | pretty-printer for this value exists, then it is returned. If no such | |
1882 | printer exists, then this returns @code{None}. | |
1883 | @end defun | |
1884 | ||
c4a3dbaf TT |
1885 | Normally, a pretty-printer can respect the user's print settings |
1886 | (including temporarily applied settings, such as @samp{/x}) simply by | |
1887 | calling @code{Value.format_string} (@pxref{Values From Inferior}). | |
1888 | However, these settings can also be queried directly: | |
1889 | ||
c4a3dbaf TT |
1890 | @defun gdb.print_options () |
1891 | Return a dictionary whose keys are the valid keywords that can be | |
1892 | given to @code{Value.format_string}, and whose values are the user's | |
1893 | settings. During a @code{print} or other operation, the values will | |
1894 | reflect any flags that are temporarily in effect. | |
1895 | ||
1896 | @smallexample | |
1897 | (gdb) python print (gdb.print_options ()['max_elements']) | |
1898 | 200 | |
1899 | @end smallexample | |
1900 | @end defun | |
1901 | ||
329baa95 DE |
1902 | @node Selecting Pretty-Printers |
1903 | @subsubsection Selecting Pretty-Printers | |
b3ce5e5f | 1904 | @cindex selecting python pretty-printers |
329baa95 | 1905 | |
48869a5f TT |
1906 | @value{GDBN} provides several ways to register a pretty-printer: |
1907 | globally, per program space, and per objfile. When choosing how to | |
1908 | register your pretty-printer, a good rule is to register it with the | |
1909 | smallest scope possible: that is prefer a specific objfile first, then | |
1910 | a program space, and only register a printer globally as a last | |
1911 | resort. | |
1912 | ||
48869a5f | 1913 | @defvar gdb.pretty_printers |
329baa95 DE |
1914 | The Python list @code{gdb.pretty_printers} contains an array of |
1915 | functions or callable objects that have been registered via addition | |
1916 | as a pretty-printer. Printers in this list are called @code{global} | |
1917 | printers, they're available when debugging all inferiors. | |
48869a5f TT |
1918 | @end defvar |
1919 | ||
329baa95 DE |
1920 | Each @code{gdb.Progspace} contains a @code{pretty_printers} attribute. |
1921 | Each @code{gdb.Objfile} also contains a @code{pretty_printers} | |
1922 | attribute. | |
1923 | ||
1924 | Each function on these lists is passed a single @code{gdb.Value} | |
1925 | argument and should return a pretty-printer object conforming to the | |
1926 | interface definition above (@pxref{Pretty Printing API}). If a function | |
1927 | cannot create a pretty-printer for the value, it should return | |
1928 | @code{None}. | |
1929 | ||
1930 | @value{GDBN} first checks the @code{pretty_printers} attribute of each | |
1931 | @code{gdb.Objfile} in the current program space and iteratively calls | |
1932 | each enabled lookup routine in the list for that @code{gdb.Objfile} | |
1933 | until it receives a pretty-printer object. | |
1934 | If no pretty-printer is found in the objfile lists, @value{GDBN} then | |
1935 | searches the pretty-printer list of the current program space, | |
1936 | calling each enabled function until an object is returned. | |
1937 | After these lists have been exhausted, it tries the global | |
1938 | @code{gdb.pretty_printers} list, again calling each enabled function until an | |
1939 | object is returned. | |
1940 | ||
1941 | The order in which the objfiles are searched is not specified. For a | |
1942 | given list, functions are always invoked from the head of the list, | |
1943 | and iterated over sequentially until the end of the list, or a printer | |
1944 | object is returned. | |
1945 | ||
1946 | For various reasons a pretty-printer may not work. | |
1947 | For example, the underlying data structure may have changed and | |
1948 | the pretty-printer is out of date. | |
1949 | ||
1950 | The consequences of a broken pretty-printer are severe enough that | |
1951 | @value{GDBN} provides support for enabling and disabling individual | |
1952 | printers. For example, if @code{print frame-arguments} is on, | |
1953 | a backtrace can become highly illegible if any argument is printed | |
1954 | with a broken printer. | |
1955 | ||
1956 | Pretty-printers are enabled and disabled by attaching an @code{enabled} | |
1957 | attribute to the registered function or callable object. If this attribute | |
1958 | is present and its value is @code{False}, the printer is disabled, otherwise | |
1959 | the printer is enabled. | |
1960 | ||
1961 | @node Writing a Pretty-Printer | |
1962 | @subsubsection Writing a Pretty-Printer | |
1963 | @cindex writing a pretty-printer | |
1964 | ||
1965 | A pretty-printer consists of two parts: a lookup function to detect | |
1966 | if the type is supported, and the printer itself. | |
1967 | ||
1968 | Here is an example showing how a @code{std::string} printer might be | |
1969 | written. @xref{Pretty Printing API}, for details on the API this class | |
fb282576 TT |
1970 | must provide. Note that this example uses the @code{gdb.ValuePrinter} |
1971 | base class, and is careful to use a leading underscore for its local | |
1972 | state. | |
329baa95 DE |
1973 | |
1974 | @smallexample | |
fb282576 | 1975 | class StdStringPrinter(gdb.ValuePrinter): |
329baa95 DE |
1976 | "Print a std::string" |
1977 | ||
1978 | def __init__(self, val): | |
fb282576 | 1979 | self.__val = val |
329baa95 DE |
1980 | |
1981 | def to_string(self): | |
fb282576 | 1982 | return self.__val['_M_dataplus']['_M_p'] |
329baa95 DE |
1983 | |
1984 | def display_hint(self): | |
1985 | return 'string' | |
1986 | @end smallexample | |
1987 | ||
1988 | And here is an example showing how a lookup function for the printer | |
1989 | example above might be written. | |
1990 | ||
1991 | @smallexample | |
1992 | def str_lookup_function(val): | |
1993 | lookup_tag = val.type.tag | |
f9e59d06 | 1994 | if lookup_tag is None: |
329baa95 DE |
1995 | return None |
1996 | regex = re.compile("^std::basic_string<char,.*>$") | |
1997 | if regex.match(lookup_tag): | |
1998 | return StdStringPrinter(val) | |
1999 | return None | |
2000 | @end smallexample | |
2001 | ||
2002 | The example lookup function extracts the value's type, and attempts to | |
2003 | match it to a type that it can pretty-print. If it is a type the | |
2004 | printer can pretty-print, it will return a printer object. If not, it | |
2005 | returns @code{None}. | |
2006 | ||
2007 | We recommend that you put your core pretty-printers into a Python | |
2008 | package. If your pretty-printers are for use with a library, we | |
2009 | further recommend embedding a version number into the package name. | |
2010 | This practice will enable @value{GDBN} to load multiple versions of | |
2011 | your pretty-printers at the same time, because they will have | |
2012 | different names. | |
2013 | ||
2014 | You should write auto-loaded code (@pxref{Python Auto-loading}) such that it | |
2015 | can be evaluated multiple times without changing its meaning. An | |
2016 | ideal auto-load file will consist solely of @code{import}s of your | |
2017 | printer modules, followed by a call to a register pretty-printers with | |
2018 | the current objfile. | |
2019 | ||
2020 | Taken as a whole, this approach will scale nicely to multiple | |
2021 | inferiors, each potentially using a different library version. | |
2022 | Embedding a version number in the Python package name will ensure that | |
2023 | @value{GDBN} is able to load both sets of printers simultaneously. | |
2024 | Then, because the search for pretty-printers is done by objfile, and | |
2025 | because your auto-loaded code took care to register your library's | |
2026 | printers with a specific objfile, @value{GDBN} will find the correct | |
2027 | printers for the specific version of the library used by each | |
2028 | inferior. | |
2029 | ||
2030 | To continue the @code{std::string} example (@pxref{Pretty Printing API}), | |
2031 | this code might appear in @code{gdb.libstdcxx.v6}: | |
2032 | ||
2033 | @smallexample | |
2034 | def register_printers(objfile): | |
2035 | objfile.pretty_printers.append(str_lookup_function) | |
2036 | @end smallexample | |
2037 | ||
2038 | @noindent | |
2039 | And then the corresponding contents of the auto-load file would be: | |
2040 | ||
2041 | @smallexample | |
2042 | import gdb.libstdcxx.v6 | |
2043 | gdb.libstdcxx.v6.register_printers(gdb.current_objfile()) | |
2044 | @end smallexample | |
2045 | ||
2046 | The previous example illustrates a basic pretty-printer. | |
2047 | There are a few things that can be improved on. | |
2048 | The printer doesn't have a name, making it hard to identify in a | |
2049 | list of installed printers. The lookup function has a name, but | |
2050 | lookup functions can have arbitrary, even identical, names. | |
2051 | ||
2052 | Second, the printer only handles one type, whereas a library typically has | |
2053 | several types. One could install a lookup function for each desired type | |
2054 | in the library, but one could also have a single lookup function recognize | |
2055 | several types. The latter is the conventional way this is handled. | |
2056 | If a pretty-printer can handle multiple data types, then its | |
2057 | @dfn{subprinters} are the printers for the individual data types. | |
2058 | ||
2059 | The @code{gdb.printing} module provides a formal way of solving these | |
2060 | problems (@pxref{gdb.printing}). | |
2061 | Here is another example that handles multiple types. | |
2062 | ||
2063 | These are the types we are going to pretty-print: | |
2064 | ||
2065 | @smallexample | |
2066 | struct foo @{ int a, b; @}; | |
2067 | struct bar @{ struct foo x, y; @}; | |
2068 | @end smallexample | |
2069 | ||
2070 | Here are the printers: | |
2071 | ||
2072 | @smallexample | |
fb282576 | 2073 | class fooPrinter(gdb.ValuePrinter): |
329baa95 DE |
2074 | """Print a foo object.""" |
2075 | ||
2076 | def __init__(self, val): | |
fb282576 | 2077 | self.__val = val |
329baa95 DE |
2078 | |
2079 | def to_string(self): | |
fb282576 TT |
2080 | return ("a=<" + str(self.__val["a"]) + |
2081 | "> b=<" + str(self.__val["b"]) + ">") | |
329baa95 | 2082 | |
fb282576 | 2083 | class barPrinter(gdb.ValuePrinter): |
329baa95 DE |
2084 | """Print a bar object.""" |
2085 | ||
2086 | def __init__(self, val): | |
fb282576 | 2087 | self.__val = val |
329baa95 DE |
2088 | |
2089 | def to_string(self): | |
fb282576 TT |
2090 | return ("x=<" + str(self.__val["x"]) + |
2091 | "> y=<" + str(self.__val["y"]) + ">") | |
329baa95 DE |
2092 | @end smallexample |
2093 | ||
2094 | This example doesn't need a lookup function, that is handled by the | |
2095 | @code{gdb.printing} module. Instead a function is provided to build up | |
2096 | the object that handles the lookup. | |
2097 | ||
2098 | @smallexample | |
2099 | import gdb.printing | |
2100 | ||
2101 | def build_pretty_printer(): | |
2102 | pp = gdb.printing.RegexpCollectionPrettyPrinter( | |
2103 | "my_library") | |
2104 | pp.add_printer('foo', '^foo$', fooPrinter) | |
2105 | pp.add_printer('bar', '^bar$', barPrinter) | |
2106 | return pp | |
2107 | @end smallexample | |
2108 | ||
2109 | And here is the autoload support: | |
2110 | ||
2111 | @smallexample | |
2112 | import gdb.printing | |
2113 | import my_library | |
2114 | gdb.printing.register_pretty_printer( | |
2115 | gdb.current_objfile(), | |
2116 | my_library.build_pretty_printer()) | |
2117 | @end smallexample | |
2118 | ||
2119 | Finally, when this printer is loaded into @value{GDBN}, here is the | |
2120 | corresponding output of @samp{info pretty-printer}: | |
2121 | ||
2122 | @smallexample | |
2123 | (gdb) info pretty-printer | |
2124 | my_library.so: | |
2125 | my_library | |
2126 | foo | |
2127 | bar | |
2128 | @end smallexample | |
2129 | ||
2130 | @node Type Printing API | |
2131 | @subsubsection Type Printing API | |
2132 | @cindex type printing API for Python | |
2133 | ||
2134 | @value{GDBN} provides a way for Python code to customize type display. | |
2135 | This is mainly useful for substituting canonical typedef names for | |
2136 | types. | |
2137 | ||
2138 | @cindex type printer | |
2139 | A @dfn{type printer} is just a Python object conforming to a certain | |
2140 | protocol. A simple base class implementing the protocol is provided; | |
2141 | see @ref{gdb.types}. A type printer must supply at least: | |
2142 | ||
2143 | @defivar type_printer enabled | |
2144 | A boolean which is True if the printer is enabled, and False | |
2145 | otherwise. This is manipulated by the @code{enable type-printer} | |
2146 | and @code{disable type-printer} commands. | |
2147 | @end defivar | |
2148 | ||
2149 | @defivar type_printer name | |
2150 | The name of the type printer. This must be a string. This is used by | |
2151 | the @code{enable type-printer} and @code{disable type-printer} | |
2152 | commands. | |
2153 | @end defivar | |
2154 | ||
2155 | @defmethod type_printer instantiate (self) | |
2156 | This is called by @value{GDBN} at the start of type-printing. It is | |
2157 | only called if the type printer is enabled. This method must return a | |
2158 | new object that supplies a @code{recognize} method, as described below. | |
2159 | @end defmethod | |
2160 | ||
2161 | ||
2162 | When displaying a type, say via the @code{ptype} command, @value{GDBN} | |
2163 | will compute a list of type recognizers. This is done by iterating | |
2164 | first over the per-objfile type printers (@pxref{Objfiles In Python}), | |
2165 | followed by the per-progspace type printers (@pxref{Progspaces In | |
2166 | Python}), and finally the global type printers. | |
2167 | ||
2168 | @value{GDBN} will call the @code{instantiate} method of each enabled | |
2169 | type printer. If this method returns @code{None}, then the result is | |
2170 | ignored; otherwise, it is appended to the list of recognizers. | |
2171 | ||
2172 | Then, when @value{GDBN} is going to display a type name, it iterates | |
2173 | over the list of recognizers. For each one, it calls the recognition | |
2174 | function, stopping if the function returns a non-@code{None} value. | |
2175 | The recognition function is defined as: | |
2176 | ||
2177 | @defmethod type_recognizer recognize (self, type) | |
2178 | If @var{type} is not recognized, return @code{None}. Otherwise, | |
2179 | return a string which is to be printed as the name of @var{type}. | |
697aa1b7 EZ |
2180 | The @var{type} argument will be an instance of @code{gdb.Type} |
2181 | (@pxref{Types In Python}). | |
329baa95 DE |
2182 | @end defmethod |
2183 | ||
2184 | @value{GDBN} uses this two-pass approach so that type printers can | |
2185 | efficiently cache information without holding on to it too long. For | |
2186 | example, it can be convenient to look up type information in a type | |
2187 | printer and hold it for a recognizer's lifetime; if a single pass were | |
2188 | done then type printers would have to make use of the event system in | |
2189 | order to avoid holding information that could become stale as the | |
2190 | inferior changed. | |
2191 | ||
2192 | @node Frame Filter API | |
521b499b | 2193 | @subsubsection Filtering Frames |
329baa95 DE |
2194 | @cindex frame filters api |
2195 | ||
2196 | Frame filters are Python objects that manipulate the visibility of a | |
2197 | frame or frames when a backtrace (@pxref{Backtrace}) is printed by | |
2198 | @value{GDBN}. | |
2199 | ||
2200 | Only commands that print a backtrace, or, in the case of @sc{gdb/mi} | |
2201 | commands (@pxref{GDB/MI}), those that return a collection of frames | |
2202 | are affected. The commands that work with frame filters are: | |
2203 | ||
2204 | @code{backtrace} (@pxref{backtrace-command,, The backtrace command}), | |
2205 | @code{-stack-list-frames} | |
2206 | (@pxref{-stack-list-frames,, The -stack-list-frames command}), | |
2207 | @code{-stack-list-variables} (@pxref{-stack-list-variables,, The | |
2208 | -stack-list-variables command}), @code{-stack-list-arguments} | |
2209 | @pxref{-stack-list-arguments,, The -stack-list-arguments command}) and | |
2210 | @code{-stack-list-locals} (@pxref{-stack-list-locals,, The | |
2211 | -stack-list-locals command}). | |
2212 | ||
2213 | A frame filter works by taking an iterator as an argument, applying | |
2214 | actions to the contents of that iterator, and returning another | |
2215 | iterator (or, possibly, the same iterator it was provided in the case | |
2216 | where the filter does not perform any operations). Typically, frame | |
2217 | filters utilize tools such as the Python's @code{itertools} module to | |
2218 | work with and create new iterators from the source iterator. | |
2219 | Regardless of how a filter chooses to apply actions, it must not alter | |
2220 | the underlying @value{GDBN} frame or frames, or attempt to alter the | |
2221 | call-stack within @value{GDBN}. This preserves data integrity within | |
2222 | @value{GDBN}. Frame filters are executed on a priority basis and care | |
2223 | should be taken that some frame filters may have been executed before, | |
2224 | and that some frame filters will be executed after. | |
2225 | ||
2226 | An important consideration when designing frame filters, and well | |
2227 | worth reflecting upon, is that frame filters should avoid unwinding | |
2228 | the call stack if possible. Some stacks can run very deep, into the | |
2229 | tens of thousands in some cases. To search every frame when a frame | |
2230 | filter executes may be too expensive at that step. The frame filter | |
2231 | cannot know how many frames it has to iterate over, and it may have to | |
2232 | iterate through them all. This ends up duplicating effort as | |
2233 | @value{GDBN} performs this iteration when it prints the frames. If | |
2234 | the filter can defer unwinding frames until frame decorators are | |
2235 | executed, after the last filter has executed, it should. @xref{Frame | |
2236 | Decorator API}, for more information on decorators. Also, there are | |
2237 | examples for both frame decorators and filters in later chapters. | |
2238 | @xref{Writing a Frame Filter}, for more information. | |
2239 | ||
2240 | The Python dictionary @code{gdb.frame_filters} contains key/object | |
2241 | pairings that comprise a frame filter. Frame filters in this | |
2242 | dictionary are called @code{global} frame filters, and they are | |
2243 | available when debugging all inferiors. These frame filters must | |
2244 | register with the dictionary directly. In addition to the | |
2245 | @code{global} dictionary, there are other dictionaries that are loaded | |
2246 | with different inferiors via auto-loading (@pxref{Python | |
2247 | Auto-loading}). The two other areas where frame filter dictionaries | |
2248 | can be found are: @code{gdb.Progspace} which contains a | |
2249 | @code{frame_filters} dictionary attribute, and each @code{gdb.Objfile} | |
2250 | object which also contains a @code{frame_filters} dictionary | |
2251 | attribute. | |
2252 | ||
2253 | When a command is executed from @value{GDBN} that is compatible with | |
2254 | frame filters, @value{GDBN} combines the @code{global}, | |
2255 | @code{gdb.Progspace} and all @code{gdb.Objfile} dictionaries currently | |
2256 | loaded. All of the @code{gdb.Objfile} dictionaries are combined, as | |
2257 | several frames, and thus several object files, might be in use. | |
2258 | @value{GDBN} then prunes any frame filter whose @code{enabled} | |
2259 | attribute is @code{False}. This pruned list is then sorted according | |
2260 | to the @code{priority} attribute in each filter. | |
2261 | ||
2262 | Once the dictionaries are combined, pruned and sorted, @value{GDBN} | |
2263 | creates an iterator which wraps each frame in the call stack in a | |
2264 | @code{FrameDecorator} object, and calls each filter in order. The | |
2265 | output from the previous filter will always be the input to the next | |
2266 | filter, and so on. | |
2267 | ||
2268 | Frame filters have a mandatory interface which each frame filter must | |
2269 | implement, defined here: | |
2270 | ||
2271 | @defun FrameFilter.filter (iterator) | |
2272 | @value{GDBN} will call this method on a frame filter when it has | |
2273 | reached the order in the priority list for that filter. | |
2274 | ||
2275 | For example, if there are four frame filters: | |
2276 | ||
2277 | @smallexample | |
2278 | Name Priority | |
2279 | ||
2280 | Filter1 5 | |
2281 | Filter2 10 | |
2282 | Filter3 100 | |
2283 | Filter4 1 | |
2284 | @end smallexample | |
2285 | ||
2286 | The order that the frame filters will be called is: | |
2287 | ||
2288 | @smallexample | |
2289 | Filter3 -> Filter2 -> Filter1 -> Filter4 | |
2290 | @end smallexample | |
2291 | ||
2292 | Note that the output from @code{Filter3} is passed to the input of | |
2293 | @code{Filter2}, and so on. | |
2294 | ||
2295 | This @code{filter} method is passed a Python iterator. This iterator | |
2296 | contains a sequence of frame decorators that wrap each | |
2297 | @code{gdb.Frame}, or a frame decorator that wraps another frame | |
2298 | decorator. The first filter that is executed in the sequence of frame | |
2299 | filters will receive an iterator entirely comprised of default | |
2300 | @code{FrameDecorator} objects. However, after each frame filter is | |
2301 | executed, the previous frame filter may have wrapped some or all of | |
2302 | the frame decorators with their own frame decorator. As frame | |
2303 | decorators must also conform to a mandatory interface, these | |
2304 | decorators can be assumed to act in a uniform manner (@pxref{Frame | |
2305 | Decorator API}). | |
2306 | ||
2307 | This method must return an object conforming to the Python iterator | |
2308 | protocol. Each item in the iterator must be an object conforming to | |
2309 | the frame decorator interface. If a frame filter does not wish to | |
2310 | perform any operations on this iterator, it should return that | |
2311 | iterator untouched. | |
2312 | ||
2313 | This method is not optional. If it does not exist, @value{GDBN} will | |
2314 | raise and print an error. | |
2315 | @end defun | |
2316 | ||
2317 | @defvar FrameFilter.name | |
2318 | The @code{name} attribute must be Python string which contains the | |
2319 | name of the filter displayed by @value{GDBN} (@pxref{Frame Filter | |
2320 | Management}). This attribute may contain any combination of letters | |
2321 | or numbers. Care should be taken to ensure that it is unique. This | |
2322 | attribute is mandatory. | |
2323 | @end defvar | |
2324 | ||
2325 | @defvar FrameFilter.enabled | |
2326 | The @code{enabled} attribute must be Python boolean. This attribute | |
2327 | indicates to @value{GDBN} whether the frame filter is enabled, and | |
2328 | should be considered when frame filters are executed. If | |
2329 | @code{enabled} is @code{True}, then the frame filter will be executed | |
2330 | when any of the backtrace commands detailed earlier in this chapter | |
2331 | are executed. If @code{enabled} is @code{False}, then the frame | |
2332 | filter will not be executed. This attribute is mandatory. | |
2333 | @end defvar | |
2334 | ||
2335 | @defvar FrameFilter.priority | |
2336 | The @code{priority} attribute must be Python integer. This attribute | |
2337 | controls the order of execution in relation to other frame filters. | |
2338 | There are no imposed limits on the range of @code{priority} other than | |
2339 | it must be a valid integer. The higher the @code{priority} attribute, | |
2340 | the sooner the frame filter will be executed in relation to other | |
2341 | frame filters. Although @code{priority} can be negative, it is | |
2342 | recommended practice to assume zero is the lowest priority that a | |
2343 | frame filter can be assigned. Frame filters that have the same | |
2344 | priority are executed in unsorted order in that priority slot. This | |
521b499b | 2345 | attribute is mandatory. 100 is a good default priority. |
329baa95 DE |
2346 | @end defvar |
2347 | ||
2348 | @node Frame Decorator API | |
521b499b | 2349 | @subsubsection Decorating Frames |
329baa95 DE |
2350 | @cindex frame decorator api |
2351 | ||
2352 | Frame decorators are sister objects to frame filters (@pxref{Frame | |
2353 | Filter API}). Frame decorators are applied by a frame filter and can | |
2354 | only be used in conjunction with frame filters. | |
2355 | ||
2356 | The purpose of a frame decorator is to customize the printed content | |
2357 | of each @code{gdb.Frame} in commands where frame filters are executed. | |
2358 | This concept is called decorating a frame. Frame decorators decorate | |
2359 | a @code{gdb.Frame} with Python code contained within each API call. | |
2360 | This separates the actual data contained in a @code{gdb.Frame} from | |
2361 | the decorated data produced by a frame decorator. This abstraction is | |
2362 | necessary to maintain integrity of the data contained in each | |
2363 | @code{gdb.Frame}. | |
2364 | ||
2365 | Frame decorators have a mandatory interface, defined below. | |
2366 | ||
2367 | @value{GDBN} already contains a frame decorator called | |
2368 | @code{FrameDecorator}. This contains substantial amounts of | |
2369 | boilerplate code to decorate the content of a @code{gdb.Frame}. It is | |
2370 | recommended that other frame decorators inherit and extend this | |
2371 | object, and only to override the methods needed. | |
2372 | ||
521b499b TT |
2373 | @tindex gdb.FrameDecorator |
2374 | @code{FrameDecorator} is defined in the Python module | |
2375 | @code{gdb.FrameDecorator}, so your code can import it like: | |
2376 | @smallexample | |
2377 | from gdb.FrameDecorator import FrameDecorator | |
2378 | @end smallexample | |
2379 | ||
329baa95 DE |
2380 | @defun FrameDecorator.elided (self) |
2381 | ||
2382 | The @code{elided} method groups frames together in a hierarchical | |
2383 | system. An example would be an interpreter, where multiple low-level | |
2384 | frames make up a single call in the interpreted language. In this | |
2385 | example, the frame filter would elide the low-level frames and present | |
2386 | a single high-level frame, representing the call in the interpreted | |
2387 | language, to the user. | |
2388 | ||
2389 | The @code{elided} function must return an iterable and this iterable | |
2390 | must contain the frames that are being elided wrapped in a suitable | |
2391 | frame decorator. If no frames are being elided this function may | |
2392 | return an empty iterable, or @code{None}. Elided frames are indented | |
2393 | from normal frames in a @code{CLI} backtrace, or in the case of | |
c96452ad | 2394 | @sc{gdb/mi}, are placed in the @code{children} field of the eliding |
329baa95 DE |
2395 | frame. |
2396 | ||
2397 | It is the frame filter's task to also filter out the elided frames from | |
2398 | the source iterator. This will avoid printing the frame twice. | |
2399 | @end defun | |
2400 | ||
2401 | @defun FrameDecorator.function (self) | |
2402 | ||
2403 | This method returns the name of the function in the frame that is to | |
2404 | be printed. | |
2405 | ||
2406 | This method must return a Python string describing the function, or | |
2407 | @code{None}. | |
2408 | ||
2409 | If this function returns @code{None}, @value{GDBN} will not print any | |
2410 | data for this field. | |
2411 | @end defun | |
2412 | ||
2413 | @defun FrameDecorator.address (self) | |
2414 | ||
2415 | This method returns the address of the frame that is to be printed. | |
2416 | ||
2417 | This method must return a Python numeric integer type of sufficient | |
2418 | size to describe the address of the frame, or @code{None}. | |
2419 | ||
2420 | If this function returns a @code{None}, @value{GDBN} will not print | |
2421 | any data for this field. | |
2422 | @end defun | |
2423 | ||
2424 | @defun FrameDecorator.filename (self) | |
2425 | ||
2426 | This method returns the filename and path associated with this frame. | |
2427 | ||
2428 | This method must return a Python string containing the filename and | |
2429 | the path to the object file backing the frame, or @code{None}. | |
2430 | ||
2431 | If this function returns a @code{None}, @value{GDBN} will not print | |
2432 | any data for this field. | |
2433 | @end defun | |
2434 | ||
2435 | @defun FrameDecorator.line (self): | |
2436 | ||
2437 | This method returns the line number associated with the current | |
2438 | position within the function addressed by this frame. | |
2439 | ||
2440 | This method must return a Python integer type, or @code{None}. | |
2441 | ||
2442 | If this function returns a @code{None}, @value{GDBN} will not print | |
2443 | any data for this field. | |
2444 | @end defun | |
2445 | ||
2446 | @defun FrameDecorator.frame_args (self) | |
2447 | @anchor{frame_args} | |
2448 | ||
2449 | This method must return an iterable, or @code{None}. Returning an | |
2450 | empty iterable, or @code{None} means frame arguments will not be | |
2451 | printed for this frame. This iterable must contain objects that | |
2452 | implement two methods, described here. | |
2453 | ||
6596a5d4 | 2454 | This object must implement a @code{symbol} method which takes a |
329baa95 DE |
2455 | single @code{self} parameter and must return a @code{gdb.Symbol} |
2456 | (@pxref{Symbols In Python}), or a Python string. The object must also | |
2457 | implement a @code{value} method which takes a single @code{self} | |
2458 | parameter and must return a @code{gdb.Value} (@pxref{Values From | |
2459 | Inferior}), a Python value, or @code{None}. If the @code{value} | |
2460 | method returns @code{None}, and the @code{argument} method returns a | |
2461 | @code{gdb.Symbol}, @value{GDBN} will look-up and print the value of | |
2462 | the @code{gdb.Symbol} automatically. | |
2463 | ||
2464 | A brief example: | |
2465 | ||
2466 | @smallexample | |
2467 | class SymValueWrapper(): | |
2468 | ||
2469 | def __init__(self, symbol, value): | |
2470 | self.sym = symbol | |
2471 | self.val = value | |
2472 | ||
2473 | def value(self): | |
2474 | return self.val | |
2475 | ||
2476 | def symbol(self): | |
2477 | return self.sym | |
2478 | ||
2479 | class SomeFrameDecorator() | |
2480 | ... | |
2481 | ... | |
2482 | def frame_args(self): | |
2483 | args = [] | |
2484 | try: | |
2485 | block = self.inferior_frame.block() | |
2486 | except: | |
2487 | return None | |
2488 | ||
2489 | # Iterate over all symbols in a block. Only add | |
2490 | # symbols that are arguments. | |
2491 | for sym in block: | |
2492 | if not sym.is_argument: | |
2493 | continue | |
2494 | args.append(SymValueWrapper(sym,None)) | |
2495 | ||
2496 | # Add example synthetic argument. | |
2497 | args.append(SymValueWrapper(``foo'', 42)) | |
2498 | ||
2499 | return args | |
2500 | @end smallexample | |
2501 | @end defun | |
2502 | ||
2503 | @defun FrameDecorator.frame_locals (self) | |
2504 | ||
2505 | This method must return an iterable or @code{None}. Returning an | |
2506 | empty iterable, or @code{None} means frame local arguments will not be | |
2507 | printed for this frame. | |
2508 | ||
2509 | The object interface, the description of the various strategies for | |
2510 | reading frame locals, and the example are largely similar to those | |
2511 | described in the @code{frame_args} function, (@pxref{frame_args,,The | |
2512 | frame filter frame_args function}). Below is a modified example: | |
2513 | ||
2514 | @smallexample | |
2515 | class SomeFrameDecorator() | |
2516 | ... | |
2517 | ... | |
2518 | def frame_locals(self): | |
2519 | vars = [] | |
2520 | try: | |
2521 | block = self.inferior_frame.block() | |
2522 | except: | |
2523 | return None | |
2524 | ||
2525 | # Iterate over all symbols in a block. Add all | |
2526 | # symbols, except arguments. | |
2527 | for sym in block: | |
2528 | if sym.is_argument: | |
2529 | continue | |
2530 | vars.append(SymValueWrapper(sym,None)) | |
2531 | ||
2532 | # Add an example of a synthetic local variable. | |
2533 | vars.append(SymValueWrapper(``bar'', 99)) | |
2534 | ||
2535 | return vars | |
2536 | @end smallexample | |
2537 | @end defun | |
2538 | ||
2539 | @defun FrameDecorator.inferior_frame (self): | |
2540 | ||
2541 | This method must return the underlying @code{gdb.Frame} that this | |
2542 | frame decorator is decorating. @value{GDBN} requires the underlying | |
2543 | frame for internal frame information to determine how to print certain | |
2544 | values when printing a frame. | |
2545 | @end defun | |
2546 | ||
2547 | @node Writing a Frame Filter | |
2548 | @subsubsection Writing a Frame Filter | |
2549 | @cindex writing a frame filter | |
2550 | ||
2551 | There are three basic elements that a frame filter must implement: it | |
2552 | must correctly implement the documented interface (@pxref{Frame Filter | |
2553 | API}), it must register itself with @value{GDBN}, and finally, it must | |
2554 | decide if it is to work on the data provided by @value{GDBN}. In all | |
2555 | cases, whether it works on the iterator or not, each frame filter must | |
2556 | return an iterator. A bare-bones frame filter follows the pattern in | |
2557 | the following example. | |
2558 | ||
2559 | @smallexample | |
2560 | import gdb | |
2561 | ||
2562 | class FrameFilter(): | |
2563 | ||
2564 | def __init__(self): | |
2565 | # Frame filter attribute creation. | |
2566 | # | |
2567 | # 'name' is the name of the filter that GDB will display. | |
2568 | # | |
2569 | # 'priority' is the priority of the filter relative to other | |
2570 | # filters. | |
2571 | # | |
2572 | # 'enabled' is a boolean that indicates whether this filter is | |
2573 | # enabled and should be executed. | |
2574 | ||
2575 | self.name = "Foo" | |
2576 | self.priority = 100 | |
2577 | self.enabled = True | |
2578 | ||
2579 | # Register this frame filter with the global frame_filters | |
2580 | # dictionary. | |
2581 | gdb.frame_filters[self.name] = self | |
2582 | ||
2583 | def filter(self, frame_iter): | |
2584 | # Just return the iterator. | |
2585 | return frame_iter | |
2586 | @end smallexample | |
2587 | ||
2588 | The frame filter in the example above implements the three | |
2589 | requirements for all frame filters. It implements the API, self | |
2590 | registers, and makes a decision on the iterator (in this case, it just | |
2591 | returns the iterator untouched). | |
2592 | ||
2593 | The first step is attribute creation and assignment, and as shown in | |
2594 | the comments the filter assigns the following attributes: @code{name}, | |
2595 | @code{priority} and whether the filter should be enabled with the | |
2596 | @code{enabled} attribute. | |
2597 | ||
2598 | The second step is registering the frame filter with the dictionary or | |
2599 | dictionaries that the frame filter has interest in. As shown in the | |
2600 | comments, this filter just registers itself with the global dictionary | |
2601 | @code{gdb.frame_filters}. As noted earlier, @code{gdb.frame_filters} | |
2602 | is a dictionary that is initialized in the @code{gdb} module when | |
2603 | @value{GDBN} starts. What dictionary a filter registers with is an | |
2604 | important consideration. Generally, if a filter is specific to a set | |
2605 | of code, it should be registered either in the @code{objfile} or | |
2606 | @code{progspace} dictionaries as they are specific to the program | |
2607 | currently loaded in @value{GDBN}. The global dictionary is always | |
2608 | present in @value{GDBN} and is never unloaded. Any filters registered | |
2609 | with the global dictionary will exist until @value{GDBN} exits. To | |
2610 | avoid filters that may conflict, it is generally better to register | |
2611 | frame filters against the dictionaries that more closely align with | |
2612 | the usage of the filter currently in question. @xref{Python | |
2613 | Auto-loading}, for further information on auto-loading Python scripts. | |
2614 | ||
2615 | @value{GDBN} takes a hands-off approach to frame filter registration, | |
2616 | therefore it is the frame filter's responsibility to ensure | |
2617 | registration has occurred, and that any exceptions are handled | |
2618 | appropriately. In particular, you may wish to handle exceptions | |
2619 | relating to Python dictionary key uniqueness. It is mandatory that | |
2620 | the dictionary key is the same as frame filter's @code{name} | |
2621 | attribute. When a user manages frame filters (@pxref{Frame Filter | |
2622 | Management}), the names @value{GDBN} will display are those contained | |
2623 | in the @code{name} attribute. | |
2624 | ||
2625 | The final step of this example is the implementation of the | |
2626 | @code{filter} method. As shown in the example comments, we define the | |
2627 | @code{filter} method and note that the method must take an iterator, | |
2628 | and also must return an iterator. In this bare-bones example, the | |
2629 | frame filter is not very useful as it just returns the iterator | |
2630 | untouched. However this is a valid operation for frame filters that | |
2631 | have the @code{enabled} attribute set, but decide not to operate on | |
2632 | any frames. | |
2633 | ||
2634 | In the next example, the frame filter operates on all frames and | |
2635 | utilizes a frame decorator to perform some work on the frames. | |
2636 | @xref{Frame Decorator API}, for further information on the frame | |
2637 | decorator interface. | |
2638 | ||
2639 | This example works on inlined frames. It highlights frames which are | |
2640 | inlined by tagging them with an ``[inlined]'' tag. By applying a | |
2641 | frame decorator to all frames with the Python @code{itertools imap} | |
2642 | method, the example defers actions to the frame decorator. Frame | |
2643 | decorators are only processed when @value{GDBN} prints the backtrace. | |
2644 | ||
2645 | This introduces a new decision making topic: whether to perform | |
2646 | decision making operations at the filtering step, or at the printing | |
2647 | step. In this example's approach, it does not perform any filtering | |
2648 | decisions at the filtering step beyond mapping a frame decorator to | |
2649 | each frame. This allows the actual decision making to be performed | |
2650 | when each frame is printed. This is an important consideration, and | |
2651 | well worth reflecting upon when designing a frame filter. An issue | |
2652 | that frame filters should avoid is unwinding the stack if possible. | |
2653 | Some stacks can run very deep, into the tens of thousands in some | |
2654 | cases. To search every frame to determine if it is inlined ahead of | |
2655 | time may be too expensive at the filtering step. The frame filter | |
2656 | cannot know how many frames it has to iterate over, and it would have | |
2657 | to iterate through them all. This ends up duplicating effort as | |
2658 | @value{GDBN} performs this iteration when it prints the frames. | |
2659 | ||
2660 | In this example decision making can be deferred to the printing step. | |
2661 | As each frame is printed, the frame decorator can examine each frame | |
2662 | in turn when @value{GDBN} iterates. From a performance viewpoint, | |
2663 | this is the most appropriate decision to make as it avoids duplicating | |
2664 | the effort that the printing step would undertake anyway. Also, if | |
2665 | there are many frame filters unwinding the stack during filtering, it | |
2666 | can substantially delay the printing of the backtrace which will | |
2667 | result in large memory usage, and a poor user experience. | |
2668 | ||
2669 | @smallexample | |
2670 | class InlineFilter(): | |
2671 | ||
2672 | def __init__(self): | |
2673 | self.name = "InlinedFrameFilter" | |
2674 | self.priority = 100 | |
2675 | self.enabled = True | |
2676 | gdb.frame_filters[self.name] = self | |
2677 | ||
2678 | def filter(self, frame_iter): | |
2679 | frame_iter = itertools.imap(InlinedFrameDecorator, | |
2680 | frame_iter) | |
2681 | return frame_iter | |
2682 | @end smallexample | |
2683 | ||
2684 | This frame filter is somewhat similar to the earlier example, except | |
2685 | that the @code{filter} method applies a frame decorator object called | |
2686 | @code{InlinedFrameDecorator} to each element in the iterator. The | |
2687 | @code{imap} Python method is light-weight. It does not proactively | |
2688 | iterate over the iterator, but rather creates a new iterator which | |
2689 | wraps the existing one. | |
2690 | ||
2691 | Below is the frame decorator for this example. | |
2692 | ||
2693 | @smallexample | |
2694 | class InlinedFrameDecorator(FrameDecorator): | |
2695 | ||
2696 | def __init__(self, fobj): | |
2697 | super(InlinedFrameDecorator, self).__init__(fobj) | |
2698 | ||
2699 | def function(self): | |
3067d0b1 | 2700 | frame = self.inferior_frame() |
329baa95 DE |
2701 | name = str(frame.name()) |
2702 | ||
2703 | if frame.type() == gdb.INLINE_FRAME: | |
2704 | name = name + " [inlined]" | |
2705 | ||
2706 | return name | |
2707 | @end smallexample | |
2708 | ||
2709 | This frame decorator only defines and overrides the @code{function} | |
2710 | method. It lets the supplied @code{FrameDecorator}, which is shipped | |
2711 | with @value{GDBN}, perform the other work associated with printing | |
2712 | this frame. | |
2713 | ||
2714 | The combination of these two objects create this output from a | |
2715 | backtrace: | |
2716 | ||
2717 | @smallexample | |
2718 | #0 0x004004e0 in bar () at inline.c:11 | |
2719 | #1 0x00400566 in max [inlined] (b=6, a=12) at inline.c:21 | |
2720 | #2 0x00400566 in main () at inline.c:31 | |
2721 | @end smallexample | |
2722 | ||
2723 | So in the case of this example, a frame decorator is applied to all | |
2724 | frames, regardless of whether they may be inlined or not. As | |
2725 | @value{GDBN} iterates over the iterator produced by the frame filters, | |
2726 | @value{GDBN} executes each frame decorator which then makes a decision | |
2727 | on what to print in the @code{function} callback. Using a strategy | |
2728 | like this is a way to defer decisions on the frame content to printing | |
2729 | time. | |
2730 | ||
2731 | @subheading Eliding Frames | |
2732 | ||
2733 | It might be that the above example is not desirable for representing | |
2734 | inlined frames, and a hierarchical approach may be preferred. If we | |
2735 | want to hierarchically represent frames, the @code{elided} frame | |
2736 | decorator interface might be preferable. | |
2737 | ||
2738 | This example approaches the issue with the @code{elided} method. This | |
2739 | example is quite long, but very simplistic. It is out-of-scope for | |
2740 | this section to write a complete example that comprehensively covers | |
2741 | all approaches of finding and printing inlined frames. However, this | |
2742 | example illustrates the approach an author might use. | |
2743 | ||
2744 | This example comprises of three sections. | |
2745 | ||
2746 | @smallexample | |
2747 | class InlineFrameFilter(): | |
2748 | ||
2749 | def __init__(self): | |
2750 | self.name = "InlinedFrameFilter" | |
2751 | self.priority = 100 | |
2752 | self.enabled = True | |
2753 | gdb.frame_filters[self.name] = self | |
2754 | ||
2755 | def filter(self, frame_iter): | |
2756 | return ElidingInlineIterator(frame_iter) | |
2757 | @end smallexample | |
2758 | ||
2759 | This frame filter is very similar to the other examples. The only | |
2760 | difference is this frame filter is wrapping the iterator provided to | |
2761 | it (@code{frame_iter}) with a custom iterator called | |
2762 | @code{ElidingInlineIterator}. This again defers actions to when | |
2763 | @value{GDBN} prints the backtrace, as the iterator is not traversed | |
2764 | until printing. | |
2765 | ||
2766 | The iterator for this example is as follows. It is in this section of | |
2767 | the example where decisions are made on the content of the backtrace. | |
2768 | ||
2769 | @smallexample | |
2770 | class ElidingInlineIterator: | |
2771 | def __init__(self, ii): | |
2772 | self.input_iterator = ii | |
2773 | ||
2774 | def __iter__(self): | |
2775 | return self | |
2776 | ||
2777 | def next(self): | |
2778 | frame = next(self.input_iterator) | |
2779 | ||
2780 | if frame.inferior_frame().type() != gdb.INLINE_FRAME: | |
2781 | return frame | |
2782 | ||
2783 | try: | |
2784 | eliding_frame = next(self.input_iterator) | |
2785 | except StopIteration: | |
2786 | return frame | |
2787 | return ElidingFrameDecorator(eliding_frame, [frame]) | |
2788 | @end smallexample | |
2789 | ||
2790 | This iterator implements the Python iterator protocol. When the | |
2791 | @code{next} function is called (when @value{GDBN} prints each frame), | |
2792 | the iterator checks if this frame decorator, @code{frame}, is wrapping | |
2793 | an inlined frame. If it is not, it returns the existing frame decorator | |
2794 | untouched. If it is wrapping an inlined frame, it assumes that the | |
2795 | inlined frame was contained within the next oldest frame, | |
2796 | @code{eliding_frame}, which it fetches. It then creates and returns a | |
2797 | frame decorator, @code{ElidingFrameDecorator}, which contains both the | |
2798 | elided frame, and the eliding frame. | |
2799 | ||
2800 | @smallexample | |
2801 | class ElidingInlineDecorator(FrameDecorator): | |
2802 | ||
2803 | def __init__(self, frame, elided_frames): | |
2804 | super(ElidingInlineDecorator, self).__init__(frame) | |
2805 | self.frame = frame | |
2806 | self.elided_frames = elided_frames | |
2807 | ||
2808 | def elided(self): | |
2809 | return iter(self.elided_frames) | |
2810 | @end smallexample | |
2811 | ||
2812 | This frame decorator overrides one function and returns the inlined | |
2813 | frame in the @code{elided} method. As before it lets | |
2814 | @code{FrameDecorator} do the rest of the work involved in printing | |
2815 | this frame. This produces the following output. | |
2816 | ||
2817 | @smallexample | |
2818 | #0 0x004004e0 in bar () at inline.c:11 | |
2819 | #2 0x00400529 in main () at inline.c:25 | |
2820 | #1 0x00400529 in max (b=6, a=12) at inline.c:15 | |
2821 | @end smallexample | |
2822 | ||
2823 | In that output, @code{max} which has been inlined into @code{main} is | |
2824 | printed hierarchically. Another approach would be to combine the | |
2825 | @code{function} method, and the @code{elided} method to both print a | |
2826 | marker in the inlined frame, and also show the hierarchical | |
2827 | relationship. | |
2828 | ||
d11916aa SS |
2829 | @node Unwinding Frames in Python |
2830 | @subsubsection Unwinding Frames in Python | |
2831 | @cindex unwinding frames in Python | |
2832 | ||
2833 | In @value{GDBN} terminology ``unwinding'' is the process of finding | |
2834 | the previous frame (that is, caller's) from the current one. An | |
2835 | unwinder has three methods. The first one checks if it can handle | |
2836 | given frame (``sniff'' it). For the frames it can sniff an unwinder | |
2837 | provides two additional methods: it can return frame's ID, and it can | |
2838 | fetch registers from the previous frame. A running @value{GDBN} | |
2839 | mantains a list of the unwinders and calls each unwinder's sniffer in | |
2840 | turn until it finds the one that recognizes the current frame. There | |
2841 | is an API to register an unwinder. | |
2842 | ||
2843 | The unwinders that come with @value{GDBN} handle standard frames. | |
2844 | However, mixed language applications (for example, an application | |
2845 | running Java Virtual Machine) sometimes use frame layouts that cannot | |
2846 | be handled by the @value{GDBN} unwinders. You can write Python code | |
2847 | that can handle such custom frames. | |
2848 | ||
2849 | You implement a frame unwinder in Python as a class with which has two | |
2850 | attributes, @code{name} and @code{enabled}, with obvious meanings, and | |
2851 | a single method @code{__call__}, which examines a given frame and | |
2852 | returns an object (an instance of @code{gdb.UnwindInfo class)} | |
2853 | describing it. If an unwinder does not recognize a frame, it should | |
2854 | return @code{None}. The code in @value{GDBN} that enables writing | |
2855 | unwinders in Python uses this object to return frame's ID and previous | |
2856 | frame registers when @value{GDBN} core asks for them. | |
2857 | ||
e7b5068c TT |
2858 | An unwinder should do as little work as possible. Some otherwise |
2859 | innocuous operations can cause problems (even crashes, as this code is | |
01312843 | 2860 | not well-hardened yet). For example, making an inferior call from |
e7b5068c TT |
2861 | an unwinder is unadvisable, as an inferior call will reset |
2862 | @value{GDBN}'s stack unwinding process, potentially causing re-entrant | |
2863 | unwinding. | |
2864 | ||
d11916aa SS |
2865 | @subheading Unwinder Input |
2866 | ||
2867 | An object passed to an unwinder (a @code{gdb.PendingFrame} instance) | |
2868 | provides a method to read frame's registers: | |
2869 | ||
56fcb715 AB |
2870 | @defun PendingFrame.read_register (register) |
2871 | This method returns the contents of @var{register} in the | |
43d5901d | 2872 | frame as a @code{gdb.Value} object. For a description of the |
56fcb715 AB |
2873 | acceptable values of @var{register} see |
2874 | @ref{gdbpy_frame_read_register,,Frame.read_register}. If @var{register} | |
43d5901d AB |
2875 | does not name a register for the current architecture, this method |
2876 | will throw an exception. | |
e7b5068c TT |
2877 | |
2878 | Note that this method will always return a @code{gdb.Value} for a | |
2879 | valid register name. This does not mean that the value will be valid. | |
2880 | For example, you may request a register that an earlier unwinder could | |
2881 | not unwind---the value will be unavailable. Instead, the | |
2882 | @code{gdb.Value} returned from this method will be lazy; that is, its | |
2883 | underlying bits will not be fetched until it is first used. So, | |
2884 | attempting to use such a value will cause an exception at the point of | |
2885 | use. | |
2886 | ||
2887 | The type of the returned @code{gdb.Value} depends on the register and | |
2888 | the architecture. It is common for registers to have a scalar type, | |
2889 | like @code{long long}; but many other types are possible, such as | |
2890 | pointer, pointer-to-function, floating point or vector types. | |
d11916aa SS |
2891 | @end defun |
2892 | ||
2893 | It also provides a factory method to create a @code{gdb.UnwindInfo} | |
2894 | instance to be returned to @value{GDBN}: | |
2895 | ||
3712e78c | 2896 | @anchor{gdb.PendingFrame.create_unwind_info} |
d11916aa SS |
2897 | @defun PendingFrame.create_unwind_info (frame_id) |
2898 | Returns a new @code{gdb.UnwindInfo} instance identified by given | |
a8afc8a7 AB |
2899 | @var{frame_id}. The @var{frame_id} is used internally by @value{GDBN} |
2900 | to identify the frames within the current thread's stack. The | |
2901 | attributes of @var{frame_id} determine what type of frame is | |
2902 | created within @value{GDBN}: | |
d11916aa SS |
2903 | |
2904 | @table @code | |
d11916aa | 2905 | @item sp, pc |
e7b5068c TT |
2906 | The frame is identified by the given stack address and PC. The stack |
2907 | address must be chosen so that it is constant throughout the lifetime | |
2908 | of the frame, so a typical choice is the value of the stack pointer at | |
2909 | the start of the function---in the DWARF standard, this would be the | |
2910 | ``Call Frame Address''. | |
d11916aa | 2911 | |
e7b5068c TT |
2912 | This is the most common case by far. The other cases are documented |
2913 | for completeness but are only useful in specialized situations. | |
2914 | ||
2915 | @item sp, pc, special | |
2916 | The frame is identified by the stack address, the PC, and a | |
2917 | ``special'' address. The special address is used on architectures | |
2918 | that can have frames that do not change the stack, but which are still | |
2919 | distinct, for example the IA-64, which has a second stack for | |
2920 | registers. Both @var{sp} and @var{special} must be constant | |
2921 | throughout the lifetime of the frame. | |
d11916aa SS |
2922 | |
2923 | @item sp | |
e7b5068c TT |
2924 | The frame is identified by the stack address only. Any other stack |
2925 | frame with a matching @var{sp} will be considered to match this frame. | |
2926 | Inside gdb, this is called a ``wild frame''. You will never need | |
2927 | this. | |
d11916aa | 2928 | @end table |
e7b5068c | 2929 | |
64826d05 AB |
2930 | Each attribute value should either be an instance of @code{gdb.Value} |
2931 | or an integer. | |
d11916aa | 2932 | |
3712e78c AB |
2933 | A helper class is provided in the @code{gdb.unwinder} module that can |
2934 | be used to represent a frame-id | |
2935 | (@pxref{gdb.unwinder.FrameId}). | |
2936 | ||
d11916aa SS |
2937 | @end defun |
2938 | ||
87dbc774 AB |
2939 | @defun PendingFrame.architecture () |
2940 | Return the @code{gdb.Architecture} (@pxref{Architectures In Python}) | |
2941 | for this @code{gdb.PendingFrame}. This represents the architecture of | |
2942 | the particular frame being unwound. | |
2943 | @end defun | |
2944 | ||
d52b8007 AB |
2945 | @defun PendingFrame.level () |
2946 | Return an integer, the stack frame level for this frame. | |
2947 | @xref{Frames, ,Stack Frames}. | |
2948 | @end defun | |
2949 | ||
86b35b71 AB |
2950 | @defun PendingFrame.name () |
2951 | Returns the function name of this pending frame, or @code{None} if it | |
2952 | can't be obtained. | |
2953 | @end defun | |
2954 | ||
2955 | @defun PendingFrame.is_valid () | |
2956 | Returns true if the @code{gdb.PendingFrame} object is valid, false if | |
2957 | not. A pending frame object becomes invalid when the call to the | |
2958 | unwinder, for which the pending frame was created, returns. | |
2959 | ||
2960 | All @code{gdb.PendingFrame} methods, except this one, will raise an | |
2961 | exception if the pending frame object is invalid at the time the | |
2962 | method is called. | |
2963 | @end defun | |
2964 | ||
2965 | @defun PendingFrame.pc () | |
2966 | Returns the pending frame's resume address. | |
2967 | @end defun | |
2968 | ||
2969 | @defun PendingFrame.block () | |
2970 | Return the pending frame's code block (@pxref{Blocks In Python}). If | |
2971 | the frame does not have a block -- for example, if there is no | |
2972 | debugging information for the code in question -- then this will raise | |
2973 | a @code{RuntimeError} exception. | |
2974 | @end defun | |
2975 | ||
2976 | @defun PendingFrame.function () | |
2977 | Return the symbol for the function corresponding to this pending frame. | |
2978 | @xref{Symbols In Python}. | |
2979 | @end defun | |
2980 | ||
2981 | @defun PendingFrame.find_sal () | |
2982 | Return the pending frame's symtab and line object (@pxref{Symbol | |
2983 | Tables In Python}). | |
2984 | @end defun | |
2985 | ||
2986 | @defun PendingFrame.language () | |
2987 | Return the language of this frame, as a string, or None. | |
2988 | @end defun | |
2989 | ||
d11916aa SS |
2990 | @subheading Unwinder Output: UnwindInfo |
2991 | ||
2992 | Use @code{PendingFrame.create_unwind_info} method described above to | |
2993 | create a @code{gdb.UnwindInfo} instance. Use the following method to | |
2994 | specify caller registers that have been saved in this frame: | |
2995 | ||
d2d62da6 AB |
2996 | @defun gdb.UnwindInfo.add_saved_register (register, value) |
2997 | @var{register} identifies the register, for a description of the acceptable | |
43d5901d | 2998 | values see @ref{gdbpy_frame_read_register,,Frame.read_register}. |
d11916aa SS |
2999 | @var{value} is a register value (a @code{gdb.Value} object). |
3000 | @end defun | |
3001 | ||
6bf5f25b AB |
3002 | @subheading The @code{gdb.unwinder} Module |
3003 | ||
3004 | @value{GDBN} comes with a @code{gdb.unwinder} module which contains | |
3712e78c | 3005 | the following classes: |
6bf5f25b AB |
3006 | |
3007 | @deftp {class} gdb.unwinder.Unwinder | |
3008 | The @code{Unwinder} class is a base class from which user created | |
3009 | unwinders can derive, though it is not required that unwinders derive | |
3010 | from this class, so long as any user created unwinder has the required | |
3011 | @code{name} and @code{enabled} attributes. | |
3012 | ||
ebb83b77 | 3013 | @defun gdb.unwinder.Unwinder.__init__(name) |
6bf5f25b AB |
3014 | The @var{name} is a string used to reference this unwinder within some |
3015 | @value{GDBN} commands (@pxref{Managing Registered Unwinders}). | |
3016 | @end defun | |
3017 | ||
3018 | @defvar gdb.unwinder.name | |
3019 | A read-only attribute which is a string, the name of this unwinder. | |
3020 | @end defvar | |
3021 | ||
3022 | @defvar gdb.unwinder.enabled | |
3023 | A modifiable attribute containing a boolean; when @code{True}, the | |
3024 | unwinder is enabled, and will be used by @value{GDBN}. When | |
3025 | @code{False}, the unwinder has been disabled, and will not be used. | |
3026 | @end defvar | |
3027 | @end deftp | |
3028 | ||
3712e78c AB |
3029 | @anchor{gdb.unwinder.FrameId} |
3030 | @deftp {class} gdb.unwinder.FrameId | |
3031 | This is a class suitable for being used as the frame-id when calling | |
3032 | @code{gdb.PendingFrame.create_unwind_info}. It is not required to use | |
3033 | this class, any class with the required attribute | |
3034 | (@pxref{gdb.PendingFrame.create_unwind_info}) will be accepted, but in | |
3035 | most cases this class will be sufficient. | |
3036 | ||
3037 | @code{gdb.unwinder.FrameId} has the following method: | |
3038 | ||
ebb83b77 | 3039 | @defun gdb.unwinder.FrameId.__init__(sp, pc, special = @code{None}) |
3712e78c AB |
3040 | The @var{sp} and @var{pc} arguments are required and should be either |
3041 | a @code{gdb.Value} object, or an integer. | |
3042 | ||
3043 | The @var{special} argument is optional; if specified, it should be a | |
3044 | @code{gdb.Value} object, or an integer. | |
3045 | @end defun | |
3046 | ||
3047 | @code{gdb.unwinder.FrameId} has the following read-only attributes: | |
3048 | ||
3049 | @defvar gdb.unwinder.sp | |
3050 | The @var{sp} value passed to the constructor. | |
3051 | @end defvar | |
3052 | ||
3053 | @defvar gdb.unwinder.pc | |
3054 | The @var{pc} value passed to the constructor. | |
3055 | @end defvar | |
3056 | ||
3057 | @defvar gdb.unwinder.special | |
3058 | The @var{special} value passed to the constructor, or @code{None} if | |
3059 | no such value was passed. | |
3060 | @end defvar | |
3061 | @end deftp | |
3062 | ||
a8afc8a7 AB |
3063 | @subheading Registering an Unwinder |
3064 | ||
3065 | Object files and program spaces can have unwinders registered with | |
3066 | them. In addition, you can register unwinders globally. | |
3067 | ||
3068 | The @code{gdb.unwinders} module provides the function to register an | |
3069 | unwinder: | |
3070 | ||
3071 | @defun gdb.unwinder.register_unwinder (locus, unwinder, replace=False) | |
3072 | @var{locus} specifies to which unwinder list to prepend the | |
3073 | @var{unwinder}. It can be either an object file (@pxref{Objfiles In | |
3074 | Python}), a program space (@pxref{Progspaces In Python}), or | |
3075 | @code{None}, in which case the unwinder is registered globally. The | |
3076 | newly added @var{unwinder} will be called before any other unwinder | |
3077 | from the same locus. Two unwinders in the same locus cannot have the | |
3078 | same name. An attempt to add an unwinder with an already existing | |
3079 | name raises an exception unless @var{replace} is @code{True}, in which | |
3080 | case the old unwinder is deleted and the new unwinder is registered in | |
3081 | its place. | |
3082 | ||
3083 | @value{GDBN} first calls the unwinders from all the object files in no | |
3084 | particular order, then the unwinders from the current program space, | |
3085 | then the globally registered unwinders, and finally the unwinders | |
3086 | builtin to @value{GDBN}. | |
3087 | @end defun | |
3088 | ||
d11916aa SS |
3089 | @subheading Unwinder Skeleton Code |
3090 | ||
6bf5f25b | 3091 | Here is an example of how to structure a user created unwinder: |
d11916aa SS |
3092 | |
3093 | @smallexample | |
3712e78c | 3094 | from gdb.unwinder import Unwinder, FrameId |
d11916aa SS |
3095 | |
3096 | class MyUnwinder(Unwinder): | |
a8afc8a7 AB |
3097 | def __init__(self): |
3098 | super().__init___("MyUnwinder_Name") | |
d11916aa | 3099 | |
a8afc8a7 | 3100 | def __call__(self, pending_frame): |
d11916aa SS |
3101 | if not <we recognize frame>: |
3102 | return None | |
a8afc8a7 AB |
3103 | |
3104 | # Create a FrameID. Usually the frame is identified by a | |
3105 | # stack pointer and the function address. | |
3106 | sp = ... compute a stack address ... | |
3107 | pc = ... compute function address ... | |
d11916aa SS |
3108 | unwind_info = pending_frame.create_unwind_info(FrameId(sp, pc)) |
3109 | ||
a8afc8a7 | 3110 | # Find the values of the registers in the caller's frame and |
d11916aa | 3111 | # save them in the result: |
a8afc8a7 | 3112 | unwind_info.add_saved_register(<register-number>, <register-value>) |
d11916aa SS |
3113 | .... |
3114 | ||
3115 | # Return the result: | |
3116 | return unwind_info | |
3117 | ||
a8afc8a7 | 3118 | gdb.unwinder.register_unwinder(<locus>, MyUnwinder(), <replace>) |
d11916aa SS |
3119 | @end smallexample |
3120 | ||
6bf5f25b AB |
3121 | @anchor{Managing Registered Unwinders} |
3122 | @subheading Managing Registered Unwinders | |
3123 | @value{GDBN} defines 3 commands to manage registered unwinders. These | |
3124 | are: | |
3125 | ||
3126 | @table @code | |
3127 | @item info unwinder @r{[} @var{locus} @r{[} @var{name-regexp} @r{]} @r{]} | |
3128 | Lists all registered unwinders. Arguments @var{locus} and | |
3129 | @var{name-regexp} are both optional and can be used to filter which | |
3130 | unwinders are listed. | |
3131 | ||
3132 | The @var{locus} argument should be either @kbd{global}, | |
3133 | @kbd{progspace}, or the name of an object file. Only unwinders | |
3134 | registered for the specified locus will be listed. | |
3135 | ||
3136 | The @var{name-regexp} is a regular expression used to match against | |
3137 | unwinder names. When trying to match against unwinder names that | |
3138 | include a string enclose @var{name-regexp} in quotes. | |
3139 | @item disable unwinder @r{[} @var{locus} @r{[} @var{name-regexp} @r{]} @r{]} | |
3140 | The @var{locus} and @var{name-regexp} are interpreted as in @kbd{info | |
3141 | unwinder} above, but instead of listing the matching unwinders, all of | |
3142 | the matching unwinders are disabled. The @code{enabled} field of each | |
3143 | matching unwinder is set to @code{False}. | |
3144 | @item enable unwinder @r{[} @var{locus} @r{[} @var{name-regexp} @r{]} @r{]} | |
3145 | The @var{locus} and @var{name-regexp} are interpreted as in @kbd{info | |
3146 | unwinder} above, but instead of listing the matching unwinders, all of | |
3147 | the matching unwinders are enabled. The @code{enabled} field of each | |
3148 | matching unwinder is set to @code{True}. | |
3149 | @end table | |
3150 | ||
0c6e92a5 SC |
3151 | @node Xmethods In Python |
3152 | @subsubsection Xmethods In Python | |
3153 | @cindex xmethods in Python | |
3154 | ||
3155 | @dfn{Xmethods} are additional methods or replacements for existing | |
3156 | methods of a C@t{++} class. This feature is useful for those cases | |
3157 | where a method defined in C@t{++} source code could be inlined or | |
3158 | optimized out by the compiler, making it unavailable to @value{GDBN}. | |
3159 | For such cases, one can define an xmethod to serve as a replacement | |
3160 | for the method defined in the C@t{++} source code. @value{GDBN} will | |
3161 | then invoke the xmethod, instead of the C@t{++} method, to | |
3162 | evaluate expressions. One can also use xmethods when debugging | |
3163 | with core files. Moreover, when debugging live programs, invoking an | |
3164 | xmethod need not involve running the inferior (which can potentially | |
3165 | perturb its state). Hence, even if the C@t{++} method is available, it | |
3166 | is better to use its replacement xmethod if one is defined. | |
3167 | ||
3168 | The xmethods feature in Python is available via the concepts of an | |
3169 | @dfn{xmethod matcher} and an @dfn{xmethod worker}. To | |
3170 | implement an xmethod, one has to implement a matcher and a | |
3171 | corresponding worker for it (more than one worker can be | |
3172 | implemented, each catering to a different overloaded instance of the | |
3173 | method). Internally, @value{GDBN} invokes the @code{match} method of a | |
3174 | matcher to match the class type and method name. On a match, the | |
3175 | @code{match} method returns a list of matching @emph{worker} objects. | |
3176 | Each worker object typically corresponds to an overloaded instance of | |
3177 | the xmethod. They implement a @code{get_arg_types} method which | |
3178 | returns a sequence of types corresponding to the arguments the xmethod | |
3179 | requires. @value{GDBN} uses this sequence of types to perform | |
3180 | overload resolution and picks a winning xmethod worker. A winner | |
3181 | is also selected from among the methods @value{GDBN} finds in the | |
3182 | C@t{++} source code. Next, the winning xmethod worker and the | |
3183 | winning C@t{++} method are compared to select an overall winner. In | |
3184 | case of a tie between a xmethod worker and a C@t{++} method, the | |
3185 | xmethod worker is selected as the winner. That is, if a winning | |
3186 | xmethod worker is found to be equivalent to the winning C@t{++} | |
3187 | method, then the xmethod worker is treated as a replacement for | |
3188 | the C@t{++} method. @value{GDBN} uses the overall winner to invoke the | |
3189 | method. If the winning xmethod worker is the overall winner, then | |
897c3d32 | 3190 | the corresponding xmethod is invoked via the @code{__call__} method |
0c6e92a5 SC |
3191 | of the worker object. |
3192 | ||
3193 | If one wants to implement an xmethod as a replacement for an | |
3194 | existing C@t{++} method, then they have to implement an equivalent | |
3195 | xmethod which has exactly the same name and takes arguments of | |
3196 | exactly the same type as the C@t{++} method. If the user wants to | |
3197 | invoke the C@t{++} method even though a replacement xmethod is | |
3198 | available for that method, then they can disable the xmethod. | |
3199 | ||
3200 | @xref{Xmethod API}, for API to implement xmethods in Python. | |
3201 | @xref{Writing an Xmethod}, for implementing xmethods in Python. | |
3202 | ||
3203 | @node Xmethod API | |
3204 | @subsubsection Xmethod API | |
3205 | @cindex xmethod API | |
3206 | ||
3207 | The @value{GDBN} Python API provides classes, interfaces and functions | |
3208 | to implement, register and manipulate xmethods. | |
3209 | @xref{Xmethods In Python}. | |
3210 | ||
3211 | An xmethod matcher should be an instance of a class derived from | |
3212 | @code{XMethodMatcher} defined in the module @code{gdb.xmethod}, or an | |
3213 | object with similar interface and attributes. An instance of | |
3214 | @code{XMethodMatcher} has the following attributes: | |
3215 | ||
3216 | @defvar name | |
3217 | The name of the matcher. | |
3218 | @end defvar | |
3219 | ||
3220 | @defvar enabled | |
3221 | A boolean value indicating whether the matcher is enabled or disabled. | |
3222 | @end defvar | |
3223 | ||
3224 | @defvar methods | |
3225 | A list of named methods managed by the matcher. Each object in the list | |
3226 | is an instance of the class @code{XMethod} defined in the module | |
3227 | @code{gdb.xmethod}, or any object with the following attributes: | |
3228 | ||
3229 | @table @code | |
3230 | ||
3231 | @item name | |
3232 | Name of the xmethod which should be unique for each xmethod | |
3233 | managed by the matcher. | |
3234 | ||
3235 | @item enabled | |
3236 | A boolean value indicating whether the xmethod is enabled or | |
3237 | disabled. | |
3238 | ||
3239 | @end table | |
3240 | ||
3241 | The class @code{XMethod} is a convenience class with same | |
3242 | attributes as above along with the following constructor: | |
3243 | ||
dd5d5494 | 3244 | @defun XMethod.__init__ (self, name) |
0c6e92a5 SC |
3245 | Constructs an enabled xmethod with name @var{name}. |
3246 | @end defun | |
3247 | @end defvar | |
3248 | ||
3249 | @noindent | |
3250 | The @code{XMethodMatcher} class has the following methods: | |
3251 | ||
dd5d5494 | 3252 | @defun XMethodMatcher.__init__ (self, name) |
0c6e92a5 SC |
3253 | Constructs an enabled xmethod matcher with name @var{name}. The |
3254 | @code{methods} attribute is initialized to @code{None}. | |
3255 | @end defun | |
3256 | ||
dd5d5494 | 3257 | @defun XMethodMatcher.match (self, class_type, method_name) |
0c6e92a5 SC |
3258 | Derived classes should override this method. It should return a |
3259 | xmethod worker object (or a sequence of xmethod worker | |
3260 | objects) matching the @var{class_type} and @var{method_name}. | |
3261 | @var{class_type} is a @code{gdb.Type} object, and @var{method_name} | |
3262 | is a string value. If the matcher manages named methods as listed in | |
3263 | its @code{methods} attribute, then only those worker objects whose | |
3264 | corresponding entries in the @code{methods} list are enabled should be | |
3265 | returned. | |
3266 | @end defun | |
3267 | ||
3268 | An xmethod worker should be an instance of a class derived from | |
3269 | @code{XMethodWorker} defined in the module @code{gdb.xmethod}, | |
3270 | or support the following interface: | |
3271 | ||
dd5d5494 | 3272 | @defun XMethodWorker.get_arg_types (self) |
0c6e92a5 SC |
3273 | This method returns a sequence of @code{gdb.Type} objects corresponding |
3274 | to the arguments that the xmethod takes. It can return an empty | |
3275 | sequence or @code{None} if the xmethod does not take any arguments. | |
3276 | If the xmethod takes a single argument, then a single | |
3277 | @code{gdb.Type} object corresponding to it can be returned. | |
3278 | @end defun | |
3279 | ||
2ce1cdbf DE |
3280 | @defun XMethodWorker.get_result_type (self, *args) |
3281 | This method returns a @code{gdb.Type} object representing the type | |
3282 | of the result of invoking this xmethod. | |
3283 | The @var{args} argument is the same tuple of arguments that would be | |
3284 | passed to the @code{__call__} method of this worker. | |
3285 | @end defun | |
3286 | ||
dd5d5494 | 3287 | @defun XMethodWorker.__call__ (self, *args) |
0c6e92a5 SC |
3288 | This is the method which does the @emph{work} of the xmethod. The |
3289 | @var{args} arguments is the tuple of arguments to the xmethod. Each | |
3290 | element in this tuple is a gdb.Value object. The first element is | |
3291 | always the @code{this} pointer value. | |
3292 | @end defun | |
3293 | ||
3294 | For @value{GDBN} to lookup xmethods, the xmethod matchers | |
3295 | should be registered using the following function defined in the module | |
3296 | @code{gdb.xmethod}: | |
3297 | ||
dd5d5494 | 3298 | @defun register_xmethod_matcher (locus, matcher, replace=False) |
0c6e92a5 SC |
3299 | The @code{matcher} is registered with @code{locus}, replacing an |
3300 | existing matcher with the same name as @code{matcher} if | |
3301 | @code{replace} is @code{True}. @code{locus} can be a | |
3302 | @code{gdb.Objfile} object (@pxref{Objfiles In Python}), or a | |
1e47491b | 3303 | @code{gdb.Progspace} object (@pxref{Progspaces In Python}), or |
0c6e92a5 SC |
3304 | @code{None}. If it is @code{None}, then @code{matcher} is registered |
3305 | globally. | |
3306 | @end defun | |
3307 | ||
3308 | @node Writing an Xmethod | |
3309 | @subsubsection Writing an Xmethod | |
3310 | @cindex writing xmethods in Python | |
3311 | ||
3312 | Implementing xmethods in Python will require implementing xmethod | |
3313 | matchers and xmethod workers (@pxref{Xmethods In Python}). Consider | |
3314 | the following C@t{++} class: | |
3315 | ||
3316 | @smallexample | |
3317 | class MyClass | |
3318 | @{ | |
3319 | public: | |
3320 | MyClass (int a) : a_(a) @{ @} | |
3321 | ||
3322 | int geta (void) @{ return a_; @} | |
3323 | int operator+ (int b); | |
3324 | ||
3325 | private: | |
3326 | int a_; | |
3327 | @}; | |
3328 | ||
3329 | int | |
3330 | MyClass::operator+ (int b) | |
3331 | @{ | |
3332 | return a_ + b; | |
3333 | @} | |
3334 | @end smallexample | |
3335 | ||
3336 | @noindent | |
3337 | Let us define two xmethods for the class @code{MyClass}, one | |
3338 | replacing the method @code{geta}, and another adding an overloaded | |
3339 | flavor of @code{operator+} which takes a @code{MyClass} argument (the | |
3340 | C@t{++} code above already has an overloaded @code{operator+} | |
3341 | which takes an @code{int} argument). The xmethod matcher can be | |
3342 | defined as follows: | |
3343 | ||
3344 | @smallexample | |
3345 | class MyClass_geta(gdb.xmethod.XMethod): | |
3346 | def __init__(self): | |
3347 | gdb.xmethod.XMethod.__init__(self, 'geta') | |
3348 | ||
3349 | def get_worker(self, method_name): | |
3350 | if method_name == 'geta': | |
3351 | return MyClassWorker_geta() | |
3352 | ||
3353 | ||
3354 | class MyClass_sum(gdb.xmethod.XMethod): | |
3355 | def __init__(self): | |
3356 | gdb.xmethod.XMethod.__init__(self, 'sum') | |
3357 | ||
3358 | def get_worker(self, method_name): | |
3359 | if method_name == 'operator+': | |
3360 | return MyClassWorker_plus() | |
3361 | ||
3362 | ||
3363 | class MyClassMatcher(gdb.xmethod.XMethodMatcher): | |
3364 | def __init__(self): | |
3365 | gdb.xmethod.XMethodMatcher.__init__(self, 'MyClassMatcher') | |
3366 | # List of methods 'managed' by this matcher | |
3367 | self.methods = [MyClass_geta(), MyClass_sum()] | |
3368 | ||
3369 | def match(self, class_type, method_name): | |
3370 | if class_type.tag != 'MyClass': | |
3371 | return None | |
3372 | workers = [] | |
3373 | for method in self.methods: | |
3374 | if method.enabled: | |
3375 | worker = method.get_worker(method_name) | |
3376 | if worker: | |
3377 | workers.append(worker) | |
3378 | ||
3379 | return workers | |
3380 | @end smallexample | |
3381 | ||
3382 | @noindent | |
3383 | Notice that the @code{match} method of @code{MyClassMatcher} returns | |
3384 | a worker object of type @code{MyClassWorker_geta} for the @code{geta} | |
3385 | method, and a worker object of type @code{MyClassWorker_plus} for the | |
3386 | @code{operator+} method. This is done indirectly via helper classes | |
3387 | derived from @code{gdb.xmethod.XMethod}. One does not need to use the | |
3388 | @code{methods} attribute in a matcher as it is optional. However, if a | |
3389 | matcher manages more than one xmethod, it is a good practice to list the | |
3390 | xmethods in the @code{methods} attribute of the matcher. This will then | |
3391 | facilitate enabling and disabling individual xmethods via the | |
3392 | @code{enable/disable} commands. Notice also that a worker object is | |
3393 | returned only if the corresponding entry in the @code{methods} attribute | |
3394 | of the matcher is enabled. | |
3395 | ||
3396 | The implementation of the worker classes returned by the matcher setup | |
3397 | above is as follows: | |
3398 | ||
3399 | @smallexample | |
3400 | class MyClassWorker_geta(gdb.xmethod.XMethodWorker): | |
3401 | def get_arg_types(self): | |
3402 | return None | |
2ce1cdbf DE |
3403 | |
3404 | def get_result_type(self, obj): | |
3405 | return gdb.lookup_type('int') | |
0c6e92a5 SC |
3406 | |
3407 | def __call__(self, obj): | |
3408 | return obj['a_'] | |
3409 | ||
3410 | ||
3411 | class MyClassWorker_plus(gdb.xmethod.XMethodWorker): | |
3412 | def get_arg_types(self): | |
3413 | return gdb.lookup_type('MyClass') | |
2ce1cdbf DE |
3414 | |
3415 | def get_result_type(self, obj): | |
3416 | return gdb.lookup_type('int') | |
0c6e92a5 SC |
3417 | |
3418 | def __call__(self, obj, other): | |
3419 | return obj['a_'] + other['a_'] | |
3420 | @end smallexample | |
3421 | ||
3422 | For @value{GDBN} to actually lookup a xmethod, it has to be | |
3423 | registered with it. The matcher defined above is registered with | |
3424 | @value{GDBN} globally as follows: | |
3425 | ||
3426 | @smallexample | |
3427 | gdb.xmethod.register_xmethod_matcher(None, MyClassMatcher()) | |
3428 | @end smallexample | |
3429 | ||
3430 | If an object @code{obj} of type @code{MyClass} is initialized in C@t{++} | |
3431 | code as follows: | |
3432 | ||
3433 | @smallexample | |
3434 | MyClass obj(5); | |
3435 | @end smallexample | |
3436 | ||
3437 | @noindent | |
3438 | then, after loading the Python script defining the xmethod matchers | |
000f9cbe | 3439 | and workers into @value{GDBN}, invoking the method @code{geta} or using |
0c6e92a5 SC |
3440 | the operator @code{+} on @code{obj} will invoke the xmethods |
3441 | defined above: | |
3442 | ||
3443 | @smallexample | |
3444 | (gdb) p obj.geta() | |
3445 | $1 = 5 | |
3446 | ||
3447 | (gdb) p obj + obj | |
3448 | $2 = 10 | |
3449 | @end smallexample | |
3450 | ||
3451 | Consider another example with a C++ template class: | |
3452 | ||
3453 | @smallexample | |
3454 | template <class T> | |
3455 | class MyTemplate | |
3456 | @{ | |
3457 | public: | |
3458 | MyTemplate () : dsize_(10), data_ (new T [10]) @{ @} | |
3459 | ~MyTemplate () @{ delete [] data_; @} | |
3460 | ||
3461 | int footprint (void) | |
3462 | @{ | |
3463 | return sizeof (T) * dsize_ + sizeof (MyTemplate<T>); | |
3464 | @} | |
3465 | ||
3466 | private: | |
3467 | int dsize_; | |
3468 | T *data_; | |
3469 | @}; | |
3470 | @end smallexample | |
3471 | ||
3472 | Let us implement an xmethod for the above class which serves as a | |
3473 | replacement for the @code{footprint} method. The full code listing | |
3474 | of the xmethod workers and xmethod matchers is as follows: | |
3475 | ||
3476 | @smallexample | |
3477 | class MyTemplateWorker_footprint(gdb.xmethod.XMethodWorker): | |
3478 | def __init__(self, class_type): | |
3479 | self.class_type = class_type | |
2ce1cdbf | 3480 | |
0c6e92a5 SC |
3481 | def get_arg_types(self): |
3482 | return None | |
2ce1cdbf DE |
3483 | |
3484 | def get_result_type(self): | |
3485 | return gdb.lookup_type('int') | |
3486 | ||
0c6e92a5 SC |
3487 | def __call__(self, obj): |
3488 | return (self.class_type.sizeof + | |
3489 | obj['dsize_'] * | |
3490 | self.class_type.template_argument(0).sizeof) | |
3491 | ||
3492 | ||
3493 | class MyTemplateMatcher_footprint(gdb.xmethod.XMethodMatcher): | |
3494 | def __init__(self): | |
3495 | gdb.xmethod.XMethodMatcher.__init__(self, 'MyTemplateMatcher') | |
3496 | ||
3497 | def match(self, class_type, method_name): | |
3498 | if (re.match('MyTemplate<[ \t\n]*[_a-zA-Z][ _a-zA-Z0-9]*>', | |
3499 | class_type.tag) and | |
3500 | method_name == 'footprint'): | |
3501 | return MyTemplateWorker_footprint(class_type) | |
3502 | @end smallexample | |
3503 | ||
3504 | Notice that, in this example, we have not used the @code{methods} | |
3505 | attribute of the matcher as the matcher manages only one xmethod. The | |
3506 | user can enable/disable this xmethod by enabling/disabling the matcher | |
3507 | itself. | |
3508 | ||
329baa95 DE |
3509 | @node Inferiors In Python |
3510 | @subsubsection Inferiors In Python | |
3511 | @cindex inferiors in Python | |
3512 | ||
3513 | @findex gdb.Inferior | |
3514 | Programs which are being run under @value{GDBN} are called inferiors | |
65c574f6 | 3515 | (@pxref{Inferiors Connections and Programs}). Python scripts can access |
329baa95 DE |
3516 | information about and manipulate inferiors controlled by @value{GDBN} |
3517 | via objects of the @code{gdb.Inferior} class. | |
3518 | ||
3519 | The following inferior-related functions are available in the @code{gdb} | |
3520 | module: | |
3521 | ||
3522 | @defun gdb.inferiors () | |
3523 | Return a tuple containing all inferior objects. | |
3524 | @end defun | |
3525 | ||
3526 | @defun gdb.selected_inferior () | |
3527 | Return an object representing the current inferior. | |
3528 | @end defun | |
3529 | ||
3530 | A @code{gdb.Inferior} object has the following attributes: | |
3531 | ||
3532 | @defvar Inferior.num | |
b080fe54 AB |
3533 | ID of inferior, as assigned by @value{GDBN}. You can use this to make |
3534 | Python breakpoints inferior-specific, for example | |
3535 | (@pxref{python_breakpoint_inferior,,The Breakpoint.inferior | |
3536 | attribute}). | |
329baa95 DE |
3537 | @end defvar |
3538 | ||
0e3b7c25 AB |
3539 | @anchor{gdbpy_inferior_connection} |
3540 | @defvar Inferior.connection | |
3541 | The @code{gdb.TargetConnection} for this inferior (@pxref{Connections | |
3542 | In Python}), or @code{None} if this inferior has no connection. | |
3543 | @end defvar | |
3544 | ||
55789354 TBA |
3545 | @defvar Inferior.connection_num |
3546 | ID of inferior's connection as assigned by @value{GDBN}, or None if | |
0e3b7c25 AB |
3547 | the inferior is not connected to a target. @xref{Inferiors Connections |
3548 | and Programs}. This is equivalent to | |
3549 | @code{gdb.Inferior.connection.num} in the case where | |
3550 | @code{gdb.Inferior.connection} is not @code{None}. | |
55789354 TBA |
3551 | @end defvar |
3552 | ||
329baa95 DE |
3553 | @defvar Inferior.pid |
3554 | Process ID of the inferior, as assigned by the underlying operating | |
3555 | system. | |
3556 | @end defvar | |
3557 | ||
3558 | @defvar Inferior.was_attached | |
3559 | Boolean signaling whether the inferior was created using `attach', or | |
3560 | started by @value{GDBN} itself. | |
3561 | @end defvar | |
3562 | ||
31531132 TT |
3563 | @defvar Inferior.main_name |
3564 | A string holding the name of this inferior's ``main'' function, if it | |
3565 | can be determined. If the name of main is not known, this is | |
3566 | @code{None}. | |
3567 | @end defvar | |
3568 | ||
a40bf0c2 SM |
3569 | @defvar Inferior.progspace |
3570 | The inferior's program space. @xref{Progspaces In Python}. | |
3571 | @end defvar | |
3572 | ||
31531132 TT |
3573 | @defvar Inferior.arguments |
3574 | The inferior's command line arguments, if known. This corresponds to | |
3575 | the @code{set args} and @code{show args} commands. @xref{Arguments}. | |
3576 | ||
3577 | When accessed, the value is a string holding all the arguments. The | |
3578 | contents are quoted as they would be when passed to the shell. If | |
3579 | there are no arguments, the value is @code{None}. | |
3580 | ||
3581 | Either a string or a sequence of strings can be assigned to this | |
3582 | attribute. When a string is assigned, it is assumed to have any | |
3583 | necessary quoting for the shell; when a sequence is assigned, the | |
3584 | quoting is applied by @value{GDBN}. | |
3585 | @end defvar | |
3586 | ||
329baa95 DE |
3587 | A @code{gdb.Inferior} object has the following methods: |
3588 | ||
3589 | @defun Inferior.is_valid () | |
3590 | Returns @code{True} if the @code{gdb.Inferior} object is valid, | |
3591 | @code{False} if not. A @code{gdb.Inferior} object will become invalid | |
3592 | if the inferior no longer exists within @value{GDBN}. All other | |
3593 | @code{gdb.Inferior} methods will throw an exception if it is invalid | |
3594 | at the time the method is called. | |
3595 | @end defun | |
3596 | ||
3597 | @defun Inferior.threads () | |
3598 | This method returns a tuple holding all the threads which are valid | |
3599 | when it is called. If there are no valid threads, the method will | |
3600 | return an empty tuple. | |
3601 | @end defun | |
3602 | ||
add5ded5 TT |
3603 | @defun Inferior.architecture () |
3604 | Return the @code{gdb.Architecture} (@pxref{Architectures In Python}) | |
3605 | for this inferior. This represents the architecture of the inferior | |
3606 | as a whole. Some platforms can have multiple architectures in a | |
3607 | single address space, so this may not match the architecture of a | |
163cffef | 3608 | particular frame (@pxref{Frames In Python}). |
9e1698c6 | 3609 | @end defun |
add5ded5 | 3610 | |
15e15b2d | 3611 | @anchor{gdbpy_inferior_read_memory} |
329baa95 | 3612 | @defun Inferior.read_memory (address, length) |
914a96d7 TT |
3613 | Read @var{length} addressable memory units from the inferior, starting |
3614 | at @var{address}. Returns a @code{memoryview} object, which behaves | |
3615 | much like an array or a string. It can be modified and given to the | |
3616 | @code{Inferior.write_memory} function. | |
329baa95 DE |
3617 | @end defun |
3618 | ||
329baa95 DE |
3619 | @defun Inferior.write_memory (address, buffer @r{[}, length@r{]}) |
3620 | Write the contents of @var{buffer} to the inferior, starting at | |
3621 | @var{address}. The @var{buffer} parameter must be a Python object | |
3622 | which supports the buffer protocol, i.e., a string, an array or the | |
3623 | object returned from @code{Inferior.read_memory}. If given, @var{length} | |
a86c90e6 SM |
3624 | determines the number of addressable memory units from @var{buffer} to be |
3625 | written. | |
329baa95 DE |
3626 | @end defun |
3627 | ||
329baa95 DE |
3628 | @defun Inferior.search_memory (address, length, pattern) |
3629 | Search a region of the inferior memory starting at @var{address} with | |
3630 | the given @var{length} using the search pattern supplied in | |
3631 | @var{pattern}. The @var{pattern} parameter must be a Python object | |
3632 | which supports the buffer protocol, i.e., a string, an array or the | |
3633 | object returned from @code{gdb.read_memory}. Returns a Python @code{Long} | |
3634 | containing the address where the pattern was found, or @code{None} if | |
3635 | the pattern could not be found. | |
3636 | @end defun | |
3637 | ||
da2c323b | 3638 | @findex Inferior.thread_from_thread_handle |
2b0c8b01 KB |
3639 | @defun Inferior.thread_from_handle (handle) |
3640 | Return the thread object corresponding to @var{handle}, a thread | |
da2c323b KB |
3641 | library specific data structure such as @code{pthread_t} for pthreads |
3642 | library implementations. | |
2b0c8b01 KB |
3643 | |
3644 | The function @code{Inferior.thread_from_thread_handle} provides | |
3645 | the same functionality, but use of @code{Inferior.thread_from_thread_handle} | |
3646 | is deprecated. | |
da2c323b KB |
3647 | @end defun |
3648 | ||
31531132 TT |
3649 | |
3650 | The environment that will be passed to the inferior can be changed | |
3651 | from Python by using the following methods. These methods only take | |
3652 | effect when the inferior is started -- they will not affect an | |
3653 | inferior that is already executing. | |
3654 | ||
31531132 TT |
3655 | @defun Inferior.clear_env () |
3656 | Clear the current environment variables that will be passed to this | |
3657 | inferior. | |
3658 | @end defun | |
3659 | ||
31531132 TT |
3660 | @defun Inferior.set_env (name, value) |
3661 | Set the environment variable @var{name} to have the indicated value. | |
3662 | Both parameters must be strings. | |
3663 | @end defun | |
3664 | ||
31531132 TT |
3665 | @defun Inferior.unset_env (name) |
3666 | Unset the environment variable @var{name}. @var{name} must be a | |
3667 | string. | |
3668 | @end defun | |
3669 | ||
13cd9bce AB |
3670 | One may add arbitrary attributes to @code{gdb.Inferior} objects in the |
3671 | usual Python way. This is useful if, for example, one needs to do | |
3672 | some extra record keeping associated with the inferior. | |
3673 | ||
53d08890 AB |
3674 | @anchor{choosing attribute names} |
3675 | When selecting a name for a new attribute, avoid starting the new | |
3676 | attribute name with a lower case letter; future attributes added by | |
3677 | @value{GDBN} will start with a lower case letter. Additionally, avoid | |
3678 | starting attribute names with two underscore characters, as these | |
3679 | could clash with Python builtin attribute names. | |
3680 | ||
13cd9bce AB |
3681 | In this contrived example we record the time when an inferior last |
3682 | stopped: | |
3683 | ||
3684 | @smallexample | |
3685 | @group | |
3686 | (@value{GDBP}) python | |
3687 | import datetime | |
3688 | ||
3689 | def thread_stopped(event): | |
3690 | if event.inferior_thread is not None: | |
3691 | thread = event.inferior_thread | |
3692 | else: | |
3693 | thread = gdb.selected_thread() | |
3694 | inferior = thread.inferior | |
3695 | inferior._last_stop_time = datetime.datetime.today() | |
3696 | ||
3697 | gdb.events.stop.connect(thread_stopped) | |
3698 | @end group | |
3699 | @group | |
3700 | (@value{GDBP}) file /tmp/hello | |
3701 | Reading symbols from /tmp/hello... | |
3702 | (@value{GDBP}) start | |
3703 | Temporary breakpoint 1 at 0x401198: file /tmp/hello.c, line 18. | |
3704 | Starting program: /tmp/hello | |
3705 | ||
3706 | Temporary breakpoint 1, main () at /tmp/hello.c:18 | |
3707 | 18 printf ("Hello World\n"); | |
3708 | (@value{GDBP}) python print(gdb.selected_inferior()._last_stop_time) | |
3709 | 2024-01-04 14:48:41.347036 | |
3710 | @end group | |
3711 | @end smallexample | |
3712 | ||
329baa95 DE |
3713 | @node Events In Python |
3714 | @subsubsection Events In Python | |
3715 | @cindex inferior events in Python | |
3716 | ||
3717 | @value{GDBN} provides a general event facility so that Python code can be | |
3718 | notified of various state changes, particularly changes that occur in | |
3719 | the inferior. | |
3720 | ||
3721 | An @dfn{event} is just an object that describes some state change. The | |
3722 | type of the object and its attributes will vary depending on the details | |
3723 | of the change. All the existing events are described below. | |
3724 | ||
3725 | In order to be notified of an event, you must register an event handler | |
3726 | with an @dfn{event registry}. An event registry is an object in the | |
3727 | @code{gdb.events} module which dispatches particular events. A registry | |
3728 | provides methods to register and unregister event handlers: | |
3729 | ||
3730 | @defun EventRegistry.connect (object) | |
3731 | Add the given callable @var{object} to the registry. This object will be | |
3732 | called when an event corresponding to this registry occurs. | |
3733 | @end defun | |
3734 | ||
3735 | @defun EventRegistry.disconnect (object) | |
3736 | Remove the given @var{object} from the registry. Once removed, the object | |
3737 | will no longer receive notifications of events. | |
3738 | @end defun | |
3739 | ||
3740 | Here is an example: | |
3741 | ||
3742 | @smallexample | |
3743 | def exit_handler (event): | |
f3bdc2db | 3744 | print ("event type: exit") |
1cb56ad3 AB |
3745 | if hasattr (event, 'exit_code'): |
3746 | print ("exit code: %d" % (event.exit_code)) | |
3747 | else: | |
3748 | print ("exit code not available") | |
329baa95 DE |
3749 | |
3750 | gdb.events.exited.connect (exit_handler) | |
3751 | @end smallexample | |
3752 | ||
3753 | In the above example we connect our handler @code{exit_handler} to the | |
3754 | registry @code{events.exited}. Once connected, @code{exit_handler} gets | |
3755 | called when the inferior exits. The argument @dfn{event} in this example is | |
3756 | of type @code{gdb.ExitedEvent}. As you can see in the example the | |
3757 | @code{ExitedEvent} object has an attribute which indicates the exit code of | |
3758 | the inferior. | |
3759 | ||
77d97a0a TT |
3760 | Some events can be thread specific when @value{GDBN} is running in |
3761 | non-stop mode. When represented in Python, these events all extend | |
3762 | @code{gdb.ThreadEvent}. This event is a base class and is never | |
3763 | emitted directly; instead, events which are emitted by this or other | |
3764 | modules might extend this event. Examples of these events are | |
3765 | @code{gdb.BreakpointEvent} and @code{gdb.ContinueEvent}. | |
3766 | @code{gdb.ThreadEvent} holds the following attributes: | |
329baa95 DE |
3767 | |
3768 | @defvar ThreadEvent.inferior_thread | |
3769 | In non-stop mode this attribute will be set to the specific thread which was | |
3770 | involved in the emitted event. Otherwise, it will be set to @code{None}. | |
3771 | @end defvar | |
3772 | ||
77d97a0a TT |
3773 | The following is a listing of the event registries that are available and |
3774 | details of the events they emit: | |
329baa95 | 3775 | |
77d97a0a TT |
3776 | @table @code |
3777 | ||
3778 | @item events.cont | |
3779 | Emits @code{gdb.ContinueEvent}, which extends @code{gdb.ThreadEvent}. | |
3780 | This event indicates that the inferior has been continued after a | |
3781 | stop. For inherited attribute refer to @code{gdb.ThreadEvent} above. | |
329baa95 DE |
3782 | |
3783 | @item events.exited | |
77d97a0a TT |
3784 | Emits @code{events.ExitedEvent}, which indicates that the inferior has |
3785 | exited. @code{events.ExitedEvent} has two attributes: | |
3786 | ||
329baa95 DE |
3787 | @defvar ExitedEvent.exit_code |
3788 | An integer representing the exit code, if available, which the inferior | |
3789 | has returned. (The exit code could be unavailable if, for example, | |
3790 | @value{GDBN} detaches from the inferior.) If the exit code is unavailable, | |
3791 | the attribute does not exist. | |
3792 | @end defvar | |
77d97a0a | 3793 | |
373832b6 | 3794 | @defvar ExitedEvent.inferior |
329baa95 DE |
3795 | A reference to the inferior which triggered the @code{exited} event. |
3796 | @end defvar | |
3797 | ||
3798 | @item events.stop | |
77d97a0a | 3799 | Emits @code{gdb.StopEvent}, which extends @code{gdb.ThreadEvent}. |
329baa95 | 3800 | |
77d97a0a TT |
3801 | Indicates that the inferior has stopped. All events emitted by this |
3802 | registry extend @code{gdb.StopEvent}. As a child of | |
3803 | @code{gdb.ThreadEvent}, @code{gdb.StopEvent} will indicate the stopped | |
3804 | thread when @value{GDBN} is running in non-stop mode. Refer to | |
3805 | @code{gdb.ThreadEvent} above for more details. | |
329baa95 | 3806 | |
e187e7c9 TT |
3807 | @code{gdb.StopEvent} has the following additional attributes: |
3808 | ||
3809 | @defvar StopEvent.details | |
3810 | A dictionary holding any details relevant to the stop. The exact keys | |
3811 | and values depend on the type of stop, but are identical to the | |
3812 | corresponding MI output (@pxref{GDB/MI Async Records}). | |
3813 | ||
3814 | A dictionary was used for this (rather than adding attributes directly | |
3815 | to the event object) so that the MI keys could be used unchanged. | |
3816 | @end defvar | |
3817 | ||
77d97a0a | 3818 | Emits @code{gdb.SignalEvent}, which extends @code{gdb.StopEvent}. |
329baa95 | 3819 | |
77d97a0a TT |
3820 | This event indicates that the inferior or one of its threads has |
3821 | received a signal. @code{gdb.SignalEvent} has the following | |
3822 | attributes: | |
329baa95 DE |
3823 | |
3824 | @defvar SignalEvent.stop_signal | |
3825 | A string representing the signal received by the inferior. A list of possible | |
3826 | signal values can be obtained by running the command @code{info signals} in | |
3827 | the @value{GDBN} command prompt. | |
3828 | @end defvar | |
3829 | ||
77d97a0a TT |
3830 | Also emits @code{gdb.BreakpointEvent}, which extends |
3831 | @code{gdb.StopEvent}. | |
329baa95 DE |
3832 | |
3833 | @code{gdb.BreakpointEvent} event indicates that one or more breakpoints have | |
3834 | been hit, and has the following attributes: | |
3835 | ||
3836 | @defvar BreakpointEvent.breakpoints | |
3837 | A sequence containing references to all the breakpoints (type | |
3838 | @code{gdb.Breakpoint}) that were hit. | |
3839 | @xref{Breakpoints In Python}, for details of the @code{gdb.Breakpoint} object. | |
3840 | @end defvar | |
77d97a0a | 3841 | |
329baa95 | 3842 | @defvar BreakpointEvent.breakpoint |
1c76a0e2 TT |
3843 | A reference to the first breakpoint that was hit. This attribute is |
3844 | maintained for backward compatibility and is now deprecated in favor | |
3845 | of the @code{gdb.BreakpointEvent.breakpoints} attribute. | |
329baa95 DE |
3846 | @end defvar |
3847 | ||
3848 | @item events.new_objfile | |
3849 | Emits @code{gdb.NewObjFileEvent} which indicates that a new object file has | |
3850 | been loaded by @value{GDBN}. @code{gdb.NewObjFileEvent} has one attribute: | |
3851 | ||
3852 | @defvar NewObjFileEvent.new_objfile | |
3853 | A reference to the object file (@code{gdb.Objfile}) which has been loaded. | |
3854 | @xref{Objfiles In Python}, for details of the @code{gdb.Objfile} object. | |
3855 | @end defvar | |
3856 | ||
0b4fe76f TT |
3857 | @item events.free_objfile |
3858 | Emits @code{gdb.FreeObjFileEvent} which indicates that an object file | |
3859 | is about to be removed from @value{GDBN}. One reason this can happen | |
3860 | is when the inferior calls @code{dlclose}. | |
3861 | @code{gdb.FreeObjFileEvent} has one attribute: | |
3862 | ||
079e7983 | 3863 | @defvar FreeObjFileEvent.objfile |
0b4fe76f TT |
3864 | A reference to the object file (@code{gdb.Objfile}) which will be unloaded. |
3865 | @xref{Objfiles In Python}, for details of the @code{gdb.Objfile} object. | |
3866 | @end defvar | |
3867 | ||
4ffbba72 DE |
3868 | @item events.clear_objfiles |
3869 | Emits @code{gdb.ClearObjFilesEvent} which indicates that the list of object | |
3870 | files for a program space has been reset. | |
3871 | @code{gdb.ClearObjFilesEvent} has one attribute: | |
3872 | ||
3873 | @defvar ClearObjFilesEvent.progspace | |
3874 | A reference to the program space (@code{gdb.Progspace}) whose objfile list has | |
3875 | been cleared. @xref{Progspaces In Python}. | |
3876 | @end defvar | |
3877 | ||
fb5af5e3 TT |
3878 | @item events.inferior_call |
3879 | Emits events just before and after a function in the inferior is | |
3880 | called by @value{GDBN}. Before an inferior call, this emits an event | |
3881 | of type @code{gdb.InferiorCallPreEvent}, and after an inferior call, | |
3882 | this emits an event of type @code{gdb.InferiorCallPostEvent}. | |
3883 | ||
3884 | @table @code | |
3885 | @tindex gdb.InferiorCallPreEvent | |
3886 | @item @code{gdb.InferiorCallPreEvent} | |
3887 | Indicates that a function in the inferior is about to be called. | |
162078c8 NB |
3888 | |
3889 | @defvar InferiorCallPreEvent.ptid | |
3890 | The thread in which the call will be run. | |
3891 | @end defvar | |
3892 | ||
3893 | @defvar InferiorCallPreEvent.address | |
3894 | The location of the function to be called. | |
3895 | @end defvar | |
3896 | ||
fb5af5e3 TT |
3897 | @tindex gdb.InferiorCallPostEvent |
3898 | @item @code{gdb.InferiorCallPostEvent} | |
3899 | Indicates that a function in the inferior has just been called. | |
162078c8 NB |
3900 | |
3901 | @defvar InferiorCallPostEvent.ptid | |
3902 | The thread in which the call was run. | |
3903 | @end defvar | |
3904 | ||
3905 | @defvar InferiorCallPostEvent.address | |
3906 | The location of the function that was called. | |
3907 | @end defvar | |
fb5af5e3 | 3908 | @end table |
162078c8 NB |
3909 | |
3910 | @item events.memory_changed | |
3911 | Emits @code{gdb.MemoryChangedEvent} which indicates that the memory of the | |
3912 | inferior has been modified by the @value{GDBN} user, for instance via a | |
3913 | command like @w{@code{set *addr = value}}. The event has the following | |
3914 | attributes: | |
3915 | ||
3916 | @defvar MemoryChangedEvent.address | |
3917 | The start address of the changed region. | |
3918 | @end defvar | |
3919 | ||
3920 | @defvar MemoryChangedEvent.length | |
3921 | Length in bytes of the changed region. | |
3922 | @end defvar | |
3923 | ||
3924 | @item events.register_changed | |
3925 | Emits @code{gdb.RegisterChangedEvent} which indicates that a register in the | |
3926 | inferior has been modified by the @value{GDBN} user. | |
3927 | ||
3928 | @defvar RegisterChangedEvent.frame | |
3929 | A gdb.Frame object representing the frame in which the register was modified. | |
3930 | @end defvar | |
3931 | @defvar RegisterChangedEvent.regnum | |
3932 | Denotes which register was modified. | |
3933 | @end defvar | |
3934 | ||
dac790e1 TT |
3935 | @item events.breakpoint_created |
3936 | This is emitted when a new breakpoint has been created. The argument | |
3937 | that is passed is the new @code{gdb.Breakpoint} object. | |
3938 | ||
3939 | @item events.breakpoint_modified | |
3940 | This is emitted when a breakpoint has been modified in some way. The | |
3941 | argument that is passed is the new @code{gdb.Breakpoint} object. | |
3942 | ||
3943 | @item events.breakpoint_deleted | |
3944 | This is emitted when a breakpoint has been deleted. The argument that | |
3945 | is passed is the @code{gdb.Breakpoint} object. When this event is | |
3946 | emitted, the @code{gdb.Breakpoint} object will already be in its | |
3947 | invalid state; that is, the @code{is_valid} method will return | |
3948 | @code{False}. | |
3949 | ||
3f77c769 TT |
3950 | @item events.before_prompt |
3951 | This event carries no payload. It is emitted each time @value{GDBN} | |
3952 | presents a prompt to the user. | |
3953 | ||
7c96f8c1 TT |
3954 | @item events.new_inferior |
3955 | This is emitted when a new inferior is created. Note that the | |
3956 | inferior is not necessarily running; in fact, it may not even have an | |
3957 | associated executable. | |
3958 | ||
3959 | The event is of type @code{gdb.NewInferiorEvent}. This has a single | |
3960 | attribute: | |
3961 | ||
3962 | @defvar NewInferiorEvent.inferior | |
3963 | The new inferior, a @code{gdb.Inferior} object. | |
3964 | @end defvar | |
3965 | ||
3966 | @item events.inferior_deleted | |
3967 | This is emitted when an inferior has been deleted. Note that this is | |
3968 | not the same as process exit; it is notified when the inferior itself | |
3969 | is removed, say via @code{remove-inferiors}. | |
3970 | ||
3971 | The event is of type @code{gdb.InferiorDeletedEvent}. This has a single | |
3972 | attribute: | |
3973 | ||
77d97a0a | 3974 | @defvar InferiorDeletedEvent.inferior |
7c96f8c1 TT |
3975 | The inferior that is being removed, a @code{gdb.Inferior} object. |
3976 | @end defvar | |
3977 | ||
3978 | @item events.new_thread | |
3979 | This is emitted when @value{GDBN} notices a new thread. The event is of | |
3980 | type @code{gdb.NewThreadEvent}, which extends @code{gdb.ThreadEvent}. | |
3981 | This has a single attribute: | |
3982 | ||
3983 | @defvar NewThreadEvent.inferior_thread | |
3984 | The new thread. | |
3985 | @end defvar | |
3986 | ||
28ab5960 SF |
3987 | @item events.thread_exited |
3988 | This is emitted when @value{GDBN} notices a thread has exited. The event | |
3989 | is of type @code{gdb.ThreadExitedEvent} which extends @code{gdb.ThreadEvent}. | |
3990 | This has a single attribute: | |
3991 | ||
3992 | @defvar ThreadExitedEvent.inferior_thread | |
3993 | The exiting thread. | |
3994 | @end defvar | |
3995 | ||
b1f0f284 AB |
3996 | @item events.gdb_exiting |
3997 | This is emitted when @value{GDBN} exits. This event is not emitted if | |
3998 | @value{GDBN} exits as a result of an internal error, or after an | |
3999 | unexpected signal. The event is of type @code{gdb.GdbExitingEvent}, | |
4000 | which has a single attribute: | |
4001 | ||
4002 | @defvar GdbExitingEvent.exit_code | |
4003 | An integer, the value of the exit code @value{GDBN} will return. | |
4004 | @end defvar | |
4005 | ||
0e3b7c25 AB |
4006 | @item events.connection_removed |
4007 | This is emitted when @value{GDBN} removes a connection | |
4008 | (@pxref{Connections In Python}). The event is of type | |
4009 | @code{gdb.ConnectionEvent}. This has a single read-only attribute: | |
4010 | ||
4011 | @defvar ConnectionEvent.connection | |
4012 | The @code{gdb.TargetConnection} that is being removed. | |
4013 | @end defvar | |
4014 | ||
42f297ad AB |
4015 | @item events.executable_changed |
4016 | Emits @code{gdb.ExecutableChangedEvent} which indicates that the | |
4017 | @code{gdb.Progspace.executable_filename} has changed. | |
4018 | ||
4019 | This event is emitted when either the value of | |
4020 | @code{gdb.Progspace.executable_filename } has changed to name a | |
4021 | different file, or the executable file named by | |
4022 | @code{gdb.Progspace.executable_filename} has changed on disk, and | |
4023 | @value{GDBN} has therefore reloaded it. | |
4024 | ||
4025 | @defvar ExecutableChangedEvent.progspace | |
4026 | The @code{gdb.Progspace} in which the current executable has changed. | |
4027 | The file name of the updated executable will be visible in | |
4028 | @code{gdb.Progspace.executable_filename} (@pxref{Progspaces In Python}). | |
4029 | @end defvar | |
4030 | @defvar ExecutableChangedEvent.reload | |
4031 | This attribute will be @code{True} if the value of | |
4032 | @code{gdb.Progspace.executable_filename} didn't change, but the file | |
4033 | it names changed on disk instead, and @value{GDBN} reloaded it. | |
4034 | ||
4035 | When this attribute is @code{False}, the value in | |
4036 | @code{gdb.Progspace.executable_filename} was changed to name a | |
4037 | different file. | |
4038 | @end defvar | |
4039 | ||
4040 | Remember that @value{GDBN} tracks the executable file and the symbol | |
4041 | file separately, these are visible as | |
4042 | @code{gdb.Progspace.executable_filename} and | |
4043 | @code{gdb.Progspace.filename} respectively. When using the @kbd{file} | |
4044 | command, @value{GDBN} updates both of these fields, but the executable | |
4045 | file is updated first, so when this event is emitted, the executable | |
4046 | filename will have changed, but the symbol filename might still hold | |
4047 | its previous value. | |
59912fb2 AB |
4048 | |
4049 | @item events.new_progspace | |
4050 | This is emitted when @value{GDBN} adds a new program space | |
4051 | (@pxref{Progspaces In Python,,Program Spaces In Python}). The event | |
4052 | is of type @code{gdb.NewProgspaceEvent}, and has a single read-only | |
4053 | attribute: | |
4054 | ||
4055 | @defvar NewProgspaceEvent.progspace | |
4056 | The @code{gdb.Progspace} that was added to @value{GDBN}. | |
4057 | @end defvar | |
4058 | ||
4059 | No @code{NewProgspaceEvent} is emitted for the very first program | |
4060 | space, which is assigned to the first inferior. This first program | |
4061 | space is created within @value{GDBN} before any Python scripts are | |
4062 | sourced. | |
4063 | ||
4064 | @item events.free_progspace | |
4065 | This is emitted when @value{GDBN} removes a program space | |
4066 | (@pxref{Progspaces In Python,,Program Spaces In Python}), for example | |
4067 | as a result of the @kbd{remove-inferiors} command | |
4068 | (@pxref{remove_inferiors_cli,,@kbd{remove-inferiors}}). The event is | |
4069 | of type @code{gdb.FreeProgspaceEvent}, and has a single read-only | |
4070 | attribute: | |
4071 | ||
4072 | @defvar FreeProgspaceEvent.progspace | |
4073 | The @code{gdb.Progspace} that is about to be removed from | |
4074 | @value{GDBN}. | |
4075 | @end defvar | |
4076 | ||
329baa95 DE |
4077 | @end table |
4078 | ||
4079 | @node Threads In Python | |
4080 | @subsubsection Threads In Python | |
4081 | @cindex threads in python | |
4082 | ||
4083 | @findex gdb.InferiorThread | |
4084 | Python scripts can access information about, and manipulate inferior threads | |
4085 | controlled by @value{GDBN}, via objects of the @code{gdb.InferiorThread} class. | |
4086 | ||
4087 | The following thread-related functions are available in the @code{gdb} | |
4088 | module: | |
4089 | ||
329baa95 DE |
4090 | @defun gdb.selected_thread () |
4091 | This function returns the thread object for the selected thread. If there | |
4092 | is no selected thread, this will return @code{None}. | |
4093 | @end defun | |
4094 | ||
14796d29 | 4095 | To get the list of threads for an inferior, use the @code{Inferior.threads()} |
0ca4866a | 4096 | method. @xref{Inferiors In Python}. |
14796d29 | 4097 | |
329baa95 DE |
4098 | A @code{gdb.InferiorThread} object has the following attributes: |
4099 | ||
4100 | @defvar InferiorThread.name | |
4101 | The name of the thread. If the user specified a name using | |
4102 | @code{thread name}, then this returns that name. Otherwise, if an | |
4103 | OS-supplied name is available, then it is returned. Otherwise, this | |
4104 | returns @code{None}. | |
4105 | ||
4106 | This attribute can be assigned to. The new value must be a string | |
4107 | object, which sets the new name, or @code{None}, which removes any | |
4108 | user-specified thread name. | |
4109 | @end defvar | |
4110 | ||
4111 | @defvar InferiorThread.num | |
5d5658a1 | 4112 | The per-inferior number of the thread, as assigned by GDB. |
329baa95 DE |
4113 | @end defvar |
4114 | ||
22a02324 PA |
4115 | @defvar InferiorThread.global_num |
4116 | The global ID of the thread, as assigned by GDB. You can use this to | |
4117 | make Python breakpoints thread-specific, for example | |
4118 | (@pxref{python_breakpoint_thread,,The Breakpoint.thread attribute}). | |
4119 | @end defvar | |
4120 | ||
28ab5960 | 4121 | @anchor{inferior_thread_ptid} |
329baa95 DE |
4122 | @defvar InferiorThread.ptid |
4123 | ID of the thread, as assigned by the operating system. This attribute is a | |
4124 | tuple containing three integers. The first is the Process ID (PID); the second | |
4125 | is the Lightweight Process ID (LWPID), and the third is the Thread ID (TID). | |
4126 | Either the LWPID or TID may be 0, which indicates that the operating system | |
4127 | does not use that identifier. | |
4128 | @end defvar | |
4129 | ||
76118e16 AB |
4130 | @defvar InferiorThread.ptid_string |
4131 | This read-only attribute contains a string representing | |
4132 | @code{InferiorThread.ptid}. This is the string that @value{GDBN} uses | |
4133 | in the @samp{Target Id} column in the @kbd{info threads} output | |
4134 | (@pxref{info_threads,,@samp{info threads}}). | |
4135 | @end defvar | |
4136 | ||
84654457 PA |
4137 | @defvar InferiorThread.inferior |
4138 | The inferior this thread belongs to. This attribute is represented as | |
4139 | a @code{gdb.Inferior} object. This attribute is not writable. | |
4140 | @end defvar | |
4141 | ||
659971cb AB |
4142 | @defvar InferiorThread.details |
4143 | A string containing target specific thread state information. The | |
4144 | format of this string varies by target. If there is no additional | |
4145 | state information for this thread, then this attribute contains | |
4146 | @code{None}. | |
4147 | ||
4148 | For example, on a @sc{gnu}/Linux system, a thread that is in the | |
4149 | process of exiting will return the string @samp{Exiting}. For remote | |
4150 | targets the @code{details} string will be obtained with the | |
4151 | @samp{qThreadExtraInfo} remote packet, if the target supports it | |
4152 | (@pxref{qThreadExtraInfo,,@samp{qThreadExtraInfo}}). | |
4153 | ||
4154 | @value{GDBN} displays the @code{details} string as part of the | |
4155 | @samp{Target Id} column, in the @code{info threads} output | |
4156 | (@pxref{info_threads,,@samp{info threads}}). | |
4157 | @end defvar | |
4158 | ||
329baa95 DE |
4159 | A @code{gdb.InferiorThread} object has the following methods: |
4160 | ||
4161 | @defun InferiorThread.is_valid () | |
4162 | Returns @code{True} if the @code{gdb.InferiorThread} object is valid, | |
4163 | @code{False} if not. A @code{gdb.InferiorThread} object will become | |
4164 | invalid if the thread exits, or the inferior that the thread belongs | |
4165 | is deleted. All other @code{gdb.InferiorThread} methods will throw an | |
4166 | exception if it is invalid at the time the method is called. | |
4167 | @end defun | |
4168 | ||
4169 | @defun InferiorThread.switch () | |
4170 | This changes @value{GDBN}'s currently selected thread to the one represented | |
4171 | by this object. | |
4172 | @end defun | |
4173 | ||
4174 | @defun InferiorThread.is_stopped () | |
4175 | Return a Boolean indicating whether the thread is stopped. | |
4176 | @end defun | |
4177 | ||
4178 | @defun InferiorThread.is_running () | |
4179 | Return a Boolean indicating whether the thread is running. | |
4180 | @end defun | |
4181 | ||
4182 | @defun InferiorThread.is_exited () | |
4183 | Return a Boolean indicating whether the thread is exited. | |
4184 | @end defun | |
4185 | ||
c369f8f0 KB |
4186 | @defun InferiorThread.handle () |
4187 | Return the thread object's handle, represented as a Python @code{bytes} | |
4188 | object. A @code{gdb.Value} representation of the handle may be | |
4189 | constructed via @code{gdb.Value(bufobj, type)} where @var{bufobj} is | |
4190 | the Python @code{bytes} representation of the handle and @var{type} is | |
4191 | a @code{gdb.Type} for the handle type. | |
4192 | @end defun | |
4193 | ||
1d586eda AB |
4194 | One may add arbitrary attributes to @code{gdb.InferiorThread} objects |
4195 | in the usual Python way. This is useful if, for example, one needs to | |
4196 | do some extra record keeping associated with the thread. | |
4197 | ||
53d08890 AB |
4198 | @xref{choosing attribute names}, for guidance on selecting a suitable |
4199 | name for new attributes. | |
4200 | ||
1d586eda AB |
4201 | In this contrived example we record the time when a thread last |
4202 | stopped: | |
4203 | ||
4204 | @smallexample | |
4205 | @group | |
4206 | (@value{GDBP}) python | |
4207 | import datetime | |
4208 | ||
4209 | def thread_stopped(event): | |
4210 | if event.inferior_thread is not None: | |
4211 | thread = event.inferior_thread | |
4212 | else: | |
4213 | thread = gdb.selected_thread() | |
4214 | thread._last_stop_time = datetime.datetime.today() | |
4215 | ||
4216 | gdb.events.stop.connect(thread_stopped) | |
4217 | @end group | |
4218 | @group | |
4219 | (@value{GDBP}) file /tmp/hello | |
4220 | Reading symbols from /tmp/hello... | |
4221 | (@value{GDBP}) start | |
4222 | Temporary breakpoint 1 at 0x401198: file /tmp/hello.c, line 18. | |
4223 | Starting program: /tmp/hello | |
4224 | ||
4225 | Temporary breakpoint 1, main () at /tmp/hello.c:18 | |
4226 | 18 printf ("Hello World\n"); | |
4227 | (@value{GDBP}) python print(gdb.selected_thread()._last_stop_time) | |
4228 | 2024-01-04 14:48:41.347036 | |
4229 | @end group | |
4230 | @end smallexample | |
4231 | ||
0a0faf9f TW |
4232 | @node Recordings In Python |
4233 | @subsubsection Recordings In Python | |
4234 | @cindex recordings in python | |
4235 | ||
4236 | The following recordings-related functions | |
4237 | (@pxref{Process Record and Replay}) are available in the @code{gdb} | |
4238 | module: | |
4239 | ||
4240 | @defun gdb.start_recording (@r{[}method@r{]}, @r{[}format@r{]}) | |
4241 | Start a recording using the given @var{method} and @var{format}. If | |
4242 | no @var{format} is given, the default format for the recording method | |
4243 | is used. If no @var{method} is given, the default method will be used. | |
4244 | Returns a @code{gdb.Record} object on success. Throw an exception on | |
4245 | failure. | |
4246 | ||
4247 | The following strings can be passed as @var{method}: | |
4248 | ||
4249 | @itemize @bullet | |
4250 | @item | |
4251 | @code{"full"} | |
4252 | @item | |
4253 | @code{"btrace"}: Possible values for @var{format}: @code{"pt"}, | |
4254 | @code{"bts"} or leave out for default format. | |
4255 | @end itemize | |
4256 | @end defun | |
4257 | ||
4258 | @defun gdb.current_recording () | |
4259 | Access a currently running recording. Return a @code{gdb.Record} | |
4260 | object on success. Return @code{None} if no recording is currently | |
4261 | active. | |
4262 | @end defun | |
4263 | ||
4264 | @defun gdb.stop_recording () | |
4265 | Stop the current recording. Throw an exception if no recording is | |
4266 | currently active. All record objects become invalid after this call. | |
4267 | @end defun | |
4268 | ||
4269 | A @code{gdb.Record} object has the following attributes: | |
4270 | ||
0a0faf9f TW |
4271 | @defvar Record.method |
4272 | A string with the current recording method, e.g.@: @code{full} or | |
4273 | @code{btrace}. | |
4274 | @end defvar | |
4275 | ||
4276 | @defvar Record.format | |
4277 | A string with the current recording format, e.g.@: @code{bt}, @code{pts} or | |
4278 | @code{None}. | |
4279 | @end defvar | |
4280 | ||
4281 | @defvar Record.begin | |
4282 | A method specific instruction object representing the first instruction | |
4283 | in this recording. | |
4284 | @end defvar | |
4285 | ||
4286 | @defvar Record.end | |
4287 | A method specific instruction object representing the current | |
4288 | instruction, that is not actually part of the recording. | |
4289 | @end defvar | |
4290 | ||
4291 | @defvar Record.replay_position | |
4292 | The instruction representing the current replay position. If there is | |
4293 | no replay active, this will be @code{None}. | |
4294 | @end defvar | |
4295 | ||
4296 | @defvar Record.instruction_history | |
4297 | A list with all recorded instructions. | |
4298 | @end defvar | |
4299 | ||
4300 | @defvar Record.function_call_history | |
4301 | A list with all recorded function call segments. | |
4302 | @end defvar | |
4303 | ||
4304 | A @code{gdb.Record} object has the following methods: | |
4305 | ||
4306 | @defun Record.goto (instruction) | |
4307 | Move the replay position to the given @var{instruction}. | |
4308 | @end defun | |
4309 | ||
d050f7d7 TW |
4310 | The common @code{gdb.Instruction} class that recording method specific |
4311 | instruction objects inherit from, has the following attributes: | |
0a0faf9f | 4312 | |
d050f7d7 | 4313 | @defvar Instruction.pc |
913aeadd | 4314 | An integer representing this instruction's address. |
0a0faf9f TW |
4315 | @end defvar |
4316 | ||
d050f7d7 | 4317 | @defvar Instruction.data |
914a96d7 | 4318 | A @code{memoryview} object holding the raw instruction data. |
0a0faf9f TW |
4319 | @end defvar |
4320 | ||
d050f7d7 | 4321 | @defvar Instruction.decoded |
913aeadd | 4322 | A human readable string with the disassembled instruction. |
0a0faf9f TW |
4323 | @end defvar |
4324 | ||
d050f7d7 | 4325 | @defvar Instruction.size |
913aeadd | 4326 | The size of the instruction in bytes. |
0a0faf9f TW |
4327 | @end defvar |
4328 | ||
d050f7d7 TW |
4329 | Additionally @code{gdb.RecordInstruction} has the following attributes: |
4330 | ||
4331 | @defvar RecordInstruction.number | |
4332 | An integer identifying this instruction. @code{number} corresponds to | |
4333 | the numbers seen in @code{record instruction-history} | |
4334 | (@pxref{Process Record and Replay}). | |
4335 | @end defvar | |
4336 | ||
4337 | @defvar RecordInstruction.sal | |
4338 | A @code{gdb.Symtab_and_line} object representing the associated symtab | |
4339 | and line of this instruction. May be @code{None} if no debug information is | |
4340 | available. | |
4341 | @end defvar | |
4342 | ||
0ed5da75 | 4343 | @defvar RecordInstruction.is_speculative |
d050f7d7 | 4344 | A boolean indicating whether the instruction was executed speculatively. |
913aeadd TW |
4345 | @end defvar |
4346 | ||
33b5899f | 4347 | If an error occurred during recording or decoding a recording, this error is |
913aeadd TW |
4348 | represented by a @code{gdb.RecordGap} object in the instruction list. It has |
4349 | the following attributes: | |
4350 | ||
4351 | @defvar RecordGap.number | |
4352 | An integer identifying this gap. @code{number} corresponds to the numbers seen | |
4353 | in @code{record instruction-history} (@pxref{Process Record and Replay}). | |
4354 | @end defvar | |
4355 | ||
4356 | @defvar RecordGap.error_code | |
4357 | A numerical representation of the reason for the gap. The value is specific to | |
4358 | the current recording method. | |
4359 | @end defvar | |
4360 | ||
4361 | @defvar RecordGap.error_string | |
4362 | A human readable string with the reason for the gap. | |
0a0faf9f TW |
4363 | @end defvar |
4364 | ||
14f819c8 | 4365 | A @code{gdb.RecordFunctionSegment} object has the following attributes: |
0a0faf9f | 4366 | |
14f819c8 TW |
4367 | @defvar RecordFunctionSegment.number |
4368 | An integer identifying this function segment. @code{number} corresponds to | |
0a0faf9f TW |
4369 | the numbers seen in @code{record function-call-history} |
4370 | (@pxref{Process Record and Replay}). | |
4371 | @end defvar | |
4372 | ||
14f819c8 | 4373 | @defvar RecordFunctionSegment.symbol |
0a0faf9f | 4374 | A @code{gdb.Symbol} object representing the associated symbol. May be |
14f819c8 | 4375 | @code{None} if no debug information is available. |
0a0faf9f TW |
4376 | @end defvar |
4377 | ||
14f819c8 | 4378 | @defvar RecordFunctionSegment.level |
0a0faf9f TW |
4379 | An integer representing the function call's stack level. May be |
4380 | @code{None} if the function call is a gap. | |
4381 | @end defvar | |
4382 | ||
14f819c8 | 4383 | @defvar RecordFunctionSegment.instructions |
0ed5da75 | 4384 | A list of @code{gdb.RecordInstruction} or @code{gdb.RecordGap} objects |
913aeadd | 4385 | associated with this function call. |
0a0faf9f TW |
4386 | @end defvar |
4387 | ||
14f819c8 TW |
4388 | @defvar RecordFunctionSegment.up |
4389 | A @code{gdb.RecordFunctionSegment} object representing the caller's | |
0a0faf9f TW |
4390 | function segment. If the call has not been recorded, this will be the |
4391 | function segment to which control returns. If neither the call nor the | |
4392 | return have been recorded, this will be @code{None}. | |
4393 | @end defvar | |
4394 | ||
14f819c8 TW |
4395 | @defvar RecordFunctionSegment.prev |
4396 | A @code{gdb.RecordFunctionSegment} object representing the previous | |
0a0faf9f TW |
4397 | segment of this function call. May be @code{None}. |
4398 | @end defvar | |
4399 | ||
14f819c8 TW |
4400 | @defvar RecordFunctionSegment.next |
4401 | A @code{gdb.RecordFunctionSegment} object representing the next segment of | |
0a0faf9f TW |
4402 | this function call. May be @code{None}. |
4403 | @end defvar | |
4404 | ||
4405 | The following example demonstrates the usage of these objects and | |
4406 | functions to create a function that will rewind a record to the last | |
4407 | time a function in a different file was executed. This would typically | |
4408 | be used to track the execution of user provided callback functions in a | |
4409 | library which typically are not visible in a back trace. | |
4410 | ||
4411 | @smallexample | |
4412 | def bringback (): | |
4413 | rec = gdb.current_recording () | |
4414 | if not rec: | |
4415 | return | |
4416 | ||
4417 | insn = rec.instruction_history | |
4418 | if len (insn) == 0: | |
4419 | return | |
4420 | ||
4421 | try: | |
4422 | position = insn.index (rec.replay_position) | |
4423 | except: | |
4424 | position = -1 | |
4425 | try: | |
4426 | filename = insn[position].sal.symtab.fullname () | |
4427 | except: | |
4428 | filename = None | |
4429 | ||
4430 | for i in reversed (insn[:position]): | |
4431 | try: | |
4432 | current = i.sal.symtab.fullname () | |
4433 | except: | |
4434 | current = None | |
4435 | ||
4436 | if filename == current: | |
4437 | continue | |
4438 | ||
4439 | rec.goto (i) | |
4440 | return | |
4441 | @end smallexample | |
4442 | ||
4443 | Another possible application is to write a function that counts the | |
4444 | number of code executions in a given line range. This line range can | |
4445 | contain parts of functions or span across several functions and is not | |
4446 | limited to be contiguous. | |
4447 | ||
4448 | @smallexample | |
4449 | def countrange (filename, linerange): | |
4450 | count = 0 | |
4451 | ||
4452 | def filter_only (file_name): | |
4453 | for call in gdb.current_recording ().function_call_history: | |
4454 | try: | |
4455 | if file_name in call.symbol.symtab.fullname (): | |
4456 | yield call | |
4457 | except: | |
4458 | pass | |
4459 | ||
4460 | for c in filter_only (filename): | |
4461 | for i in c.instructions: | |
4462 | try: | |
4463 | if i.sal.line in linerange: | |
4464 | count += 1 | |
4465 | break; | |
4466 | except: | |
4467 | pass | |
4468 | ||
4469 | return count | |
4470 | @end smallexample | |
4471 | ||
740b42ce AB |
4472 | @node CLI Commands In Python |
4473 | @subsubsection CLI Commands In Python | |
329baa95 | 4474 | |
740b42ce AB |
4475 | @cindex CLI commands in python |
4476 | @cindex commands in python, CLI | |
4477 | @cindex python commands, CLI | |
329baa95 DE |
4478 | You can implement new @value{GDBN} CLI commands in Python. A CLI |
4479 | command is implemented using an instance of the @code{gdb.Command} | |
4480 | class, most commonly using a subclass. | |
4481 | ||
ebb83b77 | 4482 | @defun Command.__init__ (name, command_class @r{[}, completer_class @r{[}, prefix@r{]]}) |
329baa95 DE |
4483 | The object initializer for @code{Command} registers the new command |
4484 | with @value{GDBN}. This initializer is normally invoked from the | |
4485 | subclass' own @code{__init__} method. | |
4486 | ||
4487 | @var{name} is the name of the command. If @var{name} consists of | |
4488 | multiple words, then the initial words are looked for as prefix | |
4489 | commands. In this case, if one of the prefix commands does not exist, | |
4490 | an exception is raised. | |
4491 | ||
4492 | There is no support for multi-line commands. | |
4493 | ||
4494 | @var{command_class} should be one of the @samp{COMMAND_} constants | |
4495 | defined below. This argument tells @value{GDBN} how to categorize the | |
4496 | new command in the help system. | |
4497 | ||
4498 | @var{completer_class} is an optional argument. If given, it should be | |
4499 | one of the @samp{COMPLETE_} constants defined below. This argument | |
4500 | tells @value{GDBN} how to perform completion for this command. If not | |
4501 | given, @value{GDBN} will attempt to complete using the object's | |
4502 | @code{complete} method (see below); if no such method is found, an | |
4503 | error will occur when completion is attempted. | |
4504 | ||
4505 | @var{prefix} is an optional argument. If @code{True}, then the new | |
4506 | command is a prefix command; sub-commands of this command may be | |
4507 | registered. | |
4508 | ||
4509 | The help text for the new command is taken from the Python | |
4510 | documentation string for the command's class, if there is one. If no | |
4511 | documentation string is provided, the default value ``This command is | |
4512 | not documented.'' is used. | |
4513 | @end defun | |
4514 | ||
4515 | @cindex don't repeat Python command | |
4516 | @defun Command.dont_repeat () | |
4517 | By default, a @value{GDBN} command is repeated when the user enters a | |
4518 | blank line at the command prompt. A command can suppress this | |
285dfa0f TT |
4519 | behavior by invoking the @code{dont_repeat} method at some point in |
4520 | its @code{invoke} method (normally this is done early in case of | |
4521 | exception). This is similar to the user command @code{dont-repeat}, | |
4522 | see @ref{Define, dont-repeat}. | |
329baa95 DE |
4523 | @end defun |
4524 | ||
4525 | @defun Command.invoke (argument, from_tty) | |
4526 | This method is called by @value{GDBN} when this command is invoked. | |
4527 | ||
4528 | @var{argument} is a string. It is the argument to the command, after | |
4529 | leading and trailing whitespace has been stripped. | |
4530 | ||
4531 | @var{from_tty} is a boolean argument. When true, this means that the | |
4532 | command was entered by the user at the terminal; when false it means | |
4533 | that the command came from elsewhere. | |
4534 | ||
4535 | If this method throws an exception, it is turned into a @value{GDBN} | |
4536 | @code{error} call. Otherwise, the return value is ignored. | |
4537 | ||
4538 | @findex gdb.string_to_argv | |
4539 | To break @var{argument} up into an argv-like string use | |
4540 | @code{gdb.string_to_argv}. This function behaves identically to | |
4541 | @value{GDBN}'s internal argument lexer @code{buildargv}. | |
4542 | It is recommended to use this for consistency. | |
4543 | Arguments are separated by spaces and may be quoted. | |
4544 | Example: | |
4545 | ||
4546 | @smallexample | |
4547 | print gdb.string_to_argv ("1 2\ \\\"3 '4 \"5' \"6 '7\"") | |
4548 | ['1', '2 "3', '4 "5', "6 '7"] | |
4549 | @end smallexample | |
4550 | ||
4551 | @end defun | |
4552 | ||
4553 | @cindex completion of Python commands | |
4554 | @defun Command.complete (text, word) | |
4555 | This method is called by @value{GDBN} when the user attempts | |
4556 | completion on this command. All forms of completion are handled by | |
4557 | this method, that is, the @key{TAB} and @key{M-?} key bindings | |
4558 | (@pxref{Completion}), and the @code{complete} command (@pxref{Help, | |
4559 | complete}). | |
4560 | ||
697aa1b7 EZ |
4561 | The arguments @var{text} and @var{word} are both strings; @var{text} |
4562 | holds the complete command line up to the cursor's location, while | |
329baa95 DE |
4563 | @var{word} holds the last word of the command line; this is computed |
4564 | using a word-breaking heuristic. | |
4565 | ||
4566 | The @code{complete} method can return several values: | |
4567 | @itemize @bullet | |
4568 | @item | |
4569 | If the return value is a sequence, the contents of the sequence are | |
4570 | used as the completions. It is up to @code{complete} to ensure that the | |
4571 | contents actually do complete the word. A zero-length sequence is | |
4572 | allowed, it means that there were no completions available. Only | |
4573 | string elements of the sequence are used; other elements in the | |
4574 | sequence are ignored. | |
4575 | ||
4576 | @item | |
4577 | If the return value is one of the @samp{COMPLETE_} constants defined | |
4578 | below, then the corresponding @value{GDBN}-internal completion | |
4579 | function is invoked, and its result is used. | |
4580 | ||
4581 | @item | |
4582 | All other results are treated as though there were no available | |
4583 | completions. | |
4584 | @end itemize | |
4585 | @end defun | |
4586 | ||
4587 | When a new command is registered, it must be declared as a member of | |
4588 | some general class of commands. This is used to classify top-level | |
4589 | commands in the on-line help system; note that prefix commands are not | |
4590 | listed under their own category but rather that of their top-level | |
4591 | command. The available classifications are represented by constants | |
4592 | defined in the @code{gdb} module: | |
4593 | ||
4594 | @table @code | |
4595 | @findex COMMAND_NONE | |
4596 | @findex gdb.COMMAND_NONE | |
4597 | @item gdb.COMMAND_NONE | |
4598 | The command does not belong to any particular class. A command in | |
4599 | this category will not be displayed in any of the help categories. | |
4600 | ||
4601 | @findex COMMAND_RUNNING | |
4602 | @findex gdb.COMMAND_RUNNING | |
4603 | @item gdb.COMMAND_RUNNING | |
4604 | The command is related to running the inferior. For example, | |
4605 | @code{start}, @code{step}, and @code{continue} are in this category. | |
4606 | Type @kbd{help running} at the @value{GDBN} prompt to see a list of | |
4607 | commands in this category. | |
4608 | ||
4609 | @findex COMMAND_DATA | |
4610 | @findex gdb.COMMAND_DATA | |
4611 | @item gdb.COMMAND_DATA | |
4612 | The command is related to data or variables. For example, | |
4613 | @code{call}, @code{find}, and @code{print} are in this category. Type | |
4614 | @kbd{help data} at the @value{GDBN} prompt to see a list of commands | |
4615 | in this category. | |
4616 | ||
4617 | @findex COMMAND_STACK | |
4618 | @findex gdb.COMMAND_STACK | |
4619 | @item gdb.COMMAND_STACK | |
4620 | The command has to do with manipulation of the stack. For example, | |
4621 | @code{backtrace}, @code{frame}, and @code{return} are in this | |
4622 | category. Type @kbd{help stack} at the @value{GDBN} prompt to see a | |
4623 | list of commands in this category. | |
4624 | ||
4625 | @findex COMMAND_FILES | |
4626 | @findex gdb.COMMAND_FILES | |
4627 | @item gdb.COMMAND_FILES | |
4628 | This class is used for file-related commands. For example, | |
4629 | @code{file}, @code{list} and @code{section} are in this category. | |
4630 | Type @kbd{help files} at the @value{GDBN} prompt to see a list of | |
4631 | commands in this category. | |
4632 | ||
4633 | @findex COMMAND_SUPPORT | |
4634 | @findex gdb.COMMAND_SUPPORT | |
4635 | @item gdb.COMMAND_SUPPORT | |
4636 | This should be used for ``support facilities'', generally meaning | |
4637 | things that are useful to the user when interacting with @value{GDBN}, | |
4638 | but not related to the state of the inferior. For example, | |
4639 | @code{help}, @code{make}, and @code{shell} are in this category. Type | |
4640 | @kbd{help support} at the @value{GDBN} prompt to see a list of | |
4641 | commands in this category. | |
4642 | ||
4643 | @findex COMMAND_STATUS | |
4644 | @findex gdb.COMMAND_STATUS | |
4645 | @item gdb.COMMAND_STATUS | |
4646 | The command is an @samp{info}-related command, that is, related to the | |
4647 | state of @value{GDBN} itself. For example, @code{info}, @code{macro}, | |
4648 | and @code{show} are in this category. Type @kbd{help status} at the | |
4649 | @value{GDBN} prompt to see a list of commands in this category. | |
4650 | ||
4651 | @findex COMMAND_BREAKPOINTS | |
4652 | @findex gdb.COMMAND_BREAKPOINTS | |
4653 | @item gdb.COMMAND_BREAKPOINTS | |
4654 | The command has to do with breakpoints. For example, @code{break}, | |
4655 | @code{clear}, and @code{delete} are in this category. Type @kbd{help | |
4656 | breakpoints} at the @value{GDBN} prompt to see a list of commands in | |
4657 | this category. | |
4658 | ||
4659 | @findex COMMAND_TRACEPOINTS | |
4660 | @findex gdb.COMMAND_TRACEPOINTS | |
4661 | @item gdb.COMMAND_TRACEPOINTS | |
4662 | The command has to do with tracepoints. For example, @code{trace}, | |
4663 | @code{actions}, and @code{tfind} are in this category. Type | |
4664 | @kbd{help tracepoints} at the @value{GDBN} prompt to see a list of | |
4665 | commands in this category. | |
4666 | ||
2b2fbab8 TT |
4667 | @findex COMMAND_TUI |
4668 | @findex gdb.COMMAND_TUI | |
4669 | @item gdb.COMMAND_TUI | |
4670 | The command has to do with the text user interface (@pxref{TUI}). | |
4671 | Type @kbd{help tui} at the @value{GDBN} prompt to see a list of | |
4672 | commands in this category. | |
4673 | ||
329baa95 DE |
4674 | @findex COMMAND_USER |
4675 | @findex gdb.COMMAND_USER | |
4676 | @item gdb.COMMAND_USER | |
4677 | The command is a general purpose command for the user, and typically | |
4678 | does not fit in one of the other categories. | |
4679 | Type @kbd{help user-defined} at the @value{GDBN} prompt to see | |
4680 | a list of commands in this category, as well as the list of gdb macros | |
4681 | (@pxref{Sequences}). | |
4682 | ||
4683 | @findex COMMAND_OBSCURE | |
4684 | @findex gdb.COMMAND_OBSCURE | |
4685 | @item gdb.COMMAND_OBSCURE | |
4686 | The command is only used in unusual circumstances, or is not of | |
4687 | general interest to users. For example, @code{checkpoint}, | |
4688 | @code{fork}, and @code{stop} are in this category. Type @kbd{help | |
4689 | obscure} at the @value{GDBN} prompt to see a list of commands in this | |
4690 | category. | |
4691 | ||
4692 | @findex COMMAND_MAINTENANCE | |
4693 | @findex gdb.COMMAND_MAINTENANCE | |
4694 | @item gdb.COMMAND_MAINTENANCE | |
4695 | The command is only useful to @value{GDBN} maintainers. The | |
4696 | @code{maintenance} and @code{flushregs} commands are in this category. | |
4697 | Type @kbd{help internals} at the @value{GDBN} prompt to see a list of | |
4698 | commands in this category. | |
4699 | @end table | |
4700 | ||
4701 | A new command can use a predefined completion function, either by | |
4702 | specifying it via an argument at initialization, or by returning it | |
4703 | from the @code{complete} method. These predefined completion | |
4704 | constants are all defined in the @code{gdb} module: | |
4705 | ||
b3ce5e5f DE |
4706 | @vtable @code |
4707 | @vindex COMPLETE_NONE | |
329baa95 DE |
4708 | @item gdb.COMPLETE_NONE |
4709 | This constant means that no completion should be done. | |
4710 | ||
b3ce5e5f | 4711 | @vindex COMPLETE_FILENAME |
329baa95 DE |
4712 | @item gdb.COMPLETE_FILENAME |
4713 | This constant means that filename completion should be performed. | |
4714 | ||
b3ce5e5f | 4715 | @vindex COMPLETE_LOCATION |
329baa95 DE |
4716 | @item gdb.COMPLETE_LOCATION |
4717 | This constant means that location completion should be done. | |
5541bfdc | 4718 | @xref{Location Specifications}. |
329baa95 | 4719 | |
b3ce5e5f | 4720 | @vindex COMPLETE_COMMAND |
329baa95 DE |
4721 | @item gdb.COMPLETE_COMMAND |
4722 | This constant means that completion should examine @value{GDBN} | |
4723 | command names. | |
4724 | ||
b3ce5e5f | 4725 | @vindex COMPLETE_SYMBOL |
329baa95 DE |
4726 | @item gdb.COMPLETE_SYMBOL |
4727 | This constant means that completion should be done using symbol names | |
4728 | as the source. | |
4729 | ||
b3ce5e5f | 4730 | @vindex COMPLETE_EXPRESSION |
329baa95 DE |
4731 | @item gdb.COMPLETE_EXPRESSION |
4732 | This constant means that completion should be done on expressions. | |
4733 | Often this means completing on symbol names, but some language | |
4734 | parsers also have support for completing on field names. | |
b3ce5e5f | 4735 | @end vtable |
329baa95 DE |
4736 | |
4737 | The following code snippet shows how a trivial CLI command can be | |
4738 | implemented in Python: | |
4739 | ||
4740 | @smallexample | |
4741 | class HelloWorld (gdb.Command): | |
4742 | """Greet the whole world.""" | |
4743 | ||
4744 | def __init__ (self): | |
4745 | super (HelloWorld, self).__init__ ("hello-world", gdb.COMMAND_USER) | |
4746 | ||
4747 | def invoke (self, arg, from_tty): | |
f3bdc2db | 4748 | print ("Hello, World!") |
329baa95 DE |
4749 | |
4750 | HelloWorld () | |
4751 | @end smallexample | |
4752 | ||
4753 | The last line instantiates the class, and is necessary to trigger the | |
4754 | registration of the command with @value{GDBN}. Depending on how the | |
4755 | Python code is read into @value{GDBN}, you may need to import the | |
4756 | @code{gdb} module explicitly. | |
4757 | ||
740b42ce | 4758 | @node GDB/MI Commands In Python |
c96452ad | 4759 | @subsubsection @sc{gdb/mi} Commands In Python |
740b42ce AB |
4760 | |
4761 | @cindex MI commands in python | |
4762 | @cindex commands in python, GDB/MI | |
4763 | @cindex python commands, GDB/MI | |
c96452ad TT |
4764 | It is possible to add @sc{gdb/mi} (@pxref{GDB/MI}) commands |
4765 | implemented in Python. A @sc{gdb/mi} command is implemented using an | |
740b42ce AB |
4766 | instance of the @code{gdb.MICommand} class, most commonly using a |
4767 | subclass. | |
4768 | ||
4769 | @defun MICommand.__init__ (name) | |
4770 | The object initializer for @code{MICommand} registers the new command | |
4771 | with @value{GDBN}. This initializer is normally invoked from the | |
4772 | subclass' own @code{__init__} method. | |
4773 | ||
4774 | @var{name} is the name of the command. It must be a valid name of a | |
c96452ad TT |
4775 | @sc{gdb/mi} command, and in particular must start with a hyphen |
4776 | (@code{-}). Reusing the name of a built-in @sc{gdb/mi} is not | |
740b42ce | 4777 | allowed, and a @code{RuntimeError} will be raised. Using the name |
c96452ad | 4778 | of an @sc{gdb/mi} command previously defined in Python is allowed, the |
740b42ce AB |
4779 | previous command will be replaced with the new command. |
4780 | @end defun | |
4781 | ||
4782 | @defun MICommand.invoke (arguments) | |
4783 | This method is called by @value{GDBN} when the new MI command is | |
4784 | invoked. | |
4785 | ||
4786 | @var{arguments} is a list of strings. Note, that @code{--thread} | |
4787 | and @code{--frame} arguments are handled by @value{GDBN} itself therefore | |
4788 | they do not show up in @code{arguments}. | |
4789 | ||
4790 | If this method raises an exception, then it is turned into a | |
c96452ad | 4791 | @sc{gdb/mi} @code{^error} response. Only @code{gdb.GdbError} |
740b42ce AB |
4792 | exceptions (or its sub-classes) should be used for reporting errors to |
4793 | users, any other exception type is treated as a failure of the | |
4794 | @code{invoke} method, and the exception will be printed to the error | |
4795 | stream according to the @kbd{set python print-stack} setting | |
4796 | (@pxref{set_python_print_stack,,@kbd{set python print-stack}}). | |
4797 | ||
c96452ad | 4798 | If this method returns @code{None}, then the @sc{gdb/mi} command will |
740b42ce AB |
4799 | return a @code{^done} response with no additional values. |
4800 | ||
4801 | Otherwise, the return value must be a dictionary, which is converted | |
c96452ad | 4802 | to a @sc{gdb/mi} @var{result-record} (@pxref{GDB/MI Output Syntax}). |
740b42ce AB |
4803 | The keys of this dictionary must be strings, and are used as |
4804 | @var{variable} names in the @var{result-record}, these strings must | |
4805 | comply with the naming rules detailed below. The values of this | |
4806 | dictionary are recursively handled as follows: | |
4807 | ||
4808 | @itemize | |
4809 | @item | |
4810 | If the value is Python sequence or iterator, it is converted to | |
c96452ad | 4811 | @sc{gdb/mi} @var{list} with elements converted recursively. |
740b42ce AB |
4812 | |
4813 | @item | |
4814 | If the value is Python dictionary, it is converted to | |
c96452ad | 4815 | @sc{gdb/mi} @var{tuple}. Keys in that dictionary must be strings, |
740b42ce AB |
4816 | which comply with the @var{variable} naming rules detailed below. |
4817 | Values are converted recursively. | |
4818 | ||
4819 | @item | |
4820 | Otherwise, value is first converted to a Python string using | |
c96452ad | 4821 | @code{str ()} and then converted to @sc{gdb/mi} @var{const}. |
740b42ce AB |
4822 | @end itemize |
4823 | ||
c96452ad | 4824 | The strings used for @var{variable} names in the @sc{gdb/mi} output |
740b42ce AB |
4825 | must follow the following rules; the string must be at least one |
4826 | character long, the first character must be in the set | |
4827 | @code{[a-zA-Z]}, while every subsequent character must be in the set | |
4828 | @code{[-_a-zA-Z0-9]}. | |
4829 | @end defun | |
4830 | ||
4831 | An instance of @code{MICommand} has the following attributes: | |
4832 | ||
4833 | @defvar MICommand.name | |
c96452ad | 4834 | A string, the name of this @sc{gdb/mi} command, as was passed to the |
740b42ce AB |
4835 | @code{__init__} method. This attribute is read-only. |
4836 | @end defvar | |
4837 | ||
4838 | @defvar MICommand.installed | |
4839 | A boolean value indicating if this command is installed ready for a | |
4840 | user to call from the command line. Commands are automatically | |
4841 | installed when they are instantiated, after which this attribute will | |
4842 | be @code{True}. | |
4843 | ||
4844 | If later, a new command is created with the same name, then the | |
4845 | original command will become uninstalled, and this attribute will be | |
4846 | @code{False}. | |
4847 | ||
4848 | This attribute is read-write, setting this attribute to @code{False} | |
4849 | will uninstall the command, removing it from the set of available | |
4850 | commands. Setting this attribute to @code{True} will install the | |
4851 | command for use. If there is already a Python command with this name | |
4852 | installed, the currently installed command will be uninstalled, and | |
a8afc8a7 | 4853 | this command installed in its stead. |
740b42ce AB |
4854 | @end defvar |
4855 | ||
12d290fb | 4856 | The following code snippet shows how some trivial MI commands can be |
740b42ce AB |
4857 | implemented in Python: |
4858 | ||
4859 | @smallexample | |
4860 | class MIEcho(gdb.MICommand): | |
4861 | """Echo arguments passed to the command.""" | |
4862 | ||
4863 | def __init__(self, name, mode): | |
4864 | self._mode = mode | |
4865 | super(MIEcho, self).__init__(name) | |
4866 | ||
4867 | def invoke(self, argv): | |
4868 | if self._mode == 'dict': | |
4869 | return @{ 'dict': @{ 'argv' : argv @} @} | |
4870 | elif self._mode == 'list': | |
4871 | return @{ 'list': argv @} | |
4872 | else: | |
4873 | return @{ 'string': ", ".join(argv) @} | |
4874 | ||
4875 | ||
4876 | MIEcho("-echo-dict", "dict") | |
4877 | MIEcho("-echo-list", "list") | |
4878 | MIEcho("-echo-string", "string") | |
4879 | @end smallexample | |
4880 | ||
4881 | The last three lines instantiate the class three times, creating three | |
c96452ad | 4882 | new @sc{gdb/mi} commands @code{-echo-dict}, @code{-echo-list}, and |
740b42ce AB |
4883 | @code{-echo-string}. Each time a subclass of @code{gdb.MICommand} is |
4884 | instantiated, the new command is automatically registered with | |
4885 | @value{GDBN}. | |
4886 | ||
4887 | Depending on how the Python code is read into @value{GDBN}, you may | |
4888 | need to import the @code{gdb} module explicitly. | |
4889 | ||
4890 | The following example shows a @value{GDBN} session in which the above | |
4891 | commands have been added: | |
4892 | ||
4893 | @smallexample | |
4894 | (@value{GDBP}) | |
4895 | -echo-dict abc def ghi | |
4896 | ^done,dict=@{argv=["abc","def","ghi"]@} | |
4897 | (@value{GDBP}) | |
4898 | -echo-list abc def ghi | |
4899 | ^done,list=["abc","def","ghi"] | |
4900 | (@value{GDBP}) | |
4901 | -echo-string abc def ghi | |
4902 | ^done,string="abc, def, ghi" | |
4903 | (@value{GDBP}) | |
4904 | @end smallexample | |
4905 | ||
c97d123d TT |
4906 | Conversely, it is possible to execute @sc{gdb/mi} commands from |
4907 | Python, with the results being a Python object and not a | |
4908 | specially-formatted string. This is done with the | |
4909 | @code{gdb.execute_mi} function. | |
4910 | ||
c97d123d TT |
4911 | @defun gdb.execute_mi (command @r{[}, arg @r{]}@dots{}) |
4912 | Invoke a @sc{gdb/mi} command. @var{command} is the name of the | |
4913 | command, a string. The arguments, @var{arg}, are passed to the | |
4914 | command. Each argument must also be a string. | |
4915 | ||
4916 | This function returns a Python dictionary whose contents reflect the | |
4917 | corresponding @sc{GDB/MI} command's output. Refer to the | |
4918 | documentation for these commands for details. Lists are represented | |
4919 | as Python lists, and tuples are represented as Python dictionaries. | |
4920 | ||
4921 | If the command fails, it will raise a Python exception. | |
4922 | @end defun | |
4923 | ||
4924 | Here is how this works using the commands from the example above: | |
4925 | ||
4926 | @smallexample | |
4927 | (@value{GDBP}) python print(gdb.execute_mi("-echo-dict", "abc", "def", "ghi")) | |
4928 | @{'dict': @{'argv': ['abc', 'def', 'ghi']@}@} | |
4929 | (@value{GDBP}) python print(gdb.execute_mi("-echo-list", "abc", "def", "ghi")) | |
4930 | @{'list': ['abc', 'def', 'ghi']@} | |
4931 | (@value{GDBP}) python print(gdb.execute_mi("-echo-string", "abc", "def", "ghi")) | |
4932 | @{'string': 'abc, def, ghi'@} | |
4933 | @end smallexample | |
4934 | ||
4825fd2d JV |
4935 | @node GDB/MI Notifications In Python |
4936 | @subsubsection @sc{gdb/mi} Notifications In Python | |
4937 | ||
4938 | @cindex MI notifications in python | |
4939 | @cindex notifications in python, GDB/MI | |
4940 | @cindex python notifications, GDB/MI | |
4941 | ||
4942 | It is possible to emit @sc{gdb/mi} notifications from | |
4943 | Python. Use the @code{gdb.notify_mi} function to do that. | |
4944 | ||
4945 | @defun gdb.notify_mi (name @r{[}, data@r{]}) | |
4946 | Emit a @sc{gdb/mi} asynchronous notification. @var{name} is the name of the | |
4947 | notification, consisting of alphanumeric characters and a hyphen (@code{-}). | |
4948 | @var{data} is any additional data to be emitted with the notification, passed | |
4949 | as a Python dictionary. This argument is optional. The dictionary is converted | |
4950 | to a @sc{gdb/mi} @var{result} records (@pxref{GDB/MI Output Syntax}) the same way | |
4951 | as result of Python MI command (@pxref{GDB/MI Commands In Python}). | |
4952 | ||
4953 | If @var{data} is @code{None} then no additional values are emitted. | |
4954 | @end defun | |
4955 | ||
4956 | While using existing notification names (@pxref{GDB/MI Async Records}) with | |
4957 | @code{gdb.notify_mi} is allowed, users are encouraged to prefix user-defined | |
4958 | notification with a hyphen (@code{-}) to avoid possible conflict. | |
4959 | @value{GDBN} will never introduce notification starting with hyphen. | |
4960 | ||
4961 | Here is how to emit @code{=-connection-removed} whenever a connection to remote | |
4962 | GDB server is closed (@pxref{Connections In Python}): | |
4963 | ||
4964 | @smallexample | |
4965 | def notify_connection_removed(event): | |
4966 | data = @{"id": event.connection.num, "type": event.connection.type@} | |
4967 | gdb.notify_mi("-connection-removed", data) | |
4968 | ||
4969 | ||
4970 | gdb.events.connection_removed.connect(notify_connection_removed) | |
4971 | @end smallexample | |
4972 | ||
4973 | Then, each time a connection is closed, there will be a notification on MI channel: | |
4974 | ||
4975 | @smallexample | |
4976 | =-connection-removed,id="1",type="remote" | |
4977 | @end smallexample | |
4978 | ||
329baa95 DE |
4979 | @node Parameters In Python |
4980 | @subsubsection Parameters In Python | |
4981 | ||
4982 | @cindex parameters in python | |
4983 | @cindex python parameters | |
4984 | @tindex gdb.Parameter | |
4985 | @tindex Parameter | |
4986 | You can implement new @value{GDBN} parameters using Python. A new | |
4987 | parameter is implemented as an instance of the @code{gdb.Parameter} | |
4988 | class. | |
4989 | ||
4990 | Parameters are exposed to the user via the @code{set} and | |
4991 | @code{show} commands. @xref{Help}. | |
4992 | ||
4993 | There are many parameters that already exist and can be set in | |
4994 | @value{GDBN}. Two examples are: @code{set follow fork} and | |
4995 | @code{set charset}. Setting these parameters influences certain | |
4996 | behavior in @value{GDBN}. Similarly, you can define parameters that | |
4997 | can be used to influence behavior in custom Python scripts and commands. | |
4998 | ||
ebb83b77 | 4999 | @defun Parameter.__init__ (name, command_class, parameter_class @r{[}, enum_sequence@r{]}) |
329baa95 DE |
5000 | The object initializer for @code{Parameter} registers the new |
5001 | parameter with @value{GDBN}. This initializer is normally invoked | |
5002 | from the subclass' own @code{__init__} method. | |
5003 | ||
5004 | @var{name} is the name of the new parameter. If @var{name} consists | |
5005 | of multiple words, then the initial words are looked for as prefix | |
5006 | parameters. An example of this can be illustrated with the | |
5007 | @code{set print} set of parameters. If @var{name} is | |
5008 | @code{print foo}, then @code{print} will be searched as the prefix | |
5009 | parameter. In this case the parameter can subsequently be accessed in | |
5010 | @value{GDBN} as @code{set print foo}. | |
5011 | ||
5012 | If @var{name} consists of multiple words, and no prefix parameter group | |
5013 | can be found, an exception is raised. | |
5014 | ||
ebb83b77 | 5015 | @var{command_class} should be one of the @samp{COMMAND_} constants |
740b42ce | 5016 | (@pxref{CLI Commands In Python}). This argument tells @value{GDBN} how to |
329baa95 DE |
5017 | categorize the new parameter in the help system. |
5018 | ||
ebb83b77 | 5019 | @var{parameter_class} should be one of the @samp{PARAM_} constants |
329baa95 DE |
5020 | defined below. This argument tells @value{GDBN} the type of the new |
5021 | parameter; this information is used for input validation and | |
5022 | completion. | |
5023 | ||
ebb83b77 TT |
5024 | If @var{parameter_class} is @code{PARAM_ENUM}, then |
5025 | @var{enum_sequence} must be a sequence of strings. These strings | |
329baa95 DE |
5026 | represent the possible values for the parameter. |
5027 | ||
ebb83b77 | 5028 | If @var{parameter_class} is not @code{PARAM_ENUM}, then the presence |
329baa95 DE |
5029 | of a fourth argument will cause an exception to be thrown. |
5030 | ||
bbea6807 AB |
5031 | The help text for the new parameter includes the Python documentation |
5032 | string from the parameter's class, if there is one. If there is no | |
5033 | documentation string, a default value is used. The documentation | |
5034 | string is included in the output of the parameters @code{help set} and | |
5035 | @code{help show} commands, and should be written taking this into | |
5036 | account. | |
329baa95 DE |
5037 | @end defun |
5038 | ||
5039 | @defvar Parameter.set_doc | |
5040 | If this attribute exists, and is a string, then its value is used as | |
bbea6807 AB |
5041 | the first part of the help text for this parameter's @code{set} |
5042 | command. The second part of the help text is taken from the | |
5043 | documentation string for the parameter's class, if there is one. | |
5044 | ||
5045 | The value of @code{set_doc} should give a brief summary specific to | |
5046 | the set action, this text is only displayed when the user runs the | |
5047 | @code{help set} command for this parameter. The class documentation | |
5048 | should be used to give a fuller description of what the parameter | |
5049 | does, this text is displayed for both the @code{help set} and | |
5050 | @code{help show} commands. | |
5051 | ||
5052 | The @code{set_doc} value is examined when @code{Parameter.__init__} is | |
5053 | invoked; subsequent changes have no effect. | |
329baa95 DE |
5054 | @end defvar |
5055 | ||
5056 | @defvar Parameter.show_doc | |
5057 | If this attribute exists, and is a string, then its value is used as | |
bbea6807 AB |
5058 | the first part of the help text for this parameter's @code{show} |
5059 | command. The second part of the help text is taken from the | |
5060 | documentation string for the parameter's class, if there is one. | |
5061 | ||
5062 | The value of @code{show_doc} should give a brief summary specific to | |
5063 | the show action, this text is only displayed when the user runs the | |
5064 | @code{help show} command for this parameter. The class documentation | |
5065 | should be used to give a fuller description of what the parameter | |
5066 | does, this text is displayed for both the @code{help set} and | |
5067 | @code{help show} commands. | |
5068 | ||
5069 | The @code{show_doc} value is examined when @code{Parameter.__init__} | |
5070 | is invoked; subsequent changes have no effect. | |
329baa95 DE |
5071 | @end defvar |
5072 | ||
5073 | @defvar Parameter.value | |
5074 | The @code{value} attribute holds the underlying value of the | |
5075 | parameter. It can be read and assigned to just as any other | |
5076 | attribute. @value{GDBN} does validation when assignments are made. | |
5077 | @end defvar | |
5078 | ||
984ee559 TT |
5079 | There are two methods that may be implemented in any @code{Parameter} |
5080 | class. These are: | |
329baa95 DE |
5081 | |
5082 | @defun Parameter.get_set_string (self) | |
984ee559 TT |
5083 | If this method exists, @value{GDBN} will call it when a |
5084 | @var{parameter}'s value has been changed via the @code{set} API (for | |
5085 | example, @kbd{set foo off}). The @code{value} attribute has already | |
5086 | been populated with the new value and may be used in output. This | |
5087 | method must return a string. If the returned string is not empty, | |
5088 | @value{GDBN} will present it to the user. | |
ae778caf TT |
5089 | |
5090 | If this method raises the @code{gdb.GdbError} exception | |
5091 | (@pxref{Exception Handling}), then @value{GDBN} will print the | |
5092 | exception's string and the @code{set} command will fail. Note, | |
5093 | however, that the @code{value} attribute will not be reset in this | |
5094 | case. So, if your parameter must validate values, it should store the | |
5095 | old value internally and reset the exposed value, like so: | |
5096 | ||
5097 | @smallexample | |
5098 | class ExampleParam (gdb.Parameter): | |
5099 | def __init__ (self, name): | |
5100 | super (ExampleParam, self).__init__ (name, | |
5101 | gdb.COMMAND_DATA, | |
5102 | gdb.PARAM_BOOLEAN) | |
5103 | self.value = True | |
5104 | self.saved_value = True | |
5105 | def validate(self): | |
5106 | return False | |
5107 | def get_set_string (self): | |
5108 | if not self.validate(): | |
5109 | self.value = self.saved_value | |
5110 | raise gdb.GdbError('Failed to validate') | |
5111 | self.saved_value = self.value | |
763b8efd | 5112 | return "" |
ae778caf | 5113 | @end smallexample |
329baa95 DE |
5114 | @end defun |
5115 | ||
5116 | @defun Parameter.get_show_string (self, svalue) | |
5117 | @value{GDBN} will call this method when a @var{parameter}'s | |
5118 | @code{show} API has been invoked (for example, @kbd{show foo}). The | |
5119 | argument @code{svalue} receives the string representation of the | |
5120 | current value. This method must return a string. | |
5121 | @end defun | |
5122 | ||
5123 | When a new parameter is defined, its type must be specified. The | |
5124 | available types are represented by constants defined in the @code{gdb} | |
5125 | module: | |
5126 | ||
5127 | @table @code | |
5128 | @findex PARAM_BOOLEAN | |
5129 | @findex gdb.PARAM_BOOLEAN | |
5130 | @item gdb.PARAM_BOOLEAN | |
5131 | The value is a plain boolean. The Python boolean values, @code{True} | |
5132 | and @code{False} are the only valid values. | |
5133 | ||
5134 | @findex PARAM_AUTO_BOOLEAN | |
5135 | @findex gdb.PARAM_AUTO_BOOLEAN | |
5136 | @item gdb.PARAM_AUTO_BOOLEAN | |
5137 | The value has three possible states: true, false, and @samp{auto}. In | |
5138 | Python, true and false are represented using boolean constants, and | |
5139 | @samp{auto} is represented using @code{None}. | |
5140 | ||
5141 | @findex PARAM_UINTEGER | |
5142 | @findex gdb.PARAM_UINTEGER | |
5143 | @item gdb.PARAM_UINTEGER | |
7aeb03e2 MR |
5144 | The value is an unsigned integer. The value of @code{None} should be |
5145 | interpreted to mean ``unlimited'' (literal @code{'unlimited'} can also | |
5146 | be used to set that value), and the value of 0 is reserved and should | |
5147 | not be used. | |
329baa95 DE |
5148 | |
5149 | @findex PARAM_INTEGER | |
5150 | @findex gdb.PARAM_INTEGER | |
5151 | @item gdb.PARAM_INTEGER | |
7aeb03e2 MR |
5152 | The value is a signed integer. The value of @code{None} should be |
5153 | interpreted to mean ``unlimited'' (literal @code{'unlimited'} can also | |
5154 | be used to set that value), and the value of 0 is reserved and should | |
5155 | not be used. | |
329baa95 DE |
5156 | |
5157 | @findex PARAM_STRING | |
5158 | @findex gdb.PARAM_STRING | |
5159 | @item gdb.PARAM_STRING | |
5160 | The value is a string. When the user modifies the string, any escape | |
5161 | sequences, such as @samp{\t}, @samp{\f}, and octal escapes, are | |
5162 | translated into corresponding characters and encoded into the current | |
5163 | host charset. | |
5164 | ||
5165 | @findex PARAM_STRING_NOESCAPE | |
5166 | @findex gdb.PARAM_STRING_NOESCAPE | |
5167 | @item gdb.PARAM_STRING_NOESCAPE | |
5168 | The value is a string. When the user modifies the string, escapes are | |
5169 | passed through untranslated. | |
5170 | ||
5171 | @findex PARAM_OPTIONAL_FILENAME | |
5172 | @findex gdb.PARAM_OPTIONAL_FILENAME | |
5173 | @item gdb.PARAM_OPTIONAL_FILENAME | |
5174 | The value is a either a filename (a string), or @code{None}. | |
5175 | ||
5176 | @findex PARAM_FILENAME | |
5177 | @findex gdb.PARAM_FILENAME | |
5178 | @item gdb.PARAM_FILENAME | |
5179 | The value is a filename. This is just like | |
5180 | @code{PARAM_STRING_NOESCAPE}, but uses file names for completion. | |
5181 | ||
5182 | @findex PARAM_ZINTEGER | |
5183 | @findex gdb.PARAM_ZINTEGER | |
5184 | @item gdb.PARAM_ZINTEGER | |
7aeb03e2 MR |
5185 | The value is a signed integer. This is like @code{PARAM_INTEGER}, |
5186 | except that 0 is allowed and the value of @code{None} is not supported. | |
329baa95 | 5187 | |
0489430a TT |
5188 | @findex PARAM_ZUINTEGER |
5189 | @findex gdb.PARAM_ZUINTEGER | |
5190 | @item gdb.PARAM_ZUINTEGER | |
7aeb03e2 MR |
5191 | The value is an unsigned integer. This is like @code{PARAM_UINTEGER}, |
5192 | except that 0 is allowed and the value of @code{None} is not supported. | |
0489430a TT |
5193 | |
5194 | @findex PARAM_ZUINTEGER_UNLIMITED | |
5195 | @findex gdb.PARAM_ZUINTEGER_UNLIMITED | |
5196 | @item gdb.PARAM_ZUINTEGER_UNLIMITED | |
7aeb03e2 MR |
5197 | The value is a signed integer. This is like @code{PARAM_INTEGER} |
5198 | including that the value of @code{None} should be interpreted to mean | |
5199 | ``unlimited'' (literal @code{'unlimited'} can also be used to set that | |
5200 | value), except that 0 is allowed, and the value cannot be negative, | |
5201 | except the special value -1 is returned for the setting of ``unlimited''. | |
0489430a | 5202 | |
329baa95 DE |
5203 | @findex PARAM_ENUM |
5204 | @findex gdb.PARAM_ENUM | |
5205 | @item gdb.PARAM_ENUM | |
5206 | The value is a string, which must be one of a collection string | |
5207 | constants provided when the parameter is created. | |
5208 | @end table | |
5209 | ||
5210 | @node Functions In Python | |
5211 | @subsubsection Writing new convenience functions | |
5212 | ||
5213 | @cindex writing convenience functions | |
5214 | @cindex convenience functions in python | |
5215 | @cindex python convenience functions | |
5216 | @tindex gdb.Function | |
5217 | @tindex Function | |
5218 | You can implement new convenience functions (@pxref{Convenience Vars}) | |
5219 | in Python. A convenience function is an instance of a subclass of the | |
5220 | class @code{gdb.Function}. | |
5221 | ||
5222 | @defun Function.__init__ (name) | |
5223 | The initializer for @code{Function} registers the new function with | |
5224 | @value{GDBN}. The argument @var{name} is the name of the function, | |
5225 | a string. The function will be visible to the user as a convenience | |
5226 | variable of type @code{internal function}, whose name is the same as | |
5227 | the given @var{name}. | |
5228 | ||
5229 | The documentation for the new function is taken from the documentation | |
5230 | string for the new class. | |
5231 | @end defun | |
5232 | ||
ebb83b77 | 5233 | @defun Function.invoke (*args) |
329baa95 DE |
5234 | When a convenience function is evaluated, its arguments are converted |
5235 | to instances of @code{gdb.Value}, and then the function's | |
5236 | @code{invoke} method is called. Note that @value{GDBN} does not | |
5237 | predetermine the arity of convenience functions. Instead, all | |
5238 | available arguments are passed to @code{invoke}, following the | |
5239 | standard Python calling convention. In particular, a convenience | |
5240 | function can have default values for parameters without ill effect. | |
5241 | ||
5242 | The return value of this method is used as its value in the enclosing | |
5243 | expression. If an ordinary Python value is returned, it is converted | |
5244 | to a @code{gdb.Value} following the usual rules. | |
5245 | @end defun | |
5246 | ||
5247 | The following code snippet shows how a trivial convenience function can | |
5248 | be implemented in Python: | |
5249 | ||
5250 | @smallexample | |
5251 | class Greet (gdb.Function): | |
5252 | """Return string to greet someone. | |
5253 | Takes a name as argument.""" | |
5254 | ||
5255 | def __init__ (self): | |
5256 | super (Greet, self).__init__ ("greet") | |
5257 | ||
5258 | def invoke (self, name): | |
5259 | return "Hello, %s!" % name.string () | |
5260 | ||
5261 | Greet () | |
5262 | @end smallexample | |
5263 | ||
5264 | The last line instantiates the class, and is necessary to trigger the | |
5265 | registration of the function with @value{GDBN}. Depending on how the | |
5266 | Python code is read into @value{GDBN}, you may need to import the | |
5267 | @code{gdb} module explicitly. | |
5268 | ||
5269 | Now you can use the function in an expression: | |
5270 | ||
5271 | @smallexample | |
5272 | (gdb) print $greet("Bob") | |
5273 | $1 = "Hello, Bob!" | |
5274 | @end smallexample | |
5275 | ||
5276 | @node Progspaces In Python | |
5277 | @subsubsection Program Spaces In Python | |
5278 | ||
5279 | @cindex progspaces in python | |
5280 | @tindex gdb.Progspace | |
5281 | @tindex Progspace | |
5282 | A program space, or @dfn{progspace}, represents a symbolic view | |
5283 | of an address space. | |
5284 | It consists of all of the objfiles of the program. | |
5285 | @xref{Objfiles In Python}. | |
65c574f6 | 5286 | @xref{Inferiors Connections and Programs, program spaces}, for more details |
329baa95 DE |
5287 | about program spaces. |
5288 | ||
5289 | The following progspace-related functions are available in the | |
5290 | @code{gdb} module: | |
5291 | ||
329baa95 DE |
5292 | @defun gdb.current_progspace () |
5293 | This function returns the program space of the currently selected inferior. | |
65c574f6 | 5294 | @xref{Inferiors Connections and Programs}. This is identical to |
a40bf0c2 SM |
5295 | @code{gdb.selected_inferior().progspace} (@pxref{Inferiors In Python}) and is |
5296 | included for historical compatibility. | |
329baa95 DE |
5297 | @end defun |
5298 | ||
329baa95 DE |
5299 | @defun gdb.progspaces () |
5300 | Return a sequence of all the progspaces currently known to @value{GDBN}. | |
5301 | @end defun | |
5302 | ||
5303 | Each progspace is represented by an instance of the @code{gdb.Progspace} | |
5304 | class. | |
5305 | ||
5306 | @defvar Progspace.filename | |
ce65386d AB |
5307 | The file name, as a string, of the main symbol file (from which debug |
5308 | symbols have been loaded) for the progspace, e.g.@: the argument to | |
5309 | the @kbd{symbol-file} or @kbd{file} commands. | |
5310 | ||
5311 | If there is no main symbol table currently loaded, then this attribute | |
5312 | will be @code{None}. | |
329baa95 DE |
5313 | @end defvar |
5314 | ||
5ce85461 AB |
5315 | @defvar Progspace.symbol_file |
5316 | The @code{gdb.Objfile} representing the main symbol file (from which | |
5317 | debug symbols have been loaded) for the @code{gdb.Progspace}. This is | |
5318 | the symbol file set by the @kbd{symbol-file} or @kbd{file} commands. | |
5319 | ||
5320 | This will be the @code{gdb.Objfile} representing | |
5321 | @code{Progspace.filename} when @code{Progspace.filename} is not | |
5322 | @code{None}. | |
5323 | ||
5324 | If there is no main symbol table currently loaded, then this attribute | |
5325 | will be @code{None}. | |
5326 | ||
5327 | If the @code{Progspace} is invalid, i.e.@:, when | |
5328 | @code{Progspace.is_valid()} returns @code{False}, then attempting to | |
5329 | access this attribute will raise a @code{RuntimeError} exception. | |
5330 | @end defvar | |
5331 | ||
4e02aca0 AB |
5332 | @defvar Progspace.executable_filename |
5333 | The file name, as a string, of the executable file in use by this | |
5334 | program space. The executable file is the file that @value{GDBN} will | |
5335 | invoke in order to start an inferior when using a native target. The | |
5336 | file name within this attribute is updated by the @kbd{exec-file} and | |
5337 | @kbd{file} commands. | |
5338 | ||
5339 | If no executable is currently set within this @code{Progspace} then | |
5340 | this attribute contains @code{None}. | |
5341 | ||
5342 | If the @code{Progspace} is invalid, i.e.@:, when | |
5343 | @code{Progspace.is_valid()} returns @code{False}, then attempting to | |
5344 | access this attribute will raise a @code{RuntimeError} exception. | |
5345 | @end defvar | |
5346 | ||
329baa95 DE |
5347 | @defvar Progspace.pretty_printers |
5348 | The @code{pretty_printers} attribute is a list of functions. It is | |
5349 | used to look up pretty-printers. A @code{Value} is passed to each | |
5350 | function in order; if the function returns @code{None}, then the | |
5351 | search continues. Otherwise, the return value should be an object | |
5352 | which is used to format the value. @xref{Pretty Printing API}, for more | |
5353 | information. | |
5354 | @end defvar | |
5355 | ||
5356 | @defvar Progspace.type_printers | |
5357 | The @code{type_printers} attribute is a list of type printer objects. | |
5358 | @xref{Type Printing API}, for more information. | |
5359 | @end defvar | |
5360 | ||
5361 | @defvar Progspace.frame_filters | |
5362 | The @code{frame_filters} attribute is a dictionary of frame filter | |
5363 | objects. @xref{Frame Filter API}, for more information. | |
5364 | @end defvar | |
5365 | ||
8f6c452b AB |
5366 | @defvar Progspace.missing_debug_handlers |
5367 | The @code{missing_debug_handlers} attribute is a list of the missing | |
5368 | debug handler objects for this program space. @xref{Missing Debug | |
5369 | Info In Python}, for more information. | |
5370 | @end defvar | |
5371 | ||
8743a9cd TT |
5372 | A program space has the following methods: |
5373 | ||
8743a9cd TT |
5374 | @defun Progspace.block_for_pc (pc) |
5375 | Return the innermost @code{gdb.Block} containing the given @var{pc} | |
5376 | value. If the block cannot be found for the @var{pc} value specified, | |
5377 | the function will return @code{None}. | |
5378 | @end defun | |
5379 | ||
8743a9cd TT |
5380 | @defun Progspace.find_pc_line (pc) |
5381 | Return the @code{gdb.Symtab_and_line} object corresponding to the | |
5382 | @var{pc} value. @xref{Symbol Tables In Python}. If an invalid value | |
5383 | of @var{pc} is passed as an argument, then the @code{symtab} and | |
5384 | @code{line} attributes of the returned @code{gdb.Symtab_and_line} | |
5385 | object will be @code{None} and 0 respectively. | |
5386 | @end defun | |
5387 | ||
8743a9cd TT |
5388 | @defun Progspace.is_valid () |
5389 | Returns @code{True} if the @code{gdb.Progspace} object is valid, | |
5390 | @code{False} if not. A @code{gdb.Progspace} object can become invalid | |
5391 | if the program space file it refers to is not referenced by any | |
5392 | inferior. All other @code{gdb.Progspace} methods will throw an | |
5393 | exception if it is invalid at the time the method is called. | |
5394 | @end defun | |
5395 | ||
8743a9cd TT |
5396 | @defun Progspace.objfiles () |
5397 | Return a sequence of all the objfiles referenced by this program | |
5398 | space. @xref{Objfiles In Python}. | |
5399 | @end defun | |
5400 | ||
8743a9cd TT |
5401 | @defun Progspace.solib_name (address) |
5402 | Return the name of the shared library holding the given @var{address} | |
5403 | as a string, or @code{None}. | |
5404 | @end defun | |
5405 | ||
27b2eff1 TT |
5406 | @defun Progspace.objfile_for_address (address) |
5407 | Return the @code{gdb.Objfile} holding the given address, or | |
5408 | @code{None} if no objfile covers it. | |
5409 | @end defun | |
5410 | ||
02be9a71 DE |
5411 | One may add arbitrary attributes to @code{gdb.Progspace} objects |
5412 | in the usual Python way. | |
5413 | This is useful if, for example, one needs to do some extra record keeping | |
5414 | associated with the program space. | |
5415 | ||
53d08890 AB |
5416 | @xref{choosing attribute names}, for guidance on selecting a suitable |
5417 | name for new attributes. | |
5418 | ||
02be9a71 DE |
5419 | In this contrived example, we want to perform some processing when |
5420 | an objfile with a certain symbol is loaded, but we only want to do | |
5421 | this once because it is expensive. To achieve this we record the results | |
5422 | with the program space because we can't predict when the desired objfile | |
5423 | will be loaded. | |
5424 | ||
5425 | @smallexample | |
7ccdf9c0 AB |
5426 | (@value{GDBP}) python |
5427 | @group | |
02be9a71 DE |
5428 | def clear_objfiles_handler(event): |
5429 | event.progspace.expensive_computation = None | |
5430 | def expensive(symbol): | |
5431 | """A mock routine to perform an "expensive" computation on symbol.""" | |
f3bdc2db | 5432 | print ("Computing the answer to the ultimate question ...") |
02be9a71 | 5433 | return 42 |
7ccdf9c0 AB |
5434 | @end group |
5435 | @group | |
02be9a71 DE |
5436 | def new_objfile_handler(event): |
5437 | objfile = event.new_objfile | |
5438 | progspace = objfile.progspace | |
5439 | if not hasattr(progspace, 'expensive_computation') or \ | |
5440 | progspace.expensive_computation is None: | |
5441 | # We use 'main' for the symbol to keep the example simple. | |
5442 | # Note: There's no current way to constrain the lookup | |
5443 | # to one objfile. | |
5444 | symbol = gdb.lookup_global_symbol('main') | |
5445 | if symbol is not None: | |
5446 | progspace.expensive_computation = expensive(symbol) | |
5447 | gdb.events.clear_objfiles.connect(clear_objfiles_handler) | |
5448 | gdb.events.new_objfile.connect(new_objfile_handler) | |
5449 | end | |
7ccdf9c0 AB |
5450 | @end group |
5451 | @group | |
5452 | (@value{GDBP}) file /tmp/hello | |
0bab6cf1 | 5453 | Reading symbols from /tmp/hello... |
02be9a71 | 5454 | Computing the answer to the ultimate question ... |
7ccdf9c0 | 5455 | (@value{GDBP}) python print(gdb.current_progspace().expensive_computation) |
02be9a71 | 5456 | 42 |
7ccdf9c0 | 5457 | (@value{GDBP}) run |
02be9a71 DE |
5458 | Starting program: /tmp/hello |
5459 | Hello. | |
5460 | [Inferior 1 (process 4242) exited normally] | |
7ccdf9c0 | 5461 | @end group |
02be9a71 DE |
5462 | @end smallexample |
5463 | ||
329baa95 DE |
5464 | @node Objfiles In Python |
5465 | @subsubsection Objfiles In Python | |
5466 | ||
5467 | @cindex objfiles in python | |
5468 | @tindex gdb.Objfile | |
5469 | @tindex Objfile | |
5470 | @value{GDBN} loads symbols for an inferior from various | |
5471 | symbol-containing files (@pxref{Files}). These include the primary | |
5472 | executable file, any shared libraries used by the inferior, and any | |
5473 | separate debug info files (@pxref{Separate Debug Files}). | |
5474 | @value{GDBN} calls these symbol-containing files @dfn{objfiles}. | |
5475 | ||
5476 | The following objfile-related functions are available in the | |
5477 | @code{gdb} module: | |
5478 | ||
329baa95 DE |
5479 | @defun gdb.current_objfile () |
5480 | When auto-loading a Python script (@pxref{Python Auto-loading}), @value{GDBN} | |
5481 | sets the ``current objfile'' to the corresponding objfile. This | |
5482 | function returns the current objfile. If there is no current objfile, | |
5483 | this function returns @code{None}. | |
5484 | @end defun | |
5485 | ||
329baa95 | 5486 | @defun gdb.objfiles () |
74d3fbbb SM |
5487 | Return a sequence of objfiles referenced by the current program space. |
5488 | @xref{Objfiles In Python}, and @ref{Progspaces In Python}. This is identical | |
5489 | to @code{gdb.selected_inferior().progspace.objfiles()} and is included for | |
5490 | historical compatibility. | |
329baa95 DE |
5491 | @end defun |
5492 | ||
b13d7831 | 5493 | @defun gdb.lookup_objfile (name @r{[}, by_build_id@r{]}) |
6dddd6a5 DE |
5494 | Look up @var{name}, a file name or build ID, in the list of objfiles |
5495 | for the current program space (@pxref{Progspaces In Python}). | |
5496 | If the objfile is not found throw the Python @code{ValueError} exception. | |
5497 | ||
5498 | If @var{name} is a relative file name, then it will match any | |
5499 | source file name with the same trailing components. For example, if | |
5500 | @var{name} is @samp{gcc/expr.c}, then it will match source file | |
5501 | name of @file{/build/trunk/gcc/expr.c}, but not | |
5502 | @file{/build/trunk/libcpp/expr.c} or @file{/build/trunk/gcc/x-expr.c}. | |
5503 | ||
5504 | If @var{by_build_id} is provided and is @code{True} then @var{name} | |
5505 | is the build ID of the objfile. Otherwise, @var{name} is a file name. | |
5506 | This is supported only on some operating systems, notably those which use | |
5507 | the ELF format for binary files and the @sc{gnu} Binutils. For more details | |
5508 | about this feature, see the description of the @option{--build-id} | |
f5a476a7 | 5509 | command-line option in @ref{Options, , Command Line Options, ld, |
6dddd6a5 DE |
5510 | The GNU Linker}. |
5511 | @end defun | |
5512 | ||
329baa95 DE |
5513 | Each objfile is represented by an instance of the @code{gdb.Objfile} |
5514 | class. | |
5515 | ||
5516 | @defvar Objfile.filename | |
1b549396 DE |
5517 | The file name of the objfile as a string, with symbolic links resolved. |
5518 | ||
5519 | The value is @code{None} if the objfile is no longer valid. | |
5520 | See the @code{gdb.Objfile.is_valid} method, described below. | |
329baa95 DE |
5521 | @end defvar |
5522 | ||
3a8b707a DE |
5523 | @defvar Objfile.username |
5524 | The file name of the objfile as specified by the user as a string. | |
5525 | ||
5526 | The value is @code{None} if the objfile is no longer valid. | |
5527 | See the @code{gdb.Objfile.is_valid} method, described below. | |
5528 | @end defvar | |
5529 | ||
99298c95 TT |
5530 | @defvar Objfile.is_file |
5531 | An objfile often comes from an ordinary file, but in some cases it may | |
5532 | be constructed from the contents of memory. This attribute is | |
5533 | @code{True} for file-backed objfiles, and @code{False} for other | |
5534 | kinds. | |
5535 | @end defvar | |
5536 | ||
a0be3e44 DE |
5537 | @defvar Objfile.owner |
5538 | For separate debug info objfiles this is the corresponding @code{gdb.Objfile} | |
5539 | object that debug info is being provided for. | |
5540 | Otherwise this is @code{None}. | |
5541 | Separate debug info objfiles are added with the | |
5542 | @code{gdb.Objfile.add_separate_debug_file} method, described below. | |
5543 | @end defvar | |
5544 | ||
7c50a931 DE |
5545 | @defvar Objfile.build_id |
5546 | The build ID of the objfile as a string. | |
5547 | If the objfile does not have a build ID then the value is @code{None}. | |
5548 | ||
5549 | This is supported only on some operating systems, notably those which use | |
5550 | the ELF format for binary files and the @sc{gnu} Binutils. For more details | |
5551 | about this feature, see the description of the @option{--build-id} | |
f5a476a7 | 5552 | command-line option in @ref{Options, , Command Line Options, ld, |
7c50a931 DE |
5553 | The GNU Linker}. |
5554 | @end defvar | |
5555 | ||
d096d8c1 DE |
5556 | @defvar Objfile.progspace |
5557 | The containing program space of the objfile as a @code{gdb.Progspace} | |
5558 | object. @xref{Progspaces In Python}. | |
5559 | @end defvar | |
5560 | ||
329baa95 DE |
5561 | @defvar Objfile.pretty_printers |
5562 | The @code{pretty_printers} attribute is a list of functions. It is | |
5563 | used to look up pretty-printers. A @code{Value} is passed to each | |
5564 | function in order; if the function returns @code{None}, then the | |
5565 | search continues. Otherwise, the return value should be an object | |
5566 | which is used to format the value. @xref{Pretty Printing API}, for more | |
5567 | information. | |
5568 | @end defvar | |
5569 | ||
5570 | @defvar Objfile.type_printers | |
5571 | The @code{type_printers} attribute is a list of type printer objects. | |
5572 | @xref{Type Printing API}, for more information. | |
5573 | @end defvar | |
5574 | ||
5575 | @defvar Objfile.frame_filters | |
5576 | The @code{frame_filters} attribute is a dictionary of frame filter | |
5577 | objects. @xref{Frame Filter API}, for more information. | |
5578 | @end defvar | |
5579 | ||
02be9a71 DE |
5580 | One may add arbitrary attributes to @code{gdb.Objfile} objects |
5581 | in the usual Python way. | |
5582 | This is useful if, for example, one needs to do some extra record keeping | |
5583 | associated with the objfile. | |
5584 | ||
53d08890 AB |
5585 | @xref{choosing attribute names}, for guidance on selecting a suitable |
5586 | name for new attributes. | |
5587 | ||
02be9a71 DE |
5588 | In this contrived example we record the time when @value{GDBN} |
5589 | loaded the objfile. | |
5590 | ||
5591 | @smallexample | |
7ccdf9c0 AB |
5592 | @group |
5593 | (@value{GDBP}) python | |
02be9a71 DE |
5594 | import datetime |
5595 | def new_objfile_handler(event): | |
5596 | # Set the time_loaded attribute of the new objfile. | |
5597 | event.new_objfile.time_loaded = datetime.datetime.today() | |
5598 | gdb.events.new_objfile.connect(new_objfile_handler) | |
5599 | end | |
7ccdf9c0 AB |
5600 | @end group |
5601 | @group | |
5602 | (@value{GDBP}) file ./hello | |
0bab6cf1 | 5603 | Reading symbols from ./hello... |
7ccdf9c0 | 5604 | (@value{GDBP}) python print(gdb.objfiles()[0].time_loaded) |
02be9a71 | 5605 | 2014-10-09 11:41:36.770345 |
7ccdf9c0 | 5606 | @end group |
02be9a71 DE |
5607 | @end smallexample |
5608 | ||
329baa95 DE |
5609 | A @code{gdb.Objfile} object has the following methods: |
5610 | ||
5611 | @defun Objfile.is_valid () | |
5612 | Returns @code{True} if the @code{gdb.Objfile} object is valid, | |
5613 | @code{False} if not. A @code{gdb.Objfile} object can become invalid | |
5614 | if the object file it refers to is not loaded in @value{GDBN} any | |
5615 | longer. All other @code{gdb.Objfile} methods will throw an exception | |
5616 | if it is invalid at the time the method is called. | |
5617 | @end defun | |
5618 | ||
86e4ed39 DE |
5619 | @defun Objfile.add_separate_debug_file (file) |
5620 | Add @var{file} to the list of files that @value{GDBN} will search for | |
5621 | debug information for the objfile. | |
5622 | This is useful when the debug info has been removed from the program | |
5623 | and stored in a separate file. @value{GDBN} has built-in support for | |
5624 | finding separate debug info files (@pxref{Separate Debug Files}), but if | |
5625 | the file doesn't live in one of the standard places that @value{GDBN} | |
5626 | searches then this function can be used to add a debug info file | |
5627 | from a different place. | |
5628 | @end defun | |
5629 | ||
c620ed88 CB |
5630 | @defun Objfile.lookup_global_symbol (name @r{[}, domain@r{]}) |
5631 | Search for a global symbol named @var{name} in this objfile. Optionally, the | |
5632 | search scope can be restricted with the @var{domain} argument. | |
5633 | The @var{domain} argument must be a domain constant defined in the @code{gdb} | |
5634 | module and described in @ref{Symbols In Python}. This function is similar to | |
5635 | @code{gdb.lookup_global_symbol}, except that the search is limited to this | |
5636 | objfile. | |
5637 | ||
5638 | The result is a @code{gdb.Symbol} object or @code{None} if the symbol | |
5639 | is not found. | |
5640 | @end defun | |
5641 | ||
5642 | @defun Objfile.lookup_static_symbol (name @r{[}, domain@r{]}) | |
5643 | Like @code{Objfile.lookup_global_symbol}, but searches for a global | |
5644 | symbol with static linkage named @var{name} in this objfile. | |
5645 | @end defun | |
5646 | ||
329baa95 | 5647 | @node Frames In Python |
849cba3b | 5648 | @subsubsection Accessing inferior stack frames from Python |
329baa95 DE |
5649 | |
5650 | @cindex frames in python | |
5651 | When the debugged program stops, @value{GDBN} is able to analyze its call | |
5652 | stack (@pxref{Frames,,Stack frames}). The @code{gdb.Frame} class | |
5653 | represents a frame in the stack. A @code{gdb.Frame} object is only valid | |
5654 | while its corresponding frame exists in the inferior's stack. If you try | |
5655 | to use an invalid frame object, @value{GDBN} will throw a @code{gdb.error} | |
5656 | exception (@pxref{Exception Handling}). | |
5657 | ||
5658 | Two @code{gdb.Frame} objects can be compared for equality with the @code{==} | |
5659 | operator, like: | |
5660 | ||
5661 | @smallexample | |
5662 | (@value{GDBP}) python print gdb.newest_frame() == gdb.selected_frame () | |
5663 | True | |
5664 | @end smallexample | |
5665 | ||
5666 | The following frame-related functions are available in the @code{gdb} module: | |
5667 | ||
329baa95 DE |
5668 | @defun gdb.selected_frame () |
5669 | Return the selected frame object. (@pxref{Selection,,Selecting a Frame}). | |
5670 | @end defun | |
5671 | ||
329baa95 DE |
5672 | @defun gdb.newest_frame () |
5673 | Return the newest frame object for the selected thread. | |
5674 | @end defun | |
5675 | ||
5676 | @defun gdb.frame_stop_reason_string (reason) | |
5677 | Return a string explaining the reason why @value{GDBN} stopped unwinding | |
5678 | frames, as expressed by the given @var{reason} code (an integer, see the | |
5679 | @code{unwind_stop_reason} method further down in this section). | |
5680 | @end defun | |
5681 | ||
e0f3fd7c TT |
5682 | @defun gdb.invalidate_cached_frames |
5683 | @value{GDBN} internally keeps a cache of the frames that have been | |
5684 | unwound. This function invalidates this cache. | |
5685 | ||
5686 | This function should not generally be called by ordinary Python code. | |
5687 | It is documented for the sake of completeness. | |
5688 | @end defun | |
5689 | ||
329baa95 DE |
5690 | A @code{gdb.Frame} object has the following methods: |
5691 | ||
5692 | @defun Frame.is_valid () | |
5693 | Returns true if the @code{gdb.Frame} object is valid, false if not. | |
5694 | A frame object can become invalid if the frame it refers to doesn't | |
5695 | exist anymore in the inferior. All @code{gdb.Frame} methods will throw | |
5696 | an exception if it is invalid at the time the method is called. | |
5697 | @end defun | |
5698 | ||
5699 | @defun Frame.name () | |
5700 | Returns the function name of the frame, or @code{None} if it can't be | |
5701 | obtained. | |
5702 | @end defun | |
5703 | ||
5704 | @defun Frame.architecture () | |
5705 | Returns the @code{gdb.Architecture} object corresponding to the frame's | |
5706 | architecture. @xref{Architectures In Python}. | |
5707 | @end defun | |
5708 | ||
5709 | @defun Frame.type () | |
5710 | Returns the type of the frame. The value can be one of: | |
5711 | @table @code | |
5712 | @item gdb.NORMAL_FRAME | |
5713 | An ordinary stack frame. | |
5714 | ||
5715 | @item gdb.DUMMY_FRAME | |
5716 | A fake stack frame that was created by @value{GDBN} when performing an | |
5717 | inferior function call. | |
5718 | ||
5719 | @item gdb.INLINE_FRAME | |
5720 | A frame representing an inlined function. The function was inlined | |
5721 | into a @code{gdb.NORMAL_FRAME} that is older than this one. | |
5722 | ||
5723 | @item gdb.TAILCALL_FRAME | |
5724 | A frame representing a tail call. @xref{Tail Call Frames}. | |
5725 | ||
5726 | @item gdb.SIGTRAMP_FRAME | |
5727 | A signal trampoline frame. This is the frame created by the OS when | |
5728 | it calls into a signal handler. | |
5729 | ||
5730 | @item gdb.ARCH_FRAME | |
5731 | A fake stack frame representing a cross-architecture call. | |
5732 | ||
5733 | @item gdb.SENTINEL_FRAME | |
5734 | This is like @code{gdb.NORMAL_FRAME}, but it is only used for the | |
5735 | newest frame. | |
5736 | @end table | |
5737 | @end defun | |
5738 | ||
5739 | @defun Frame.unwind_stop_reason () | |
5740 | Return an integer representing the reason why it's not possible to find | |
5741 | more frames toward the outermost frame. Use | |
5742 | @code{gdb.frame_stop_reason_string} to convert the value returned by this | |
5743 | function to a string. The value can be one of: | |
5744 | ||
5745 | @table @code | |
5746 | @item gdb.FRAME_UNWIND_NO_REASON | |
5747 | No particular reason (older frames should be available). | |
5748 | ||
5749 | @item gdb.FRAME_UNWIND_NULL_ID | |
5750 | The previous frame's analyzer returns an invalid result. This is no | |
5751 | longer used by @value{GDBN}, and is kept only for backward | |
5752 | compatibility. | |
5753 | ||
5754 | @item gdb.FRAME_UNWIND_OUTERMOST | |
5755 | This frame is the outermost. | |
5756 | ||
5757 | @item gdb.FRAME_UNWIND_UNAVAILABLE | |
5758 | Cannot unwind further, because that would require knowing the | |
5759 | values of registers or memory that have not been collected. | |
5760 | ||
5761 | @item gdb.FRAME_UNWIND_INNER_ID | |
5762 | This frame ID looks like it ought to belong to a NEXT frame, | |
5763 | but we got it for a PREV frame. Normally, this is a sign of | |
5764 | unwinder failure. It could also indicate stack corruption. | |
5765 | ||
5766 | @item gdb.FRAME_UNWIND_SAME_ID | |
5767 | This frame has the same ID as the previous one. That means | |
5768 | that unwinding further would almost certainly give us another | |
5769 | frame with exactly the same ID, so break the chain. Normally, | |
5770 | this is a sign of unwinder failure. It could also indicate | |
5771 | stack corruption. | |
5772 | ||
5773 | @item gdb.FRAME_UNWIND_NO_SAVED_PC | |
5774 | The frame unwinder did not find any saved PC, but we needed | |
5775 | one to unwind further. | |
5776 | ||
53e8a631 AB |
5777 | @item gdb.FRAME_UNWIND_MEMORY_ERROR |
5778 | The frame unwinder caused an error while trying to access memory. | |
5779 | ||
329baa95 DE |
5780 | @item gdb.FRAME_UNWIND_FIRST_ERROR |
5781 | Any stop reason greater or equal to this value indicates some kind | |
5782 | of error. This special value facilitates writing code that tests | |
5783 | for errors in unwinding in a way that will work correctly even if | |
5784 | the list of the other values is modified in future @value{GDBN} | |
5785 | versions. Using it, you could write: | |
5786 | @smallexample | |
5787 | reason = gdb.selected_frame().unwind_stop_reason () | |
5788 | reason_str = gdb.frame_stop_reason_string (reason) | |
5789 | if reason >= gdb.FRAME_UNWIND_FIRST_ERROR: | |
33b5899f | 5790 | print ("An error occurred: %s" % reason_str) |
329baa95 DE |
5791 | @end smallexample |
5792 | @end table | |
5793 | ||
5794 | @end defun | |
5795 | ||
5796 | @defun Frame.pc () | |
5797 | Returns the frame's resume address. | |
5798 | @end defun | |
5799 | ||
5800 | @defun Frame.block () | |
60c0454d TT |
5801 | Return the frame's code block. @xref{Blocks In Python}. If the frame |
5802 | does not have a block -- for example, if there is no debugging | |
5803 | information for the code in question -- then this will throw an | |
5804 | exception. | |
329baa95 DE |
5805 | @end defun |
5806 | ||
5807 | @defun Frame.function () | |
5808 | Return the symbol for the function corresponding to this frame. | |
5809 | @xref{Symbols In Python}. | |
5810 | @end defun | |
5811 | ||
5812 | @defun Frame.older () | |
3f33695b TT |
5813 | Return the frame that called this frame. If this is the oldest frame, |
5814 | return @code{None}. | |
329baa95 DE |
5815 | @end defun |
5816 | ||
5817 | @defun Frame.newer () | |
3f33695b TT |
5818 | Return the frame called by this frame. If this is the newest frame, |
5819 | return @code{None}. | |
329baa95 DE |
5820 | @end defun |
5821 | ||
5822 | @defun Frame.find_sal () | |
5823 | Return the frame's symtab and line object. | |
5824 | @xref{Symbol Tables In Python}. | |
5825 | @end defun | |
5826 | ||
0f767f94 | 5827 | @anchor{gdbpy_frame_read_register} |
5f3b99cf | 5828 | @defun Frame.read_register (register) |
43d5901d AB |
5829 | Return the value of @var{register} in this frame. Returns a |
5830 | @code{Gdb.Value} object. Throws an exception if @var{register} does | |
5831 | not exist. The @var{register} argument must be one of the following: | |
5832 | @enumerate | |
5833 | @item | |
5834 | A string that is the name of a valid register (e.g., @code{'sp'} or | |
5835 | @code{'rax'}). | |
5836 | @item | |
5837 | A @code{gdb.RegisterDescriptor} object (@pxref{Registers In Python}). | |
5838 | @item | |
5839 | A @value{GDBN} internal, platform specific number. Using these | |
5840 | numbers is supported for historic reasons, but is not recommended as | |
5841 | future changes to @value{GDBN} could change the mapping between | |
5842 | numbers and the registers they represent, breaking any Python code | |
5843 | that uses the platform-specific numbers. The numbers are usually | |
5844 | found in the corresponding @file{@var{platform}-tdep.h} file in the | |
5845 | @value{GDBN} source tree. | |
5846 | @end enumerate | |
5847 | Using a string to access registers will be slightly slower than the | |
5848 | other two methods as @value{GDBN} must look up the mapping between | |
5849 | name and internal register number. If performance is critical | |
5850 | consider looking up and caching a @code{gdb.RegisterDescriptor} | |
5851 | object. | |
5f3b99cf SS |
5852 | @end defun |
5853 | ||
329baa95 DE |
5854 | @defun Frame.read_var (variable @r{[}, block@r{]}) |
5855 | Return the value of @var{variable} in this frame. If the optional | |
5856 | argument @var{block} is provided, search for the variable from that | |
5857 | block; otherwise start at the frame's current block (which is | |
697aa1b7 EZ |
5858 | determined by the frame's current program counter). The @var{variable} |
5859 | argument must be a string or a @code{gdb.Symbol} object; @var{block} must be a | |
329baa95 DE |
5860 | @code{gdb.Block} object. |
5861 | @end defun | |
5862 | ||
5863 | @defun Frame.select () | |
5864 | Set this frame to be the selected frame. @xref{Stack, ,Examining the | |
5865 | Stack}. | |
5866 | @end defun | |
5867 | ||
4ead09a2 TT |
5868 | @defun Frame.static_link () |
5869 | In some languages (e.g., Ada, but also a GNU C extension), a nested | |
5870 | function can access the variables in the outer scope. This is done | |
5871 | via a ``static link'', which is a reference from the nested frame to | |
5872 | the appropriate outer frame. | |
5873 | ||
5874 | This method returns this frame's static link frame, if one exists. If | |
5875 | there is no static link, this method returns @code{None}. | |
5876 | @end defun | |
5877 | ||
d52b8007 AB |
5878 | @defun Frame.level () |
5879 | Return an integer, the stack frame level for this frame. @xref{Frames, ,Stack Frames}. | |
5880 | @end defun | |
5881 | ||
80fa4b2a TT |
5882 | @defun Frame.language () |
5883 | Return a string, the source language for this frame. | |
5884 | @end defun | |
5885 | ||
329baa95 | 5886 | @node Blocks In Python |
849cba3b | 5887 | @subsubsection Accessing blocks from Python |
329baa95 DE |
5888 | |
5889 | @cindex blocks in python | |
5890 | @tindex gdb.Block | |
5891 | ||
5892 | In @value{GDBN}, symbols are stored in blocks. A block corresponds | |
5893 | roughly to a scope in the source code. Blocks are organized | |
5894 | hierarchically, and are represented individually in Python as a | |
5895 | @code{gdb.Block}. Blocks rely on debugging information being | |
5896 | available. | |
5897 | ||
5898 | A frame has a block. Please see @ref{Frames In Python}, for a more | |
5899 | in-depth discussion of frames. | |
5900 | ||
5901 | The outermost block is known as the @dfn{global block}. The global | |
5902 | block typically holds public global variables and functions. | |
5903 | ||
5904 | The block nested just inside the global block is the @dfn{static | |
5905 | block}. The static block typically holds file-scoped variables and | |
5906 | functions. | |
5907 | ||
5908 | @value{GDBN} provides a method to get a block's superblock, but there | |
5909 | is currently no way to examine the sub-blocks of a block, or to | |
5910 | iterate over all the blocks in a symbol table (@pxref{Symbol Tables In | |
5911 | Python}). | |
5912 | ||
5913 | Here is a short example that should help explain blocks: | |
5914 | ||
5915 | @smallexample | |
5916 | /* This is in the global block. */ | |
5917 | int global; | |
5918 | ||
5919 | /* This is in the static block. */ | |
5920 | static int file_scope; | |
5921 | ||
5922 | /* 'function' is in the global block, and 'argument' is | |
5923 | in a block nested inside of 'function'. */ | |
5924 | int function (int argument) | |
5925 | @{ | |
5926 | /* 'local' is in a block inside 'function'. It may or may | |
5927 | not be in the same block as 'argument'. */ | |
5928 | int local; | |
5929 | ||
5930 | @{ | |
5931 | /* 'inner' is in a block whose superblock is the one holding | |
5932 | 'local'. */ | |
5933 | int inner; | |
5934 | ||
5935 | /* If this call is expanded by the compiler, you may see | |
5936 | a nested block here whose function is 'inline_function' | |
5937 | and whose superblock is the one holding 'inner'. */ | |
5938 | inline_function (); | |
5939 | @} | |
5940 | @} | |
5941 | @end smallexample | |
5942 | ||
5943 | A @code{gdb.Block} is iterable. The iterator returns the symbols | |
5944 | (@pxref{Symbols In Python}) local to the block. Python programs | |
5945 | should not assume that a specific block object will always contain a | |
5946 | given symbol, since changes in @value{GDBN} features and | |
5947 | infrastructure may cause symbols move across blocks in a symbol | |
0b27c27d CB |
5948 | table. You can also use Python's @dfn{dictionary syntax} to access |
5949 | variables in this block, e.g.: | |
5950 | ||
5951 | @smallexample | |
5952 | symbol = some_block['variable'] # symbol is of type gdb.Symbol | |
5953 | @end smallexample | |
329baa95 DE |
5954 | |
5955 | The following block-related functions are available in the @code{gdb} | |
5956 | module: | |
5957 | ||
329baa95 DE |
5958 | @defun gdb.block_for_pc (pc) |
5959 | Return the innermost @code{gdb.Block} containing the given @var{pc} | |
5960 | value. If the block cannot be found for the @var{pc} value specified, | |
8743a9cd TT |
5961 | the function will return @code{None}. This is identical to |
5962 | @code{gdb.current_progspace().block_for_pc(pc)} and is included for | |
5963 | historical compatibility. | |
329baa95 DE |
5964 | @end defun |
5965 | ||
5966 | A @code{gdb.Block} object has the following methods: | |
5967 | ||
5968 | @defun Block.is_valid () | |
5969 | Returns @code{True} if the @code{gdb.Block} object is valid, | |
5970 | @code{False} if not. A block object can become invalid if the block it | |
5971 | refers to doesn't exist anymore in the inferior. All other | |
5972 | @code{gdb.Block} methods will throw an exception if it is invalid at | |
5973 | the time the method is called. The block's validity is also checked | |
5974 | during iteration over symbols of the block. | |
5975 | @end defun | |
5976 | ||
5977 | A @code{gdb.Block} object has the following attributes: | |
5978 | ||
5979 | @defvar Block.start | |
5980 | The start address of the block. This attribute is not writable. | |
5981 | @end defvar | |
5982 | ||
5983 | @defvar Block.end | |
22eb9e92 TT |
5984 | One past the last address that appears in the block. This attribute |
5985 | is not writable. | |
329baa95 DE |
5986 | @end defvar |
5987 | ||
5988 | @defvar Block.function | |
5989 | The name of the block represented as a @code{gdb.Symbol}. If the | |
5990 | block is not named, then this attribute holds @code{None}. This | |
5991 | attribute is not writable. | |
5992 | ||
5993 | For ordinary function blocks, the superblock is the static block. | |
5994 | However, you should note that it is possible for a function block to | |
5995 | have a superblock that is not the static block -- for instance this | |
5996 | happens for an inlined function. | |
5997 | @end defvar | |
5998 | ||
5999 | @defvar Block.superblock | |
6000 | The block containing this block. If this parent block does not exist, | |
6001 | this attribute holds @code{None}. This attribute is not writable. | |
6002 | @end defvar | |
6003 | ||
6004 | @defvar Block.global_block | |
6005 | The global block associated with this block. This attribute is not | |
6006 | writable. | |
6007 | @end defvar | |
6008 | ||
6009 | @defvar Block.static_block | |
6010 | The static block associated with this block. This attribute is not | |
6011 | writable. | |
6012 | @end defvar | |
6013 | ||
6014 | @defvar Block.is_global | |
6015 | @code{True} if the @code{gdb.Block} object is a global block, | |
6016 | @code{False} if not. This attribute is not | |
6017 | writable. | |
6018 | @end defvar | |
6019 | ||
6020 | @defvar Block.is_static | |
6021 | @code{True} if the @code{gdb.Block} object is a static block, | |
6022 | @code{False} if not. This attribute is not writable. | |
6023 | @end defvar | |
6024 | ||
6025 | @node Symbols In Python | |
849cba3b | 6026 | @subsubsection Python representation of Symbols |
329baa95 DE |
6027 | |
6028 | @cindex symbols in python | |
6029 | @tindex gdb.Symbol | |
6030 | ||
6031 | @value{GDBN} represents every variable, function and type as an | |
6032 | entry in a symbol table. @xref{Symbols, ,Examining the Symbol Table}. | |
6033 | Similarly, Python represents these symbols in @value{GDBN} with the | |
6034 | @code{gdb.Symbol} object. | |
6035 | ||
6036 | The following symbol-related functions are available in the @code{gdb} | |
6037 | module: | |
6038 | ||
329baa95 DE |
6039 | @defun gdb.lookup_symbol (name @r{[}, block @r{[}, domain@r{]]}) |
6040 | This function searches for a symbol by name. The search scope can be | |
6041 | restricted to the parameters defined in the optional domain and block | |
6042 | arguments. | |
6043 | ||
6044 | @var{name} is the name of the symbol. It must be a string. The | |
6045 | optional @var{block} argument restricts the search to symbols visible | |
6046 | in that @var{block}. The @var{block} argument must be a | |
6047 | @code{gdb.Block} object. If omitted, the block for the current frame | |
6048 | is used. The optional @var{domain} argument restricts | |
6049 | the search to the domain type. The @var{domain} argument must be a | |
6050 | domain constant defined in the @code{gdb} module and described later | |
6051 | in this chapter. | |
6052 | ||
6053 | The result is a tuple of two elements. | |
6054 | The first element is a @code{gdb.Symbol} object or @code{None} if the symbol | |
6055 | is not found. | |
6056 | If the symbol is found, the second element is @code{True} if the symbol | |
6057 | is a field of a method's object (e.g., @code{this} in C@t{++}), | |
6058 | otherwise it is @code{False}. | |
6059 | If the symbol is not found, the second element is @code{False}. | |
6060 | @end defun | |
6061 | ||
329baa95 DE |
6062 | @defun gdb.lookup_global_symbol (name @r{[}, domain@r{]}) |
6063 | This function searches for a global symbol by name. | |
6064 | The search scope can be restricted to by the domain argument. | |
6065 | ||
6066 | @var{name} is the name of the symbol. It must be a string. | |
6067 | The optional @var{domain} argument restricts the search to the domain type. | |
6068 | The @var{domain} argument must be a domain constant defined in the @code{gdb} | |
6069 | module and described later in this chapter. | |
6070 | ||
6071 | The result is a @code{gdb.Symbol} object or @code{None} if the symbol | |
6072 | is not found. | |
6073 | @end defun | |
6074 | ||
2906593f CB |
6075 | @defun gdb.lookup_static_symbol (name @r{[}, domain@r{]}) |
6076 | This function searches for a global symbol with static linkage by name. | |
6077 | The search scope can be restricted to by the domain argument. | |
6078 | ||
6079 | @var{name} is the name of the symbol. It must be a string. | |
6080 | The optional @var{domain} argument restricts the search to the domain type. | |
6081 | The @var{domain} argument must be a domain constant defined in the @code{gdb} | |
6082 | module and described later in this chapter. | |
6083 | ||
6084 | The result is a @code{gdb.Symbol} object or @code{None} if the symbol | |
6085 | is not found. | |
6086 | ||
6087 | Note that this function will not find function-scoped static variables. To look | |
6088 | up such variables, iterate over the variables of the function's | |
6089 | @code{gdb.Block} and check that @code{block.addr_class} is | |
6090 | @code{gdb.SYMBOL_LOC_STATIC}. | |
09ff83af AB |
6091 | |
6092 | There can be multiple global symbols with static linkage with the same | |
6093 | name. This function will only return the first matching symbol that | |
6094 | it finds. Which symbol is found depends on where @value{GDBN} is | |
6095 | currently stopped, as @value{GDBN} will first search for matching | |
6096 | symbols in the current object file, and then search all other object | |
6097 | files. If the application is not yet running then @value{GDBN} will | |
6098 | search all object files in the order they appear in the debug | |
6099 | information. | |
2906593f CB |
6100 | @end defun |
6101 | ||
086baaf1 AB |
6102 | @defun gdb.lookup_static_symbols (name @r{[}, domain@r{]}) |
6103 | Similar to @code{gdb.lookup_static_symbol}, this function searches for | |
6104 | global symbols with static linkage by name, and optionally restricted | |
6105 | by the domain argument. However, this function returns a list of all | |
6106 | matching symbols found, not just the first one. | |
6107 | ||
6108 | @var{name} is the name of the symbol. It must be a string. | |
6109 | The optional @var{domain} argument restricts the search to the domain type. | |
6110 | The @var{domain} argument must be a domain constant defined in the @code{gdb} | |
6111 | module and described later in this chapter. | |
6112 | ||
6113 | The result is a list of @code{gdb.Symbol} objects which could be empty | |
6114 | if no matching symbols were found. | |
6115 | ||
6116 | Note that this function will not find function-scoped static variables. To look | |
6117 | up such variables, iterate over the variables of the function's | |
6118 | @code{gdb.Block} and check that @code{block.addr_class} is | |
6119 | @code{gdb.SYMBOL_LOC_STATIC}. | |
6120 | @end defun | |
6121 | ||
329baa95 DE |
6122 | A @code{gdb.Symbol} object has the following attributes: |
6123 | ||
6124 | @defvar Symbol.type | |
6125 | The type of the symbol or @code{None} if no type is recorded. | |
6126 | This attribute is represented as a @code{gdb.Type} object. | |
6127 | @xref{Types In Python}. This attribute is not writable. | |
6128 | @end defvar | |
6129 | ||
6130 | @defvar Symbol.symtab | |
6131 | The symbol table in which the symbol appears. This attribute is | |
6132 | represented as a @code{gdb.Symtab} object. @xref{Symbol Tables In | |
6133 | Python}. This attribute is not writable. | |
6134 | @end defvar | |
6135 | ||
6136 | @defvar Symbol.line | |
6137 | The line number in the source code at which the symbol was defined. | |
6138 | This is an integer. | |
6139 | @end defvar | |
6140 | ||
6141 | @defvar Symbol.name | |
6142 | The name of the symbol as a string. This attribute is not writable. | |
6143 | @end defvar | |
6144 | ||
6145 | @defvar Symbol.linkage_name | |
6146 | The name of the symbol, as used by the linker (i.e., may be mangled). | |
6147 | This attribute is not writable. | |
6148 | @end defvar | |
6149 | ||
6150 | @defvar Symbol.print_name | |
6151 | The name of the symbol in a form suitable for output. This is either | |
6152 | @code{name} or @code{linkage_name}, depending on whether the user | |
6153 | asked @value{GDBN} to display demangled or mangled names. | |
6154 | @end defvar | |
6155 | ||
6156 | @defvar Symbol.addr_class | |
6157 | The address class of the symbol. This classifies how to find the value | |
6158 | of a symbol. Each address class is a constant defined in the | |
6159 | @code{gdb} module and described later in this chapter. | |
6160 | @end defvar | |
6161 | ||
6162 | @defvar Symbol.needs_frame | |
6163 | This is @code{True} if evaluating this symbol's value requires a frame | |
6164 | (@pxref{Frames In Python}) and @code{False} otherwise. Typically, | |
6165 | local variables will require a frame, but other symbols will not. | |
6166 | @end defvar | |
6167 | ||
6168 | @defvar Symbol.is_argument | |
6169 | @code{True} if the symbol is an argument of a function. | |
6170 | @end defvar | |
6171 | ||
6172 | @defvar Symbol.is_constant | |
6173 | @code{True} if the symbol is a constant. | |
6174 | @end defvar | |
6175 | ||
6176 | @defvar Symbol.is_function | |
6177 | @code{True} if the symbol is a function or a method. | |
6178 | @end defvar | |
6179 | ||
6180 | @defvar Symbol.is_variable | |
5006ea55 TT |
6181 | @code{True} if the symbol is a variable, as opposed to something like |
6182 | a function or type. Note that this also returns @code{False} for | |
6183 | arguments. | |
329baa95 DE |
6184 | @end defvar |
6185 | ||
6186 | A @code{gdb.Symbol} object has the following methods: | |
6187 | ||
6188 | @defun Symbol.is_valid () | |
6189 | Returns @code{True} if the @code{gdb.Symbol} object is valid, | |
6190 | @code{False} if not. A @code{gdb.Symbol} object can become invalid if | |
6191 | the symbol it refers to does not exist in @value{GDBN} any longer. | |
6192 | All other @code{gdb.Symbol} methods will throw an exception if it is | |
6193 | invalid at the time the method is called. | |
6194 | @end defun | |
6195 | ||
6196 | @defun Symbol.value (@r{[}frame@r{]}) | |
6197 | Compute the value of the symbol, as a @code{gdb.Value}. For | |
6198 | functions, this computes the address of the function, cast to the | |
6199 | appropriate type. If the symbol requires a frame in order to compute | |
6200 | its value, then @var{frame} must be given. If @var{frame} is not | |
6201 | given, or if @var{frame} is invalid, then this method will throw an | |
6202 | exception. | |
6203 | @end defun | |
6204 | ||
6205 | The available domain categories in @code{gdb.Symbol} are represented | |
6206 | as constants in the @code{gdb} module: | |
6207 | ||
b3ce5e5f DE |
6208 | @vtable @code |
6209 | @vindex SYMBOL_UNDEF_DOMAIN | |
329baa95 DE |
6210 | @item gdb.SYMBOL_UNDEF_DOMAIN |
6211 | This is used when a domain has not been discovered or none of the | |
6212 | following domains apply. This usually indicates an error either | |
6213 | in the symbol information or in @value{GDBN}'s handling of symbols. | |
b3ce5e5f DE |
6214 | |
6215 | @vindex SYMBOL_VAR_DOMAIN | |
329baa95 DE |
6216 | @item gdb.SYMBOL_VAR_DOMAIN |
6217 | This domain contains variables, function names, typedef names and enum | |
6218 | type values. | |
b3ce5e5f DE |
6219 | |
6220 | @vindex SYMBOL_STRUCT_DOMAIN | |
329baa95 DE |
6221 | @item gdb.SYMBOL_STRUCT_DOMAIN |
6222 | This domain holds struct, union and enum type names. | |
b3ce5e5f DE |
6223 | |
6224 | @vindex SYMBOL_LABEL_DOMAIN | |
329baa95 DE |
6225 | @item gdb.SYMBOL_LABEL_DOMAIN |
6226 | This domain contains names of labels (for gotos). | |
b3ce5e5f | 6227 | |
51e78fc5 TT |
6228 | @vindex SYMBOL_MODULE_DOMAIN |
6229 | @item gdb.SYMBOL_MODULE_DOMAIN | |
6230 | This domain contains names of Fortran module types. | |
6231 | ||
6232 | @vindex SYMBOL_COMMON_BLOCK_DOMAIN | |
6233 | @item gdb.SYMBOL_COMMON_BLOCK_DOMAIN | |
6234 | This domain contains names of Fortran common blocks. | |
b3ce5e5f | 6235 | @end vtable |
329baa95 DE |
6236 | |
6237 | The available address class categories in @code{gdb.Symbol} are represented | |
6238 | as constants in the @code{gdb} module: | |
6239 | ||
b3ce5e5f DE |
6240 | @vtable @code |
6241 | @vindex SYMBOL_LOC_UNDEF | |
329baa95 DE |
6242 | @item gdb.SYMBOL_LOC_UNDEF |
6243 | If this is returned by address class, it indicates an error either in | |
6244 | the symbol information or in @value{GDBN}'s handling of symbols. | |
b3ce5e5f DE |
6245 | |
6246 | @vindex SYMBOL_LOC_CONST | |
329baa95 DE |
6247 | @item gdb.SYMBOL_LOC_CONST |
6248 | Value is constant int. | |
b3ce5e5f DE |
6249 | |
6250 | @vindex SYMBOL_LOC_STATIC | |
329baa95 DE |
6251 | @item gdb.SYMBOL_LOC_STATIC |
6252 | Value is at a fixed address. | |
b3ce5e5f DE |
6253 | |
6254 | @vindex SYMBOL_LOC_REGISTER | |
329baa95 DE |
6255 | @item gdb.SYMBOL_LOC_REGISTER |
6256 | Value is in a register. | |
b3ce5e5f DE |
6257 | |
6258 | @vindex SYMBOL_LOC_ARG | |
329baa95 DE |
6259 | @item gdb.SYMBOL_LOC_ARG |
6260 | Value is an argument. This value is at the offset stored within the | |
6261 | symbol inside the frame's argument list. | |
b3ce5e5f DE |
6262 | |
6263 | @vindex SYMBOL_LOC_REF_ARG | |
329baa95 DE |
6264 | @item gdb.SYMBOL_LOC_REF_ARG |
6265 | Value address is stored in the frame's argument list. Just like | |
6266 | @code{LOC_ARG} except that the value's address is stored at the | |
6267 | offset, not the value itself. | |
b3ce5e5f DE |
6268 | |
6269 | @vindex SYMBOL_LOC_REGPARM_ADDR | |
329baa95 DE |
6270 | @item gdb.SYMBOL_LOC_REGPARM_ADDR |
6271 | Value is a specified register. Just like @code{LOC_REGISTER} except | |
6272 | the register holds the address of the argument instead of the argument | |
6273 | itself. | |
b3ce5e5f DE |
6274 | |
6275 | @vindex SYMBOL_LOC_LOCAL | |
329baa95 DE |
6276 | @item gdb.SYMBOL_LOC_LOCAL |
6277 | Value is a local variable. | |
b3ce5e5f DE |
6278 | |
6279 | @vindex SYMBOL_LOC_TYPEDEF | |
329baa95 DE |
6280 | @item gdb.SYMBOL_LOC_TYPEDEF |
6281 | Value not used. Symbols in the domain @code{SYMBOL_STRUCT_DOMAIN} all | |
6282 | have this class. | |
b3ce5e5f | 6283 | |
868027a4 HD |
6284 | @vindex SYMBOL_LOC_LABEL |
6285 | @item gdb.SYMBOL_LOC_LABEL | |
6286 | Value is a label. | |
6287 | ||
b3ce5e5f | 6288 | @vindex SYMBOL_LOC_BLOCK |
329baa95 DE |
6289 | @item gdb.SYMBOL_LOC_BLOCK |
6290 | Value is a block. | |
b3ce5e5f DE |
6291 | |
6292 | @vindex SYMBOL_LOC_CONST_BYTES | |
329baa95 DE |
6293 | @item gdb.SYMBOL_LOC_CONST_BYTES |
6294 | Value is a byte-sequence. | |
b3ce5e5f DE |
6295 | |
6296 | @vindex SYMBOL_LOC_UNRESOLVED | |
329baa95 DE |
6297 | @item gdb.SYMBOL_LOC_UNRESOLVED |
6298 | Value is at a fixed address, but the address of the variable has to be | |
6299 | determined from the minimal symbol table whenever the variable is | |
6300 | referenced. | |
b3ce5e5f DE |
6301 | |
6302 | @vindex SYMBOL_LOC_OPTIMIZED_OUT | |
329baa95 DE |
6303 | @item gdb.SYMBOL_LOC_OPTIMIZED_OUT |
6304 | The value does not actually exist in the program. | |
b3ce5e5f DE |
6305 | |
6306 | @vindex SYMBOL_LOC_COMPUTED | |
329baa95 DE |
6307 | @item gdb.SYMBOL_LOC_COMPUTED |
6308 | The value's address is a computed location. | |
51e78fc5 | 6309 | |
2c5731b6 HD |
6310 | @vindex SYMBOL_LOC_COMMON_BLOCK |
6311 | @item gdb.SYMBOL_LOC_COMMON_BLOCK | |
51e78fc5 TT |
6312 | The value's address is a symbol. This is only used for Fortran common |
6313 | blocks. | |
b3ce5e5f | 6314 | @end vtable |
329baa95 DE |
6315 | |
6316 | @node Symbol Tables In Python | |
849cba3b | 6317 | @subsubsection Symbol table representation in Python |
329baa95 DE |
6318 | |
6319 | @cindex symbol tables in python | |
6320 | @tindex gdb.Symtab | |
6321 | @tindex gdb.Symtab_and_line | |
6322 | ||
6323 | Access to symbol table data maintained by @value{GDBN} on the inferior | |
6324 | is exposed to Python via two objects: @code{gdb.Symtab_and_line} and | |
6325 | @code{gdb.Symtab}. Symbol table and line data for a frame is returned | |
6326 | from the @code{find_sal} method in @code{gdb.Frame} object. | |
6327 | @xref{Frames In Python}. | |
6328 | ||
6329 | For more information on @value{GDBN}'s symbol table management, see | |
6330 | @ref{Symbols, ,Examining the Symbol Table}, for more information. | |
6331 | ||
6332 | A @code{gdb.Symtab_and_line} object has the following attributes: | |
6333 | ||
6334 | @defvar Symtab_and_line.symtab | |
6335 | The symbol table object (@code{gdb.Symtab}) for this frame. | |
6336 | This attribute is not writable. | |
6337 | @end defvar | |
6338 | ||
6339 | @defvar Symtab_and_line.pc | |
6340 | Indicates the start of the address range occupied by code for the | |
6341 | current source line. This attribute is not writable. | |
6342 | @end defvar | |
6343 | ||
6344 | @defvar Symtab_and_line.last | |
6345 | Indicates the end of the address range occupied by code for the current | |
6346 | source line. This attribute is not writable. | |
6347 | @end defvar | |
6348 | ||
6349 | @defvar Symtab_and_line.line | |
6350 | Indicates the current line number for this object. This | |
6351 | attribute is not writable. | |
6352 | @end defvar | |
6353 | ||
6354 | A @code{gdb.Symtab_and_line} object has the following methods: | |
6355 | ||
6356 | @defun Symtab_and_line.is_valid () | |
6357 | Returns @code{True} if the @code{gdb.Symtab_and_line} object is valid, | |
6358 | @code{False} if not. A @code{gdb.Symtab_and_line} object can become | |
6359 | invalid if the Symbol table and line object it refers to does not | |
6360 | exist in @value{GDBN} any longer. All other | |
6361 | @code{gdb.Symtab_and_line} methods will throw an exception if it is | |
6362 | invalid at the time the method is called. | |
6363 | @end defun | |
6364 | ||
6365 | A @code{gdb.Symtab} object has the following attributes: | |
6366 | ||
6367 | @defvar Symtab.filename | |
6368 | The symbol table's source filename. This attribute is not writable. | |
6369 | @end defvar | |
6370 | ||
6371 | @defvar Symtab.objfile | |
6372 | The symbol table's backing object file. @xref{Objfiles In Python}. | |
6373 | This attribute is not writable. | |
6374 | @end defvar | |
6375 | ||
2b4fd423 DE |
6376 | @defvar Symtab.producer |
6377 | The name and possibly version number of the program that | |
6378 | compiled the code in the symbol table. | |
6379 | The contents of this string is up to the compiler. | |
6380 | If no producer information is available then @code{None} is returned. | |
6381 | This attribute is not writable. | |
6382 | @end defvar | |
6383 | ||
329baa95 DE |
6384 | A @code{gdb.Symtab} object has the following methods: |
6385 | ||
6386 | @defun Symtab.is_valid () | |
6387 | Returns @code{True} if the @code{gdb.Symtab} object is valid, | |
6388 | @code{False} if not. A @code{gdb.Symtab} object can become invalid if | |
6389 | the symbol table it refers to does not exist in @value{GDBN} any | |
6390 | longer. All other @code{gdb.Symtab} methods will throw an exception | |
6391 | if it is invalid at the time the method is called. | |
6392 | @end defun | |
6393 | ||
6394 | @defun Symtab.fullname () | |
6395 | Return the symbol table's source absolute file name. | |
6396 | @end defun | |
6397 | ||
6398 | @defun Symtab.global_block () | |
6399 | Return the global block of the underlying symbol table. | |
6400 | @xref{Blocks In Python}. | |
6401 | @end defun | |
6402 | ||
6403 | @defun Symtab.static_block () | |
6404 | Return the static block of the underlying symbol table. | |
6405 | @xref{Blocks In Python}. | |
6406 | @end defun | |
6407 | ||
6408 | @defun Symtab.linetable () | |
6409 | Return the line table associated with the symbol table. | |
6410 | @xref{Line Tables In Python}. | |
6411 | @end defun | |
6412 | ||
6413 | @node Line Tables In Python | |
6414 | @subsubsection Manipulating line tables using Python | |
6415 | ||
6416 | @cindex line tables in python | |
6417 | @tindex gdb.LineTable | |
6418 | ||
6419 | Python code can request and inspect line table information from a | |
6420 | symbol table that is loaded in @value{GDBN}. A line table is a | |
6421 | mapping of source lines to their executable locations in memory. To | |
6422 | acquire the line table information for a particular symbol table, use | |
6423 | the @code{linetable} function (@pxref{Symbol Tables In Python}). | |
6424 | ||
6425 | A @code{gdb.LineTable} is iterable. The iterator returns | |
6426 | @code{LineTableEntry} objects that correspond to the source line and | |
6427 | address for each line table entry. @code{LineTableEntry} objects have | |
6428 | the following attributes: | |
6429 | ||
6430 | @defvar LineTableEntry.line | |
6431 | The source line number for this line table entry. This number | |
6432 | corresponds to the actual line of source. This attribute is not | |
6433 | writable. | |
6434 | @end defvar | |
6435 | ||
6436 | @defvar LineTableEntry.pc | |
6437 | The address that is associated with the line table entry where the | |
6438 | executable code for that source line resides in memory. This | |
6439 | attribute is not writable. | |
6440 | @end defvar | |
6441 | ||
6442 | As there can be multiple addresses for a single source line, you may | |
6443 | receive multiple @code{LineTableEntry} objects with matching | |
6444 | @code{line} attributes, but with different @code{pc} attributes. The | |
6445 | iterator is sorted in ascending @code{pc} order. Here is a small | |
6446 | example illustrating iterating over a line table. | |
6447 | ||
6448 | @smallexample | |
6449 | symtab = gdb.selected_frame().find_sal().symtab | |
6450 | linetable = symtab.linetable() | |
6451 | for line in linetable: | |
f3bdc2db | 6452 | print ("Line: "+str(line.line)+" Address: "+hex(line.pc)) |
329baa95 DE |
6453 | @end smallexample |
6454 | ||
6455 | This will have the following output: | |
6456 | ||
6457 | @smallexample | |
6458 | Line: 33 Address: 0x4005c8L | |
6459 | Line: 37 Address: 0x4005caL | |
6460 | Line: 39 Address: 0x4005d2L | |
6461 | Line: 40 Address: 0x4005f8L | |
6462 | Line: 42 Address: 0x4005ffL | |
6463 | Line: 44 Address: 0x400608L | |
6464 | Line: 42 Address: 0x40060cL | |
6465 | Line: 45 Address: 0x400615L | |
6466 | @end smallexample | |
6467 | ||
6468 | In addition to being able to iterate over a @code{LineTable}, it also | |
6469 | has the following direct access methods: | |
6470 | ||
6471 | @defun LineTable.line (line) | |
6472 | Return a Python @code{Tuple} of @code{LineTableEntry} objects for any | |
697aa1b7 EZ |
6473 | entries in the line table for the given @var{line}, which specifies |
6474 | the source code line. If there are no entries for that source code | |
329baa95 DE |
6475 | @var{line}, the Python @code{None} is returned. |
6476 | @end defun | |
6477 | ||
6478 | @defun LineTable.has_line (line) | |
6479 | Return a Python @code{Boolean} indicating whether there is an entry in | |
6480 | the line table for this source line. Return @code{True} if an entry | |
6481 | is found, or @code{False} if not. | |
6482 | @end defun | |
6483 | ||
6484 | @defun LineTable.source_lines () | |
6485 | Return a Python @code{List} of the source line numbers in the symbol | |
6486 | table. Only lines with executable code locations are returned. The | |
6487 | contents of the @code{List} will just be the source line entries | |
6488 | represented as Python @code{Long} values. | |
6489 | @end defun | |
6490 | ||
6491 | @node Breakpoints In Python | |
6492 | @subsubsection Manipulating breakpoints using Python | |
6493 | ||
6494 | @cindex breakpoints in python | |
6495 | @tindex gdb.Breakpoint | |
6496 | ||
6497 | Python code can manipulate breakpoints via the @code{gdb.Breakpoint} | |
6498 | class. | |
6499 | ||
0b982d68 SM |
6500 | A breakpoint can be created using one of the two forms of the |
6501 | @code{gdb.Breakpoint} constructor. The first one accepts a string | |
6502 | like one would pass to the @code{break} | |
6503 | (@pxref{Set Breaks,,Setting Breakpoints}) and @code{watch} | |
6504 | (@pxref{Set Watchpoints, , Setting Watchpoints}) commands, and can be used to | |
6505 | create both breakpoints and watchpoints. The second accepts separate Python | |
6506 | arguments similar to @ref{Explicit Locations}, and can only be used to create | |
6507 | breakpoints. | |
6508 | ||
b89641ba | 6509 | @defun Breakpoint.__init__ (spec @r{[}, type @r{][}, wp_class @r{][}, internal @r{][}, temporary @r{][}, qualified @r{]}) |
0b982d68 SM |
6510 | Create a new breakpoint according to @var{spec}, which is a string naming the |
6511 | location of a breakpoint, or an expression that defines a watchpoint. The | |
6512 | string should describe a location in a format recognized by the @code{break} | |
6513 | command (@pxref{Set Breaks,,Setting Breakpoints}) or, in the case of a | |
6514 | watchpoint, by the @code{watch} command | |
6515 | (@pxref{Set Watchpoints, , Setting Watchpoints}). | |
6516 | ||
6517 | The optional @var{type} argument specifies the type of the breakpoint to create, | |
6518 | as defined below. | |
6519 | ||
6520 | The optional @var{wp_class} argument defines the class of watchpoint to create, | |
6521 | if @var{type} is @code{gdb.BP_WATCHPOINT}. If @var{wp_class} is omitted, it | |
6522 | defaults to @code{gdb.WP_WRITE}. | |
6523 | ||
6524 | The optional @var{internal} argument allows the breakpoint to become invisible | |
6525 | to the user. The breakpoint will neither be reported when created, nor will it | |
6526 | be listed in the output from @code{info breakpoints} (but will be listed with | |
6527 | the @code{maint info breakpoints} command). | |
6528 | ||
6529 | The optional @var{temporary} argument makes the breakpoint a temporary | |
6530 | breakpoint. Temporary breakpoints are deleted after they have been hit. Any | |
6531 | further access to the Python breakpoint after it has been hit will result in a | |
6532 | runtime error (as that breakpoint has now been automatically deleted). | |
b89641ba SM |
6533 | |
6534 | The optional @var{qualified} argument is a boolean that allows interpreting | |
6535 | the function passed in @code{spec} as a fully-qualified name. It is equivalent | |
6536 | to @code{break}'s @code{-qualified} flag (@pxref{Linespec Locations} and | |
6537 | @ref{Explicit Locations}). | |
6538 | ||
0b982d68 SM |
6539 | @end defun |
6540 | ||
b89641ba | 6541 | @defun Breakpoint.__init__ (@r{[} source @r{][}, function @r{][}, label @r{][}, line @r{]}, @r{][} internal @r{][}, temporary @r{][}, qualified @r{]}) |
0b982d68 SM |
6542 | This second form of creating a new breakpoint specifies the explicit |
6543 | location (@pxref{Explicit Locations}) using keywords. The new breakpoint will | |
6544 | be created in the specified source file @var{source}, at the specified | |
6545 | @var{function}, @var{label} and @var{line}. | |
6546 | ||
b89641ba SM |
6547 | @var{internal}, @var{temporary} and @var{qualified} have the same usage as |
6548 | explained previously. | |
329baa95 DE |
6549 | @end defun |
6550 | ||
cda75e70 TT |
6551 | The available types are represented by constants defined in the @code{gdb} |
6552 | module: | |
6553 | ||
6554 | @vtable @code | |
6555 | @vindex BP_BREAKPOINT | |
6556 | @item gdb.BP_BREAKPOINT | |
6557 | Normal code breakpoint. | |
6558 | ||
325d39e4 HD |
6559 | @vindex BP_HARDWARE_BREAKPOINT |
6560 | @item gdb.BP_HARDWARE_BREAKPOINT | |
6561 | Hardware assisted code breakpoint. | |
6562 | ||
cda75e70 TT |
6563 | @vindex BP_WATCHPOINT |
6564 | @item gdb.BP_WATCHPOINT | |
6565 | Watchpoint breakpoint. | |
6566 | ||
6567 | @vindex BP_HARDWARE_WATCHPOINT | |
6568 | @item gdb.BP_HARDWARE_WATCHPOINT | |
6569 | Hardware assisted watchpoint. | |
6570 | ||
6571 | @vindex BP_READ_WATCHPOINT | |
6572 | @item gdb.BP_READ_WATCHPOINT | |
6573 | Hardware assisted read watchpoint. | |
6574 | ||
6575 | @vindex BP_ACCESS_WATCHPOINT | |
6576 | @item gdb.BP_ACCESS_WATCHPOINT | |
6577 | Hardware assisted access watchpoint. | |
6b95f5ad AB |
6578 | |
6579 | @vindex BP_CATCHPOINT | |
6580 | @item gdb.BP_CATCHPOINT | |
6581 | Catchpoint. Currently, this type can't be used when creating | |
6582 | @code{gdb.Breakpoint} objects, but will be present in | |
6583 | @code{gdb.Breakpoint} objects reported from | |
6584 | @code{gdb.BreakpointEvent}s (@pxref{Events In Python}). | |
cda75e70 TT |
6585 | @end vtable |
6586 | ||
802021d4 | 6587 | The available watchpoint types are represented by constants defined in the |
cda75e70 TT |
6588 | @code{gdb} module: |
6589 | ||
6590 | @vtable @code | |
6591 | @vindex WP_READ | |
6592 | @item gdb.WP_READ | |
6593 | Read only watchpoint. | |
6594 | ||
6595 | @vindex WP_WRITE | |
6596 | @item gdb.WP_WRITE | |
6597 | Write only watchpoint. | |
6598 | ||
6599 | @vindex WP_ACCESS | |
6600 | @item gdb.WP_ACCESS | |
6601 | Read/Write watchpoint. | |
6602 | @end vtable | |
6603 | ||
329baa95 DE |
6604 | @defun Breakpoint.stop (self) |
6605 | The @code{gdb.Breakpoint} class can be sub-classed and, in | |
6606 | particular, you may choose to implement the @code{stop} method. | |
6607 | If this method is defined in a sub-class of @code{gdb.Breakpoint}, | |
6608 | it will be called when the inferior reaches any location of a | |
6609 | breakpoint which instantiates that sub-class. If the method returns | |
6610 | @code{True}, the inferior will be stopped at the location of the | |
6611 | breakpoint, otherwise the inferior will continue. | |
6612 | ||
6613 | If there are multiple breakpoints at the same location with a | |
6614 | @code{stop} method, each one will be called regardless of the | |
6615 | return status of the previous. This ensures that all @code{stop} | |
6616 | methods have a chance to execute at that location. In this scenario | |
6617 | if one of the methods returns @code{True} but the others return | |
6618 | @code{False}, the inferior will still be stopped. | |
6619 | ||
6620 | You should not alter the execution state of the inferior (i.e.@:, step, | |
6621 | next, etc.), alter the current frame context (i.e.@:, change the current | |
6622 | active frame), or alter, add or delete any breakpoint. As a general | |
6623 | rule, you should not alter any data within @value{GDBN} or the inferior | |
6624 | at this time. | |
6625 | ||
6626 | Example @code{stop} implementation: | |
6627 | ||
6628 | @smallexample | |
6629 | class MyBreakpoint (gdb.Breakpoint): | |
6630 | def stop (self): | |
6631 | inf_val = gdb.parse_and_eval("foo") | |
6632 | if inf_val == 3: | |
6633 | return True | |
6634 | return False | |
6635 | @end smallexample | |
6636 | @end defun | |
6637 | ||
329baa95 DE |
6638 | @defun Breakpoint.is_valid () |
6639 | Return @code{True} if this @code{Breakpoint} object is valid, | |
6640 | @code{False} otherwise. A @code{Breakpoint} object can become invalid | |
6641 | if the user deletes the breakpoint. In this case, the object still | |
6642 | exists, but the underlying breakpoint does not. In the cases of | |
6643 | watchpoint scope, the watchpoint remains valid even if execution of the | |
6644 | inferior leaves the scope of that watchpoint. | |
6645 | @end defun | |
6646 | ||
fab3a15d | 6647 | @defun Breakpoint.delete () |
329baa95 DE |
6648 | Permanently deletes the @value{GDBN} breakpoint. This also |
6649 | invalidates the Python @code{Breakpoint} object. Any further access | |
6650 | to this object's attributes or methods will raise an error. | |
6651 | @end defun | |
6652 | ||
6653 | @defvar Breakpoint.enabled | |
6654 | This attribute is @code{True} if the breakpoint is enabled, and | |
fab3a15d SM |
6655 | @code{False} otherwise. This attribute is writable. You can use it to enable |
6656 | or disable the breakpoint. | |
329baa95 DE |
6657 | @end defvar |
6658 | ||
6659 | @defvar Breakpoint.silent | |
6660 | This attribute is @code{True} if the breakpoint is silent, and | |
6661 | @code{False} otherwise. This attribute is writable. | |
6662 | ||
6663 | Note that a breakpoint can also be silent if it has commands and the | |
6664 | first command is @code{silent}. This is not reported by the | |
6665 | @code{silent} attribute. | |
6666 | @end defvar | |
6667 | ||
93daf339 TT |
6668 | @defvar Breakpoint.pending |
6669 | This attribute is @code{True} if the breakpoint is pending, and | |
6670 | @code{False} otherwise. @xref{Set Breaks}. This attribute is | |
6671 | read-only. | |
6672 | @end defvar | |
6673 | ||
22a02324 | 6674 | @anchor{python_breakpoint_thread} |
329baa95 | 6675 | @defvar Breakpoint.thread |
b080fe54 AB |
6676 | If the breakpoint is thread-specific (@pxref{Thread-Specific |
6677 | Breakpoints}), this attribute holds the thread's global id. If the | |
6678 | breakpoint is not thread-specific, this attribute is @code{None}. | |
6679 | This attribute is writable. | |
6680 | ||
6681 | Only one of @code{Breakpoint.thread} or @code{Breakpoint.inferior} can | |
6682 | be set to a valid id at any time, that is, a breakpoint can be thread | |
6683 | specific, or inferior specific, but not both. | |
6684 | @end defvar | |
6685 | ||
6686 | @anchor{python_breakpoint_inferior} | |
6687 | @defvar Breakpoint.inferior | |
6688 | If the breakpoint is inferior-specific (@pxref{Inferior-Specific | |
6689 | Breakpoints}), this attribute holds the inferior's id. If the | |
6690 | breakpoint is not inferior-specific, this attribute is @code{None}. | |
6691 | ||
6692 | This attribute can be written for breakpoints of type | |
6693 | @code{gdb.BP_BREAKPOINT} and @code{gdb.BP_HARDWARE_BREAKPOINT}. | |
329baa95 DE |
6694 | @end defvar |
6695 | ||
6696 | @defvar Breakpoint.task | |
6697 | If the breakpoint is Ada task-specific, this attribute holds the Ada task | |
6698 | id. If the breakpoint is not task-specific (or the underlying | |
6699 | language is not Ada), this attribute is @code{None}. This attribute | |
6700 | is writable. | |
6701 | @end defvar | |
6702 | ||
6703 | @defvar Breakpoint.ignore_count | |
6704 | This attribute holds the ignore count for the breakpoint, an integer. | |
6705 | This attribute is writable. | |
6706 | @end defvar | |
6707 | ||
6708 | @defvar Breakpoint.number | |
6709 | This attribute holds the breakpoint's number --- the identifier used by | |
6710 | the user to manipulate the breakpoint. This attribute is not writable. | |
6711 | @end defvar | |
6712 | ||
6713 | @defvar Breakpoint.type | |
6714 | This attribute holds the breakpoint's type --- the identifier used to | |
6715 | determine the actual breakpoint type or use-case. This attribute is not | |
6716 | writable. | |
6717 | @end defvar | |
6718 | ||
6719 | @defvar Breakpoint.visible | |
6720 | This attribute tells whether the breakpoint is visible to the user | |
6721 | when set, or when the @samp{info breakpoints} command is run. This | |
6722 | attribute is not writable. | |
6723 | @end defvar | |
6724 | ||
6725 | @defvar Breakpoint.temporary | |
6726 | This attribute indicates whether the breakpoint was created as a | |
6727 | temporary breakpoint. Temporary breakpoints are automatically deleted | |
6728 | after that breakpoint has been hit. Access to this attribute, and all | |
6729 | other attributes and functions other than the @code{is_valid} | |
6730 | function, will result in an error after the breakpoint has been hit | |
6731 | (as it has been automatically deleted). This attribute is not | |
6732 | writable. | |
6733 | @end defvar | |
6734 | ||
329baa95 DE |
6735 | @defvar Breakpoint.hit_count |
6736 | This attribute holds the hit count for the breakpoint, an integer. | |
6737 | This attribute is writable, but currently it can only be set to zero. | |
6738 | @end defvar | |
6739 | ||
6740 | @defvar Breakpoint.location | |
6741 | This attribute holds the location of the breakpoint, as specified by | |
6742 | the user. It is a string. If the breakpoint does not have a location | |
6743 | (that is, it is a watchpoint) the attribute's value is @code{None}. This | |
6744 | attribute is not writable. | |
6745 | @end defvar | |
6746 | ||
e5213e2c SF |
6747 | @defvar Breakpoint.locations |
6748 | Get the most current list of breakpoint locations that are inserted for this | |
6749 | breakpoint, with elements of type @code{gdb.BreakpointLocation} | |
6750 | (described below). This functionality matches that of the | |
6751 | @code{info breakpoint} command (@pxref{Set Breaks}), in that it only retrieves | |
6752 | the most current list of locations, thus the list itself when returned is | |
6753 | not updated behind the scenes. This attribute is not writable. | |
6754 | @end defvar | |
6755 | ||
329baa95 DE |
6756 | @defvar Breakpoint.expression |
6757 | This attribute holds a breakpoint expression, as specified by | |
6758 | the user. It is a string. If the breakpoint does not have an | |
6759 | expression (the breakpoint is not a watchpoint) the attribute's value | |
6760 | is @code{None}. This attribute is not writable. | |
6761 | @end defvar | |
6762 | ||
6763 | @defvar Breakpoint.condition | |
6764 | This attribute holds the condition of the breakpoint, as specified by | |
6765 | the user. It is a string. If there is no condition, this attribute's | |
6766 | value is @code{None}. This attribute is writable. | |
6767 | @end defvar | |
6768 | ||
6769 | @defvar Breakpoint.commands | |
6770 | This attribute holds the commands attached to the breakpoint. If | |
6771 | there are commands, this attribute's value is a string holding all the | |
6772 | commands, separated by newlines. If there are no commands, this | |
a913fffb | 6773 | attribute is @code{None}. This attribute is writable. |
329baa95 DE |
6774 | @end defvar |
6775 | ||
e5213e2c SF |
6776 | @subheading Breakpoint Locations |
6777 | ||
6778 | A breakpoint location is one of the actual places where a breakpoint has been | |
6779 | set, represented in the Python API by the @code{gdb.BreakpointLocation} | |
6780 | type. This type is never instantiated by the user directly, but is retrieved | |
6781 | from @code{Breakpoint.locations} which returns a list of breakpoint | |
6782 | locations where it is currently set. Breakpoint locations can become | |
6783 | invalid if new symbol files are loaded or dynamically loaded libraries are | |
6784 | closed. Accessing the attributes of an invalidated breakpoint location will | |
6785 | throw a @code{RuntimeError} exception. Access the @code{Breakpoint.locations} | |
6786 | attribute again to retrieve the new and valid breakpoints location list. | |
6787 | ||
6788 | @defvar BreakpointLocation.source | |
6789 | This attribute returns the source file path and line number where this location | |
6790 | was set. The type of the attribute is a tuple of @var{string} and | |
6791 | @var{long}. If the breakpoint location doesn't have a source location, | |
6792 | it returns None, which is the case for watchpoints and catchpoints. | |
6793 | This will throw a @code{RuntimeError} exception if the location | |
6794 | has been invalidated. This attribute is not writable. | |
6795 | @end defvar | |
6796 | ||
6797 | @defvar BreakpointLocation.address | |
6798 | This attribute returns the address where this location was set. | |
6799 | This attribute is of type long. This will throw a @code{RuntimeError} | |
6800 | exception if the location has been invalidated. This attribute is | |
6801 | not writable. | |
6802 | @end defvar | |
6803 | ||
6804 | @defvar BreakpointLocation.enabled | |
6805 | This attribute holds the value for whether or not this location is enabled. | |
6806 | This attribute is writable (boolean). This will throw a @code{RuntimeError} | |
6807 | exception if the location has been invalidated. | |
6808 | @end defvar | |
6809 | ||
6810 | @defvar BreakpointLocation.owner | |
6811 | This attribute holds a reference to the @code{gdb.Breakpoint} owner object, | |
6812 | from which this @code{gdb.BreakpointLocation} was retrieved from. | |
6813 | This will throw a @code{RuntimeError} exception if the location has been | |
6814 | invalidated. This attribute is not writable. | |
6815 | @end defvar | |
6816 | ||
6817 | @defvar BreakpointLocation.function | |
6818 | This attribute gets the name of the function where this location was set. | |
6819 | If no function could be found this attribute returns @code{None}. | |
6820 | This will throw a @code{RuntimeError} exception if the location has | |
6821 | been invalidated. This attribute is not writable. | |
6822 | @end defvar | |
6823 | ||
6824 | @defvar BreakpointLocation.fullname | |
6825 | This attribute gets the full name of where this location was set. If no | |
6826 | full name could be found, this attribute returns @code{None}. | |
6827 | This will throw a @code{RuntimeError} exception if the location has | |
6828 | been invalidated. This attribute is not writable. | |
6829 | @end defvar | |
6830 | ||
6831 | @defvar BreakpointLocation.thread_groups | |
6832 | This attribute gets the thread groups it was set in. It returns a @code{List} | |
6833 | of the thread group ID's. This will throw a @code{RuntimeError} | |
6834 | exception if the location has been invalidated. This attribute | |
6835 | is not writable. | |
6836 | @end defvar | |
6837 | ||
329baa95 DE |
6838 | @node Finish Breakpoints in Python |
6839 | @subsubsection Finish Breakpoints | |
6840 | ||
6841 | @cindex python finish breakpoints | |
6842 | @tindex gdb.FinishBreakpoint | |
6843 | ||
6844 | A finish breakpoint is a temporary breakpoint set at the return address of | |
6845 | a frame, based on the @code{finish} command. @code{gdb.FinishBreakpoint} | |
6846 | extends @code{gdb.Breakpoint}. The underlying breakpoint will be disabled | |
6847 | and deleted when the execution will run out of the breakpoint scope (i.e.@: | |
6848 | @code{Breakpoint.stop} or @code{FinishBreakpoint.out_of_scope} triggered). | |
6849 | Finish breakpoints are thread specific and must be create with the right | |
6850 | thread selected. | |
6851 | ||
6852 | @defun FinishBreakpoint.__init__ (@r{[}frame@r{]} @r{[}, internal@r{]}) | |
6853 | Create a finish breakpoint at the return address of the @code{gdb.Frame} | |
6854 | object @var{frame}. If @var{frame} is not provided, this defaults to the | |
6855 | newest frame. The optional @var{internal} argument allows the breakpoint to | |
6856 | become invisible to the user. @xref{Breakpoints In Python}, for further | |
6857 | details about this argument. | |
6858 | @end defun | |
6859 | ||
6860 | @defun FinishBreakpoint.out_of_scope (self) | |
6861 | In some circumstances (e.g.@: @code{longjmp}, C@t{++} exceptions, @value{GDBN} | |
6862 | @code{return} command, @dots{}), a function may not properly terminate, and | |
6863 | thus never hit the finish breakpoint. When @value{GDBN} notices such a | |
6864 | situation, the @code{out_of_scope} callback will be triggered. | |
6865 | ||
6866 | You may want to sub-class @code{gdb.FinishBreakpoint} and override this | |
6867 | method: | |
6868 | ||
6869 | @smallexample | |
6870 | class MyFinishBreakpoint (gdb.FinishBreakpoint) | |
6871 | def stop (self): | |
f3bdc2db | 6872 | print ("normal finish") |
329baa95 DE |
6873 | return True |
6874 | ||
6875 | def out_of_scope (): | |
f3bdc2db | 6876 | print ("abnormal finish") |
329baa95 DE |
6877 | @end smallexample |
6878 | @end defun | |
6879 | ||
6880 | @defvar FinishBreakpoint.return_value | |
6881 | When @value{GDBN} is stopped at a finish breakpoint and the frame | |
6882 | used to build the @code{gdb.FinishBreakpoint} object had debug symbols, this | |
6883 | attribute will contain a @code{gdb.Value} object corresponding to the return | |
6884 | value of the function. The value will be @code{None} if the function return | |
6885 | type is @code{void} or if the return value was not computable. This attribute | |
6886 | is not writable. | |
6887 | @end defvar | |
6888 | ||
6889 | @node Lazy Strings In Python | |
849cba3b | 6890 | @subsubsection Python representation of lazy strings |
329baa95 DE |
6891 | |
6892 | @cindex lazy strings in python | |
6893 | @tindex gdb.LazyString | |
6894 | ||
6895 | A @dfn{lazy string} is a string whose contents is not retrieved or | |
6896 | encoded until it is needed. | |
6897 | ||
6898 | A @code{gdb.LazyString} is represented in @value{GDBN} as an | |
6899 | @code{address} that points to a region of memory, an @code{encoding} | |
6900 | that will be used to encode that region of memory, and a @code{length} | |
6901 | to delimit the region of memory that represents the string. The | |
6902 | difference between a @code{gdb.LazyString} and a string wrapped within | |
6903 | a @code{gdb.Value} is that a @code{gdb.LazyString} will be treated | |
6904 | differently by @value{GDBN} when printing. A @code{gdb.LazyString} is | |
6905 | retrieved and encoded during printing, while a @code{gdb.Value} | |
6906 | wrapping a string is immediately retrieved and encoded on creation. | |
6907 | ||
6908 | A @code{gdb.LazyString} object has the following functions: | |
6909 | ||
6910 | @defun LazyString.value () | |
6911 | Convert the @code{gdb.LazyString} to a @code{gdb.Value}. This value | |
6912 | will point to the string in memory, but will lose all the delayed | |
6913 | retrieval, encoding and handling that @value{GDBN} applies to a | |
6914 | @code{gdb.LazyString}. | |
6915 | @end defun | |
6916 | ||
6917 | @defvar LazyString.address | |
6918 | This attribute holds the address of the string. This attribute is not | |
6919 | writable. | |
6920 | @end defvar | |
6921 | ||
6922 | @defvar LazyString.length | |
6923 | This attribute holds the length of the string in characters. If the | |
6924 | length is -1, then the string will be fetched and encoded up to the | |
6925 | first null of appropriate width. This attribute is not writable. | |
6926 | @end defvar | |
6927 | ||
6928 | @defvar LazyString.encoding | |
6929 | This attribute holds the encoding that will be applied to the string | |
6930 | when the string is printed by @value{GDBN}. If the encoding is not | |
6931 | set, or contains an empty string, then @value{GDBN} will select the | |
6932 | most appropriate encoding when the string is printed. This attribute | |
6933 | is not writable. | |
6934 | @end defvar | |
6935 | ||
6936 | @defvar LazyString.type | |
6937 | This attribute holds the type that is represented by the lazy string's | |
f8d99587 | 6938 | type. For a lazy string this is a pointer or array type. To |
329baa95 DE |
6939 | resolve this to the lazy string's character type, use the type's |
6940 | @code{target} method. @xref{Types In Python}. This attribute is not | |
6941 | writable. | |
6942 | @end defvar | |
6943 | ||
6944 | @node Architectures In Python | |
6945 | @subsubsection Python representation of architectures | |
6946 | @cindex Python architectures | |
6947 | ||
6948 | @value{GDBN} uses architecture specific parameters and artifacts in a | |
6949 | number of its various computations. An architecture is represented | |
6950 | by an instance of the @code{gdb.Architecture} class. | |
6951 | ||
6952 | A @code{gdb.Architecture} class has the following methods: | |
6953 | ||
8b87fbe6 | 6954 | @anchor{gdbpy_architecture_name} |
329baa95 DE |
6955 | @defun Architecture.name () |
6956 | Return the name (string value) of the architecture. | |
6957 | @end defun | |
6958 | ||
ebb83b77 | 6959 | @defun Architecture.disassemble (start_pc @r{[}, end_pc @r{[}, count@r{]]}) |
329baa95 DE |
6960 | Return a list of disassembled instructions starting from the memory |
6961 | address @var{start_pc}. The optional arguments @var{end_pc} and | |
6962 | @var{count} determine the number of instructions in the returned list. | |
6963 | If both the optional arguments @var{end_pc} and @var{count} are | |
6964 | specified, then a list of at most @var{count} disassembled instructions | |
6965 | whose start address falls in the closed memory address interval from | |
6966 | @var{start_pc} to @var{end_pc} are returned. If @var{end_pc} is not | |
6967 | specified, but @var{count} is specified, then @var{count} number of | |
6968 | instructions starting from the address @var{start_pc} are returned. If | |
6969 | @var{count} is not specified but @var{end_pc} is specified, then all | |
6970 | instructions whose start address falls in the closed memory address | |
6971 | interval from @var{start_pc} to @var{end_pc} are returned. If neither | |
6972 | @var{end_pc} nor @var{count} are specified, then a single instruction at | |
6973 | @var{start_pc} is returned. For all of these cases, each element of the | |
6974 | returned list is a Python @code{dict} with the following string keys: | |
6975 | ||
6976 | @table @code | |
6977 | ||
6978 | @item addr | |
6979 | The value corresponding to this key is a Python long integer capturing | |
6980 | the memory address of the instruction. | |
6981 | ||
6982 | @item asm | |
6983 | The value corresponding to this key is a string value which represents | |
6984 | the instruction with assembly language mnemonics. The assembly | |
6985 | language flavor used is the same as that specified by the current CLI | |
6986 | variable @code{disassembly-flavor}. @xref{Machine Code}. | |
6987 | ||
6988 | @item length | |
6989 | The value corresponding to this key is the length (integer value) of the | |
6990 | instruction in bytes. | |
6991 | ||
6992 | @end table | |
6993 | @end defun | |
6994 | ||
d3771fe2 TT |
6995 | @defun Architecture.integer_type (size @r{[}, signed@r{]}) |
6996 | This function looks up an integer type by its @var{size}, and | |
6997 | optionally whether or not it is signed. | |
6998 | ||
6999 | @var{size} is the size, in bits, of the desired integer type. Only | |
7000 | certain sizes are currently supported: 0, 8, 16, 24, 32, 64, and 128. | |
7001 | ||
7002 | If @var{signed} is not specified, it defaults to @code{True}. If | |
7003 | @var{signed} is @code{False}, the returned type will be unsigned. | |
7004 | ||
7005 | If the indicated type cannot be found, this function will throw a | |
7006 | @code{ValueError} exception. | |
7007 | @end defun | |
7008 | ||
0f767f94 | 7009 | @anchor{gdbpy_architecture_registers} |
ebb83b77 | 7010 | @defun Architecture.registers (@r{[} reggroup @r{]}) |
0f767f94 AB |
7011 | Return a @code{gdb.RegisterDescriptorIterator} (@pxref{Registers In |
7012 | Python}) for all of the registers in @var{reggroup}, a string that is | |
7013 | the name of a register group. If @var{reggroup} is omitted, or is the | |
7014 | empty string, then the register group @samp{all} is assumed. | |
7015 | @end defun | |
7016 | ||
64cb3757 AB |
7017 | @anchor{gdbpy_architecture_reggroups} |
7018 | @defun Architecture.register_groups () | |
7019 | Return a @code{gdb.RegisterGroupsIterator} (@pxref{Registers In | |
7020 | Python}) for all of the register groups available for the | |
7021 | @code{gdb.Architecture}. | |
7022 | @end defun | |
7023 | ||
0f767f94 AB |
7024 | @node Registers In Python |
7025 | @subsubsection Registers In Python | |
7026 | @cindex Registers In Python | |
7027 | ||
7028 | Python code can request from a @code{gdb.Architecture} information | |
7029 | about the set of registers available | |
7030 | (@pxref{gdbpy_architecture_registers,,@code{Architecture.registers}}). | |
7031 | The register information is returned as a | |
7032 | @code{gdb.RegisterDescriptorIterator}, which is an iterator that in | |
7033 | turn returns @code{gdb.RegisterDescriptor} objects. | |
7034 | ||
7035 | A @code{gdb.RegisterDescriptor} does not provide the value of a | |
7036 | register (@pxref{gdbpy_frame_read_register,,@code{Frame.read_register}} | |
7037 | for reading a register's value), instead the @code{RegisterDescriptor} | |
7038 | is a way to discover which registers are available for a particular | |
7039 | architecture. | |
7040 | ||
7041 | A @code{gdb.RegisterDescriptor} has the following read-only properties: | |
7042 | ||
7043 | @defvar RegisterDescriptor.name | |
7044 | The name of this register. | |
7045 | @end defvar | |
7046 | ||
14fa8fb3 AB |
7047 | It is also possible to lookup a register descriptor based on its name |
7048 | using the following @code{gdb.RegisterDescriptorIterator} function: | |
7049 | ||
ebb83b77 | 7050 | @defun RegisterDescriptorIterator.find (name) |
14fa8fb3 AB |
7051 | Takes @var{name} as an argument, which must be a string, and returns a |
7052 | @code{gdb.RegisterDescriptor} for the register with that name, or | |
7053 | @code{None} if there is no register with that name. | |
7054 | @end defun | |
7055 | ||
64cb3757 AB |
7056 | Python code can also request from a @code{gdb.Architecture} |
7057 | information about the set of register groups available on a given | |
7058 | architecture | |
7059 | (@pxref{gdbpy_architecture_reggroups,,@code{Architecture.register_groups}}). | |
7060 | ||
7061 | Every register can be a member of zero or more register groups. Some | |
7062 | register groups are used internally within @value{GDBN} to control | |
7063 | things like which registers must be saved when calling into the | |
7064 | program being debugged (@pxref{Calling,,Calling Program Functions}). | |
7065 | Other register groups exist to allow users to easily see related sets | |
7066 | of registers in commands like @code{info registers} | |
7067 | (@pxref{info_registers_reggroup,,@code{info registers | |
7068 | @var{reggroup}}}). | |
7069 | ||
7070 | The register groups information is returned as a | |
7071 | @code{gdb.RegisterGroupsIterator}, which is an iterator that in turn | |
7072 | returns @code{gdb.RegisterGroup} objects. | |
7073 | ||
7074 | A @code{gdb.RegisterGroup} object has the following read-only | |
7075 | properties: | |
7076 | ||
7077 | @defvar RegisterGroup.name | |
7078 | A string that is the name of this register group. | |
7079 | @end defvar | |
7080 | ||
0e3b7c25 AB |
7081 | @node Connections In Python |
7082 | @subsubsection Connections In Python | |
7083 | @cindex connections in python | |
7084 | @value{GDBN} lets you run and debug multiple programs in a single | |
7085 | session. Each program being debugged has a connection, the connection | |
7086 | describes how @value{GDBN} controls the program being debugged. | |
7087 | Examples of different connection types are @samp{native} and | |
7088 | @samp{remote}. @xref{Inferiors Connections and Programs}. | |
7089 | ||
24b2de7b AB |
7090 | Connections in @value{GDBN} are represented as instances of |
7091 | @code{gdb.TargetConnection}, or as one of its sub-classes. To get a | |
7092 | list of all connections use @code{gdb.connections} | |
0e3b7c25 AB |
7093 | (@pxref{gdbpy_connections,,gdb.connections}). |
7094 | ||
7095 | To get the connection for a single @code{gdb.Inferior} read its | |
7096 | @code{gdb.Inferior.connection} attribute | |
7097 | (@pxref{gdbpy_inferior_connection,,gdb.Inferior.connection}). | |
7098 | ||
24b2de7b AB |
7099 | Currently there is only a single sub-class of |
7100 | @code{gdb.TargetConnection}, @code{gdb.RemoteTargetConnection}, | |
7101 | however, additional sub-classes may be added in future releases of | |
7102 | @value{GDBN}. As a result you should avoid writing code like: | |
7103 | ||
7104 | @smallexample | |
7105 | conn = gdb.selected_inferior().connection | |
7106 | if type(conn) is gdb.RemoteTargetConnection: | |
7107 | print("This is a remote target connection") | |
7108 | @end smallexample | |
7109 | ||
7110 | @noindent | |
7111 | as this may fail when more connection types are added. Instead, you | |
7112 | should write: | |
7113 | ||
7114 | @smallexample | |
7115 | conn = gdb.selected_inferior().connection | |
7116 | if isinstance(conn, gdb.RemoteTargetConnection): | |
7117 | print("This is a remote target connection") | |
7118 | @end smallexample | |
7119 | ||
0e3b7c25 AB |
7120 | A @code{gdb.TargetConnection} has the following method: |
7121 | ||
7122 | @defun TargetConnection.is_valid () | |
7123 | Return @code{True} if the @code{gdb.TargetConnection} object is valid, | |
7124 | @code{False} if not. A @code{gdb.TargetConnection} will become | |
7125 | invalid if the connection no longer exists within @value{GDBN}, this | |
7126 | might happen when no inferiors are using the connection, but could be | |
7127 | delayed until the user replaces the current target. | |
7128 | ||
7129 | Reading any of the @code{gdb.TargetConnection} properties will throw | |
7130 | an exception if the connection is invalid. | |
7131 | @end defun | |
7132 | ||
7133 | A @code{gdb.TargetConnection} has the following read-only properties: | |
7134 | ||
7135 | @defvar TargetConnection.num | |
7136 | An integer assigned by @value{GDBN} to uniquely identify this | |
7137 | connection. This is the same value as displayed in the @samp{Num} | |
7138 | column of the @code{info connections} command output (@pxref{Inferiors | |
7139 | Connections and Programs,,info connections}). | |
7140 | @end defvar | |
7141 | ||
7142 | @defvar TargetConnection.type | |
7143 | A string that describes what type of connection this is. This string | |
7144 | will be one of the valid names that can be passed to the @code{target} | |
7145 | command (@pxref{Target Commands,,target command}). | |
7146 | @end defvar | |
7147 | ||
7148 | @defvar TargetConnection.description | |
7149 | A string that gives a short description of this target type. This is | |
7150 | the same string that is displayed in the @samp{Description} column of | |
7151 | the @code{info connection} command output (@pxref{Inferiors | |
7152 | Connections and Programs,,info connections}). | |
7153 | @end defvar | |
7154 | ||
7155 | @defvar TargetConnection.details | |
7156 | An optional string that gives additional information about this | |
7157 | connection. This attribute can be @code{None} if there are no | |
7158 | additional details for this connection. | |
7159 | ||
7160 | An example of a connection type that might have additional details is | |
7161 | the @samp{remote} connection, in this case the details string can | |
7162 | contain the @samp{@var{hostname}:@var{port}} that was used to connect | |
7163 | to the remote target. | |
7164 | @end defvar | |
7165 | ||
24b2de7b AB |
7166 | The @code{gdb.RemoteTargetConnection} class is a sub-class of |
7167 | @code{gdb.TargetConnection}, and is used to represent @samp{remote} | |
7168 | and @samp{extended-remote} connections. In addition to the attributes | |
7169 | and methods available from the @code{gdb.TargetConnection} base class, | |
7170 | a @code{gdb.RemoteTargetConnection} has the following method: | |
7171 | ||
7172 | @kindex maint packet | |
ebb83b77 | 7173 | @defun RemoteTargetConnection.send_packet (packet) |
24b2de7b AB |
7174 | This method sends @var{packet} to the remote target and returns the |
7175 | response. The @var{packet} should either be a @code{bytes} object, or | |
7176 | a @code{Unicode} string. | |
7177 | ||
7178 | If @var{packet} is a @code{Unicode} string, then the string is encoded | |
7179 | to a @code{bytes} object using the @sc{ascii} codec. If the string | |
7180 | can't be encoded then an @code{UnicodeError} is raised. | |
7181 | ||
7182 | If @var{packet} is not a @code{bytes} object, or a @code{Unicode} | |
7183 | string, then a @code{TypeError} is raised. If @var{packet} is empty | |
7184 | then a @code{ValueError} is raised. | |
7185 | ||
914a96d7 TT |
7186 | The response is returned as a @code{bytes} object. If it is known |
7187 | that the response can be represented as a string then this can be | |
7188 | decoded from the buffer. For example, if it is known that the | |
24b2de7b AB |
7189 | response is an @sc{ascii} string: |
7190 | ||
7191 | @smallexample | |
7192 | remote_connection.send_packet("some_packet").decode("ascii") | |
7193 | @end smallexample | |
7194 | ||
24b2de7b AB |
7195 | The prefix, suffix, and checksum (as required by the remote serial |
7196 | protocol) are automatically added to the outgoing packet, and removed | |
7197 | from the incoming packet before the contents of the reply are | |
7198 | returned. | |
7199 | ||
7200 | This is equivalent to the @code{maintenance packet} command | |
7201 | (@pxref{maint packet}). | |
7202 | @end defun | |
7203 | ||
01b1af32 TT |
7204 | @node TUI Windows In Python |
7205 | @subsubsection Implementing new TUI windows | |
7206 | @cindex Python TUI Windows | |
7207 | ||
7208 | New TUI (@pxref{TUI}) windows can be implemented in Python. | |
7209 | ||
ebb83b77 | 7210 | @defun gdb.register_window_type (name, factory) |
01b1af32 TT |
7211 | Because TUI windows are created and destroyed depending on the layout |
7212 | the user chooses, new window types are implemented by registering a | |
7213 | factory function with @value{GDBN}. | |
7214 | ||
7215 | @var{name} is the name of the new window. It's an error to try to | |
7216 | replace one of the built-in windows, but other window types can be | |
7abc6ec0 AB |
7217 | replaced. The @var{name} should match the regular expression |
7218 | @code{[a-zA-Z][-_.a-zA-Z0-9]*}, it is an error to try and create a | |
7219 | window with an invalid name. | |
01b1af32 TT |
7220 | |
7221 | @var{function} is a factory function that is called to create the TUI | |
7222 | window. This is called with a single argument of type | |
7223 | @code{gdb.TuiWindow}, described below. It should return an object | |
7224 | that implements the TUI window protocol, also described below. | |
7225 | @end defun | |
7226 | ||
e8460459 | 7227 | As mentioned above, when a factory function is called, it is passed |
01b1af32 TT |
7228 | an object of type @code{gdb.TuiWindow}. This object has these |
7229 | methods and attributes: | |
7230 | ||
7231 | @defun TuiWindow.is_valid () | |
7232 | This method returns @code{True} when this window is valid. When the | |
7233 | user changes the TUI layout, windows no longer visible in the new | |
7234 | layout will be destroyed. At this point, the @code{gdb.TuiWindow} | |
7235 | will no longer be valid, and methods (and attributes) other than | |
7236 | @code{is_valid} will throw an exception. | |
29db1eb3 AB |
7237 | |
7238 | When the TUI is disabled using @code{tui disable} (@pxref{TUI | |
7239 | Commands,,tui disable}) the window is hidden rather than destroyed, | |
7240 | but @code{is_valid} will still return @code{False} and other methods | |
7241 | (and attributes) will still throw an exception. | |
01b1af32 TT |
7242 | @end defun |
7243 | ||
7244 | @defvar TuiWindow.width | |
7245 | This attribute holds the width of the window. It is not writable. | |
7246 | @end defvar | |
7247 | ||
7248 | @defvar TuiWindow.height | |
7249 | This attribute holds the height of the window. It is not writable. | |
7250 | @end defvar | |
7251 | ||
7252 | @defvar TuiWindow.title | |
7253 | This attribute holds the window's title, a string. This is normally | |
7254 | displayed above the window. This attribute can be modified. | |
7255 | @end defvar | |
7256 | ||
7257 | @defun TuiWindow.erase () | |
7258 | Remove all the contents of the window. | |
7259 | @end defun | |
7260 | ||
ebb83b77 | 7261 | @defun TuiWindow.write (string @r{[}, full_window@r{]}) |
01b1af32 TT |
7262 | Write @var{string} to the window. @var{string} can contain ANSI |
7263 | terminal escape styling sequences; @value{GDBN} will translate these | |
7264 | as appropriate for the terminal. | |
bdef5723 HD |
7265 | |
7266 | If the @var{full_window} parameter is @code{True}, then @var{string} | |
7267 | contains the full contents of the window. This is similar to calling | |
7268 | @code{erase} before @code{write}, but avoids the flickering. | |
01b1af32 TT |
7269 | @end defun |
7270 | ||
7271 | The factory function that you supply should return an object | |
7272 | conforming to the TUI window protocol. These are the method that can | |
7273 | be called on this object, which is referred to below as the ``window | |
7274 | object''. The methods documented below are optional; if the object | |
7275 | does not implement one of these methods, @value{GDBN} will not attempt | |
7276 | to call it. Additional new methods may be added to the window | |
7277 | protocol in the future. @value{GDBN} guarantees that they will begin | |
7278 | with a lower-case letter, so you can start implementation methods with | |
7279 | upper-case letters or underscore to avoid any future conflicts. | |
7280 | ||
7281 | @defun Window.close () | |
7282 | When the TUI window is closed, the @code{gdb.TuiWindow} object will be | |
7283 | put into an invalid state. At this time, @value{GDBN} will call | |
7284 | @code{close} method on the window object. | |
7285 | ||
7286 | After this method is called, @value{GDBN} will discard any references | |
7287 | it holds on this window object, and will no longer call methods on | |
7288 | this object. | |
7289 | @end defun | |
7290 | ||
7291 | @defun Window.render () | |
7292 | In some situations, a TUI window can change size. For example, this | |
7293 | can happen if the user resizes the terminal, or changes the layout. | |
7294 | When this happens, @value{GDBN} will call the @code{render} method on | |
7295 | the window object. | |
7296 | ||
7297 | If your window is intended to update in response to changes in the | |
7298 | inferior, you will probably also want to register event listeners and | |
7299 | send output to the @code{gdb.TuiWindow}. | |
7300 | @end defun | |
7301 | ||
ebb83b77 | 7302 | @defun Window.hscroll (num) |
01b1af32 TT |
7303 | This is a request to scroll the window horizontally. @var{num} is the |
7304 | amount by which to scroll, with negative numbers meaning to scroll | |
7305 | right. In the TUI model, it is the viewport that moves, not the | |
7306 | contents. A positive argument should cause the viewport to move | |
7307 | right, and so the content should appear to move to the left. | |
7308 | @end defun | |
7309 | ||
ebb83b77 | 7310 | @defun Window.vscroll (num) |
01b1af32 TT |
7311 | This is a request to scroll the window vertically. @var{num} is the |
7312 | amount by which to scroll, with negative numbers meaning to scroll | |
7313 | backward. In the TUI model, it is the viewport that moves, not the | |
7314 | contents. A positive argument should cause the viewport to move down, | |
7315 | and so the content should appear to move up. | |
7316 | @end defun | |
7317 | ||
0f6a6994 | 7318 | @anchor{python-window-click} |
ebb83b77 | 7319 | @defun Window.click (x, y, button) |
a5375566 | 7320 | This is called on a mouse click in this window. @var{x} and @var{y} are |
965c919f AB |
7321 | the mouse coordinates inside the window (0-based, from the top left |
7322 | corner), and @var{button} specifies which mouse button was used, whose | |
7323 | values can be 1 (left), 2 (middle), or 3 (right). | |
0f6a6994 MG |
7324 | |
7325 | When TUI mouse events are disabled by turning off the @code{tui mouse-events} | |
7326 | setting (@pxref{tui-mouse-events,,set tui mouse-events}), then @code{click} will | |
7327 | not be called. | |
a5375566 HD |
7328 | @end defun |
7329 | ||
15e15b2d AB |
7330 | @node Disassembly In Python |
7331 | @subsubsection Instruction Disassembly In Python | |
7332 | @cindex python instruction disassembly | |
7333 | ||
7334 | @value{GDBN}'s builtin disassembler can be extended, or even replaced, | |
7335 | using the Python API. The disassembler related features are contained | |
7336 | within the @code{gdb.disassembler} module: | |
7337 | ||
4de4e485 | 7338 | @anchor{DisassembleInfo Class} |
15e15b2d AB |
7339 | @deftp {class} gdb.disassembler.DisassembleInfo |
7340 | Disassembly is driven by instances of this class. Each time | |
7341 | @value{GDBN} needs to disassemble an instruction, an instance of this | |
7342 | class is created and passed to a registered disassembler. The | |
7343 | disassembler is then responsible for disassembling an instruction and | |
7344 | returning a result. | |
7345 | ||
7346 | Instances of this type are usually created within @value{GDBN}, | |
7347 | however, it is possible to create a copy of an instance of this type, | |
7348 | see the description of @code{__init__} for more details. | |
7349 | ||
7350 | This class has the following properties and methods: | |
7351 | ||
7352 | @defvar DisassembleInfo.address | |
7353 | A read-only integer containing the address at which @value{GDBN} | |
7354 | wishes to disassemble a single instruction. | |
7355 | @end defvar | |
7356 | ||
7357 | @defvar DisassembleInfo.architecture | |
7358 | The @code{gdb.Architecture} (@pxref{Architectures In Python}) for | |
7359 | which @value{GDBN} is currently disassembling, this property is | |
7360 | read-only. | |
7361 | @end defvar | |
7362 | ||
7363 | @defvar DisassembleInfo.progspace | |
7364 | The @code{gdb.Progspace} (@pxref{Progspaces In Python,,Program Spaces | |
7365 | In Python}) for which @value{GDBN} is currently disassembling, this | |
7366 | property is read-only. | |
7367 | @end defvar | |
7368 | ||
7369 | @defun DisassembleInfo.is_valid () | |
7370 | Returns @code{True} if the @code{DisassembleInfo} object is valid, | |
7371 | @code{False} if not. A @code{DisassembleInfo} object will become | |
7372 | invalid once the disassembly call for which the @code{DisassembleInfo} | |
7373 | was created, has returned. Calling other @code{DisassembleInfo} | |
7374 | methods, or accessing @code{DisassembleInfo} properties, will raise a | |
7375 | @code{RuntimeError} exception if it is invalid. | |
7376 | @end defun | |
7377 | ||
7378 | @defun DisassembleInfo.__init__ (info) | |
7379 | This can be used to create a new @code{DisassembleInfo} object that is | |
7380 | a copy of @var{info}. The copy will have the same @code{address}, | |
7381 | @code{architecture}, and @code{progspace} values as @var{info}, and | |
7382 | will become invalid at the same time as @var{info}. | |
7383 | ||
7384 | This method exists so that sub-classes of @code{DisassembleInfo} can | |
7385 | be created, these sub-classes must be initialized as copies of an | |
7386 | existing @code{DisassembleInfo} object, but sub-classes might choose | |
7387 | to override the @code{read_memory} method, and so control what | |
7388 | @value{GDBN} sees when reading from memory | |
7389 | (@pxref{builtin_disassemble}). | |
7390 | @end defun | |
7391 | ||
7392 | @defun DisassembleInfo.read_memory (length, offset) | |
7393 | This method allows the disassembler to read the bytes of the | |
7394 | instruction to be disassembled. The method reads @var{length} bytes, | |
7395 | starting at @var{offset} from | |
7396 | @code{DisassembleInfo.address}. | |
7397 | ||
7398 | It is important that the disassembler read the instruction bytes using | |
7399 | this method, rather than reading inferior memory directly, as in some | |
7400 | cases @value{GDBN} disassembles from an internal buffer rather than | |
7401 | directly from inferior memory, calling this method handles this | |
7402 | detail. | |
7403 | ||
7404 | Returns a buffer object, which behaves much like an array or a string, | |
7405 | just as @code{Inferior.read_memory} does | |
7406 | (@pxref{gdbpy_inferior_read_memory,,Inferior.read_memory}). The | |
7407 | length of the returned buffer will always be exactly @var{length}. | |
7408 | ||
7409 | If @value{GDBN} is unable to read the required memory then a | |
7410 | @code{gdb.MemoryError} exception is raised (@pxref{Exception | |
7411 | Handling}). | |
7412 | ||
7413 | This method can be overridden by a sub-class in order to control what | |
7414 | @value{GDBN} sees when reading from memory | |
7415 | (@pxref{builtin_disassemble}). When overriding this method it is | |
7416 | important to understand how @code{builtin_disassemble} makes use of | |
7417 | this method. | |
7418 | ||
7419 | While disassembling a single instruction there could be multiple calls | |
7420 | to this method, and the same bytes might be read multiple times. Any | |
7421 | single call might only read a subset of the total instruction bytes. | |
7422 | ||
7423 | If an implementation of @code{read_memory} is unable to read the | |
7424 | requested memory contents, for example, if there's a request to read | |
7425 | from an invalid memory address, then a @code{gdb.MemoryError} should | |
7426 | be raised. | |
7427 | ||
7428 | Raising a @code{MemoryError} inside @code{read_memory} does not | |
7429 | automatically mean a @code{MemoryError} will be raised by | |
7430 | @code{builtin_disassemble}. It is possible the @value{GDBN}'s builtin | |
7431 | disassembler is probing to see how many bytes are available. When | |
7432 | @code{read_memory} raises the @code{MemoryError} the builtin | |
7433 | disassembler might be able to perform a complete disassembly with the | |
7434 | bytes it has available, in this case @code{builtin_disassemble} will | |
7435 | not itself raise a @code{MemoryError}. | |
7436 | ||
7437 | Any other exception type raised in @code{read_memory} will propagate | |
c6d20401 | 7438 | back and be re-raised by @code{builtin_disassemble}. |
15e15b2d | 7439 | @end defun |
4de4e485 AB |
7440 | |
7441 | @defun DisassembleInfo.text_part (style, string) | |
7442 | Create a new @code{DisassemblerTextPart} representing a piece of a | |
7443 | disassembled instruction. @var{string} should be a non-empty string, | |
7444 | and @var{style} should be an appropriate style constant | |
7445 | (@pxref{Disassembler Style Constants}). | |
7446 | ||
7447 | Disassembler parts are used when creating a @code{DisassemblerResult} | |
7448 | in order to represent the styling within an instruction | |
7449 | (@pxref{DisassemblerResult Class}). | |
7450 | @end defun | |
7451 | ||
7452 | @defun DisassembleInfo.address_part (address) | |
7453 | Create a new @code{DisassemblerAddressPart}. @var{address} is the | |
7454 | value of the absolute address this part represents. A | |
7455 | @code{DisassemblerAddressPart} is displayed as an absolute address and | |
7456 | an associated symbol, the address and symbol are styled appropriately. | |
7457 | @end defun | |
7458 | ||
15e15b2d AB |
7459 | @end deftp |
7460 | ||
773e2d29 AB |
7461 | @anchor{Disassembler Class} |
7462 | @deftp {class} gdb.disassembler.Disassembler | |
15e15b2d AB |
7463 | This is a base class from which all user implemented disassemblers |
7464 | must inherit. | |
7465 | ||
7466 | @defun Disassembler.__init__ (name) | |
7467 | The constructor takes @var{name}, a string, which should be a short | |
7468 | name for this disassembler. | |
7469 | @end defun | |
7470 | ||
7471 | @defun Disassembler.__call__ (info) | |
7472 | The @code{__call__} method must be overridden by sub-classes to | |
7473 | perform disassembly. Calling @code{__call__} on this base class will | |
7474 | raise a @code{NotImplementedError} exception. | |
7475 | ||
7476 | The @var{info} argument is an instance of @code{DisassembleInfo}, and | |
7477 | describes the instruction that @value{GDBN} wants disassembling. | |
7478 | ||
7479 | If this function returns @code{None}, this indicates to @value{GDBN} | |
7480 | that this sub-class doesn't wish to disassemble the requested | |
7481 | instruction. @value{GDBN} will then use its builtin disassembler to | |
7482 | perform the disassembly. | |
7483 | ||
7484 | Alternatively, this function can return a @code{DisassemblerResult} | |
7485 | that represents the disassembled instruction, this type is described | |
7486 | in more detail below. | |
7487 | ||
7488 | The @code{__call__} method can raise a @code{gdb.MemoryError} | |
7489 | exception (@pxref{Exception Handling}) to indicate to @value{GDBN} | |
7490 | that there was a problem accessing the required memory, this will then | |
7491 | be displayed by @value{GDBN} within the disassembler output. | |
7492 | ||
7493 | Ideally, the only three outcomes from invoking @code{__call__} would | |
7494 | be a return of @code{None}, a successful disassembly returned in a | |
7495 | @code{DisassemblerResult}, or a @code{MemoryError} indicating that | |
7496 | there was a problem reading memory. | |
7497 | ||
7498 | However, as an implementation of @code{__call__} could fail due to | |
7499 | other reasons, e.g.@: some external resource required to perform | |
7500 | disassembly is temporarily unavailable, then, if @code{__call__} | |
7501 | raises a @code{GdbError}, the exception will be converted to a string | |
7502 | and printed at the end of the disassembly output, the disassembly | |
7503 | request will then stop. | |
7504 | ||
7505 | Any other exception type raised by the @code{__call__} method is | |
7506 | considered an error in the user code, the exception will be printed to | |
7507 | the error stream according to the @kbd{set python print-stack} setting | |
7508 | (@pxref{set_python_print_stack,,@kbd{set python print-stack}}). | |
7509 | @end defun | |
7510 | @end deftp | |
7511 | ||
4de4e485 | 7512 | @anchor{DisassemblerResult Class} |
773e2d29 AB |
7513 | @deftp {class} gdb.disassembler.DisassemblerResult |
7514 | This class represents the result of disassembling a single | |
7515 | instruction. An instance of this class will be returned from | |
7516 | @code{builtin_disassemble} (@pxref{builtin_disassemble}), and an | |
7517 | instance of this class should be returned from | |
7518 | @w{@code{Disassembler.__call__}} (@pxref{Disassembler Class}) if an | |
7519 | instruction was successfully disassembled. | |
7520 | ||
0af2f233 AB |
7521 | It is not possible to sub-class the @code{DisassemblerResult} class. |
7522 | ||
773e2d29 AB |
7523 | The @code{DisassemblerResult} class has the following properties and |
7524 | methods: | |
15e15b2d | 7525 | |
4de4e485 | 7526 | @defun DisassemblerResult.__init__ (length, string, parts) |
15e15b2d AB |
7527 | Initialize an instance of this class, @var{length} is the length of |
7528 | the disassembled instruction in bytes, which must be greater than | |
4de4e485 AB |
7529 | zero. |
7530 | ||
7531 | Only one of @var{string} or @var{parts} should be used to initialize a | |
7532 | new @code{DisassemblerResult}; the other one should be passed the | |
7533 | value @code{None}. Alternatively, the arguments can be passed by | |
7534 | name, and the unused argument can be ignored. | |
7535 | ||
7536 | The @var{string} argument, if not @code{None}, is a non-empty string | |
7537 | that represents the entire disassembled instruction. Building a result | |
7538 | object using the @var{string} argument does not allow for any styling | |
7539 | information to be included in the result. @value{GDBN} will style the | |
7540 | result as a single @code{DisassemblerTextPart} with @code{STYLE_TEXT} | |
7541 | style (@pxref{Disassembler Styling Parts}). | |
7542 | ||
7543 | The @var{parts} argument, if not @code{None}, is a non-empty sequence | |
7544 | of @code{DisassemblerPart} objects. Each part represents a small part | |
7545 | of the disassembled instruction along with associated styling | |
7546 | information. A result object built using @var{parts} can be displayed | |
7547 | by @value{GDBN} with full styling information | |
7548 | (@pxref{style_disassembler_enabled,,@kbd{set style disassembler | |
7549 | enabled}}). | |
15e15b2d AB |
7550 | @end defun |
7551 | ||
7552 | @defvar DisassemblerResult.length | |
7553 | A read-only property containing the length of the disassembled | |
7554 | instruction in bytes, this will always be greater than zero. | |
7555 | @end defvar | |
7556 | ||
7557 | @defvar DisassemblerResult.string | |
7558 | A read-only property containing a non-empty string representing the | |
4de4e485 AB |
7559 | disassembled instruction. The @var{string} is a representation of the |
7560 | disassembled instruction without any styling information. To see how | |
7561 | the instruction will be styled use the @var{parts} property. | |
7562 | ||
7563 | If this instance was initialized using separate | |
7564 | @code{DisassemblerPart} objects, the @var{string} property will still | |
7565 | be valid. The @var{string} value is created by concatenating the | |
7566 | @code{DisassemblerPart.string} values of each component part | |
7567 | (@pxref{Disassembler Styling Parts}). | |
7568 | @end defvar | |
7569 | ||
7570 | @defvar DisassemblerResult.parts | |
7571 | A read-only property containing a non-empty sequence of | |
7572 | @code{DisassemblerPart} objects. Each @code{DisassemblerPart} object | |
7573 | contains a small part of the instruction along with information about | |
7574 | how that part should be styled. @value{GDBN} uses this information to | |
7575 | create styled disassembler output | |
7576 | (@pxref{style_disassembler_enabled,,@kbd{set style disassembler | |
7577 | enabled}}). | |
7578 | ||
7579 | If this instance was initialized using a single string rather than | |
7580 | with a sequence of @code{DisassemblerPart} objects, the @var{parts} | |
7581 | property will still be valid. In this case the @var{parts} property | |
7582 | will hold a sequence containing a single @code{DisassemblerTextPart} | |
7583 | object, the string of which will represent the entire instruction, and | |
7584 | the style of which will be @code{STYLE_TEXT}. | |
7585 | @end defvar | |
7586 | @end deftp | |
7587 | ||
7588 | @anchor{Disassembler Styling Parts} | |
7589 | @deftp {class} gdb.disassembler.DisassemblerPart | |
7590 | This is a parent class from which the different part sub-classes | |
7591 | inherit. Only instances of the sub-classes detailed below will be | |
7592 | returned by the Python API. | |
7593 | ||
7594 | It is not possible to directly create instances of either this parent | |
7595 | class, or any of the sub-classes listed below. Instances of the | |
7596 | sub-classes listed below are created by calling | |
7597 | @code{builtin_disassemble} (@pxref{builtin_disassemble}) and are | |
7598 | returned within the @code{DisassemblerResult} object, or can be | |
7599 | created by calling the @code{text_part} and @code{address_part} | |
7600 | methods on the @code{DisassembleInfo} class (@pxref{DisassembleInfo | |
7601 | Class}). | |
7602 | ||
7603 | The @code{DisassemblerPart} class has a single property: | |
7604 | ||
7605 | @defvar DisassemblerPart.string | |
7606 | A read-only property that contains a non-empty string representing | |
7607 | this part of the disassembled instruction. The string within this | |
7608 | property doesn't include any styling information. | |
15e15b2d AB |
7609 | @end defvar |
7610 | @end deftp | |
7611 | ||
4de4e485 AB |
7612 | @deftp {class} gdb.disassembler.DisassemblerTextPart |
7613 | The @code{DisassemblerTextPart} class represents a piece of the | |
7614 | disassembled instruction and the associated style for that piece. | |
7615 | Instances of this class can't be created directly, instead call | |
7616 | @code{DisassembleInfo.text_part} to create a new instance of this | |
7617 | class (@pxref{DisassembleInfo Class}). | |
7618 | ||
7619 | As well as the properties of its parent class, the | |
7620 | @code{DisassemblerTextPart} has the following additional property: | |
7621 | ||
7622 | @defvar DisassemblerTextPart.style | |
7623 | A read-only property that contains one of the defined style constants. | |
7624 | @value{GDBN} will use this style when styling this part of the | |
7625 | disassembled instruction (@pxref{Disassembler Style Constants}). | |
7626 | @end defvar | |
7627 | @end deftp | |
7628 | ||
7629 | @deftp {class} gdb.disassembler.DisassemblerAddressPart | |
7630 | The @code{DisassemblerAddressPart} class represents an absolute | |
7631 | address within a disassembled instruction. Using a | |
7632 | @code{DisassemblerAddressPart} instead of a | |
7633 | @code{DisassemblerTextPart} with @code{STYLE_ADDRESS} is preferred, | |
7634 | @value{GDBN} will display the address as both an absolute address, and | |
7635 | will look up a suitable symbol to display next to the address. Using | |
7636 | @code{DisassemblerAddressPart} also ensures that user settings such as | |
7637 | @code{set print max-symbolic-offset} are respected. | |
7638 | ||
7639 | Here is an example of an x86-64 instruction: | |
7640 | ||
7641 | @smallexample | |
7642 | call 0x401136 <foo> | |
7643 | @end smallexample | |
7644 | ||
7645 | @noindent | |
7646 | In this instruction the @code{0x401136 <foo>} was generated from a | |
7647 | single @code{DisassemblerAddressPart}. The @code{0x401136} will be | |
7648 | styled with @code{STYLE_ADDRESS}, and @code{foo} will be styled with | |
7649 | @code{STYLE_SYMBOL}. The @code{<} and @code{>} will be styled as | |
7650 | @code{STYLE_TEXT}. | |
7651 | ||
7652 | If the inclusion of the symbol name is not required then a | |
7653 | @code{DisassemblerTextPart} with style @code{STYLE_ADDRESS} can be | |
7654 | used instead. | |
7655 | ||
7656 | Instances of this class can't be created directly, instead call | |
7657 | @code{DisassembleInfo.address_part} to create a new instance of this | |
7658 | class (@pxref{DisassembleInfo Class}). | |
7659 | ||
7660 | As well as the properties of its parent class, the | |
7661 | @code{DisassemblerAddressPart} has the following additional property: | |
7662 | ||
7663 | @defvar DisassemblerAddressPart.address | |
7664 | A read-only property that contains the @var{address} passed to this | |
7665 | object's @code{__init__} method. | |
7666 | @end defvar | |
7667 | @end deftp | |
7668 | ||
7669 | @anchor{Disassembler Style Constants} | |
7670 | ||
7671 | The following table lists all of the disassembler styles that are | |
7672 | available. @value{GDBN} maps these style constants onto its style | |
7673 | settings (@pxref{Output Styling}). In some cases, several style | |
7674 | constants produce the same style settings, and thus will produce the | |
7675 | same visual effect on the screen. This could change in future | |
7676 | releases of @value{GDBN}, so care should be taken to select the | |
7677 | correct style constant to ensure correct output styling in future | |
7678 | releases of @value{GDBN}. | |
7679 | ||
7680 | @vtable @code | |
7681 | @vindex STYLE_TEXT | |
7682 | @item gdb.disassembler.STYLE_TEXT | |
7683 | This is the default style used by @value{GDBN} when styling | |
7684 | disassembler output. This style should be used for any parts of the | |
7685 | instruction that don't fit any of the other styles listed below. | |
7686 | @value{GDBN} styles text with this style using its default style. | |
7687 | ||
7688 | @vindex STYLE_MNEMONIC | |
7689 | @item gdb.disassembler.STYLE_MNEMONIC | |
7690 | This style is used for styling the primary instruction mnemonic, which | |
7691 | usually appears at, or near, the start of the disassembled instruction | |
7692 | string. | |
7693 | ||
7694 | @value{GDBN} styles text with this style using the @code{disassembler | |
7695 | mnemonic} style setting. | |
7696 | ||
7697 | @vindex STYLE_SUB_MNEMONIC | |
7698 | @item gdb.disassembler.STYLE_SUB_MNEMONIC | |
7699 | This style is used for styling any sub-mnemonics within a disassembled | |
7700 | instruction. A sub-mnemonic is any text within the instruction that | |
7701 | controls the function of the instruction, but which is disjoint from | |
7702 | the primary mnemonic (which will have styled @code{STYLE_MNEMONIC}). | |
7703 | ||
7704 | As an example, consider this AArch64 instruction: | |
7705 | ||
7706 | @smallexample | |
7707 | add w16, w7, w1, lsl #1 | |
7708 | @end smallexample | |
7709 | ||
7710 | @noindent | |
7711 | The @code{add} is the primary instruction mnemonic, and would be given | |
7712 | style @code{STYLE_MNEMONIC}, while @code{lsl} is the sub-mnemonic, and | |
7713 | would be given the style @code{STYLE_SUB_MNEMONIC}. | |
7714 | ||
7715 | @value{GDBN} styles text with this style using the @code{disassembler | |
7716 | mnemonic} style setting. | |
7717 | ||
7718 | @vindex STYLE_ASSEMBLER_DIRECTIVE | |
7719 | @item gdb.disassembler.STYLE_ASSEMBLER_DIRECTIVE | |
7720 | Sometimes a series of bytes doesn't decode to a valid instruction. In | |
7721 | this case the disassembler may choose to represent the result of | |
7722 | disassembling using an assembler directive, for example: | |
7723 | ||
7724 | @smallexample | |
7725 | .word 0x1234 | |
7726 | @end smallexample | |
7727 | ||
7728 | @noindent | |
7729 | In this case, the @code{.word} would be give the | |
7730 | @code{STYLE_ASSEMBLER_DIRECTIVE} style. An assembler directive is | |
7731 | similar to a mnemonic in many ways but is something that is not part | |
7732 | of the architecture's instruction set. | |
7733 | ||
7734 | @value{GDBN} styles text with this style using the @code{disassembler | |
7735 | mnemonic} style setting. | |
7736 | ||
7737 | @vindex STYLE_REGISTER | |
7738 | @item gdb.disassembler.STYLE_REGISTER | |
7739 | This style is used for styling any text that represents a register | |
7740 | name, or register number, within a disassembled instruction. | |
7741 | ||
7742 | @value{GDBN} styles text with this style using the @code{disassembler | |
7743 | register} style setting. | |
7744 | ||
7745 | @vindex STYLE_ADDRESS | |
7746 | @item gdb.disassembler.STYLE_ADDRESS | |
7747 | This style is used for styling numerical values that represent | |
7748 | absolute addresses within the disassembled instruction. | |
7749 | ||
7750 | When creating a @code{DisassemblerTextPart} with this style, you | |
7751 | should consider if a @code{DisassemblerAddressPart} would be more | |
7752 | appropriate. See @ref{Disassembler Styling Parts} for a description | |
7753 | of what each part offers. | |
7754 | ||
7755 | @value{GDBN} styles text with this style using the @code{disassembler | |
7756 | address} style setting. | |
7757 | ||
7758 | @vindex STYLE_ADDRESS_OFFSET | |
7759 | @item gdb.disassembler.STYLE_ADDRESS_OFFSET | |
7760 | This style is used for styling numerical values that represent offsets | |
7761 | to addresses within the disassembled instruction. A value is | |
7762 | considered an address offset when the instruction itself is going to | |
7763 | access memory, and the value is being used to offset which address is | |
7764 | accessed. | |
7765 | ||
7766 | For example, an architecture might have an instruction that loads from | |
7767 | memory using an address within a register. If that instruction also | |
7768 | allowed for an immediate offset to be encoded into the instruction, | |
7769 | this would be an address offset. Similarly, a branch instruction | |
7770 | might jump to an address in a register plus an address offset that is | |
7771 | encoded into the instruction. | |
7772 | ||
7773 | @value{GDBN} styles text with this style using the @code{disassembler | |
7774 | immediate} style setting. | |
7775 | ||
7776 | @vindex STYLE_IMMEDIATE | |
7777 | @item gdb.disassembler.STYLE_IMMEDIATE | |
7778 | Use @code{STYLE_IMMEDIATE} for any numerical values within a | |
7779 | disassembled instruction when those values are not addresses, address | |
7780 | offsets, or register numbers (The styles @code{STYLE_ADDRESS}, | |
7781 | @code{STYLE_ADDRESS_OFFSET}, or @code{STYLE_REGISTER} can be used in | |
7782 | those cases). | |
7783 | ||
7784 | @value{GDBN} styles text with this style using the @code{disassembler | |
7785 | immediate} style setting. | |
7786 | ||
7787 | @vindex STYLE_SYMBOL | |
7788 | @item gdb.disassembler.STYLE_SYMBOL | |
7789 | This style is used for styling the textual name of a symbol that is | |
7790 | included within a disassembled instruction. A symbol name is often | |
7791 | included next to an absolute address within a disassembled instruction | |
7792 | to make it easier for the user to understand what the address is | |
7793 | referring too. For example: | |
7794 | ||
7795 | @smallexample | |
7796 | call 0x401136 <foo> | |
7797 | @end smallexample | |
7798 | ||
7799 | @noindent | |
7800 | Here @code{foo} is the name of a symbol, and should be given the | |
7801 | @code{STYLE_SYMBOL} style. | |
7802 | ||
7803 | Adding symbols next to absolute addresses like this is handled | |
7804 | automatically by the @code{DisassemblerAddressPart} class | |
7805 | (@pxref{Disassembler Styling Parts}). | |
7806 | ||
7807 | @value{GDBN} styles text with this style using the @code{disassembler | |
7808 | symbol} style setting. | |
7809 | ||
7810 | @vindex STYLE_COMMENT_START | |
7811 | @item gdb.disassembler.STYLE_COMMENT_START | |
7812 | This style is used to start a line comment in the disassembly output. | |
7813 | Unlike other styles, which only apply to the single | |
7814 | @code{DisassemblerTextPiece} to which they are applied, the comment | |
7815 | style is sticky, and overrides the style of any further pieces within | |
7816 | this instruction. | |
7817 | ||
7818 | This means that, after a @code{STYLE_COMMENT_START} piece has been | |
7819 | seen, @value{GDBN} will apply the comment style until the end of the | |
7820 | line, ignoring the specific style within a piece. | |
7821 | ||
7822 | @value{GDBN} styles text with this style using the @code{disassembler | |
7823 | comment} style setting. | |
7824 | @end vtable | |
7825 | ||
15e15b2d AB |
7826 | The following functions are also contained in the |
7827 | @code{gdb.disassembler} module: | |
7828 | ||
7829 | @defun register_disassembler (disassembler, architecture) | |
7830 | The @var{disassembler} must be a sub-class of | |
7831 | @code{gdb.disassembler.Disassembler} or @code{None}. | |
7832 | ||
7833 | The optional @var{architecture} is either a string, or the value | |
7834 | @code{None}. If it is a string, then it should be the name of an | |
7835 | architecture known to @value{GDBN}, as returned either from | |
7836 | @code{gdb.Architecture.name} | |
7837 | (@pxref{gdbpy_architecture_name,,gdb.Architecture.name}), or from | |
7838 | @code{gdb.architecture_names} | |
7839 | (@pxref{gdb_architecture_names,,gdb.architecture_names}). | |
7840 | ||
7841 | The @var{disassembler} will be installed for the architecture named by | |
7842 | @var{architecture}, or if @var{architecture} is @code{None}, then | |
7843 | @var{disassembler} will be installed as a global disassembler for use | |
7844 | by all architectures. | |
7845 | ||
7846 | @cindex disassembler in Python, global vs.@: specific | |
7847 | @cindex search order for disassembler in Python | |
7848 | @cindex look up of disassembler in Python | |
7849 | @value{GDBN} only records a single disassembler for each architecture, | |
7850 | and a single global disassembler. Calling | |
7851 | @code{register_disassembler} for an architecture, or for the global | |
7852 | disassembler, will replace any existing disassembler registered for | |
7853 | that @var{architecture} value. The previous disassembler is returned. | |
7854 | ||
7855 | If @var{disassembler} is @code{None} then any disassembler currently | |
7856 | registered for @var{architecture} is deregistered and returned. | |
7857 | ||
7858 | When @value{GDBN} is looking for a disassembler to use, @value{GDBN} | |
7859 | first looks for an architecture specific disassembler. If none has | |
7860 | been registered then @value{GDBN} looks for a global disassembler (one | |
7861 | registered with @var{architecture} set to @code{None}). Only one | |
7862 | disassembler is called to perform disassembly, so, if there is both an | |
7863 | architecture specific disassembler, and a global disassembler | |
7864 | registered, it is the architecture specific disassembler that will be | |
7865 | used. | |
7866 | ||
7867 | @value{GDBN} tracks the architecture specific, and global | |
7868 | disassemblers separately, so it doesn't matter in which order | |
7869 | disassemblers are created or registered; an architecture specific | |
7870 | disassembler, if present, will always be used in preference to a | |
7871 | global disassembler. | |
7872 | ||
7873 | You can use the @kbd{maint info python-disassemblers} command | |
7874 | (@pxref{maint info python-disassemblers}) to see which disassemblers | |
7875 | have been registered. | |
7876 | @end defun | |
7877 | ||
7878 | @anchor{builtin_disassemble} | |
7879 | @defun builtin_disassemble (info) | |
7880 | This function calls back into @value{GDBN}'s builtin disassembler to | |
7881 | disassemble the instruction identified by @var{info}, an instance, or | |
7882 | sub-class, of @code{DisassembleInfo}. | |
7883 | ||
7884 | When the builtin disassembler needs to read memory the | |
7885 | @code{read_memory} method on @var{info} will be called. By | |
7886 | sub-classing @code{DisassembleInfo} and overriding the | |
7887 | @code{read_memory} method, it is possible to intercept calls to | |
7888 | @code{read_memory} from the builtin disassembler, and to modify the | |
7889 | values returned. | |
7890 | ||
7891 | It is important to understand that, even when | |
7892 | @code{DisassembleInfo.read_memory} raises a @code{gdb.MemoryError}, it | |
7893 | is the internal disassembler itself that reports the memory error to | |
7894 | @value{GDBN}. The reason for this is that the disassembler might | |
7895 | probe memory to see if a byte is readable or not; if the byte can't be | |
7896 | read then the disassembler may choose not to report an error, but | |
7897 | instead to disassemble the bytes that it does have available. | |
7898 | ||
7899 | If the builtin disassembler is successful then an instance of | |
7900 | @code{DisassemblerResult} is returned from @code{builtin_disassemble}, | |
7901 | alternatively, if something goes wrong, an exception will be raised. | |
7902 | ||
7903 | A @code{MemoryError} will be raised if @code{builtin_disassemble} is | |
7904 | unable to read some memory that is required in order to perform | |
7905 | disassembly correctly. | |
7906 | ||
7907 | Any exception that is not a @code{MemoryError}, that is raised in a | |
7908 | call to @code{read_memory}, will pass through | |
7909 | @code{builtin_disassemble}, and be visible to the caller. | |
7910 | ||
7911 | Finally, there are a few cases where @value{GDBN}'s builtin | |
7912 | disassembler can fail for reasons that are not covered by | |
7913 | @code{MemoryError}. In these cases, a @code{GdbError} will be raised. | |
7914 | The contents of the exception will be a string describing the problem | |
7915 | the disassembler encountered. | |
7916 | @end defun | |
7917 | ||
7918 | Here is an example that registers a global disassembler. The new | |
7919 | disassembler invokes the builtin disassembler, and then adds a | |
7920 | comment, @code{## Comment}, to each line of disassembly output: | |
7921 | ||
7922 | @smallexample | |
7923 | class ExampleDisassembler(gdb.disassembler.Disassembler): | |
7924 | def __init__(self): | |
7925 | super().__init__("ExampleDisassembler") | |
7926 | ||
7927 | def __call__(self, info): | |
7928 | result = gdb.disassembler.builtin_disassemble(info) | |
7929 | length = result.length | |
7930 | text = result.string + "\t## Comment" | |
7931 | return gdb.disassembler.DisassemblerResult(length, text) | |
7932 | ||
7933 | gdb.disassembler.register_disassembler(ExampleDisassembler()) | |
7934 | @end smallexample | |
7935 | ||
7936 | The following example creates a sub-class of @code{DisassembleInfo} in | |
7937 | order to intercept the @code{read_memory} calls, within | |
7938 | @code{read_memory} any bytes read from memory have the two 4-bit | |
7939 | nibbles swapped around. This isn't a very useful adjustment, but | |
7940 | serves as an example. | |
7941 | ||
7942 | @smallexample | |
7943 | class MyInfo(gdb.disassembler.DisassembleInfo): | |
7944 | def __init__(self, info): | |
7945 | super().__init__(info) | |
7946 | ||
7947 | def read_memory(self, length, offset): | |
7948 | buffer = super().read_memory(length, offset) | |
7949 | result = bytearray() | |
7950 | for b in buffer: | |
7951 | v = int.from_bytes(b, 'little') | |
7952 | v = (v << 4) & 0xf0 | (v >> 4) | |
7953 | result.append(v) | |
7954 | return memoryview(result) | |
7955 | ||
7956 | class NibbleSwapDisassembler(gdb.disassembler.Disassembler): | |
7957 | def __init__(self): | |
7958 | super().__init__("NibbleSwapDisassembler") | |
7959 | ||
7960 | def __call__(self, info): | |
7961 | info = MyInfo(info) | |
7962 | return gdb.disassembler.builtin_disassemble(info) | |
7963 | ||
7964 | gdb.disassembler.register_disassembler(NibbleSwapDisassembler()) | |
7965 | @end smallexample | |
7966 | ||
8f6c452b AB |
7967 | @node Missing Debug Info In Python |
7968 | @subsubsection Missing Debug Info In Python | |
7969 | @cindex python, handle missing debug information | |
7970 | ||
7971 | When @value{GDBN} encounters a new objfile (@pxref{Objfiles In | |
7972 | Python}), e.g.@: the primary executable, or any shared libraries used | |
7973 | by the inferior, @value{GDBN} will attempt to load the corresponding | |
7974 | debug information for that objfile. The debug information might be | |
7975 | found within the objfile itself, or within a separate objfile which | |
7976 | @value{GDBN} will automatically locate and load. | |
7977 | ||
7978 | Sometimes though, @value{GDBN} might not find any debug information | |
7979 | for an objfile, in this case the debugging experience will be | |
7980 | restricted. | |
7981 | ||
7982 | If @value{GDBN} fails to locate any debug information for a particular | |
7983 | objfile, there is an opportunity for a Python extension to step in. A | |
7984 | Python extension can potentially locate the missing debug information | |
7985 | using some platform- or project-specific steps, and inform | |
7986 | @value{GDBN} of its location. Or a Python extension might provide | |
7987 | some platform- or project-specific advice to the user about how to | |
7988 | obtain the missing debug information. | |
7989 | ||
7990 | A missing debug information Python extension consists of a handler | |
7991 | object which has the @code{name} and @code{enabled} attributes, and | |
7992 | implements the @code{__call__} method. When @value{GDBN} encounters | |
7993 | an objfile for which it is unable to find any debug information, it | |
7994 | invokes the @code{__call__} method. Full details of how handlers are | |
7995 | written can be found below. | |
7996 | ||
7997 | @subheading The @code{gdb.missing_debug} Module | |
7998 | ||
7999 | @value{GDBN} comes with a @code{gdb.missing_debug} module which | |
8000 | contains the following class and global function: | |
8001 | ||
8002 | @deftp{class} gdb.missing_debug.MissingDebugHandler | |
8003 | ||
8004 | @code{MissingDebugHandler} is a base class from which user-created | |
8005 | handlers can derive, though it is not required that handlers derive | |
8006 | from this class, so long as any user created handler has the | |
8007 | @code{name} and @code{enabled} attributes, and implements the | |
8008 | @code{__call__} method. | |
8009 | ||
8010 | @defun MissingDebugHandler.__init__ (name) | |
8011 | The @var{name} is a string used to reference this missing debug | |
8012 | handler within some @value{GDBN} commands. Valid names consist of the | |
8013 | characters @code{[-_a-zA-Z0-9]}, creating a handler with an invalid | |
8014 | name raises a @code{ValueError} exception. | |
8015 | @end defun | |
8016 | ||
8017 | @defun MissingDebugHandler.__call__ (objfile) | |
8018 | Sub-classes must override the @code{__call__} method. The | |
8019 | @var{objfile} argument will be a @code{gdb.Objfile}, this is the | |
8020 | objfile for which @value{GDBN} was unable to find any debug | |
8021 | information. | |
8022 | ||
8023 | The return value from the @code{__call__} method indicates what | |
8024 | @value{GDBN} should do next. The possible return values are: | |
8025 | ||
8026 | @itemize @bullet | |
8027 | @item @code{None} | |
8028 | ||
8029 | This indicates that this handler could not help with @var{objfile}, | |
8030 | @value{GDBN} should call any other registered handlers. | |
8031 | ||
8032 | @item @code{True} | |
8033 | ||
8034 | This indicates that this handler has installed the debug information | |
8035 | into a location where @value{GDBN} would normally expect to find it | |
8036 | when looking for separate debug information files (@pxref{Separate | |
8037 | Debug Files}). @value{GDBN} will repeat the normal lookup process, | |
8038 | which should now find the separate debug file. | |
8039 | ||
8040 | If @value{GDBN} still doesn't find the separate debug information file | |
8041 | after this second attempt, then the Python missing debug information | |
8042 | handlers are not invoked a second time, this prevents a badly behaved | |
8043 | handler causing @value{GDBN} to get stuck in a loop. @value{GDBN} | |
8044 | will continue without any debug information for @var{objfile}. | |
8045 | ||
8046 | @item @code{False} | |
8047 | ||
8048 | This indicates that this handler has done everything that it intends | |
8049 | to do with @var{objfile}, but no separate debug information can be | |
8050 | found. @value{GDBN} will not call any other registered handlers for | |
8051 | @var{objfile}. @value{GDBN} will continue without debugging | |
8052 | information for @var{objfile}. | |
8053 | ||
8054 | @item A string | |
8055 | ||
8056 | The returned string should contain a filename. @value{GDBN} will not | |
8057 | call any further registered handlers, and will instead load the debug | |
8058 | information from the file identified by the returned filename. | |
8059 | @end itemize | |
8060 | ||
8061 | Invoking the @code{__call__} method from this base class will raise a | |
8062 | @code{NotImplementedError} exception. | |
8063 | @end defun | |
8064 | ||
8065 | @defvar MissingDebugHandler.name | |
8066 | A read-only attribute which is a string, the name of this handler | |
8067 | passed to the @code{__init__} method. | |
8068 | @end defvar | |
8069 | ||
8070 | @defvar MissingDebugHandler.enabled | |
8071 | A modifiable attribute containing a boolean; when @code{True}, the | |
8072 | handler is enabled, and will be used by @value{GDBN}. When | |
8073 | @code{False}, the handler has been disabled, and will not be used. | |
8074 | @end defvar | |
8075 | @end deftp | |
8076 | ||
8077 | @defun gdb.missing_debug.register_handler (locus, handler, replace=@code{False}) | |
8078 | Register a new missing debug handler with @value{GDBN}. | |
8079 | ||
8080 | @var{handler} is an instance of a sub-class of | |
8081 | @code{MissingDebugHandler}, or at least an instance of an object that | |
8082 | has the same attributes and methods as @code{MissingDebugHandler}. | |
8083 | ||
8084 | @var{locus} specifies to which handler list to prepend @var{handler}. | |
8085 | It can be either a @code{gdb.Progspace} (@pxref{Progspaces In Python}) | |
8086 | or @code{None}, in which case the handler is registered globally. The | |
8087 | newly registered @var{handler} will be called before any other handler | |
8088 | from the same locus. Two handlers in the same locus cannot have the | |
8089 | same name, an attempt to add a handler with an already existing name | |
8090 | raises an exception unless @var{replace} is @code{True}, in which case | |
8091 | the old handler is deleted and the new handler is prepended to the | |
8092 | selected handler list. | |
8093 | ||
8094 | @value{GDBN} first calls the handlers for the current program space, | |
8095 | and then the globally registered handlers. As soon as a handler | |
8096 | returns a value other than @code{None}, no further handlers are called | |
8097 | for this objfile. | |
8098 | @end defun | |
8099 | ||
329baa95 DE |
8100 | @node Python Auto-loading |
8101 | @subsection Python Auto-loading | |
8102 | @cindex Python auto-loading | |
8103 | ||
8104 | When a new object file is read (for example, due to the @code{file} | |
8105 | command, or because the inferior has loaded a shared library), | |
8106 | @value{GDBN} will look for Python support scripts in several ways: | |
8107 | @file{@var{objfile}-gdb.py} and @code{.debug_gdb_scripts} section. | |
8108 | @xref{Auto-loading extensions}. | |
8109 | ||
8110 | The auto-loading feature is useful for supplying application-specific | |
8111 | debugging commands and scripts. | |
8112 | ||
8113 | Auto-loading can be enabled or disabled, | |
8114 | and the list of auto-loaded scripts can be printed. | |
8115 | ||
8116 | @table @code | |
8117 | @anchor{set auto-load python-scripts} | |
8118 | @kindex set auto-load python-scripts | |
8119 | @item set auto-load python-scripts [on|off] | |
8120 | Enable or disable the auto-loading of Python scripts. | |
8121 | ||
8122 | @anchor{show auto-load python-scripts} | |
8123 | @kindex show auto-load python-scripts | |
8124 | @item show auto-load python-scripts | |
8125 | Show whether auto-loading of Python scripts is enabled or disabled. | |
8126 | ||
8127 | @anchor{info auto-load python-scripts} | |
8128 | @kindex info auto-load python-scripts | |
8129 | @cindex print list of auto-loaded Python scripts | |
8130 | @item info auto-load python-scripts [@var{regexp}] | |
8131 | Print the list of all Python scripts that @value{GDBN} auto-loaded. | |
8132 | ||
8133 | Also printed is the list of Python scripts that were mentioned in | |
9f050062 DE |
8134 | the @code{.debug_gdb_scripts} section and were either not found |
8135 | (@pxref{dotdebug_gdb_scripts section}) or were not auto-loaded due to | |
8136 | @code{auto-load safe-path} rejection (@pxref{Auto-loading}). | |
329baa95 DE |
8137 | This is useful because their names are not printed when @value{GDBN} |
8138 | tries to load them and fails. There may be many of them, and printing | |
8139 | an error message for each one is problematic. | |
8140 | ||
8141 | If @var{regexp} is supplied only Python scripts with matching names are printed. | |
8142 | ||
8143 | Example: | |
8144 | ||
8145 | @smallexample | |
8146 | (gdb) info auto-load python-scripts | |
8147 | Loaded Script | |
8148 | Yes py-section-script.py | |
8149 | full name: /tmp/py-section-script.py | |
8150 | No my-foo-pretty-printers.py | |
8151 | @end smallexample | |
8152 | @end table | |
8153 | ||
9f050062 | 8154 | When reading an auto-loaded file or script, @value{GDBN} sets the |
329baa95 DE |
8155 | @dfn{current objfile}. This is available via the @code{gdb.current_objfile} |
8156 | function (@pxref{Objfiles In Python}). This can be useful for | |
8157 | registering objfile-specific pretty-printers and frame-filters. | |
8158 | ||
8159 | @node Python modules | |
8160 | @subsection Python modules | |
8161 | @cindex python modules | |
8162 | ||
8163 | @value{GDBN} comes with several modules to assist writing Python code. | |
8164 | ||
8165 | @menu | |
8166 | * gdb.printing:: Building and registering pretty-printers. | |
8167 | * gdb.types:: Utilities for working with types. | |
8168 | * gdb.prompt:: Utilities for prompt value substitution. | |
8169 | @end menu | |
8170 | ||
8171 | @node gdb.printing | |
8172 | @subsubsection gdb.printing | |
8173 | @cindex gdb.printing | |
8174 | ||
8175 | This module provides a collection of utilities for working with | |
8176 | pretty-printers. | |
8177 | ||
8178 | @table @code | |
8179 | @item PrettyPrinter (@var{name}, @var{subprinters}=None) | |
8180 | This class specifies the API that makes @samp{info pretty-printer}, | |
8181 | @samp{enable pretty-printer} and @samp{disable pretty-printer} work. | |
8182 | Pretty-printers should generally inherit from this class. | |
8183 | ||
8184 | @item SubPrettyPrinter (@var{name}) | |
8185 | For printers that handle multiple types, this class specifies the | |
8186 | corresponding API for the subprinters. | |
8187 | ||
8188 | @item RegexpCollectionPrettyPrinter (@var{name}) | |
8189 | Utility class for handling multiple printers, all recognized via | |
8190 | regular expressions. | |
8191 | @xref{Writing a Pretty-Printer}, for an example. | |
8192 | ||
8193 | @item FlagEnumerationPrinter (@var{name}) | |
8194 | A pretty-printer which handles printing of @code{enum} values. Unlike | |
8195 | @value{GDBN}'s built-in @code{enum} printing, this printer attempts to | |
8196 | work properly when there is some overlap between the enumeration | |
697aa1b7 EZ |
8197 | constants. The argument @var{name} is the name of the printer and |
8198 | also the name of the @code{enum} type to look up. | |
329baa95 DE |
8199 | |
8200 | @item register_pretty_printer (@var{obj}, @var{printer}, @var{replace}=False) | |
8201 | Register @var{printer} with the pretty-printer list of @var{obj}. | |
8202 | If @var{replace} is @code{True} then any existing copy of the printer | |
8203 | is replaced. Otherwise a @code{RuntimeError} exception is raised | |
8204 | if a printer with the same name already exists. | |
8205 | @end table | |
8206 | ||
8207 | @node gdb.types | |
8208 | @subsubsection gdb.types | |
8209 | @cindex gdb.types | |
8210 | ||
8211 | This module provides a collection of utilities for working with | |
8212 | @code{gdb.Type} objects. | |
8213 | ||
8214 | @table @code | |
8215 | @item get_basic_type (@var{type}) | |
8216 | Return @var{type} with const and volatile qualifiers stripped, | |
8217 | and with typedefs and C@t{++} references converted to the underlying type. | |
8218 | ||
8219 | C@t{++} example: | |
8220 | ||
8221 | @smallexample | |
8222 | typedef const int const_int; | |
8223 | const_int foo (3); | |
8224 | const_int& foo_ref (foo); | |
8225 | int main () @{ return 0; @} | |
8226 | @end smallexample | |
8227 | ||
8228 | Then in gdb: | |
8229 | ||
8230 | @smallexample | |
8231 | (gdb) start | |
8232 | (gdb) python import gdb.types | |
8233 | (gdb) python foo_ref = gdb.parse_and_eval("foo_ref") | |
8234 | (gdb) python print gdb.types.get_basic_type(foo_ref.type) | |
8235 | int | |
8236 | @end smallexample | |
8237 | ||
8238 | @item has_field (@var{type}, @var{field}) | |
8239 | Return @code{True} if @var{type}, assumed to be a type with fields | |
8240 | (e.g., a structure or union), has field @var{field}. | |
8241 | ||
8242 | @item make_enum_dict (@var{enum_type}) | |
8243 | Return a Python @code{dictionary} type produced from @var{enum_type}. | |
8244 | ||
8245 | @item deep_items (@var{type}) | |
8246 | Returns a Python iterator similar to the standard | |
8247 | @code{gdb.Type.iteritems} method, except that the iterator returned | |
8248 | by @code{deep_items} will recursively traverse anonymous struct or | |
8249 | union fields. For example: | |
8250 | ||
8251 | @smallexample | |
8252 | struct A | |
8253 | @{ | |
8254 | int a; | |
8255 | union @{ | |
8256 | int b0; | |
8257 | int b1; | |
8258 | @}; | |
8259 | @}; | |
8260 | @end smallexample | |
8261 | ||
8262 | @noindent | |
8263 | Then in @value{GDBN}: | |
8264 | @smallexample | |
8265 | (@value{GDBP}) python import gdb.types | |
8266 | (@value{GDBP}) python struct_a = gdb.lookup_type("struct A") | |
8267 | (@value{GDBP}) python print struct_a.keys () | |
8268 | @{['a', '']@} | |
8269 | (@value{GDBP}) python print [k for k,v in gdb.types.deep_items(struct_a)] | |
8270 | @{['a', 'b0', 'b1']@} | |
8271 | @end smallexample | |
8272 | ||
8273 | @item get_type_recognizers () | |
8274 | Return a list of the enabled type recognizers for the current context. | |
8275 | This is called by @value{GDBN} during the type-printing process | |
8276 | (@pxref{Type Printing API}). | |
8277 | ||
8278 | @item apply_type_recognizers (recognizers, type_obj) | |
8279 | Apply the type recognizers, @var{recognizers}, to the type object | |
8280 | @var{type_obj}. If any recognizer returns a string, return that | |
8281 | string. Otherwise, return @code{None}. This is called by | |
8282 | @value{GDBN} during the type-printing process (@pxref{Type Printing | |
8283 | API}). | |
8284 | ||
8285 | @item register_type_printer (locus, printer) | |
697aa1b7 EZ |
8286 | This is a convenience function to register a type printer |
8287 | @var{printer}. The printer must implement the type printer protocol. | |
8288 | The @var{locus} argument is either a @code{gdb.Objfile}, in which case | |
8289 | the printer is registered with that objfile; a @code{gdb.Progspace}, | |
8290 | in which case the printer is registered with that progspace; or | |
8291 | @code{None}, in which case the printer is registered globally. | |
329baa95 DE |
8292 | |
8293 | @item TypePrinter | |
8294 | This is a base class that implements the type printer protocol. Type | |
8295 | printers are encouraged, but not required, to derive from this class. | |
8296 | It defines a constructor: | |
8297 | ||
8298 | @defmethod TypePrinter __init__ (self, name) | |
8299 | Initialize the type printer with the given name. The new printer | |
8300 | starts in the enabled state. | |
8301 | @end defmethod | |
8302 | ||
8303 | @end table | |
8304 | ||
8305 | @node gdb.prompt | |
8306 | @subsubsection gdb.prompt | |
8307 | @cindex gdb.prompt | |
8308 | ||
8309 | This module provides a method for prompt value-substitution. | |
8310 | ||
8311 | @table @code | |
8312 | @item substitute_prompt (@var{string}) | |
8313 | Return @var{string} with escape sequences substituted by values. Some | |
8314 | escape sequences take arguments. You can specify arguments inside | |
8315 | ``@{@}'' immediately following the escape sequence. | |
8316 | ||
8317 | The escape sequences you can pass to this function are: | |
8318 | ||
8319 | @table @code | |
8320 | @item \\ | |
8321 | Substitute a backslash. | |
8322 | @item \e | |
8323 | Substitute an ESC character. | |
8324 | @item \f | |
8325 | Substitute the selected frame; an argument names a frame parameter. | |
8326 | @item \n | |
8327 | Substitute a newline. | |
8328 | @item \p | |
8329 | Substitute a parameter's value; the argument names the parameter. | |
8330 | @item \r | |
8331 | Substitute a carriage return. | |
8332 | @item \t | |
8333 | Substitute the selected thread; an argument names a thread parameter. | |
8334 | @item \v | |
8335 | Substitute the version of GDB. | |
8336 | @item \w | |
8337 | Substitute the current working directory. | |
8338 | @item \[ | |
8339 | Begin a sequence of non-printing characters. These sequences are | |
8340 | typically used with the ESC character, and are not counted in the string | |
8341 | length. Example: ``\[\e[0;34m\](gdb)\[\e[0m\]'' will return a | |
8342 | blue-colored ``(gdb)'' prompt where the length is five. | |
8343 | @item \] | |
8344 | End a sequence of non-printing characters. | |
8345 | @end table | |
8346 | ||
8347 | For example: | |
8348 | ||
8349 | @smallexample | |
77bb17b6 | 8350 | substitute_prompt ("frame: \f, args: \p@{print frame-arguments@}") |
329baa95 DE |
8351 | @end smallexample |
8352 | ||
8353 | @exdent will return the string: | |
8354 | ||
8355 | @smallexample | |
77bb17b6 | 8356 | "frame: main, args: scalars" |
329baa95 DE |
8357 | @end smallexample |
8358 | @end table |