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1 /* Python interface to stack frames
2
3 Copyright (C) 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
4
5 This file is part of GDB.
6
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
11
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19
20 #include "defs.h"
21 #include "charset.h"
22 #include "block.h"
23 #include "frame.h"
24 #include "exceptions.h"
25 #include "symtab.h"
26 #include "stack.h"
27 #include "value.h"
28 #include "python-internal.h"
29 #include "symfile.h"
30 #include "objfiles.h"
31
32 typedef struct {
33 PyObject_HEAD
34 struct frame_id frame_id;
35 struct gdbarch *gdbarch;
36
37 /* Marks that the FRAME_ID member actually holds the ID of the frame next
38 to this, and not this frames' ID itself. This is a hack to permit Python
39 frame objects which represent invalid frames (i.e., the last frame_info
40 in a corrupt stack). The problem arises from the fact that this code
41 relies on FRAME_ID to uniquely identify a frame, which is not always true
42 for the last "frame" in a corrupt stack (it can have a null ID, or the same
43 ID as the previous frame). Whenever get_prev_frame returns NULL, we
44 record the frame_id of the next frame and set FRAME_ID_IS_NEXT to 1. */
45 int frame_id_is_next;
46 } frame_object;
47
48 /* Require a valid frame. This must be called inside a TRY_CATCH, or
49 another context in which a gdb exception is allowed. */
50 #define FRAPY_REQUIRE_VALID(frame_obj, frame) \
51 do { \
52 frame = frame_object_to_frame_info (frame_obj); \
53 if (frame == NULL) \
54 error (_("Frame is invalid.")); \
55 } while (0)
56
57 static PyTypeObject frame_object_type;
58
59 /* Returns the frame_info object corresponding to the given Python Frame
60 object. If the frame doesn't exist anymore (the frame id doesn't
61 correspond to any frame in the inferior), returns NULL. */
62
63 static struct frame_info *
64 frame_object_to_frame_info (frame_object *frame_obj)
65 {
66 struct frame_info *frame;
67
68 frame = frame_find_by_id (frame_obj->frame_id);
69 if (frame == NULL)
70 return NULL;
71
72 if (frame_obj->frame_id_is_next)
73 frame = get_prev_frame (frame);
74
75 return frame;
76 }
77
78 /* Called by the Python interpreter to obtain string representation
79 of the object. */
80
81 static PyObject *
82 frapy_str (PyObject *self)
83 {
84 char *s;
85 PyObject *result;
86 struct ui_file *strfile;
87
88 strfile = mem_fileopen ();
89 fprint_frame_id (strfile, ((frame_object *) self)->frame_id);
90 s = ui_file_xstrdup (strfile, NULL);
91 result = PyString_FromString (s);
92 xfree (s);
93
94 return result;
95 }
96
97 /* Implementation of gdb.Frame.is_valid (self) -> Boolean.
98 Returns True if the frame corresponding to the frame_id of this
99 object still exists in the inferior. */
100
101 static PyObject *
102 frapy_is_valid (PyObject *self, PyObject *args)
103 {
104 struct frame_info *frame;
105
106 frame = frame_object_to_frame_info ((frame_object *) self);
107 if (frame == NULL)
108 Py_RETURN_FALSE;
109
110 Py_RETURN_TRUE;
111 }
112
113 /* Implementation of gdb.Frame.name (self) -> String.
114 Returns the name of the function corresponding to this frame. */
115
116 static PyObject *
117 frapy_name (PyObject *self, PyObject *args)
118 {
119 struct frame_info *frame;
120 char *name;
121 enum language lang;
122 PyObject *result;
123 volatile struct gdb_exception except;
124
125 TRY_CATCH (except, RETURN_MASK_ALL)
126 {
127 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
128
129 find_frame_funname (frame, &name, &lang, NULL);
130 }
131 GDB_PY_HANDLE_EXCEPTION (except);
132
133 if (name)
134 result = PyUnicode_Decode (name, strlen (name), host_charset (), NULL);
135 else
136 {
137 result = Py_None;
138 Py_INCREF (Py_None);
139 }
140
141 return result;
142 }
143
144 /* Implementation of gdb.Frame.type (self) -> Integer.
145 Returns the frame type, namely one of the gdb.*_FRAME constants. */
146
147 static PyObject *
148 frapy_type (PyObject *self, PyObject *args)
149 {
150 struct frame_info *frame;
151 enum frame_type type = NORMAL_FRAME;/* Initialize to appease gcc warning. */
152 volatile struct gdb_exception except;
153
154 TRY_CATCH (except, RETURN_MASK_ALL)
155 {
156 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
157
158 type = get_frame_type (frame);
159 }
160 GDB_PY_HANDLE_EXCEPTION (except);
161
162 return PyInt_FromLong (type);
163 }
164
165 /* Implementation of gdb.Frame.unwind_stop_reason (self) -> Integer.
166 Returns one of the gdb.FRAME_UNWIND_* constants. */
167
168 static PyObject *
169 frapy_unwind_stop_reason (PyObject *self, PyObject *args)
170 {
171 struct frame_info *frame = NULL; /* Initialize to appease gcc warning. */
172 volatile struct gdb_exception except;
173 enum unwind_stop_reason stop_reason;
174
175 TRY_CATCH (except, RETURN_MASK_ALL)
176 {
177 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
178 }
179 GDB_PY_HANDLE_EXCEPTION (except);
180
181 stop_reason = get_frame_unwind_stop_reason (frame);
182
183 return PyInt_FromLong (stop_reason);
184 }
185
186 /* Implementation of gdb.Frame.pc (self) -> Long.
187 Returns the frame's resume address. */
188
189 static PyObject *
190 frapy_pc (PyObject *self, PyObject *args)
191 {
192 CORE_ADDR pc = 0; /* Initialize to appease gcc warning. */
193 struct frame_info *frame;
194 volatile struct gdb_exception except;
195
196 TRY_CATCH (except, RETURN_MASK_ALL)
197 {
198 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
199
200 pc = get_frame_pc (frame);
201 }
202 GDB_PY_HANDLE_EXCEPTION (except);
203
204 return gdb_py_long_from_ulongest (pc);
205 }
206
207 /* Implementation of gdb.Frame.block (self) -> gdb.Block.
208 Returns the frame's code block. */
209
210 static PyObject *
211 frapy_block (PyObject *self, PyObject *args)
212 {
213 struct frame_info *frame;
214 struct block *block = NULL, *fn_block;
215 volatile struct gdb_exception except;
216
217 TRY_CATCH (except, RETURN_MASK_ALL)
218 {
219 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
220 block = get_frame_block (frame, NULL);
221 }
222 GDB_PY_HANDLE_EXCEPTION (except);
223
224 for (fn_block = block;
225 fn_block != NULL && BLOCK_FUNCTION (fn_block) == NULL;
226 fn_block = BLOCK_SUPERBLOCK (fn_block))
227 ;
228
229 if (block == NULL || fn_block == NULL || BLOCK_FUNCTION (fn_block) == NULL)
230 {
231 PyErr_SetString (PyExc_RuntimeError,
232 _("Cannot locate object file for block."));
233 return NULL;
234 }
235
236 if (block)
237 {
238 struct symtab *symt;
239
240 symt = SYMBOL_SYMTAB (BLOCK_FUNCTION (fn_block));
241 return block_to_block_object (block, symt->objfile);
242 }
243
244 Py_RETURN_NONE;
245 }
246
247
248 /* Implementation of gdb.Frame.function (self) -> gdb.Symbol.
249 Returns the symbol for the function corresponding to this frame. */
250
251 static PyObject *
252 frapy_function (PyObject *self, PyObject *args)
253 {
254 struct symbol *sym = NULL;
255 struct frame_info *frame;
256 volatile struct gdb_exception except;
257
258 TRY_CATCH (except, RETURN_MASK_ALL)
259 {
260 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
261
262 sym = find_pc_function (get_frame_address_in_block (frame));
263 }
264 GDB_PY_HANDLE_EXCEPTION (except);
265
266 if (sym)
267 return symbol_to_symbol_object (sym);
268
269 Py_RETURN_NONE;
270 }
271
272 /* Convert a frame_info struct to a Python Frame object.
273 Sets a Python exception and returns NULL on error. */
274
275 PyObject *
276 frame_info_to_frame_object (struct frame_info *frame)
277 {
278 frame_object *frame_obj;
279
280 frame_obj = PyObject_New (frame_object, &frame_object_type);
281 if (frame_obj == NULL)
282 {
283 PyErr_SetString (PyExc_MemoryError,
284 _("Could not allocate frame object."));
285 return NULL;
286 }
287
288 /* Try to get the previous frame, to determine if this is the last frame
289 in a corrupt stack. If so, we need to store the frame_id of the next
290 frame and not of this one (which is possibly invalid). */
291 if (get_prev_frame (frame) == NULL
292 && get_frame_unwind_stop_reason (frame) != UNWIND_NO_REASON
293 && get_next_frame (frame) != NULL)
294 {
295 frame_obj->frame_id = get_frame_id (get_next_frame (frame));
296 frame_obj->frame_id_is_next = 1;
297 }
298 else
299 {
300 frame_obj->frame_id = get_frame_id (frame);
301 frame_obj->frame_id_is_next = 0;
302 }
303
304 frame_obj->gdbarch = get_frame_arch (frame);
305
306 return (PyObject *) frame_obj;
307 }
308
309 /* Implementation of gdb.Frame.older (self) -> gdb.Frame.
310 Returns the frame immediately older (outer) to this frame, or None if
311 there isn't one. */
312
313 static PyObject *
314 frapy_older (PyObject *self, PyObject *args)
315 {
316 struct frame_info *frame, *prev;
317 volatile struct gdb_exception except;
318 PyObject *prev_obj = NULL; /* Initialize to appease gcc warning. */
319
320 TRY_CATCH (except, RETURN_MASK_ALL)
321 {
322 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
323
324 prev = get_prev_frame (frame);
325 if (prev)
326 prev_obj = (PyObject *) frame_info_to_frame_object (prev);
327 else
328 {
329 Py_INCREF (Py_None);
330 prev_obj = Py_None;
331 }
332 }
333 GDB_PY_HANDLE_EXCEPTION (except);
334
335 return prev_obj;
336 }
337
338 /* Implementation of gdb.Frame.newer (self) -> gdb.Frame.
339 Returns the frame immediately newer (inner) to this frame, or None if
340 there isn't one. */
341
342 static PyObject *
343 frapy_newer (PyObject *self, PyObject *args)
344 {
345 struct frame_info *frame, *next;
346 volatile struct gdb_exception except;
347 PyObject *next_obj = NULL; /* Initialize to appease gcc warning. */
348
349 TRY_CATCH (except, RETURN_MASK_ALL)
350 {
351 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
352
353 next = get_next_frame (frame);
354 if (next)
355 next_obj = (PyObject *) frame_info_to_frame_object (next);
356 else
357 {
358 Py_INCREF (Py_None);
359 next_obj = Py_None;
360 }
361 }
362 GDB_PY_HANDLE_EXCEPTION (except);
363
364 return next_obj;
365 }
366
367 /* Implementation of gdb.Frame.find_sal (self) -> gdb.Symtab_and_line.
368 Returns the frame's symtab and line. */
369
370 static PyObject *
371 frapy_find_sal (PyObject *self, PyObject *args)
372 {
373 struct frame_info *frame;
374 struct symtab_and_line sal;
375 volatile struct gdb_exception except;
376 PyObject *sal_obj = NULL; /* Initialize to appease gcc warning. */
377
378 TRY_CATCH (except, RETURN_MASK_ALL)
379 {
380 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
381
382 find_frame_sal (frame, &sal);
383 sal_obj = symtab_and_line_to_sal_object (sal);
384 }
385 GDB_PY_HANDLE_EXCEPTION (except);
386
387 return sal_obj;
388 }
389
390 /* Implementation of gdb.Frame.read_var_value (self, variable,
391 [block]) -> gdb.Value. If the optional block argument is provided
392 start the search from that block, otherwise search from the frame's
393 current block (determined by examining the resume address of the
394 frame). The variable argument must be a string or an instance of a
395 gdb.Symbol. The block argument must be an instance of gdb.Block. Returns
396 NULL on error, with a python exception set. */
397 static PyObject *
398 frapy_read_var (PyObject *self, PyObject *args)
399 {
400 struct frame_info *frame;
401 PyObject *sym_obj, *block_obj = NULL;
402 struct symbol *var = NULL; /* gcc-4.3.2 false warning. */
403 struct value *val = NULL;
404 volatile struct gdb_exception except;
405
406 if (!PyArg_ParseTuple (args, "O|O", &sym_obj, &block_obj))
407 return NULL;
408
409 if (PyObject_TypeCheck (sym_obj, &symbol_object_type))
410 var = symbol_object_to_symbol (sym_obj);
411 else if (gdbpy_is_string (sym_obj))
412 {
413 char *var_name;
414 struct block *block = NULL;
415 struct cleanup *cleanup;
416 volatile struct gdb_exception except;
417
418 var_name = python_string_to_target_string (sym_obj);
419 if (!var_name)
420 return NULL;
421 cleanup = make_cleanup (xfree, var_name);
422
423 if (block_obj)
424 {
425 block = block_object_to_block (block_obj);
426 if (!block)
427 {
428 PyErr_SetString (PyExc_RuntimeError,
429 _("Second argument must be block."));
430 return NULL;
431 }
432 }
433
434 TRY_CATCH (except, RETURN_MASK_ALL)
435 {
436 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
437
438 if (!block)
439 block = get_frame_block (frame, NULL);
440 var = lookup_symbol (var_name, block, VAR_DOMAIN, NULL);
441 }
442 GDB_PY_HANDLE_EXCEPTION (except);
443
444 if (!var)
445 {
446 PyErr_Format (PyExc_ValueError,
447 _("Variable '%s' not found."), var_name);
448 do_cleanups (cleanup);
449
450 return NULL;
451 }
452
453 do_cleanups (cleanup);
454 }
455 else
456 {
457 PyErr_SetString (PyExc_TypeError,
458 _("Argument must be a symbol or string."));
459 return NULL;
460 }
461
462 TRY_CATCH (except, RETURN_MASK_ALL)
463 {
464 FRAPY_REQUIRE_VALID ((frame_object *) self, frame);
465
466 val = read_var_value (var, frame);
467 }
468 GDB_PY_HANDLE_EXCEPTION (except);
469
470 return value_to_value_object (val);
471 }
472
473 /* Select this frame. */
474
475 static PyObject *
476 frapy_select (PyObject *self, PyObject *args)
477 {
478 struct frame_info *fi;
479 frame_object *frame = (frame_object *) self;
480 volatile struct gdb_exception except;
481
482 TRY_CATCH (except, RETURN_MASK_ALL)
483 {
484 FRAPY_REQUIRE_VALID (frame, fi);
485
486 select_frame (fi);
487 }
488 GDB_PY_HANDLE_EXCEPTION (except);
489
490 Py_RETURN_NONE;
491 }
492
493 /* Implementation of gdb.newest_frame () -> gdb.Frame.
494 Returns the newest frame object. */
495
496 PyObject *
497 gdbpy_newest_frame (PyObject *self, PyObject *args)
498 {
499 struct frame_info *frame;
500 PyObject *frame_obj = NULL; /* Initialize to appease gcc warning. */
501 volatile struct gdb_exception except;
502
503 TRY_CATCH (except, RETURN_MASK_ALL)
504 {
505 frame = get_current_frame ();
506 frame_obj = frame_info_to_frame_object (frame);
507 }
508 GDB_PY_HANDLE_EXCEPTION (except);
509
510 return frame_obj;
511 }
512
513 /* Implementation of gdb.selected_frame () -> gdb.Frame.
514 Returns the selected frame object. */
515
516 PyObject *
517 gdbpy_selected_frame (PyObject *self, PyObject *args)
518 {
519 struct frame_info *frame;
520 PyObject *frame_obj = NULL; /* Initialize to appease gcc warning. */
521 volatile struct gdb_exception except;
522
523 TRY_CATCH (except, RETURN_MASK_ALL)
524 {
525 frame = get_selected_frame ("No frame is currently selected.");
526 frame_obj = frame_info_to_frame_object (frame);
527 }
528 GDB_PY_HANDLE_EXCEPTION (except);
529
530 return frame_obj;
531 }
532
533 /* Implementation of gdb.stop_reason_string (Integer) -> String.
534 Return a string explaining the unwind stop reason. */
535
536 PyObject *
537 gdbpy_frame_stop_reason_string (PyObject *self, PyObject *args)
538 {
539 int reason;
540 const char *str;
541
542 if (!PyArg_ParseTuple (args, "i", &reason))
543 return NULL;
544
545 if (reason < 0 || reason > UNWIND_NO_SAVED_PC)
546 {
547 PyErr_SetString (PyExc_ValueError,
548 _("Invalid frame stop reason."));
549 return NULL;
550 }
551
552 str = frame_stop_reason_string (reason);
553 return PyUnicode_Decode (str, strlen (str), host_charset (), NULL);
554 }
555
556 /* Implements the equality comparison for Frame objects.
557 All other comparison operators will throw a TypeError Python exception,
558 as they aren't valid for frames. */
559
560 static PyObject *
561 frapy_richcompare (PyObject *self, PyObject *other, int op)
562 {
563 int result;
564
565 if (!PyObject_TypeCheck (other, &frame_object_type)
566 || (op != Py_EQ && op != Py_NE))
567 {
568 Py_INCREF (Py_NotImplemented);
569 return Py_NotImplemented;
570 }
571
572 if (frame_id_eq (((frame_object *) self)->frame_id,
573 ((frame_object *) other)->frame_id))
574 result = Py_EQ;
575 else
576 result = Py_NE;
577
578 if (op == result)
579 Py_RETURN_TRUE;
580 Py_RETURN_FALSE;
581 }
582
583 /* Sets up the Frame API in the gdb module. */
584
585 void
586 gdbpy_initialize_frames (void)
587 {
588 frame_object_type.tp_new = PyType_GenericNew;
589 if (PyType_Ready (&frame_object_type) < 0)
590 return;
591
592 /* Note: These would probably be best exposed as class attributes of
593 Frame, but I don't know how to do it except by messing with the
594 type's dictionary. That seems too messy. */
595 PyModule_AddIntConstant (gdb_module, "NORMAL_FRAME", NORMAL_FRAME);
596 PyModule_AddIntConstant (gdb_module, "DUMMY_FRAME", DUMMY_FRAME);
597 PyModule_AddIntConstant (gdb_module, "INLINE_FRAME", INLINE_FRAME);
598 PyModule_AddIntConstant (gdb_module, "TAILCALL_FRAME", TAILCALL_FRAME);
599 PyModule_AddIntConstant (gdb_module, "SIGTRAMP_FRAME", SIGTRAMP_FRAME);
600 PyModule_AddIntConstant (gdb_module, "ARCH_FRAME", ARCH_FRAME);
601 PyModule_AddIntConstant (gdb_module, "SENTINEL_FRAME", SENTINEL_FRAME);
602 PyModule_AddIntConstant (gdb_module,
603 "FRAME_UNWIND_NO_REASON", UNWIND_NO_REASON);
604 PyModule_AddIntConstant (gdb_module,
605 "FRAME_UNWIND_NULL_ID", UNWIND_NULL_ID);
606 PyModule_AddIntConstant (gdb_module,
607 "FRAME_UNWIND_FIRST_ERROR", UNWIND_FIRST_ERROR);
608 PyModule_AddIntConstant (gdb_module,
609 "FRAME_UNWIND_INNER_ID", UNWIND_INNER_ID);
610 PyModule_AddIntConstant (gdb_module,
611 "FRAME_UNWIND_SAME_ID", UNWIND_SAME_ID);
612 PyModule_AddIntConstant (gdb_module,
613 "FRAME_UNWIND_NO_SAVED_PC", UNWIND_NO_SAVED_PC);
614
615 Py_INCREF (&frame_object_type);
616 PyModule_AddObject (gdb_module, "Frame", (PyObject *) &frame_object_type);
617 }
618
619 \f
620
621 static PyMethodDef frame_object_methods[] = {
622 { "is_valid", frapy_is_valid, METH_NOARGS,
623 "is_valid () -> Boolean.\n\
624 Return true if this frame is valid, false if not." },
625 { "name", frapy_name, METH_NOARGS,
626 "name () -> String.\n\
627 Return the function name of the frame, or None if it can't be determined." },
628 { "type", frapy_type, METH_NOARGS,
629 "type () -> Integer.\n\
630 Return the type of the frame." },
631 { "unwind_stop_reason", frapy_unwind_stop_reason, METH_NOARGS,
632 "unwind_stop_reason () -> Integer.\n\
633 Return the reason why it's not possible to find frames older than this." },
634 { "pc", frapy_pc, METH_NOARGS,
635 "pc () -> Long.\n\
636 Return the frame's resume address." },
637 { "block", frapy_block, METH_NOARGS,
638 "block () -> gdb.Block.\n\
639 Return the frame's code block." },
640 { "function", frapy_function, METH_NOARGS,
641 "function () -> gdb.Symbol.\n\
642 Returns the symbol for the function corresponding to this frame." },
643 { "older", frapy_older, METH_NOARGS,
644 "older () -> gdb.Frame.\n\
645 Return the frame that called this frame." },
646 { "newer", frapy_newer, METH_NOARGS,
647 "newer () -> gdb.Frame.\n\
648 Return the frame called by this frame." },
649 { "find_sal", frapy_find_sal, METH_NOARGS,
650 "find_sal () -> gdb.Symtab_and_line.\n\
651 Return the frame's symtab and line." },
652 { "read_var", frapy_read_var, METH_VARARGS,
653 "read_var (variable) -> gdb.Value.\n\
654 Return the value of the variable in this frame." },
655 { "select", frapy_select, METH_NOARGS,
656 "Select this frame as the user's current frame." },
657 {NULL} /* Sentinel */
658 };
659
660 static PyTypeObject frame_object_type = {
661 PyObject_HEAD_INIT (NULL)
662 0, /* ob_size */
663 "gdb.Frame", /* tp_name */
664 sizeof (frame_object), /* tp_basicsize */
665 0, /* tp_itemsize */
666 0, /* tp_dealloc */
667 0, /* tp_print */
668 0, /* tp_getattr */
669 0, /* tp_setattr */
670 0, /* tp_compare */
671 0, /* tp_repr */
672 0, /* tp_as_number */
673 0, /* tp_as_sequence */
674 0, /* tp_as_mapping */
675 0, /* tp_hash */
676 0, /* tp_call */
677 frapy_str, /* tp_str */
678 0, /* tp_getattro */
679 0, /* tp_setattro */
680 0, /* tp_as_buffer */
681 Py_TPFLAGS_DEFAULT, /* tp_flags */
682 "GDB frame object", /* tp_doc */
683 0, /* tp_traverse */
684 0, /* tp_clear */
685 frapy_richcompare, /* tp_richcompare */
686 0, /* tp_weaklistoffset */
687 0, /* tp_iter */
688 0, /* tp_iternext */
689 frame_object_methods, /* tp_methods */
690 0, /* tp_members */
691 0, /* tp_getset */
692 0, /* tp_base */
693 0, /* tp_dict */
694 0, /* tp_descr_get */
695 0, /* tp_descr_set */
696 0, /* tp_dictoffset */
697 0, /* tp_init */
698 0, /* tp_alloc */
699 };