gdb/exceptions.h

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2014 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 #ifndef EXCEPTIONS_H
  21 #define EXCEPTIONS_H
  22
  23 #include "ui-out.h"
  24 #include <setjmp.h>
  25
  26 /* Reasons for calling throw_exceptions().  NOTE: all reason values
  27    must be less than zero.  enum value 0 is reserved for internal use
  28    as the return value from an initial setjmp().  The function
  29    catch_exceptions() reserves values >= 0 as legal results from its
  30    wrapped function.  */
  31
  32 enum return_reason
  33   {
  34     /* User interrupt.  */
  35     RETURN_QUIT = -2,
  36     /* Any other error.  */
  37     RETURN_ERROR
  38   };
  39
  40 #define RETURN_MASK(reason)     (1 << (int)(-reason))
  41
  42 typedef enum
  43 {
  44   RETURN_MASK_QUIT = RETURN_MASK (RETURN_QUIT),
  45   RETURN_MASK_ERROR = RETURN_MASK (RETURN_ERROR),
  46   RETURN_MASK_ALL = (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
  47 } return_mask;
  48
  49 /* Describe all exceptions.  */
  50
  51 enum errors {
  52   GDB_NO_ERROR,
  53
  54   /* Any generic error, the corresponding text is in
  55      exception.message.  */
  56   GENERIC_ERROR,
  57
  58   /* Something requested was not found.  */
  59   NOT_FOUND_ERROR,
  60
  61   /* Thread library lacks support necessary for finding thread local
  62      storage.  */
  63   TLS_NO_LIBRARY_SUPPORT_ERROR,
  64
  65   /* Load module not found while attempting to find thread local storage.  */
  66   TLS_LOAD_MODULE_NOT_FOUND_ERROR,
  67
  68   /* Thread local storage has not been allocated yet.  */
  69   TLS_NOT_ALLOCATED_YET_ERROR,
  70
  71   /* Something else went wrong while attempting to find thread local
  72      storage.  The ``struct gdb_exception'' message field provides
  73      more detail.  */
  74   TLS_GENERIC_ERROR,
  75
  76   /* Problem parsing an XML document.  */
  77   XML_PARSE_ERROR,
  78
  79   /* Error accessing memory.  */
  80   MEMORY_ERROR,
  81
  82   /* Value not available.  E.g., a register was not collected in a
  83      traceframe.  */
  84   NOT_AVAILABLE_ERROR,
  85
  86   /* Value was optimized out.  Note: if the value was a register, this
  87      means the register was not saved in the frame.  */
  88   OPTIMIZED_OUT_ERROR,
  89
  90   /* DW_OP_GNU_entry_value resolving failed.  */
  91   NO_ENTRY_VALUE_ERROR,
  92
  93   /* Target throwing an error has been closed.  Current command should be
  94      aborted as the inferior state is no longer valid.  */
  95   TARGET_CLOSE_ERROR,
  96
  97   /* An undefined command was executed.  */
  98   UNDEFINED_COMMAND_ERROR,
  99
 100   /* Add more errors here.  */
 101   NR_ERRORS
 102 };
 103
 104 struct gdb_exception
 105 {
 106   enum return_reason reason;
 107   enum errors error;
 108   const char *message;
 109 };
 110
 111 /* A pre-defined non-exception.  */
 112 extern const struct gdb_exception exception_none;
 113
 114 /* Wrap set/long jmp so that it's more portable (internal to
 115    exceptions).  */
 116
 117 #if defined(HAVE_SIGSETJMP)
 118 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
 119 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
 120 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
 121 #else
 122 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
 123 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
 124 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 125 #endif
 126
 127 /* Functions to drive the exceptions state m/c (internal to
 128    exceptions).  */
 129 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (volatile struct
 130                                                  gdb_exception *exception,
 131                                                  return_mask mask);
 132 int exceptions_state_mc_action_iter (void);
 133 int exceptions_state_mc_action_iter_1 (void);
 134
 135 /* Macro to wrap up standard try/catch behavior.
 136
 137    The double loop lets us correctly handle code "break"ing out of the
 138    try catch block.  (It works as the "break" only exits the inner
 139    "while" loop, the outer for loop detects this handling it
 140    correctly.)  Of course "return" and "goto" are not so lucky.
 141
 142    For instance:
 143
 144    *INDENT-OFF*
 145
 146    volatile struct gdb_exception e;
 147    TRY_CATCH (e, RETURN_MASK_ERROR)
 148      {
 149      }
 150    switch (e.reason)
 151      {
 152      case RETURN_ERROR: ...
 153      }
 154
 155   */
 156
 157 #define TRY_CATCH(EXCEPTION,MASK) \
 158      { \
 159        EXCEPTIONS_SIGJMP_BUF *buf = \
 160          exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
 161        EXCEPTIONS_SIGSETJMP (*buf); \
 162      } \
 163      while (exceptions_state_mc_action_iter ()) \
 164        while (exceptions_state_mc_action_iter_1 ())
 165
 166 /* *INDENT-ON* */
 167
 168
 169 /* If E is an exception, print it's error message on the specified
 170    stream.  For _fprintf, prefix the message with PREFIX...  */
 171 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 172 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 173                                const char *prefix,
 174                                ...) ATTRIBUTE_PRINTF (3, 4);
 175
 176 /* Throw an exception (as described by "struct gdb_exception").  Will
 177    execute a LONG JUMP to the inner most containing exception handler
 178    established using catch_exceptions() (or similar).
 179
 180    Code normally throws an exception using error() et.al.  For various
 181    reaons, GDB also contains code that throws an exception directly.
 182    For instance, the remote*.c targets contain CNTRL-C signal handlers
 183    that propogate the QUIT event up the exception chain.  ``This could
 184    be a good thing or a dangerous thing.'' -- the Existential
 185    Wombat.  */
 186
 187 extern void throw_exception (struct gdb_exception exception)
 188      ATTRIBUTE_NORETURN;
 189 extern void throw_verror (enum errors, const char *fmt, va_list ap)
 190      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
 191 extern void throw_vfatal (const char *fmt, va_list ap)
 192      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
 193 extern void throw_error (enum errors error, const char *fmt, ...)
 194      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 195
 196 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 197    handler.  If an exception (enum return_reason) is thrown using
 198    throw_exception() than all cleanups installed since
 199    catch_exceptions() was entered are invoked, the (-ve) exception
 200    value is then returned by catch_exceptions.  If FUNC() returns
 201    normally (with a positive or zero return value) then that value is
 202    returned by catch_exceptions().  It is an internal_error() for
 203    FUNC() to return a negative value.
 204
 205    For the period of the FUNC() call: UIOUT is installed as the output
 206    builder; ERRSTRING is installed as the error/quit message; and a
 207    new cleanup_chain is established.  The old values are restored
 208    before catch_exceptions() returns.
 209
 210    The variant catch_exceptions_with_msg() is the same as
 211    catch_exceptions() but adds the ability to return an allocated
 212    copy of the gdb error message.  This is used when a silent error is
 213    issued and the caller wants to manually issue the error message.
 214
 215    MASK specifies what to catch; it is normally set to
 216    RETURN_MASK_ALL, if for no other reason than that the code which
 217    calls catch_errors might not be set up to deal with a quit which
 218    isn't caught.  But if the code can deal with it, it generally
 219    should be RETURN_MASK_ERROR, unless for some reason it is more
 220    useful to abort only the portion of the operation inside the
 221    catch_errors.  Note that quit should return to the command line
 222    fairly quickly, even if some further processing is being done.
 223
 224    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 225    builder variable should just go away.
 226
 227    This function supersedes catch_errors().
 228
 229    This function uses SETJMP() and LONGJUMP().  */
 230
 231 struct ui_out;
 232 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 233 extern int catch_exceptions (struct ui_out *uiout,
 234                              catch_exceptions_ftype *func, void *func_args,
 235                              return_mask mask);
 236 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 237 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 238                                       catch_exceptions_ftype *func,
 239                                       void *func_args,
 240                                       char **gdberrmsg,
 241                                       return_mask mask);
 242
 243 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 244    otherwize the result from CATCH_ERRORS_FTYPE is returned.  It is
 245    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 246    value.  It's unfortunate that, catch_errors() does not return an
 247    indication of the exact exception that it caught - quit_flag might
 248    help.
 249
 250    This function is superseded by catch_exceptions().  */
 251
 252 typedef int (catch_errors_ftype) (void *);
 253 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 254
 255 /* Template to catch_errors() that wraps calls to command
 256    functions.  */
 257
 258 typedef void (catch_command_errors_ftype) (char *, int);
 259 extern int catch_command_errors (catch_command_errors_ftype *func,
 260                                  char *arg, int from_tty, return_mask);
 261
 262 /* Like catch_command_errors, but works with const command and args.  */
 263
 264 typedef void (catch_command_errors_const_ftype) (const char *, int);
 265 extern int catch_command_errors_const (catch_command_errors_const_ftype *func,
 266                                        const char *arg, int from_tty, return_mask);
 267
 268 #endif