aboutsummaryrefslogtreecommitdiff
path: root/gdb/break-catch-throw.c
blob: 0074d061f24e396f0cb60b63aff9ab15efc4b0d2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
/* Everything about catch/throw catchpoints, for GDB.

   Copyright (C) 1986-2017 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "arch-utils.h"
#include <ctype.h>
#include "breakpoint.h"
#include "gdbcmd.h"
#include "inferior.h"
#include "annotate.h"
#include "valprint.h"
#include "cli/cli-utils.h"
#include "completer.h"
#include "gdb_obstack.h"
#include "mi/mi-common.h"
#include "linespec.h"
#include "probe.h"
#include "objfiles.h"
#include "cp-abi.h"
#include "gdb_regex.h"
#include "cp-support.h"
#include "location.h"

/* Enums for exception-handling support.  */
enum exception_event_kind
{
  EX_EVENT_THROW,
  EX_EVENT_RETHROW,
  EX_EVENT_CATCH
};

/* Each spot where we may place an exception-related catchpoint has
   two names: the SDT probe point and the function name.  This
   structure holds both.  */

struct exception_names
{
  /* The name of the probe point to try, in the form accepted by
     'parse_probes'.  */

  const char *probe;

  /* The name of the corresponding function.  */

  const char *function;
};

/* Names of the probe points and functions on which to break.  This is
   indexed by exception_event_kind.  */
static const struct exception_names exception_functions[] =
{
  { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
};

static struct breakpoint_ops gnu_v3_exception_catchpoint_ops;

/* The type of an exception catchpoint.  */

struct exception_catchpoint : public breakpoint
{
  ~exception_catchpoint () override;

  /* The kind of exception catchpoint.  */

  enum exception_event_kind kind;

  /* If non-NULL, an xmalloc'd string holding the source form of the
     regular expression to match against.  */

  char *exception_rx;

  /* If non-NULL, a compiled regular expression which is used to
     determine which exceptions to stop on.  */

  std::unique_ptr<compiled_regex> pattern;
};



/* A helper function that fetches exception probe arguments.  This
   fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
   It will throw an exception on any kind of failure.  */

static void
fetch_probe_arguments (struct value **arg0, struct value **arg1)
{
  struct frame_info *frame = get_selected_frame (_("No frame selected"));
  CORE_ADDR pc = get_frame_pc (frame);
  struct bound_probe pc_probe;
  unsigned n_args;

  pc_probe = find_probe_by_pc (pc);
  if (pc_probe.probe == NULL
      || strcmp (pc_probe.probe->provider, "libstdcxx") != 0
      || (strcmp (pc_probe.probe->name, "catch") != 0
	  && strcmp (pc_probe.probe->name, "throw") != 0
	  && strcmp (pc_probe.probe->name, "rethrow") != 0))
    error (_("not stopped at a C++ exception catchpoint"));

  n_args = get_probe_argument_count (pc_probe.probe, frame);
  if (n_args < 2)
    error (_("C++ exception catchpoint has too few arguments"));

  if (arg0 != NULL)
    *arg0 = evaluate_probe_argument (pc_probe.probe, 0, frame);
  *arg1 = evaluate_probe_argument (pc_probe.probe, 1, frame);

  if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
    error (_("error computing probe argument at c++ exception catchpoint"));
}



/* A helper function that returns a value indicating the kind of the
   exception catchpoint B.  */

static enum exception_event_kind
classify_exception_breakpoint (struct breakpoint *b)
{
  struct exception_catchpoint *cp = (struct exception_catchpoint *) b;

  return cp->kind;
}

/* exception_catchpoint destructor.  */

exception_catchpoint::~exception_catchpoint ()
{
  xfree (this->exception_rx);
}

/* Implement the 'check_status' method.  */

static void
check_status_exception_catchpoint (struct bpstats *bs)
{
  struct exception_catchpoint *self
    = (struct exception_catchpoint *) bs->breakpoint_at;
  std::string type_name;

  bkpt_breakpoint_ops.check_status (bs);
  if (bs->stop == 0)
    return;

  if (self->pattern == NULL)
    return;

  TRY
    {
      struct value *typeinfo_arg;
      std::string canon;

      fetch_probe_arguments (NULL, &typeinfo_arg);
      type_name = cplus_typename_from_type_info (typeinfo_arg);

      canon = cp_canonicalize_string (type_name.c_str ());
      if (!canon.empty ())
	std::swap (type_name, canon);
    }
  CATCH (e, RETURN_MASK_ERROR)
    {
      exception_print (gdb_stderr, e);
    }
  END_CATCH

  if (!type_name.empty ())
    {
      if (self->pattern->exec (type_name.c_str (), 0, NULL, 0) != 0)
	bs->stop = 0;
    }
}

/* Implement the 're_set' method.  */

static void
re_set_exception_catchpoint (struct breakpoint *self)
{
  struct symtabs_and_lines sals = {0};
  struct symtabs_and_lines sals_end = {0};
  struct cleanup *cleanup;
  enum exception_event_kind kind = classify_exception_breakpoint (self);
  struct program_space *filter_pspace = current_program_space;

  /* We first try to use the probe interface.  */
  TRY
    {
      event_location_up location
	= new_probe_location (exception_functions[kind].probe);
      sals = parse_probes (location.get (), filter_pspace, NULL);
    }
  CATCH (e, RETURN_MASK_ERROR)
    {
      /* Using the probe interface failed.  Let's fallback to the normal
	 catchpoint mode.  */
      TRY
	{
	  struct explicit_location explicit_loc;

	  initialize_explicit_location (&explicit_loc);
	  explicit_loc.function_name
	    = ASTRDUP (exception_functions[kind].function);
	  event_location_up location = new_explicit_location (&explicit_loc);
	  self->ops->decode_location (self, location.get (), filter_pspace,
				      &sals);
	}
      CATCH (ex, RETURN_MASK_ERROR)
	{
	  /* NOT_FOUND_ERROR just means the breakpoint will be
	     pending, so let it through.  */
	  if (ex.error != NOT_FOUND_ERROR)
	    throw_exception (ex);
	}
      END_CATCH
    }
  END_CATCH

  cleanup = make_cleanup (xfree, sals.sals);
  update_breakpoint_locations (self, filter_pspace, sals, sals_end);
  do_cleanups (cleanup);
}

static enum print_stop_action
print_it_exception_catchpoint (bpstat bs)
{
  struct ui_out *uiout = current_uiout;
  struct breakpoint *b = bs->breakpoint_at;
  int bp_temp;
  enum exception_event_kind kind = classify_exception_breakpoint (b);

  annotate_catchpoint (b->number);
  maybe_print_thread_hit_breakpoint (uiout);

  bp_temp = b->disposition == disp_del;
  uiout->text (bp_temp ? "Temporary catchpoint "
		       : "Catchpoint ");
  if (!uiout->is_mi_like_p ())
    uiout->field_int ("bkptno", b->number);
  uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
		: (kind == EX_EVENT_CATCH ? " (exception caught), "
		   : " (exception rethrown), ")));
  if (uiout->is_mi_like_p ())
    {
      uiout->field_string ("reason",
			   async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
      uiout->field_string ("disp", bpdisp_text (b->disposition));
      uiout->field_int ("bkptno", b->number);
    }
  return PRINT_SRC_AND_LOC;
}

static void
print_one_exception_catchpoint (struct breakpoint *b, 
				struct bp_location **last_loc)
{
  struct value_print_options opts;
  struct ui_out *uiout = current_uiout;
  enum exception_event_kind kind = classify_exception_breakpoint (b);

  get_user_print_options (&opts);
  if (opts.addressprint)
    {
      annotate_field (4);
      if (b->loc == NULL || b->loc->shlib_disabled)
	uiout->field_string ("addr", "<PENDING>");
      else
	uiout->field_core_addr ("addr",
				b->loc->gdbarch, b->loc->address);
    }
  annotate_field (5);
  if (b->loc)
    *last_loc = b->loc;

  switch (kind)
    {
    case EX_EVENT_THROW:
      uiout->field_string ("what", "exception throw");
      if (uiout->is_mi_like_p ())
	uiout->field_string ("catch-type", "throw");
      break;

    case EX_EVENT_RETHROW:
      uiout->field_string ("what", "exception rethrow");
      if (uiout->is_mi_like_p ())
	uiout->field_string ("catch-type", "rethrow");
      break;

    case EX_EVENT_CATCH:
      uiout->field_string ("what", "exception catch");
      if (uiout->is_mi_like_p ())
	uiout->field_string ("catch-type", "catch");
      break;
    }
}

/* Implement the 'print_one_detail' method.  */

static void
print_one_detail_exception_catchpoint (const struct breakpoint *b,
				       struct ui_out *uiout)
{
  const struct exception_catchpoint *cp
    = (const struct exception_catchpoint *) b;

  if (cp->exception_rx != NULL)
    {
      uiout->text (_("\tmatching: "));
      uiout->field_string ("regexp", cp->exception_rx);
      uiout->text ("\n");
    }
}

static void
print_mention_exception_catchpoint (struct breakpoint *b)
{
  struct ui_out *uiout = current_uiout;
  int bp_temp;
  enum exception_event_kind kind = classify_exception_breakpoint (b);

  bp_temp = b->disposition == disp_del;
  uiout->text (bp_temp ? _("Temporary catchpoint ")
			      : _("Catchpoint "));
  uiout->field_int ("bkptno", b->number);
  uiout->text ((kind == EX_EVENT_THROW ? _(" (throw)")
		       : (kind == EX_EVENT_CATCH ? _(" (catch)")
			  : _(" (rethrow)"))));
}

/* Implement the "print_recreate" breakpoint_ops method for throw and
   catch catchpoints.  */

static void
print_recreate_exception_catchpoint (struct breakpoint *b, 
				     struct ui_file *fp)
{
  int bp_temp;
  enum exception_event_kind kind = classify_exception_breakpoint (b);

  bp_temp = b->disposition == disp_del;
  fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
  switch (kind)
    {
    case EX_EVENT_THROW:
      fprintf_unfiltered (fp, "throw");
      break;
    case EX_EVENT_CATCH:
      fprintf_unfiltered (fp, "catch");
      break;
    case EX_EVENT_RETHROW:
      fprintf_unfiltered (fp, "rethrow");
      break;
    }
  print_recreate_thread (b, fp);
}

static void
handle_gnu_v3_exceptions (int tempflag, char *except_rx,
			  const char *cond_string,
			  enum exception_event_kind ex_event, int from_tty)
{
  std::unique_ptr<compiled_regex> pattern;

  if (except_rx != NULL)
    {
      pattern.reset (new compiled_regex (except_rx, REG_NOSUB,
					 _("invalid type-matching regexp")));
    }

  std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());

  init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
		   &gnu_v3_exception_catchpoint_ops);
  /* We need to reset 'type' in order for code in breakpoint.c to do
     the right thing.  */
  cp->type = bp_breakpoint;
  cp->kind = ex_event;
  cp->exception_rx = except_rx;
  cp->pattern = std::move (pattern);

  re_set_exception_catchpoint (cp.get ());

  install_breakpoint (0, cp.get (), 1);
  cp.release ();
}

/* Look for an "if" token in *STRING.  The "if" token must be preceded
   by whitespace.
   
   If there is any non-whitespace text between *STRING and the "if"
   token, then it is returned in a newly-xmalloc'd string.  Otherwise,
   this returns NULL.
   
   STRING is updated to point to the "if" token, if it exists, or to
   the end of the string.  */

static char *
extract_exception_regexp (const char **string)
{
  const char *start;
  const char *last, *last_space;

  start = skip_spaces_const (*string);

  last = start;
  last_space = start;
  while (*last != '\0')
    {
      const char *if_token = last;

      /* Check for the "if".  */
      if (check_for_argument (&if_token, "if", 2))
	break;

      /* No "if" token here.  Skip to the next word start.  */
      last_space = skip_to_space (last);
      last = skip_spaces_const (last_space);
    }

  *string = last;
  if (last_space > start)
    return savestring (start, last_space - start);
  return NULL;
}

/* Deal with "catch catch", "catch throw", and "catch rethrow"
   commands.  */

static void
catch_exception_command_1 (enum exception_event_kind ex_event,
			   char *arg_entry,
			   int tempflag, int from_tty)
{
  char *except_rx;
  const char *cond_string = NULL;
  struct cleanup *cleanup;
  const char *arg = arg_entry;

  if (!arg)
    arg = "";
  arg = skip_spaces_const (arg);

  except_rx = extract_exception_regexp (&arg);
  cleanup = make_cleanup (xfree, except_rx);

  cond_string = ep_parse_optional_if_clause (&arg);

  if ((*arg != '\0') && !isspace (*arg))
    error (_("Junk at end of arguments."));

  if (ex_event != EX_EVENT_THROW
      && ex_event != EX_EVENT_CATCH
      && ex_event != EX_EVENT_RETHROW)
    error (_("Unsupported or unknown exception event; cannot catch it"));

  handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
			    ex_event, from_tty);

  discard_cleanups (cleanup);
}

/* Implementation of "catch catch" command.  */

static void
catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
{
  int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;

  catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
}

/* Implementation of "catch throw" command.  */

static void
catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
{
  int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;

  catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
}

/* Implementation of "catch rethrow" command.  */

static void
catch_rethrow_command (char *arg, int from_tty,
		       struct cmd_list_element *command)
{
  int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;

  catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
}



/* Implement the 'make_value' method for the $_exception
   internalvar.  */

static struct value *
compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
{
  struct value *arg0, *arg1;
  struct type *obj_type;

  fetch_probe_arguments (&arg0, &arg1);

  /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
     the std::type_info for the exception.  Now we find the type from
     the type_info and cast the result.  */
  obj_type = cplus_type_from_type_info (arg1);
  return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
}

/* Implementation of the '$_exception' variable.  */

static const struct internalvar_funcs exception_funcs =
{
  compute_exception,
  NULL,
  NULL
};



static void
initialize_throw_catchpoint_ops (void)
{
  struct breakpoint_ops *ops;

  initialize_breakpoint_ops ();

  /* GNU v3 exception catchpoints.  */
  ops = &gnu_v3_exception_catchpoint_ops;
  *ops = bkpt_breakpoint_ops;
  ops->re_set = re_set_exception_catchpoint;
  ops->print_it = print_it_exception_catchpoint;
  ops->print_one = print_one_exception_catchpoint;
  ops->print_mention = print_mention_exception_catchpoint;
  ops->print_recreate = print_recreate_exception_catchpoint;
  ops->print_one_detail = print_one_detail_exception_catchpoint;
  ops->check_status = check_status_exception_catchpoint;
}

initialize_file_ftype _initialize_break_catch_throw;

void
_initialize_break_catch_throw (void)
{
  initialize_throw_catchpoint_ops ();

  /* Add catch and tcatch sub-commands.  */
  add_catch_command ("catch", _("\
Catch an exception, when caught."),
		     catch_catch_command,
                     NULL,
		     CATCH_PERMANENT,
		     CATCH_TEMPORARY);
  add_catch_command ("throw", _("\
Catch an exception, when thrown."),
		     catch_throw_command,
                     NULL,
		     CATCH_PERMANENT,
		     CATCH_TEMPORARY);
  add_catch_command ("rethrow", _("\
Catch an exception, when rethrown."),
		     catch_rethrow_command,
                     NULL,
		     CATCH_PERMANENT,
		     CATCH_TEMPORARY);

  create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
}