gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2013 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 "arch-utils.h"
  22 #include <ctype.h>
  23 #include "breakpoint.h"
  24 #include "gdbcmd.h"
  25 #include "inferior.h"
  26 #include "annotate.h"
  27 #include "valprint.h"
  28 #include "cli/cli-utils.h"
  29 #include "completer.h"
  30 #include "gdb_obstack.h"
  31 #include "mi/mi-common.h"
  32 #include "exceptions.h"
  33 #include "linespec.h"
  34 #include "probe.h"
  35 #include "objfiles.h"
  36 #include "cp-abi.h"
  37 #include "gdb_regex.h"
  38 #include "cp-support.h"
  39
  40 /* Enums for exception-handling support.  */
  41 enum exception_event_kind
  42 {
  43   EX_EVENT_THROW,
  44   EX_EVENT_RETHROW,
  45   EX_EVENT_CATCH
  46 };
  47
  48 /* Each spot where we may place an exception-related catchpoint has
  49    two names: the SDT probe point and the function name.  This
  50    structure holds both.  */
  51
  52 struct exception_names
  53 {
  54   /* The name of the probe point to try, in the form accepted by
  55      'parse_probes'.  */
  56
  57   const char *probe;
  58
  59   /* The name of the corresponding function.  */
  60
  61   const char *function;
  62 };
  63
  64 /* Names of the probe points and functions on which to break.  This is
  65    indexed by exception_event_kind.  */
  66 static const struct exception_names exception_functions[] =
  67 {
  68   { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  69   { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  70   { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
  71 };
  72
  73 static struct breakpoint_ops gnu_v3_exception_catchpoint_ops;
  74
  75 /* The type of an exception catchpoint.  */
  76
  77 struct exception_catchpoint
  78 {
  79   /* The base class.  */
  80
  81   struct breakpoint base;
  82
  83   /* The kind of exception catchpoint.  */
  84
  85   enum exception_event_kind kind;
  86
  87   /* If non-NULL, an xmalloc'd string holding the source form of the
  88      regular expression to match against.  */
  89
  90   char *exception_rx;
  91
  92   /* If non-NULL, an xmalloc'd, compiled regular expression which is
  93      used to determine which exceptions to stop on.  */
  94
  95   regex_t *pattern;
  96 };
  97
  98 \f
  99
 100 /* A helper function that fetches exception probe arguments.  This
 101    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
 102    It will throw an exception on any kind of failure.  */
 103
 104 static void
 105 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 106 {
 107   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 108   CORE_ADDR pc = get_frame_pc (frame);
 109   struct probe *pc_probe;
 110   const struct sym_probe_fns *pc_probe_fns;
 111   unsigned n_args;
 112
 113   pc_probe = find_probe_by_pc (pc);
 114   if (pc_probe == NULL
 115       || strcmp (pc_probe->provider, "libstdcxx") != 0
 116       || (strcmp (pc_probe->name, "catch") != 0
 117           && strcmp (pc_probe->name, "throw") != 0
 118           && strcmp (pc_probe->name, "rethrow") != 0))
 119     error (_("not stopped at a C++ exception catchpoint"));
 120
 121   gdb_assert (pc_probe->objfile != NULL);
 122   gdb_assert (pc_probe->objfile->sf != NULL);
 123   gdb_assert (pc_probe->objfile->sf->sym_probe_fns != NULL);
 124
 125   pc_probe_fns = pc_probe->objfile->sf->sym_probe_fns;
 126   n_args = pc_probe_fns->sym_get_probe_argument_count (pc_probe);
 127   if (n_args < 2)
 128     error (_("C++ exception catchpoint has too few arguments"));
 129
 130   if (arg0 != NULL)
 131     *arg0 = pc_probe_fns->sym_evaluate_probe_argument (pc_probe, 0);
 132   *arg1 = pc_probe_fns->sym_evaluate_probe_argument (pc_probe, 1);
 133
 134   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 135     error (_("error computing probe argument at c++ exception catchpoint"));
 136 }
 137
 138 \f
 139
 140 /* A helper function that returns a value indicating the kind of the
 141    exception catchpoint B.  */
 142
 143 static enum exception_event_kind
 144 classify_exception_breakpoint (struct breakpoint *b)
 145 {
 146   struct exception_catchpoint *cp = (struct exception_catchpoint *) b;
 147
 148   return cp->kind;
 149 }
 150
 151 /* Implement the 'dtor' method.  */
 152
 153 static void
 154 dtor_exception_catchpoint (struct breakpoint *self)
 155 {
 156   struct exception_catchpoint *cp = (struct exception_catchpoint *) self;
 157
 158   xfree (cp->exception_rx);
 159   if (cp->pattern != NULL)
 160     regfree (cp->pattern);
 161   bkpt_breakpoint_ops.dtor (self);
 162 }
 163
 164 /* Implement the 'check_status' method.  */
 165
 166 static void
 167 check_status_exception_catchpoint (struct bpstats *bs)
 168 {
 169   struct exception_catchpoint *self
 170     = (struct exception_catchpoint *) bs->breakpoint_at;
 171   char *typename = NULL;
 172   volatile struct gdb_exception e;
 173
 174   bkpt_breakpoint_ops.check_status (bs);
 175   if (bs->stop == 0)
 176     return;
 177
 178   if (self->pattern == NULL)
 179     return;
 180
 181   TRY_CATCH (e, RETURN_MASK_ERROR)
 182     {
 183       struct value *typeinfo_arg;
 184       char *canon;
 185
 186       fetch_probe_arguments (NULL, &typeinfo_arg);
 187       typename = cplus_typename_from_type_info (typeinfo_arg);
 188
 189       canon = cp_canonicalize_string (typename);
 190       if (canon != NULL)
 191         {
 192           xfree (typename);
 193           typename = canon;
 194         }
 195     }
 196
 197   if (e.reason < 0)
 198     exception_print (gdb_stderr, e);
 199   else if (regexec (self->pattern, typename, 0, NULL, 0) != 0)
 200     bs->stop = 0;
 201
 202   xfree (typename);
 203 }
 204
 205 /* Implement the 're_set' method.  */
 206
 207 static void
 208 re_set_exception_catchpoint (struct breakpoint *self)
 209 {
 210   struct symtabs_and_lines sals = {0};
 211   struct symtabs_and_lines sals_end = {0};
 212   volatile struct gdb_exception e;
 213   struct cleanup *cleanup;
 214   enum exception_event_kind kind = classify_exception_breakpoint (self);
 215   int pass;
 216
 217   for (pass = 0; sals.sals == NULL && pass < 2; ++pass)
 218     {
 219       TRY_CATCH (e, RETURN_MASK_ERROR)
 220         {
 221           char *spec;
 222
 223           if (pass == 0)
 224             {
 225               spec = ASTRDUP (exception_functions[kind].probe);
 226               sals = parse_probes (&spec, NULL);
 227             }
 228           else
 229             {
 230               spec = ASTRDUP (exception_functions[kind].function);
 231               self->ops->decode_linespec (self, &spec, &sals);
 232             }
 233         }
 234       /* NOT_FOUND_ERROR just means the breakpoint will be pending, so
 235          let it through.  */
 236       if (e.reason < 0 && e.error != NOT_FOUND_ERROR)
 237         throw_exception (e);
 238     }
 239
 240   cleanup = make_cleanup (xfree, sals.sals);
 241   update_breakpoint_locations (self, sals, sals_end);
 242   do_cleanups (cleanup);
 243 }
 244
 245 static enum print_stop_action
 246 print_it_exception_catchpoint (bpstat bs)
 247 {
 248   struct ui_out *uiout = current_uiout;
 249   struct breakpoint *b = bs->breakpoint_at;
 250   int bp_temp;
 251   enum exception_event_kind kind = classify_exception_breakpoint (b);
 252
 253   annotate_catchpoint (b->number);
 254
 255   bp_temp = b->disposition == disp_del;
 256   ui_out_text (uiout,
 257                bp_temp ? "Temporary catchpoint "
 258                        : "Catchpoint ");
 259   if (!ui_out_is_mi_like_p (uiout))
 260     ui_out_field_int (uiout, "bkptno", b->number);
 261   ui_out_text (uiout,
 262                (kind == EX_EVENT_THROW ? " (exception thrown), "
 263                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 264                    : " (exception rethrown), ")));
 265   if (ui_out_is_mi_like_p (uiout))
 266     {
 267       ui_out_field_string (uiout, "reason",
 268                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 269       ui_out_field_string (uiout, "disp", bpdisp_text (b->disposition));
 270       ui_out_field_int (uiout, "bkptno", b->number);
 271     }
 272   return PRINT_SRC_AND_LOC;
 273 }
 274
 275 static void
 276 print_one_exception_catchpoint (struct breakpoint *b,
 277                                 struct bp_location **last_loc)
 278 {
 279   struct value_print_options opts;
 280   struct ui_out *uiout = current_uiout;
 281   enum exception_event_kind kind = classify_exception_breakpoint (b);
 282
 283   get_user_print_options (&opts);
 284   if (opts.addressprint)
 285     {
 286       annotate_field (4);
 287       if (b->loc == NULL || b->loc->shlib_disabled)
 288         ui_out_field_string (uiout, "addr", "<PENDING>");
 289       else
 290         ui_out_field_core_addr (uiout, "addr",
 291                                 b->loc->gdbarch, b->loc->address);
 292     }
 293   annotate_field (5);
 294   if (b->loc)
 295     *last_loc = b->loc;
 296
 297   switch (kind)
 298     {
 299     case EX_EVENT_THROW:
 300       ui_out_field_string (uiout, "what", "exception throw");
 301       if (ui_out_is_mi_like_p (uiout))
 302         ui_out_field_string (uiout, "catch-type", "throw");
 303       break;
 304
 305     case EX_EVENT_RETHROW:
 306       ui_out_field_string (uiout, "what", "exception rethrow");
 307       if (ui_out_is_mi_like_p (uiout))
 308         ui_out_field_string (uiout, "catch-type", "rethrow");
 309       break;
 310
 311     case EX_EVENT_CATCH:
 312       ui_out_field_string (uiout, "what", "exception catch");
 313       if (ui_out_is_mi_like_p (uiout))
 314         ui_out_field_string (uiout, "catch-type", "catch");
 315       break;
 316     }
 317 }
 318
 319 /* Implement the 'print_one_detail' method.  */
 320
 321 static void
 322 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 323                                        struct ui_out *uiout)
 324 {
 325   const struct exception_catchpoint *cp
 326     = (const struct exception_catchpoint *) b;
 327
 328   if (cp->exception_rx != NULL)
 329     {
 330       ui_out_text (uiout, _("\tmatching: "));
 331       ui_out_field_string (uiout, "regexp", cp->exception_rx);
 332       ui_out_text (uiout, "\n");
 333     }
 334 }
 335
 336 static void
 337 print_mention_exception_catchpoint (struct breakpoint *b)
 338 {
 339   struct ui_out *uiout = current_uiout;
 340   int bp_temp;
 341   enum exception_event_kind kind = classify_exception_breakpoint (b);
 342
 343   bp_temp = b->disposition == disp_del;
 344   ui_out_text (uiout, bp_temp ? _("Temporary catchpoint ")
 345                               : _("Catchpoint "));
 346   ui_out_field_int (uiout, "bkptno", b->number);
 347   ui_out_text (uiout, (kind == EX_EVENT_THROW ? _(" (throw)")
 348                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 349                           : _(" (rethrow)"))));
 350 }
 351
 352 /* Implement the "print_recreate" breakpoint_ops method for throw and
 353    catch catchpoints.  */
 354
 355 static void
 356 print_recreate_exception_catchpoint (struct breakpoint *b,
 357                                      struct ui_file *fp)
 358 {
 359   int bp_temp;
 360   enum exception_event_kind kind = classify_exception_breakpoint (b);
 361
 362   bp_temp = b->disposition == disp_del;
 363   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 364   switch (kind)
 365     {
 366     case EX_EVENT_THROW:
 367       fprintf_unfiltered (fp, "throw");
 368       break;
 369     case EX_EVENT_CATCH:
 370       fprintf_unfiltered (fp, "catch");
 371       break;
 372     case EX_EVENT_RETHROW:
 373       fprintf_unfiltered (fp, "rethrow");
 374       break;
 375     }
 376   print_recreate_thread (b, fp);
 377 }
 378
 379 static void
 380 handle_gnu_v3_exceptions (int tempflag, char *except_rx, char *cond_string,
 381                           enum exception_event_kind ex_event, int from_tty)
 382 {
 383   struct exception_catchpoint *cp;
 384   struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
 385   regex_t *pattern = NULL;
 386
 387   if (except_rx != NULL)
 388     {
 389       pattern = XNEW (regex_t);
 390       make_cleanup (xfree, pattern);
 391
 392       compile_rx_or_error (pattern, except_rx,
 393                            _("invalid type-matching regexp"));
 394     }
 395
 396   cp = XCNEW (struct exception_catchpoint);
 397   make_cleanup (xfree, cp);
 398
 399   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 400                    &gnu_v3_exception_catchpoint_ops);
 401   /* We need to reset 'type' in order for code in breakpoint.c to do
 402      the right thing.  */
 403   cp->base.type = bp_breakpoint;
 404   cp->kind = ex_event;
 405   cp->exception_rx = except_rx;
 406   cp->pattern = pattern;
 407
 408   re_set_exception_catchpoint (&cp->base);
 409
 410   install_breakpoint (0, &cp->base, 1);
 411   discard_cleanups (cleanup);
 412 }
 413
 414 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 415    by whitespace.
 416
 417    If there is any non-whitespace text between *STRING and the "if"
 418    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 419    this returns NULL.
 420
 421    STRING is updated to point to the "if" token, if it exists, or to
 422    the end of the string.  */
 423
 424 static char *
 425 extract_exception_regexp (char **string)
 426 {
 427   char *start;
 428   char *last, *last_space;
 429
 430   start = skip_spaces (*string);
 431
 432   last = start;
 433   last_space = start;
 434   while (*last != '\0')
 435     {
 436       char *if_token = last;
 437
 438       /* Check for the "if".  */
 439       if (check_for_argument (&if_token, "if", 2))
 440         break;
 441
 442       /* No "if" token here.  Skip to the next word start.  */
 443       last_space = skip_to_space (last);
 444       last = skip_spaces (last_space);
 445     }
 446
 447   *string = last;
 448   if (last_space > start)
 449     return savestring (start, last_space - start);
 450   return NULL;
 451 }
 452
 453 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 454    commands.  */
 455
 456 static void
 457 catch_exception_command_1 (enum exception_event_kind ex_event, char *arg,
 458                            int tempflag, int from_tty)
 459 {
 460   char *except_rx;
 461   char *cond_string = NULL;
 462   struct cleanup *cleanup;
 463
 464   if (!arg)
 465     arg = "";
 466   arg = skip_spaces (arg);
 467
 468   except_rx = extract_exception_regexp (&arg);
 469   cleanup = make_cleanup (xfree, except_rx);
 470
 471   cond_string = ep_parse_optional_if_clause (&arg);
 472
 473   if ((*arg != '\0') && !isspace (*arg))
 474     error (_("Junk at end of arguments."));
 475
 476   if (ex_event != EX_EVENT_THROW
 477       && ex_event != EX_EVENT_CATCH
 478       && ex_event != EX_EVENT_RETHROW)
 479     error (_("Unsupported or unknown exception event; cannot catch it"));
 480
 481   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 482                             ex_event, from_tty);
 483
 484   discard_cleanups (cleanup);
 485 }
 486
 487 /* Implementation of "catch catch" command.  */
 488
 489 static void
 490 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 491 {
 492   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 493
 494   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 495 }
 496
 497 /* Implementation of "catch throw" command.  */
 498
 499 static void
 500 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 501 {
 502   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 503
 504   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 505 }
 506
 507 /* Implementation of "catch rethrow" command.  */
 508
 509 static void
 510 catch_rethrow_command (char *arg, int from_tty,
 511                        struct cmd_list_element *command)
 512 {
 513   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 514
 515   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 516 }
 517
 518 \f
 519
 520 /* Implement the 'make_value' method for the $_exception
 521    internalvar.  */
 522
 523 static struct value *
 524 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 525 {
 526   struct value *arg0, *arg1;
 527   struct type *obj_type;
 528
 529   fetch_probe_arguments (&arg0, &arg1);
 530
 531   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 532      the std::type_info for the exception.  Now we find the type from
 533      the type_info and cast the result.  */
 534   obj_type = cplus_type_from_type_info (arg1);
 535   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 536 }
 537
 538 /* Implementation of the '$_exception' variable.  */
 539
 540 static const struct internalvar_funcs exception_funcs =
 541 {
 542   compute_exception,
 543   NULL,
 544   NULL
 545 };
 546
 547 \f
 548
 549 static void
 550 initialize_throw_catchpoint_ops (void)
 551 {
 552   struct breakpoint_ops *ops;
 553
 554   initialize_breakpoint_ops ();
 555
 556   /* GNU v3 exception catchpoints.  */
 557   ops = &gnu_v3_exception_catchpoint_ops;
 558   *ops = bkpt_breakpoint_ops;
 559   ops->dtor = dtor_exception_catchpoint;
 560   ops->re_set = re_set_exception_catchpoint;
 561   ops->print_it = print_it_exception_catchpoint;
 562   ops->print_one = print_one_exception_catchpoint;
 563   ops->print_mention = print_mention_exception_catchpoint;
 564   ops->print_recreate = print_recreate_exception_catchpoint;
 565   ops->print_one_detail = print_one_detail_exception_catchpoint;
 566   ops->check_status = check_status_exception_catchpoint;
 567 }
 568
 569 initialize_file_ftype _initialize_break_catch_throw;
 570
 571 void
 572 _initialize_break_catch_throw (void)
 573 {
 574   initialize_throw_catchpoint_ops ();
 575
 576   /* Add catch and tcatch sub-commands.  */
 577   add_catch_command ("catch", _("\
 578 Catch an exception, when caught."),
 579                      catch_catch_command,
 580                      NULL,
 581                      CATCH_PERMANENT,
 582                      CATCH_TEMPORARY);
 583   add_catch_command ("throw", _("\
 584 Catch an exception, when thrown."),
 585                      catch_throw_command,
 586                      NULL,
 587                      CATCH_PERMANENT,
 588                      CATCH_TEMPORARY);
 589   add_catch_command ("rethrow", _("\
 590 Catch an exception, when rethrown."),
 591                      catch_rethrow_command,
 592                      NULL,
 593                      CATCH_PERMANENT,
 594                      CATCH_TEMPORARY);
 595
 596   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 597 }