gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2019 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 "linespec.h"
  33 #include "probe.h"
  34 #include "objfiles.h"
  35 #include "cp-abi.h"
  36 #include "gdb_regex.h"
  37 #include "cp-support.h"
  38 #include "location.h"
  39
  40 /* Each spot where we may place an exception-related catchpoint has
  41    two names: the SDT probe point and the function name.  This
  42    structure holds both.  */
  43
  44 struct exception_names
  45 {
  46   /* The name of the probe point to try, in the form accepted by
  47      'parse_probes'.  */
  48
  49   const char *probe;
  50
  51   /* The name of the corresponding function.  */
  52
  53   const char *function;
  54 };
  55
  56 /* Names of the probe points and functions on which to break.  This is
  57    indexed by exception_event_kind.  */
  58 static const struct exception_names exception_functions[] =
  59 {
  60   { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  61   { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  62   { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
  63 };
  64
  65 static struct breakpoint_ops gnu_v3_exception_catchpoint_ops;
  66
  67 /* The type of an exception catchpoint.  */
  68
  69 struct exception_catchpoint : public breakpoint
  70 {
  71   /* The kind of exception catchpoint.  */
  72
  73   enum exception_event_kind kind;
  74
  75   /* If not empty, a string holding the source form of the regular
  76      expression to match against.  */
  77
  78   std::string exception_rx;
  79
  80   /* If non-NULL, a compiled regular expression which is used to
  81      determine which exceptions to stop on.  */
  82
  83   std::unique_ptr<compiled_regex> pattern;
  84 };
  85
  86 /* See breakpoint.h.  */
  87
  88 bool
  89 is_exception_catchpoint (breakpoint *bp)
  90 {
  91   return bp->ops == &gnu_v3_exception_catchpoint_ops;
  92 }
  93
  94 \f
  95
  96 /* A helper function that fetches exception probe arguments.  This
  97    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
  98    It will throw an exception on any kind of failure.  */
  99
 100 static void
 101 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 102 {
 103   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 104   CORE_ADDR pc = get_frame_pc (frame);
 105   struct bound_probe pc_probe;
 106   unsigned n_args;
 107
 108   pc_probe = find_probe_by_pc (pc);
 109   if (pc_probe.prob == NULL)
 110     error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
 111
 112   if (pc_probe.prob->get_provider () != "libstdcxx"
 113       || (pc_probe.prob->get_name () != "catch"
 114           && pc_probe.prob->get_name () != "throw"
 115           && pc_probe.prob->get_name () != "rethrow"))
 116     error (_("not stopped at a C++ exception catchpoint"));
 117
 118   n_args = pc_probe.prob->get_argument_count (get_frame_arch (frame));
 119   if (n_args < 2)
 120     error (_("C++ exception catchpoint has too few arguments"));
 121
 122   if (arg0 != NULL)
 123     *arg0 = pc_probe.prob->evaluate_argument (0, frame);
 124   *arg1 = pc_probe.prob->evaluate_argument (1, frame);
 125
 126   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 127     error (_("error computing probe argument at c++ exception catchpoint"));
 128 }
 129
 130 \f
 131
 132 /* A helper function that returns a value indicating the kind of the
 133    exception catchpoint B.  */
 134
 135 static enum exception_event_kind
 136 classify_exception_breakpoint (struct breakpoint *b)
 137 {
 138   struct exception_catchpoint *cp = (struct exception_catchpoint *) b;
 139
 140   return cp->kind;
 141 }
 142
 143 /* Implement the 'check_status' method.  */
 144
 145 static void
 146 check_status_exception_catchpoint (struct bpstats *bs)
 147 {
 148   struct exception_catchpoint *self
 149     = (struct exception_catchpoint *) bs->breakpoint_at;
 150   std::string type_name;
 151
 152   bkpt_breakpoint_ops.check_status (bs);
 153   if (bs->stop == 0)
 154     return;
 155
 156   if (self->pattern == NULL)
 157     return;
 158
 159   try
 160     {
 161       struct value *typeinfo_arg;
 162       std::string canon;
 163
 164       fetch_probe_arguments (NULL, &typeinfo_arg);
 165       type_name = cplus_typename_from_type_info (typeinfo_arg);
 166
 167       canon = cp_canonicalize_string (type_name.c_str ());
 168       if (!canon.empty ())
 169         std::swap (type_name, canon);
 170     }
 171   catch (const gdb_exception_error &e)
 172     {
 173       exception_print (gdb_stderr, e);
 174     }
 175
 176   if (!type_name.empty ())
 177     {
 178       if (self->pattern->exec (type_name.c_str (), 0, NULL, 0) != 0)
 179         bs->stop = 0;
 180     }
 181 }
 182
 183 /* Implement the 're_set' method.  */
 184
 185 static void
 186 re_set_exception_catchpoint (struct breakpoint *self)
 187 {
 188   std::vector<symtab_and_line> sals;
 189   enum exception_event_kind kind = classify_exception_breakpoint (self);
 190   struct program_space *filter_pspace = current_program_space;
 191
 192   /* We first try to use the probe interface.  */
 193   try
 194     {
 195       event_location_up location
 196         = new_probe_location (exception_functions[kind].probe);
 197       sals = parse_probes (location.get (), filter_pspace, NULL);
 198     }
 199   catch (const gdb_exception_error &e)
 200     {
 201       /* Using the probe interface failed.  Let's fallback to the normal
 202          catchpoint mode.  */
 203       try
 204         {
 205           struct explicit_location explicit_loc;
 206
 207           initialize_explicit_location (&explicit_loc);
 208           explicit_loc.function_name
 209             = ASTRDUP (exception_functions[kind].function);
 210           event_location_up location = new_explicit_location (&explicit_loc);
 211           sals = self->ops->decode_location (self, location.get (),
 212                                              filter_pspace);
 213         }
 214       catch (const gdb_exception_error &ex)
 215         {
 216           /* NOT_FOUND_ERROR just means the breakpoint will be
 217              pending, so let it through.  */
 218           if (ex.error != NOT_FOUND_ERROR)
 219             throw;
 220         }
 221     }
 222
 223   update_breakpoint_locations (self, filter_pspace, sals, {});
 224 }
 225
 226 static enum print_stop_action
 227 print_it_exception_catchpoint (bpstat bs)
 228 {
 229   struct ui_out *uiout = current_uiout;
 230   struct breakpoint *b = bs->breakpoint_at;
 231   int bp_temp;
 232   enum exception_event_kind kind = classify_exception_breakpoint (b);
 233
 234   annotate_catchpoint (b->number);
 235   maybe_print_thread_hit_breakpoint (uiout);
 236
 237   bp_temp = b->disposition == disp_del;
 238   uiout->text (bp_temp ? "Temporary catchpoint "
 239                        : "Catchpoint ");
 240   uiout->field_signed ("bkptno", b->number);
 241   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 242                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 243                    : " (exception rethrown), ")));
 244   if (uiout->is_mi_like_p ())
 245     {
 246       uiout->field_string ("reason",
 247                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 248       uiout->field_string ("disp", bpdisp_text (b->disposition));
 249     }
 250   return PRINT_SRC_AND_LOC;
 251 }
 252
 253 static void
 254 print_one_exception_catchpoint (struct breakpoint *b,
 255                                 struct bp_location **last_loc)
 256 {
 257   struct value_print_options opts;
 258   struct ui_out *uiout = current_uiout;
 259   enum exception_event_kind kind = classify_exception_breakpoint (b);
 260
 261   get_user_print_options (&opts);
 262
 263   if (opts.addressprint)
 264     uiout->field_skip ("addr");
 265   annotate_field (5);
 266
 267   switch (kind)
 268     {
 269     case EX_EVENT_THROW:
 270       uiout->field_string ("what", "exception throw");
 271       if (uiout->is_mi_like_p ())
 272         uiout->field_string ("catch-type", "throw");
 273       break;
 274
 275     case EX_EVENT_RETHROW:
 276       uiout->field_string ("what", "exception rethrow");
 277       if (uiout->is_mi_like_p ())
 278         uiout->field_string ("catch-type", "rethrow");
 279       break;
 280
 281     case EX_EVENT_CATCH:
 282       uiout->field_string ("what", "exception catch");
 283       if (uiout->is_mi_like_p ())
 284         uiout->field_string ("catch-type", "catch");
 285       break;
 286     }
 287 }
 288
 289 /* Implement the 'print_one_detail' method.  */
 290
 291 static void
 292 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 293                                        struct ui_out *uiout)
 294 {
 295   const struct exception_catchpoint *cp
 296     = (const struct exception_catchpoint *) b;
 297
 298   if (!cp->exception_rx.empty ())
 299     {
 300       uiout->text (_("\tmatching: "));
 301       uiout->field_string ("regexp", cp->exception_rx.c_str ());
 302       uiout->text ("\n");
 303     }
 304 }
 305
 306 static void
 307 print_mention_exception_catchpoint (struct breakpoint *b)
 308 {
 309   struct ui_out *uiout = current_uiout;
 310   int bp_temp;
 311   enum exception_event_kind kind = classify_exception_breakpoint (b);
 312
 313   bp_temp = b->disposition == disp_del;
 314   uiout->message ("%s %d %s",
 315                   (bp_temp ? _("Temporary catchpoint ") : _("Catchpoint")),
 316                   b->number,
 317                   (kind == EX_EVENT_THROW
 318                    ? _("(throw)") : (kind == EX_EVENT_CATCH
 319                                      ? _("(catch)") : _("(rethrow)"))));
 320 }
 321
 322 /* Implement the "print_recreate" breakpoint_ops method for throw and
 323    catch catchpoints.  */
 324
 325 static void
 326 print_recreate_exception_catchpoint (struct breakpoint *b,
 327                                      struct ui_file *fp)
 328 {
 329   int bp_temp;
 330   enum exception_event_kind kind = classify_exception_breakpoint (b);
 331
 332   bp_temp = b->disposition == disp_del;
 333   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 334   switch (kind)
 335     {
 336     case EX_EVENT_THROW:
 337       fprintf_unfiltered (fp, "throw");
 338       break;
 339     case EX_EVENT_CATCH:
 340       fprintf_unfiltered (fp, "catch");
 341       break;
 342     case EX_EVENT_RETHROW:
 343       fprintf_unfiltered (fp, "rethrow");
 344       break;
 345     }
 346   print_recreate_thread (b, fp);
 347 }
 348
 349 /* Implement the "allocate_location" breakpoint_ops method for throw
 350    and catch catchpoints.  */
 351
 352 static bp_location *
 353 allocate_location_exception_catchpoint (breakpoint *self)
 354 {
 355   return new bp_location (self, bp_loc_software_breakpoint);
 356 }
 357
 358 static void
 359 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 360                           const char *cond_string,
 361                           enum exception_event_kind ex_event, int from_tty)
 362 {
 363   std::unique_ptr<compiled_regex> pattern;
 364
 365   if (!except_rx.empty ())
 366     {
 367       pattern.reset (new compiled_regex (except_rx.c_str (), REG_NOSUB,
 368                                          _("invalid type-matching regexp")));
 369     }
 370
 371   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 372
 373   init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
 374                    &gnu_v3_exception_catchpoint_ops);
 375   cp->kind = ex_event;
 376   cp->exception_rx = std::move (except_rx);
 377   cp->pattern = std::move (pattern);
 378
 379   re_set_exception_catchpoint (cp.get ());
 380
 381   install_breakpoint (0, std::move (cp), 1);
 382 }
 383
 384 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 385    by whitespace.
 386
 387    If there is any non-whitespace text between *STRING and the "if"
 388    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 389    this returns NULL.
 390
 391    STRING is updated to point to the "if" token, if it exists, or to
 392    the end of the string.  */
 393
 394 static std::string
 395 extract_exception_regexp (const char **string)
 396 {
 397   const char *start;
 398   const char *last, *last_space;
 399
 400   start = skip_spaces (*string);
 401
 402   last = start;
 403   last_space = start;
 404   while (*last != '\0')
 405     {
 406       const char *if_token = last;
 407
 408       /* Check for the "if".  */
 409       if (check_for_argument (&if_token, "if", 2))
 410         break;
 411
 412       /* No "if" token here.  Skip to the next word start.  */
 413       last_space = skip_to_space (last);
 414       last = skip_spaces (last_space);
 415     }
 416
 417   *string = last;
 418   if (last_space > start)
 419     return std::string (start, last_space - start);
 420   return std::string ();
 421 }
 422
 423 /* See breakpoint.h.  */
 424
 425 void
 426 catch_exception_event (enum exception_event_kind ex_event,
 427                        const char *arg, bool tempflag, int from_tty)
 428 {
 429   const char *cond_string = NULL;
 430
 431   if (!arg)
 432     arg = "";
 433   arg = skip_spaces (arg);
 434
 435   std::string except_rx = extract_exception_regexp (&arg);
 436
 437   cond_string = ep_parse_optional_if_clause (&arg);
 438
 439   if ((*arg != '\0') && !isspace (*arg))
 440     error (_("Junk at end of arguments."));
 441
 442   if (ex_event != EX_EVENT_THROW
 443       && ex_event != EX_EVENT_CATCH
 444       && ex_event != EX_EVENT_RETHROW)
 445     error (_("Unsupported or unknown exception event; cannot catch it"));
 446
 447   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 448                             ex_event, from_tty);
 449 }
 450
 451 /* Implementation of "catch catch" command.  */
 452
 453 static void
 454 catch_catch_command (const char *arg, int from_tty,
 455                      struct cmd_list_element *command)
 456 {
 457   bool tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 458
 459   catch_exception_event (EX_EVENT_CATCH, arg, tempflag, from_tty);
 460 }
 461
 462 /* Implementation of "catch throw" command.  */
 463
 464 static void
 465 catch_throw_command (const char *arg, int from_tty,
 466                      struct cmd_list_element *command)
 467 {
 468   bool tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 469
 470   catch_exception_event (EX_EVENT_THROW, arg, tempflag, from_tty);
 471 }
 472
 473 /* Implementation of "catch rethrow" command.  */
 474
 475 static void
 476 catch_rethrow_command (const char *arg, int from_tty,
 477                        struct cmd_list_element *command)
 478 {
 479   bool tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 480
 481   catch_exception_event (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 482 }
 483
 484 \f
 485
 486 /* Implement the 'make_value' method for the $_exception
 487    internalvar.  */
 488
 489 static struct value *
 490 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 491 {
 492   struct value *arg0, *arg1;
 493   struct type *obj_type;
 494
 495   fetch_probe_arguments (&arg0, &arg1);
 496
 497   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 498      the std::type_info for the exception.  Now we find the type from
 499      the type_info and cast the result.  */
 500   obj_type = cplus_type_from_type_info (arg1);
 501   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 502 }
 503
 504 /* Implementation of the '$_exception' variable.  */
 505
 506 static const struct internalvar_funcs exception_funcs =
 507 {
 508   compute_exception,
 509   NULL,
 510   NULL
 511 };
 512
 513 \f
 514
 515 static void
 516 initialize_throw_catchpoint_ops (void)
 517 {
 518   struct breakpoint_ops *ops;
 519
 520   initialize_breakpoint_ops ();
 521
 522   /* GNU v3 exception catchpoints.  */
 523   ops = &gnu_v3_exception_catchpoint_ops;
 524   *ops = bkpt_breakpoint_ops;
 525   ops->re_set = re_set_exception_catchpoint;
 526   ops->print_it = print_it_exception_catchpoint;
 527   ops->print_one = print_one_exception_catchpoint;
 528   ops->print_mention = print_mention_exception_catchpoint;
 529   ops->print_recreate = print_recreate_exception_catchpoint;
 530   ops->print_one_detail = print_one_detail_exception_catchpoint;
 531   ops->check_status = check_status_exception_catchpoint;
 532   ops->allocate_location = allocate_location_exception_catchpoint;
 533 }
 534
 535 void
 536 _initialize_break_catch_throw (void)
 537 {
 538   initialize_throw_catchpoint_ops ();
 539
 540   /* Add catch and tcatch sub-commands.  */
 541   add_catch_command ("catch", _("\
 542 Catch an exception, when caught."),
 543                      catch_catch_command,
 544                      NULL,
 545                      CATCH_PERMANENT,
 546                      CATCH_TEMPORARY);
 547   add_catch_command ("throw", _("\
 548 Catch an exception, when thrown."),
 549                      catch_throw_command,
 550                      NULL,
 551                      CATCH_PERMANENT,
 552                      CATCH_TEMPORARY);
 553   add_catch_command ("rethrow", _("\
 554 Catch an exception, when rethrown."),
 555                      catch_rethrow_command,
 556                      NULL,
 557                      CATCH_PERMANENT,
 558                      CATCH_TEMPORARY);
 559
 560   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 561 }