gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2021 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 #include "cli/cli-decode.h"
  40
  41 /* Each spot where we may place an exception-related catchpoint has
  42    two names: the SDT probe point and the function name.  This
  43    structure holds both.  */
  44
  45 struct exception_names
  46 {
  47   /* The name of the probe point to try, in the form accepted by
  48      'parse_probes'.  */
  49
  50   const char *probe;
  51
  52   /* The name of the corresponding function.  */
  53
  54   const char *function;
  55 };
  56
  57 /* Names of the probe points and functions on which to break.  This is
  58    indexed by exception_event_kind.  */
  59 static const struct exception_names exception_functions[] =
  60 {
  61   { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  62   { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  63   { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
  64 };
  65
  66 static struct breakpoint_ops gnu_v3_exception_catchpoint_ops;
  67
  68 /* The type of an exception catchpoint.  */
  69
  70 struct exception_catchpoint : public breakpoint
  71 {
  72   /* The kind of exception catchpoint.  */
  73
  74   enum exception_event_kind kind;
  75
  76   /* If not empty, a string holding the source form of the regular
  77      expression to match against.  */
  78
  79   std::string exception_rx;
  80
  81   /* If non-NULL, a compiled regular expression which is used to
  82      determine which exceptions to stop on.  */
  83
  84   std::unique_ptr<compiled_regex> pattern;
  85 };
  86
  87 /* See breakpoint.h.  */
  88
  89 bool
  90 is_exception_catchpoint (breakpoint *bp)
  91 {
  92   return bp->ops == &gnu_v3_exception_catchpoint_ops;
  93 }
  94
  95 \f
  96
  97 /* A helper function that fetches exception probe arguments.  This
  98    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
  99    It will throw an exception on any kind of failure.  */
 100
 101 static void
 102 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 103 {
 104   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 105   CORE_ADDR pc = get_frame_pc (frame);
 106   struct bound_probe pc_probe;
 107   unsigned n_args;
 108
 109   pc_probe = find_probe_by_pc (pc);
 110   if (pc_probe.prob == NULL)
 111     error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
 112
 113   if (pc_probe.prob->get_provider () != "libstdcxx"
 114       || (pc_probe.prob->get_name () != "catch"
 115           && pc_probe.prob->get_name () != "throw"
 116           && pc_probe.prob->get_name () != "rethrow"))
 117     error (_("not stopped at a C++ exception catchpoint"));
 118
 119   n_args = pc_probe.prob->get_argument_count (get_frame_arch (frame));
 120   if (n_args < 2)
 121     error (_("C++ exception catchpoint has too few arguments"));
 122
 123   if (arg0 != NULL)
 124     *arg0 = pc_probe.prob->evaluate_argument (0, frame);
 125   *arg1 = pc_probe.prob->evaluate_argument (1, frame);
 126
 127   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 128     error (_("error computing probe argument at c++ exception catchpoint"));
 129 }
 130
 131 \f
 132
 133 /* A helper function that returns a value indicating the kind of the
 134    exception catchpoint B.  */
 135
 136 static enum exception_event_kind
 137 classify_exception_breakpoint (struct breakpoint *b)
 138 {
 139   struct exception_catchpoint *cp = (struct exception_catchpoint *) b;
 140
 141   return cp->kind;
 142 }
 143
 144 /* Implement the 'check_status' method.  */
 145
 146 static void
 147 check_status_exception_catchpoint (struct bpstats *bs)
 148 {
 149   struct exception_catchpoint *self
 150     = (struct exception_catchpoint *) bs->breakpoint_at;
 151   std::string type_name;
 152
 153   bkpt_breakpoint_ops.check_status (bs);
 154   if (bs->stop == 0)
 155     return;
 156
 157   if (self->pattern == NULL)
 158     return;
 159
 160   const char *name = nullptr;
 161   gdb::unique_xmalloc_ptr<char> canon;
 162   try
 163     {
 164       struct value *typeinfo_arg;
 165
 166       fetch_probe_arguments (NULL, &typeinfo_arg);
 167       type_name = cplus_typename_from_type_info (typeinfo_arg);
 168
 169       canon = cp_canonicalize_string (type_name.c_str ());
 170       name = (canon != nullptr
 171               ? canon.get ()
 172               : type_name.c_str ());
 173     }
 174   catch (const gdb_exception_error &e)
 175     {
 176       exception_print (gdb_stderr, e);
 177     }
 178
 179   if (name != nullptr)
 180     {
 181       if (self->pattern->exec (name, 0, NULL, 0) != 0)
 182         bs->stop = 0;
 183     }
 184 }
 185
 186 /* Implement the 're_set' method.  */
 187
 188 static void
 189 re_set_exception_catchpoint (struct breakpoint *self)
 190 {
 191   std::vector<symtab_and_line> sals;
 192   enum exception_event_kind kind = classify_exception_breakpoint (self);
 193   struct program_space *filter_pspace = current_program_space;
 194
 195   /* We first try to use the probe interface.  */
 196   try
 197     {
 198       event_location_up location
 199         = new_probe_location (exception_functions[kind].probe);
 200       sals = parse_probes (location.get (), filter_pspace, NULL);
 201     }
 202   catch (const gdb_exception_error &e)
 203     {
 204       /* Using the probe interface failed.  Let's fallback to the normal
 205          catchpoint mode.  */
 206       try
 207         {
 208           struct explicit_location explicit_loc;
 209
 210           initialize_explicit_location (&explicit_loc);
 211           explicit_loc.function_name
 212             = ASTRDUP (exception_functions[kind].function);
 213           event_location_up location = new_explicit_location (&explicit_loc);
 214           sals = self->ops->decode_location (self, location.get (),
 215                                              filter_pspace);
 216         }
 217       catch (const gdb_exception_error &ex)
 218         {
 219           /* NOT_FOUND_ERROR just means the breakpoint will be
 220              pending, so let it through.  */
 221           if (ex.error != NOT_FOUND_ERROR)
 222             throw;
 223         }
 224     }
 225
 226   update_breakpoint_locations (self, filter_pspace, sals, {});
 227 }
 228
 229 static enum print_stop_action
 230 print_it_exception_catchpoint (bpstat bs)
 231 {
 232   struct ui_out *uiout = current_uiout;
 233   struct breakpoint *b = bs->breakpoint_at;
 234   int bp_temp;
 235   enum exception_event_kind kind = classify_exception_breakpoint (b);
 236
 237   annotate_catchpoint (b->number);
 238   maybe_print_thread_hit_breakpoint (uiout);
 239
 240   bp_temp = b->disposition == disp_del;
 241   uiout->text (bp_temp ? "Temporary catchpoint "
 242                        : "Catchpoint ");
 243   uiout->field_signed ("bkptno", b->number);
 244   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 245                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 246                    : " (exception rethrown), ")));
 247   if (uiout->is_mi_like_p ())
 248     {
 249       uiout->field_string ("reason",
 250                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 251       uiout->field_string ("disp", bpdisp_text (b->disposition));
 252     }
 253   return PRINT_SRC_AND_LOC;
 254 }
 255
 256 static void
 257 print_one_exception_catchpoint (struct breakpoint *b,
 258                                 struct bp_location **last_loc)
 259 {
 260   struct value_print_options opts;
 261   struct ui_out *uiout = current_uiout;
 262   enum exception_event_kind kind = classify_exception_breakpoint (b);
 263
 264   get_user_print_options (&opts);
 265
 266   if (opts.addressprint)
 267     uiout->field_skip ("addr");
 268   annotate_field (5);
 269
 270   switch (kind)
 271     {
 272     case EX_EVENT_THROW:
 273       uiout->field_string ("what", "exception throw");
 274       if (uiout->is_mi_like_p ())
 275         uiout->field_string ("catch-type", "throw");
 276       break;
 277
 278     case EX_EVENT_RETHROW:
 279       uiout->field_string ("what", "exception rethrow");
 280       if (uiout->is_mi_like_p ())
 281         uiout->field_string ("catch-type", "rethrow");
 282       break;
 283
 284     case EX_EVENT_CATCH:
 285       uiout->field_string ("what", "exception catch");
 286       if (uiout->is_mi_like_p ())
 287         uiout->field_string ("catch-type", "catch");
 288       break;
 289     }
 290 }
 291
 292 /* Implement the 'print_one_detail' method.  */
 293
 294 static void
 295 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 296                                        struct ui_out *uiout)
 297 {
 298   const struct exception_catchpoint *cp
 299     = (const struct exception_catchpoint *) b;
 300
 301   if (!cp->exception_rx.empty ())
 302     {
 303       uiout->text (_("\tmatching: "));
 304       uiout->field_string ("regexp", cp->exception_rx);
 305       uiout->text ("\n");
 306     }
 307 }
 308
 309 static void
 310 print_mention_exception_catchpoint (struct breakpoint *b)
 311 {
 312   struct ui_out *uiout = current_uiout;
 313   int bp_temp;
 314   enum exception_event_kind kind = classify_exception_breakpoint (b);
 315
 316   bp_temp = b->disposition == disp_del;
 317   uiout->message ("%s %d %s",
 318                   (bp_temp ? _("Temporary catchpoint ") : _("Catchpoint")),
 319                   b->number,
 320                   (kind == EX_EVENT_THROW
 321                    ? _("(throw)") : (kind == EX_EVENT_CATCH
 322                                      ? _("(catch)") : _("(rethrow)"))));
 323 }
 324
 325 /* Implement the "print_recreate" breakpoint_ops method for throw and
 326    catch catchpoints.  */
 327
 328 static void
 329 print_recreate_exception_catchpoint (struct breakpoint *b,
 330                                      struct ui_file *fp)
 331 {
 332   int bp_temp;
 333   enum exception_event_kind kind = classify_exception_breakpoint (b);
 334
 335   bp_temp = b->disposition == disp_del;
 336   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 337   switch (kind)
 338     {
 339     case EX_EVENT_THROW:
 340       fprintf_unfiltered (fp, "throw");
 341       break;
 342     case EX_EVENT_CATCH:
 343       fprintf_unfiltered (fp, "catch");
 344       break;
 345     case EX_EVENT_RETHROW:
 346       fprintf_unfiltered (fp, "rethrow");
 347       break;
 348     }
 349   print_recreate_thread (b, fp);
 350 }
 351
 352 /* Implement the "allocate_location" breakpoint_ops method for throw
 353    and catch catchpoints.  */
 354
 355 static bp_location *
 356 allocate_location_exception_catchpoint (breakpoint *self)
 357 {
 358   return new bp_location (self, bp_loc_software_breakpoint);
 359 }
 360
 361 static void
 362 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 363                           const char *cond_string,
 364                           enum exception_event_kind ex_event, int from_tty)
 365 {
 366   std::unique_ptr<compiled_regex> pattern;
 367
 368   if (!except_rx.empty ())
 369     {
 370       pattern.reset (new compiled_regex (except_rx.c_str (), REG_NOSUB,
 371                                          _("invalid type-matching regexp")));
 372     }
 373
 374   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 375
 376   init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
 377                    &gnu_v3_exception_catchpoint_ops);
 378   cp->kind = ex_event;
 379   cp->exception_rx = std::move (except_rx);
 380   cp->pattern = std::move (pattern);
 381
 382   re_set_exception_catchpoint (cp.get ());
 383
 384   install_breakpoint (0, std::move (cp), 1);
 385 }
 386
 387 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 388    by whitespace.
 389
 390    If there is any non-whitespace text between *STRING and the "if"
 391    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 392    this returns NULL.
 393
 394    STRING is updated to point to the "if" token, if it exists, or to
 395    the end of the string.  */
 396
 397 static std::string
 398 extract_exception_regexp (const char **string)
 399 {
 400   const char *start;
 401   const char *last, *last_space;
 402
 403   start = skip_spaces (*string);
 404
 405   last = start;
 406   last_space = start;
 407   while (*last != '\0')
 408     {
 409       const char *if_token = last;
 410
 411       /* Check for the "if".  */
 412       if (check_for_argument (&if_token, "if", 2))
 413         break;
 414
 415       /* No "if" token here.  Skip to the next word start.  */
 416       last_space = skip_to_space (last);
 417       last = skip_spaces (last_space);
 418     }
 419
 420   *string = last;
 421   if (last_space > start)
 422     return std::string (start, last_space - start);
 423   return std::string ();
 424 }
 425
 426 /* See breakpoint.h.  */
 427
 428 void
 429 catch_exception_event (enum exception_event_kind ex_event,
 430                        const char *arg, bool tempflag, int from_tty)
 431 {
 432   const char *cond_string = NULL;
 433
 434   if (!arg)
 435     arg = "";
 436   arg = skip_spaces (arg);
 437
 438   std::string except_rx = extract_exception_regexp (&arg);
 439
 440   cond_string = ep_parse_optional_if_clause (&arg);
 441
 442   if ((*arg != '\0') && !isspace (*arg))
 443     error (_("Junk at end of arguments."));
 444
 445   if (ex_event != EX_EVENT_THROW
 446       && ex_event != EX_EVENT_CATCH
 447       && ex_event != EX_EVENT_RETHROW)
 448     error (_("Unsupported or unknown exception event; cannot catch it"));
 449
 450   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 451                             ex_event, from_tty);
 452 }
 453
 454 /* Implementation of "catch catch" command.  */
 455
 456 static void
 457 catch_catch_command (const char *arg, int from_tty,
 458                      struct cmd_list_element *command)
 459 {
 460   bool tempflag = command->context () == CATCH_TEMPORARY;
 461
 462   catch_exception_event (EX_EVENT_CATCH, arg, tempflag, from_tty);
 463 }
 464
 465 /* Implementation of "catch throw" command.  */
 466
 467 static void
 468 catch_throw_command (const char *arg, int from_tty,
 469                      struct cmd_list_element *command)
 470 {
 471   bool tempflag = command->context () == CATCH_TEMPORARY;
 472
 473   catch_exception_event (EX_EVENT_THROW, arg, tempflag, from_tty);
 474 }
 475
 476 /* Implementation of "catch rethrow" command.  */
 477
 478 static void
 479 catch_rethrow_command (const char *arg, int from_tty,
 480                        struct cmd_list_element *command)
 481 {
 482   bool tempflag = command->context () == CATCH_TEMPORARY;
 483
 484   catch_exception_event (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 485 }
 486
 487 \f
 488
 489 /* Implement the 'make_value' method for the $_exception
 490    internalvar.  */
 491
 492 static struct value *
 493 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 494 {
 495   struct value *arg0, *arg1;
 496   struct type *obj_type;
 497
 498   fetch_probe_arguments (&arg0, &arg1);
 499
 500   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 501      the std::type_info for the exception.  Now we find the type from
 502      the type_info and cast the result.  */
 503   obj_type = cplus_type_from_type_info (arg1);
 504   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 505 }
 506
 507 /* Implementation of the '$_exception' variable.  */
 508
 509 static const struct internalvar_funcs exception_funcs =
 510 {
 511   compute_exception,
 512   NULL,
 513   NULL
 514 };
 515
 516 \f
 517
 518 static void
 519 initialize_throw_catchpoint_ops (void)
 520 {
 521   struct breakpoint_ops *ops;
 522
 523   initialize_breakpoint_ops ();
 524
 525   /* GNU v3 exception catchpoints.  */
 526   ops = &gnu_v3_exception_catchpoint_ops;
 527   *ops = bkpt_breakpoint_ops;
 528   ops->re_set = re_set_exception_catchpoint;
 529   ops->print_it = print_it_exception_catchpoint;
 530   ops->print_one = print_one_exception_catchpoint;
 531   ops->print_mention = print_mention_exception_catchpoint;
 532   ops->print_recreate = print_recreate_exception_catchpoint;
 533   ops->print_one_detail = print_one_detail_exception_catchpoint;
 534   ops->check_status = check_status_exception_catchpoint;
 535   ops->allocate_location = allocate_location_exception_catchpoint;
 536 }
 537
 538 void _initialize_break_catch_throw ();
 539 void
 540 _initialize_break_catch_throw ()
 541 {
 542   initialize_throw_catchpoint_ops ();
 543
 544   /* Add catch and tcatch sub-commands.  */
 545   add_catch_command ("catch", _("\
 546 Catch an exception, when caught."),
 547                      catch_catch_command,
 548                      NULL,
 549                      CATCH_PERMANENT,
 550                      CATCH_TEMPORARY);
 551   add_catch_command ("throw", _("\
 552 Catch an exception, when thrown."),
 553                      catch_throw_command,
 554                      NULL,
 555                      CATCH_PERMANENT,
 556                      CATCH_TEMPORARY);
 557   add_catch_command ("rethrow", _("\
 558 Catch an exception, when rethrown."),
 559                      catch_rethrow_command,
 560                      NULL,
 561                      CATCH_PERMANENT,
 562                      CATCH_TEMPORARY);
 563
 564   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 565 }