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 /* 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 : public breakpoint
  78 {
  79   /* The kind of exception catchpoint.  */
  80
  81   enum exception_event_kind kind;
  82
  83   /* If not empty, a string holding the source form of the regular
  84      expression to match against.  */
  85
  86   std::string exception_rx;
  87
  88   /* If non-NULL, a compiled regular expression which is used to
  89      determine which exceptions to stop on.  */
  90
  91   std::unique_ptr<compiled_regex> pattern;
  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       || pc_probe.prob->get_provider () != "libstdcxx"
 111       || (pc_probe.prob->get_name () != "catch"
 112           && pc_probe.prob->get_name () != "throw"
 113           && pc_probe.prob->get_name () != "rethrow"))
 114     error (_("not stopped at a C++ exception catchpoint"));
 115
 116   n_args = pc_probe.prob->get_argument_count (frame);
 117   if (n_args < 2)
 118     error (_("C++ exception catchpoint has too few arguments"));
 119
 120   if (arg0 != NULL)
 121     *arg0 = pc_probe.prob->evaluate_argument (0, frame);
 122   *arg1 = pc_probe.prob->evaluate_argument (1, frame);
 123
 124   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 125     error (_("error computing probe argument at c++ exception catchpoint"));
 126 }
 127
 128 \f
 129
 130 /* A helper function that returns a value indicating the kind of the
 131    exception catchpoint B.  */
 132
 133 static enum exception_event_kind
 134 classify_exception_breakpoint (struct breakpoint *b)
 135 {
 136   struct exception_catchpoint *cp = (struct exception_catchpoint *) b;
 137
 138   return cp->kind;
 139 }
 140
 141 /* Implement the 'check_status' method.  */
 142
 143 static void
 144 check_status_exception_catchpoint (struct bpstats *bs)
 145 {
 146   struct exception_catchpoint *self
 147     = (struct exception_catchpoint *) bs->breakpoint_at;
 148   std::string type_name;
 149
 150   bkpt_breakpoint_ops.check_status (bs);
 151   if (bs->stop == 0)
 152     return;
 153
 154   if (self->pattern == NULL)
 155     return;
 156
 157   try
 158     {
 159       struct value *typeinfo_arg;
 160       std::string canon;
 161
 162       fetch_probe_arguments (NULL, &typeinfo_arg);
 163       type_name = cplus_typename_from_type_info (typeinfo_arg);
 164
 165       canon = cp_canonicalize_string (type_name.c_str ());
 166       if (!canon.empty ())
 167         std::swap (type_name, canon);
 168     }
 169   catch (const gdb_exception_RETURN_MASK_ERROR &e)
 170     {
 171       exception_print (gdb_stderr, e);
 172     }
 173
 174   if (!type_name.empty ())
 175     {
 176       if (self->pattern->exec (type_name.c_str (), 0, NULL, 0) != 0)
 177         bs->stop = 0;
 178     }
 179 }
 180
 181 /* Implement the 're_set' method.  */
 182
 183 static void
 184 re_set_exception_catchpoint (struct breakpoint *self)
 185 {
 186   std::vector<symtab_and_line> sals;
 187   enum exception_event_kind kind = classify_exception_breakpoint (self);
 188   struct program_space *filter_pspace = current_program_space;
 189
 190   /* We first try to use the probe interface.  */
 191   try
 192     {
 193       event_location_up location
 194         = new_probe_location (exception_functions[kind].probe);
 195       sals = parse_probes (location.get (), filter_pspace, NULL);
 196     }
 197   catch (const gdb_exception_RETURN_MASK_ERROR &e)
 198     {
 199       /* Using the probe interface failed.  Let's fallback to the normal
 200          catchpoint mode.  */
 201       try
 202         {
 203           struct explicit_location explicit_loc;
 204
 205           initialize_explicit_location (&explicit_loc);
 206           explicit_loc.function_name
 207             = ASTRDUP (exception_functions[kind].function);
 208           event_location_up location = new_explicit_location (&explicit_loc);
 209           sals = self->ops->decode_location (self, location.get (),
 210                                              filter_pspace);
 211         }
 212       catch (const gdb_exception_RETURN_MASK_ERROR &ex)
 213         {
 214           /* NOT_FOUND_ERROR just means the breakpoint will be
 215              pending, so let it through.  */
 216           if (ex.error != NOT_FOUND_ERROR)
 217             throw_exception (ex);
 218         }
 219     }
 220
 221   update_breakpoint_locations (self, filter_pspace, sals, {});
 222 }
 223
 224 static enum print_stop_action
 225 print_it_exception_catchpoint (bpstat bs)
 226 {
 227   struct ui_out *uiout = current_uiout;
 228   struct breakpoint *b = bs->breakpoint_at;
 229   int bp_temp;
 230   enum exception_event_kind kind = classify_exception_breakpoint (b);
 231
 232   annotate_catchpoint (b->number);
 233   maybe_print_thread_hit_breakpoint (uiout);
 234
 235   bp_temp = b->disposition == disp_del;
 236   uiout->text (bp_temp ? "Temporary catchpoint "
 237                        : "Catchpoint ");
 238   uiout->field_int ("bkptno", b->number);
 239   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 240                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 241                    : " (exception rethrown), ")));
 242   if (uiout->is_mi_like_p ())
 243     {
 244       uiout->field_string ("reason",
 245                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 246       uiout->field_string ("disp", bpdisp_text (b->disposition));
 247     }
 248   return PRINT_SRC_AND_LOC;
 249 }
 250
 251 static void
 252 print_one_exception_catchpoint (struct breakpoint *b,
 253                                 struct bp_location **last_loc)
 254 {
 255   struct value_print_options opts;
 256   struct ui_out *uiout = current_uiout;
 257   enum exception_event_kind kind = classify_exception_breakpoint (b);
 258
 259   get_user_print_options (&opts);
 260   if (opts.addressprint)
 261     {
 262       annotate_field (4);
 263       if (b->loc == NULL || b->loc->shlib_disabled)
 264         uiout->field_string ("addr", "<PENDING>");
 265       else
 266         uiout->field_core_addr ("addr",
 267                                 b->loc->gdbarch, b->loc->address);
 268     }
 269   annotate_field (5);
 270   if (b->loc)
 271     *last_loc = b->loc;
 272
 273   switch (kind)
 274     {
 275     case EX_EVENT_THROW:
 276       uiout->field_string ("what", "exception throw");
 277       if (uiout->is_mi_like_p ())
 278         uiout->field_string ("catch-type", "throw");
 279       break;
 280
 281     case EX_EVENT_RETHROW:
 282       uiout->field_string ("what", "exception rethrow");
 283       if (uiout->is_mi_like_p ())
 284         uiout->field_string ("catch-type", "rethrow");
 285       break;
 286
 287     case EX_EVENT_CATCH:
 288       uiout->field_string ("what", "exception catch");
 289       if (uiout->is_mi_like_p ())
 290         uiout->field_string ("catch-type", "catch");
 291       break;
 292     }
 293 }
 294
 295 /* Implement the 'print_one_detail' method.  */
 296
 297 static void
 298 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 299                                        struct ui_out *uiout)
 300 {
 301   const struct exception_catchpoint *cp
 302     = (const struct exception_catchpoint *) b;
 303
 304   if (!cp->exception_rx.empty ())
 305     {
 306       uiout->text (_("\tmatching: "));
 307       uiout->field_string ("regexp", cp->exception_rx.c_str ());
 308       uiout->text ("\n");
 309     }
 310 }
 311
 312 static void
 313 print_mention_exception_catchpoint (struct breakpoint *b)
 314 {
 315   struct ui_out *uiout = current_uiout;
 316   int bp_temp;
 317   enum exception_event_kind kind = classify_exception_breakpoint (b);
 318
 319   bp_temp = b->disposition == disp_del;
 320   uiout->text (bp_temp ? _("Temporary catchpoint ")
 321                               : _("Catchpoint "));
 322   uiout->field_int ("bkptno", b->number);
 323   uiout->text ((kind == EX_EVENT_THROW ? _(" (throw)")
 324                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 325                           : _(" (rethrow)"))));
 326 }
 327
 328 /* Implement the "print_recreate" breakpoint_ops method for throw and
 329    catch catchpoints.  */
 330
 331 static void
 332 print_recreate_exception_catchpoint (struct breakpoint *b,
 333                                      struct ui_file *fp)
 334 {
 335   int bp_temp;
 336   enum exception_event_kind kind = classify_exception_breakpoint (b);
 337
 338   bp_temp = b->disposition == disp_del;
 339   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 340   switch (kind)
 341     {
 342     case EX_EVENT_THROW:
 343       fprintf_unfiltered (fp, "throw");
 344       break;
 345     case EX_EVENT_CATCH:
 346       fprintf_unfiltered (fp, "catch");
 347       break;
 348     case EX_EVENT_RETHROW:
 349       fprintf_unfiltered (fp, "rethrow");
 350       break;
 351     }
 352   print_recreate_thread (b, fp);
 353 }
 354
 355 static void
 356 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 357                           const char *cond_string,
 358                           enum exception_event_kind ex_event, int from_tty)
 359 {
 360   std::unique_ptr<compiled_regex> pattern;
 361
 362   if (!except_rx.empty ())
 363     {
 364       pattern.reset (new compiled_regex (except_rx.c_str (), REG_NOSUB,
 365                                          _("invalid type-matching regexp")));
 366     }
 367
 368   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 369
 370   init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
 371                    &gnu_v3_exception_catchpoint_ops);
 372   /* We need to reset 'type' in order for code in breakpoint.c to do
 373      the right thing.  */
 374   cp->type = bp_breakpoint;
 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 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 424    commands.  */
 425
 426 static void
 427 catch_exception_command_1 (enum exception_event_kind ex_event,
 428                            const char *arg,
 429                            int tempflag, int from_tty)
 430 {
 431   const char *cond_string = NULL;
 432
 433   if (!arg)
 434     arg = "";
 435   arg = skip_spaces (arg);
 436
 437   std::string except_rx = extract_exception_regexp (&arg);
 438
 439   cond_string = ep_parse_optional_if_clause (&arg);
 440
 441   if ((*arg != '\0') && !isspace (*arg))
 442     error (_("Junk at end of arguments."));
 443
 444   if (ex_event != EX_EVENT_THROW
 445       && ex_event != EX_EVENT_CATCH
 446       && ex_event != EX_EVENT_RETHROW)
 447     error (_("Unsupported or unknown exception event; cannot catch it"));
 448
 449   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 450                             ex_event, from_tty);
 451 }
 452
 453 /* Implementation of "catch catch" command.  */
 454
 455 static void
 456 catch_catch_command (const char *arg, int from_tty,
 457                      struct cmd_list_element *command)
 458 {
 459   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 460
 461   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 462 }
 463
 464 /* Implementation of "catch throw" command.  */
 465
 466 static void
 467 catch_throw_command (const char *arg, int from_tty,
 468                      struct cmd_list_element *command)
 469 {
 470   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 471
 472   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 473 }
 474
 475 /* Implementation of "catch rethrow" command.  */
 476
 477 static void
 478 catch_rethrow_command (const char *arg, int from_tty,
 479                        struct cmd_list_element *command)
 480 {
 481   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 482
 483   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 484 }
 485
 486 \f
 487
 488 /* Implement the 'make_value' method for the $_exception
 489    internalvar.  */
 490
 491 static struct value *
 492 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 493 {
 494   struct value *arg0, *arg1;
 495   struct type *obj_type;
 496
 497   fetch_probe_arguments (&arg0, &arg1);
 498
 499   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 500      the std::type_info for the exception.  Now we find the type from
 501      the type_info and cast the result.  */
 502   obj_type = cplus_type_from_type_info (arg1);
 503   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 504 }
 505
 506 /* Implementation of the '$_exception' variable.  */
 507
 508 static const struct internalvar_funcs exception_funcs =
 509 {
 510   compute_exception,
 511   NULL,
 512   NULL
 513 };
 514
 515 \f
 516
 517 static void
 518 initialize_throw_catchpoint_ops (void)
 519 {
 520   struct breakpoint_ops *ops;
 521
 522   initialize_breakpoint_ops ();
 523
 524   /* GNU v3 exception catchpoints.  */
 525   ops = &gnu_v3_exception_catchpoint_ops;
 526   *ops = bkpt_breakpoint_ops;
 527   ops->re_set = re_set_exception_catchpoint;
 528   ops->print_it = print_it_exception_catchpoint;
 529   ops->print_one = print_one_exception_catchpoint;
 530   ops->print_mention = print_mention_exception_catchpoint;
 531   ops->print_recreate = print_recreate_exception_catchpoint;
 532   ops->print_one_detail = print_one_detail_exception_catchpoint;
 533   ops->check_status = check_status_exception_catchpoint;
 534 }
 535
 536 void
 537 _initialize_break_catch_throw (void)
 538 {
 539   initialize_throw_catchpoint_ops ();
 540
 541   /* Add catch and tcatch sub-commands.  */
 542   add_catch_command ("catch", _("\
 543 Catch an exception, when caught."),
 544                      catch_catch_command,
 545                      NULL,
 546                      CATCH_PERMANENT,
 547                      CATCH_TEMPORARY);
 548   add_catch_command ("throw", _("\
 549 Catch an exception, when thrown."),
 550                      catch_throw_command,
 551                      NULL,
 552                      CATCH_PERMANENT,
 553                      CATCH_TEMPORARY);
 554   add_catch_command ("rethrow", _("\
 555 Catch an exception, when rethrown."),
 556                      catch_rethrow_command,
 557                      NULL,
 558                      CATCH_PERMANENT,
 559                      CATCH_TEMPORARY);
 560
 561   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 562 }