gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2017 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.probe == NULL
 110       || strcmp (pc_probe.probe->provider, "libstdcxx") != 0
 111       || (strcmp (pc_probe.probe->name, "catch") != 0
 112           && strcmp (pc_probe.probe->name, "throw") != 0
 113           && strcmp (pc_probe.probe->name, "rethrow") != 0))
 114     error (_("not stopped at a C++ exception catchpoint"));
 115
 116   n_args = get_probe_argument_count (pc_probe.probe, frame);
 117   if (n_args < 2)
 118     error (_("C++ exception catchpoint has too few arguments"));
 119
 120   if (arg0 != NULL)
 121     *arg0 = evaluate_probe_argument (pc_probe.probe, 0, frame);
 122   *arg1 = evaluate_probe_argument (pc_probe.probe, 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 (e, RETURN_MASK_ERROR)
 170     {
 171       exception_print (gdb_stderr, e);
 172     }
 173   END_CATCH
 174
 175   if (!type_name.empty ())
 176     {
 177       if (self->pattern->exec (type_name.c_str (), 0, NULL, 0) != 0)
 178         bs->stop = 0;
 179     }
 180 }
 181
 182 /* Implement the 're_set' method.  */
 183
 184 static void
 185 re_set_exception_catchpoint (struct breakpoint *self)
 186 {
 187   std::vector<symtab_and_line> sals;
 188   enum exception_event_kind kind = classify_exception_breakpoint (self);
 189   struct program_space *filter_pspace = current_program_space;
 190
 191   /* We first try to use the probe interface.  */
 192   TRY
 193     {
 194       event_location_up location
 195         = new_probe_location (exception_functions[kind].probe);
 196       sals = parse_probes (location.get (), filter_pspace, NULL);
 197     }
 198   CATCH (e, RETURN_MASK_ERROR)
 199     {
 200       /* Using the probe interface failed.  Let's fallback to the normal
 201          catchpoint mode.  */
 202       TRY
 203         {
 204           struct explicit_location explicit_loc;
 205
 206           initialize_explicit_location (&explicit_loc);
 207           explicit_loc.function_name
 208             = ASTRDUP (exception_functions[kind].function);
 209           event_location_up location = new_explicit_location (&explicit_loc);
 210           sals = self->ops->decode_location (self, location.get (),
 211                                              filter_pspace);
 212         }
 213       CATCH (ex, RETURN_MASK_ERROR)
 214         {
 215           /* NOT_FOUND_ERROR just means the breakpoint will be
 216              pending, so let it through.  */
 217           if (ex.error != NOT_FOUND_ERROR)
 218             throw_exception (ex);
 219         }
 220       END_CATCH
 221     }
 222   END_CATCH
 223
 224   update_breakpoint_locations (self, filter_pspace, sals, {});
 225 }
 226
 227 static enum print_stop_action
 228 print_it_exception_catchpoint (bpstat bs)
 229 {
 230   struct ui_out *uiout = current_uiout;
 231   struct breakpoint *b = bs->breakpoint_at;
 232   int bp_temp;
 233   enum exception_event_kind kind = classify_exception_breakpoint (b);
 234
 235   annotate_catchpoint (b->number);
 236   maybe_print_thread_hit_breakpoint (uiout);
 237
 238   bp_temp = b->disposition == disp_del;
 239   uiout->text (bp_temp ? "Temporary catchpoint "
 240                        : "Catchpoint ");
 241   if (!uiout->is_mi_like_p ())
 242     uiout->field_int ("bkptno", b->number);
 243   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 244                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 245                    : " (exception rethrown), ")));
 246   if (uiout->is_mi_like_p ())
 247     {
 248       uiout->field_string ("reason",
 249                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 250       uiout->field_string ("disp", bpdisp_text (b->disposition));
 251       uiout->field_int ("bkptno", b->number);
 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   if (opts.addressprint)
 266     {
 267       annotate_field (4);
 268       if (b->loc == NULL || b->loc->shlib_disabled)
 269         uiout->field_string ("addr", "<PENDING>");
 270       else
 271         uiout->field_core_addr ("addr",
 272                                 b->loc->gdbarch, b->loc->address);
 273     }
 274   annotate_field (5);
 275   if (b->loc)
 276     *last_loc = b->loc;
 277
 278   switch (kind)
 279     {
 280     case EX_EVENT_THROW:
 281       uiout->field_string ("what", "exception throw");
 282       if (uiout->is_mi_like_p ())
 283         uiout->field_string ("catch-type", "throw");
 284       break;
 285
 286     case EX_EVENT_RETHROW:
 287       uiout->field_string ("what", "exception rethrow");
 288       if (uiout->is_mi_like_p ())
 289         uiout->field_string ("catch-type", "rethrow");
 290       break;
 291
 292     case EX_EVENT_CATCH:
 293       uiout->field_string ("what", "exception catch");
 294       if (uiout->is_mi_like_p ())
 295         uiout->field_string ("catch-type", "catch");
 296       break;
 297     }
 298 }
 299
 300 /* Implement the 'print_one_detail' method.  */
 301
 302 static void
 303 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 304                                        struct ui_out *uiout)
 305 {
 306   const struct exception_catchpoint *cp
 307     = (const struct exception_catchpoint *) b;
 308
 309   if (!cp->exception_rx.empty ())
 310     {
 311       uiout->text (_("\tmatching: "));
 312       uiout->field_string ("regexp", cp->exception_rx.c_str ());
 313       uiout->text ("\n");
 314     }
 315 }
 316
 317 static void
 318 print_mention_exception_catchpoint (struct breakpoint *b)
 319 {
 320   struct ui_out *uiout = current_uiout;
 321   int bp_temp;
 322   enum exception_event_kind kind = classify_exception_breakpoint (b);
 323
 324   bp_temp = b->disposition == disp_del;
 325   uiout->text (bp_temp ? _("Temporary catchpoint ")
 326                               : _("Catchpoint "));
 327   uiout->field_int ("bkptno", b->number);
 328   uiout->text ((kind == EX_EVENT_THROW ? _(" (throw)")
 329                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 330                           : _(" (rethrow)"))));
 331 }
 332
 333 /* Implement the "print_recreate" breakpoint_ops method for throw and
 334    catch catchpoints.  */
 335
 336 static void
 337 print_recreate_exception_catchpoint (struct breakpoint *b,
 338                                      struct ui_file *fp)
 339 {
 340   int bp_temp;
 341   enum exception_event_kind kind = classify_exception_breakpoint (b);
 342
 343   bp_temp = b->disposition == disp_del;
 344   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 345   switch (kind)
 346     {
 347     case EX_EVENT_THROW:
 348       fprintf_unfiltered (fp, "throw");
 349       break;
 350     case EX_EVENT_CATCH:
 351       fprintf_unfiltered (fp, "catch");
 352       break;
 353     case EX_EVENT_RETHROW:
 354       fprintf_unfiltered (fp, "rethrow");
 355       break;
 356     }
 357   print_recreate_thread (b, fp);
 358 }
 359
 360 static void
 361 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 362                           const char *cond_string,
 363                           enum exception_event_kind ex_event, int from_tty)
 364 {
 365   std::unique_ptr<compiled_regex> pattern;
 366
 367   if (!except_rx.empty ())
 368     {
 369       pattern.reset (new compiled_regex (except_rx.c_str (), REG_NOSUB,
 370                                          _("invalid type-matching regexp")));
 371     }
 372
 373   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 374
 375   init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
 376                    &gnu_v3_exception_catchpoint_ops);
 377   /* We need to reset 'type' in order for code in breakpoint.c to do
 378      the right thing.  */
 379   cp->type = bp_breakpoint;
 380   cp->kind = ex_event;
 381   cp->exception_rx = std::move (except_rx);
 382   cp->pattern = std::move (pattern);
 383
 384   re_set_exception_catchpoint (cp.get ());
 385
 386   install_breakpoint (0, std::move (cp), 1);
 387 }
 388
 389 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 390    by whitespace.
 391
 392    If there is any non-whitespace text between *STRING and the "if"
 393    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 394    this returns NULL.
 395
 396    STRING is updated to point to the "if" token, if it exists, or to
 397    the end of the string.  */
 398
 399 static std::string
 400 extract_exception_regexp (const char **string)
 401 {
 402   const char *start;
 403   const char *last, *last_space;
 404
 405   start = skip_spaces (*string);
 406
 407   last = start;
 408   last_space = start;
 409   while (*last != '\0')
 410     {
 411       const char *if_token = last;
 412
 413       /* Check for the "if".  */
 414       if (check_for_argument (&if_token, "if", 2))
 415         break;
 416
 417       /* No "if" token here.  Skip to the next word start.  */
 418       last_space = skip_to_space (last);
 419       last = skip_spaces (last_space);
 420     }
 421
 422   *string = last;
 423   if (last_space > start)
 424     return std::string (start, last_space - start);
 425   return std::string ();
 426 }
 427
 428 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 429    commands.  */
 430
 431 static void
 432 catch_exception_command_1 (enum exception_event_kind ex_event,
 433                            char *arg_entry,
 434                            int tempflag, int from_tty)
 435 {
 436   const char *cond_string = NULL;
 437   const char *arg = arg_entry;
 438
 439   if (!arg)
 440     arg = "";
 441   arg = skip_spaces (arg);
 442
 443   std::string except_rx = extract_exception_regexp (&arg);
 444
 445   cond_string = ep_parse_optional_if_clause (&arg);
 446
 447   if ((*arg != '\0') && !isspace (*arg))
 448     error (_("Junk at end of arguments."));
 449
 450   if (ex_event != EX_EVENT_THROW
 451       && ex_event != EX_EVENT_CATCH
 452       && ex_event != EX_EVENT_RETHROW)
 453     error (_("Unsupported or unknown exception event; cannot catch it"));
 454
 455   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 456                             ex_event, from_tty);
 457 }
 458
 459 /* Implementation of "catch catch" command.  */
 460
 461 static void
 462 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 463 {
 464   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 465
 466   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 467 }
 468
 469 /* Implementation of "catch throw" command.  */
 470
 471 static void
 472 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 473 {
 474   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 475
 476   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 477 }
 478
 479 /* Implementation of "catch rethrow" command.  */
 480
 481 static void
 482 catch_rethrow_command (char *arg, int from_tty,
 483                        struct cmd_list_element *command)
 484 {
 485   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 486
 487   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 488 }
 489
 490 \f
 491
 492 /* Implement the 'make_value' method for the $_exception
 493    internalvar.  */
 494
 495 static struct value *
 496 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 497 {
 498   struct value *arg0, *arg1;
 499   struct type *obj_type;
 500
 501   fetch_probe_arguments (&arg0, &arg1);
 502
 503   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 504      the std::type_info for the exception.  Now we find the type from
 505      the type_info and cast the result.  */
 506   obj_type = cplus_type_from_type_info (arg1);
 507   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 508 }
 509
 510 /* Implementation of the '$_exception' variable.  */
 511
 512 static const struct internalvar_funcs exception_funcs =
 513 {
 514   compute_exception,
 515   NULL,
 516   NULL
 517 };
 518
 519 \f
 520
 521 static void
 522 initialize_throw_catchpoint_ops (void)
 523 {
 524   struct breakpoint_ops *ops;
 525
 526   initialize_breakpoint_ops ();
 527
 528   /* GNU v3 exception catchpoints.  */
 529   ops = &gnu_v3_exception_catchpoint_ops;
 530   *ops = bkpt_breakpoint_ops;
 531   ops->re_set = re_set_exception_catchpoint;
 532   ops->print_it = print_it_exception_catchpoint;
 533   ops->print_one = print_one_exception_catchpoint;
 534   ops->print_mention = print_mention_exception_catchpoint;
 535   ops->print_recreate = print_recreate_exception_catchpoint;
 536   ops->print_one_detail = print_one_detail_exception_catchpoint;
 537   ops->check_status = check_status_exception_catchpoint;
 538 }
 539
 540 void
 541 _initialize_break_catch_throw (void)
 542 {
 543   initialize_throw_catchpoint_ops ();
 544
 545   /* Add catch and tcatch sub-commands.  */
 546   add_catch_command ("catch", _("\
 547 Catch an exception, when caught."),
 548                      catch_catch_command,
 549                      NULL,
 550                      CATCH_PERMANENT,
 551                      CATCH_TEMPORARY);
 552   add_catch_command ("throw", _("\
 553 Catch an exception, when thrown."),
 554                      catch_throw_command,
 555                      NULL,
 556                      CATCH_PERMANENT,
 557                      CATCH_TEMPORARY);
 558   add_catch_command ("rethrow", _("\
 559 Catch an exception, when rethrown."),
 560                      catch_rethrow_command,
 561                      NULL,
 562                      CATCH_PERMANENT,
 563                      CATCH_TEMPORARY);
 564
 565   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 566 }