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   struct symtabs_and_lines sals = {0};
 188   struct symtabs_and_lines sals_end = {0};
 189   struct cleanup *cleanup;
 190   enum exception_event_kind kind = classify_exception_breakpoint (self);
 191   struct program_space *filter_pspace = current_program_space;
 192
 193   /* We first try to use the probe interface.  */
 194   TRY
 195     {
 196       event_location_up location
 197         = new_probe_location (exception_functions[kind].probe);
 198       sals = parse_probes (location.get (), filter_pspace, NULL);
 199     }
 200   CATCH (e, RETURN_MASK_ERROR)
 201     {
 202       /* Using the probe interface failed.  Let's fallback to the normal
 203          catchpoint mode.  */
 204       TRY
 205         {
 206           struct explicit_location explicit_loc;
 207
 208           initialize_explicit_location (&explicit_loc);
 209           explicit_loc.function_name
 210             = ASTRDUP (exception_functions[kind].function);
 211           event_location_up location = new_explicit_location (&explicit_loc);
 212           self->ops->decode_location (self, location.get (), filter_pspace,
 213                                       &sals);
 214         }
 215       CATCH (ex, RETURN_MASK_ERROR)
 216         {
 217           /* NOT_FOUND_ERROR just means the breakpoint will be
 218              pending, so let it through.  */
 219           if (ex.error != NOT_FOUND_ERROR)
 220             throw_exception (ex);
 221         }
 222       END_CATCH
 223     }
 224   END_CATCH
 225
 226   cleanup = make_cleanup (xfree, sals.sals);
 227   update_breakpoint_locations (self, filter_pspace, sals, sals_end);
 228   do_cleanups (cleanup);
 229 }
 230
 231 static enum print_stop_action
 232 print_it_exception_catchpoint (bpstat bs)
 233 {
 234   struct ui_out *uiout = current_uiout;
 235   struct breakpoint *b = bs->breakpoint_at;
 236   int bp_temp;
 237   enum exception_event_kind kind = classify_exception_breakpoint (b);
 238
 239   annotate_catchpoint (b->number);
 240   maybe_print_thread_hit_breakpoint (uiout);
 241
 242   bp_temp = b->disposition == disp_del;
 243   uiout->text (bp_temp ? "Temporary catchpoint "
 244                        : "Catchpoint ");
 245   if (!uiout->is_mi_like_p ())
 246     uiout->field_int ("bkptno", b->number);
 247   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 248                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 249                    : " (exception rethrown), ")));
 250   if (uiout->is_mi_like_p ())
 251     {
 252       uiout->field_string ("reason",
 253                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 254       uiout->field_string ("disp", bpdisp_text (b->disposition));
 255       uiout->field_int ("bkptno", b->number);
 256     }
 257   return PRINT_SRC_AND_LOC;
 258 }
 259
 260 static void
 261 print_one_exception_catchpoint (struct breakpoint *b,
 262                                 struct bp_location **last_loc)
 263 {
 264   struct value_print_options opts;
 265   struct ui_out *uiout = current_uiout;
 266   enum exception_event_kind kind = classify_exception_breakpoint (b);
 267
 268   get_user_print_options (&opts);
 269   if (opts.addressprint)
 270     {
 271       annotate_field (4);
 272       if (b->loc == NULL || b->loc->shlib_disabled)
 273         uiout->field_string ("addr", "<PENDING>");
 274       else
 275         uiout->field_core_addr ("addr",
 276                                 b->loc->gdbarch, b->loc->address);
 277     }
 278   annotate_field (5);
 279   if (b->loc)
 280     *last_loc = b->loc;
 281
 282   switch (kind)
 283     {
 284     case EX_EVENT_THROW:
 285       uiout->field_string ("what", "exception throw");
 286       if (uiout->is_mi_like_p ())
 287         uiout->field_string ("catch-type", "throw");
 288       break;
 289
 290     case EX_EVENT_RETHROW:
 291       uiout->field_string ("what", "exception rethrow");
 292       if (uiout->is_mi_like_p ())
 293         uiout->field_string ("catch-type", "rethrow");
 294       break;
 295
 296     case EX_EVENT_CATCH:
 297       uiout->field_string ("what", "exception catch");
 298       if (uiout->is_mi_like_p ())
 299         uiout->field_string ("catch-type", "catch");
 300       break;
 301     }
 302 }
 303
 304 /* Implement the 'print_one_detail' method.  */
 305
 306 static void
 307 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 308                                        struct ui_out *uiout)
 309 {
 310   const struct exception_catchpoint *cp
 311     = (const struct exception_catchpoint *) b;
 312
 313   if (!cp->exception_rx.empty ())
 314     {
 315       uiout->text (_("\tmatching: "));
 316       uiout->field_string ("regexp", cp->exception_rx.c_str ());
 317       uiout->text ("\n");
 318     }
 319 }
 320
 321 static void
 322 print_mention_exception_catchpoint (struct breakpoint *b)
 323 {
 324   struct ui_out *uiout = current_uiout;
 325   int bp_temp;
 326   enum exception_event_kind kind = classify_exception_breakpoint (b);
 327
 328   bp_temp = b->disposition == disp_del;
 329   uiout->text (bp_temp ? _("Temporary catchpoint ")
 330                               : _("Catchpoint "));
 331   uiout->field_int ("bkptno", b->number);
 332   uiout->text ((kind == EX_EVENT_THROW ? _(" (throw)")
 333                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 334                           : _(" (rethrow)"))));
 335 }
 336
 337 /* Implement the "print_recreate" breakpoint_ops method for throw and
 338    catch catchpoints.  */
 339
 340 static void
 341 print_recreate_exception_catchpoint (struct breakpoint *b,
 342                                      struct ui_file *fp)
 343 {
 344   int bp_temp;
 345   enum exception_event_kind kind = classify_exception_breakpoint (b);
 346
 347   bp_temp = b->disposition == disp_del;
 348   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 349   switch (kind)
 350     {
 351     case EX_EVENT_THROW:
 352       fprintf_unfiltered (fp, "throw");
 353       break;
 354     case EX_EVENT_CATCH:
 355       fprintf_unfiltered (fp, "catch");
 356       break;
 357     case EX_EVENT_RETHROW:
 358       fprintf_unfiltered (fp, "rethrow");
 359       break;
 360     }
 361   print_recreate_thread (b, fp);
 362 }
 363
 364 static void
 365 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 366                           const char *cond_string,
 367                           enum exception_event_kind ex_event, int from_tty)
 368 {
 369   std::unique_ptr<compiled_regex> pattern;
 370
 371   if (!except_rx.empty ())
 372     {
 373       pattern.reset (new compiled_regex (except_rx.c_str (), REG_NOSUB,
 374                                          _("invalid type-matching regexp")));
 375     }
 376
 377   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 378
 379   init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
 380                    &gnu_v3_exception_catchpoint_ops);
 381   /* We need to reset 'type' in order for code in breakpoint.c to do
 382      the right thing.  */
 383   cp->type = bp_breakpoint;
 384   cp->kind = ex_event;
 385   cp->exception_rx = std::move (except_rx);
 386   cp->pattern = std::move (pattern);
 387
 388   re_set_exception_catchpoint (cp.get ());
 389
 390   install_breakpoint (0, std::move (cp), 1);
 391 }
 392
 393 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 394    by whitespace.
 395
 396    If there is any non-whitespace text between *STRING and the "if"
 397    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 398    this returns NULL.
 399
 400    STRING is updated to point to the "if" token, if it exists, or to
 401    the end of the string.  */
 402
 403 static std::string
 404 extract_exception_regexp (const char **string)
 405 {
 406   const char *start;
 407   const char *last, *last_space;
 408
 409   start = skip_spaces_const (*string);
 410
 411   last = start;
 412   last_space = start;
 413   while (*last != '\0')
 414     {
 415       const char *if_token = last;
 416
 417       /* Check for the "if".  */
 418       if (check_for_argument (&if_token, "if", 2))
 419         break;
 420
 421       /* No "if" token here.  Skip to the next word start.  */
 422       last_space = skip_to_space (last);
 423       last = skip_spaces_const (last_space);
 424     }
 425
 426   *string = last;
 427   if (last_space > start)
 428     return std::string (start, last_space - start);
 429   return std::string ();
 430 }
 431
 432 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 433    commands.  */
 434
 435 static void
 436 catch_exception_command_1 (enum exception_event_kind ex_event,
 437                            char *arg_entry,
 438                            int tempflag, int from_tty)
 439 {
 440   const char *cond_string = NULL;
 441   const char *arg = arg_entry;
 442
 443   if (!arg)
 444     arg = "";
 445   arg = skip_spaces_const (arg);
 446
 447   std::string except_rx = extract_exception_regexp (&arg);
 448
 449   cond_string = ep_parse_optional_if_clause (&arg);
 450
 451   if ((*arg != '\0') && !isspace (*arg))
 452     error (_("Junk at end of arguments."));
 453
 454   if (ex_event != EX_EVENT_THROW
 455       && ex_event != EX_EVENT_CATCH
 456       && ex_event != EX_EVENT_RETHROW)
 457     error (_("Unsupported or unknown exception event; cannot catch it"));
 458
 459   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 460                             ex_event, from_tty);
 461 }
 462
 463 /* Implementation of "catch catch" command.  */
 464
 465 static void
 466 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 467 {
 468   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 469
 470   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 471 }
 472
 473 /* Implementation of "catch throw" command.  */
 474
 475 static void
 476 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 477 {
 478   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 479
 480   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 481 }
 482
 483 /* Implementation of "catch rethrow" command.  */
 484
 485 static void
 486 catch_rethrow_command (char *arg, int from_tty,
 487                        struct cmd_list_element *command)
 488 {
 489   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 490
 491   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 492 }
 493
 494 \f
 495
 496 /* Implement the 'make_value' method for the $_exception
 497    internalvar.  */
 498
 499 static struct value *
 500 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 501 {
 502   struct value *arg0, *arg1;
 503   struct type *obj_type;
 504
 505   fetch_probe_arguments (&arg0, &arg1);
 506
 507   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 508      the std::type_info for the exception.  Now we find the type from
 509      the type_info and cast the result.  */
 510   obj_type = cplus_type_from_type_info (arg1);
 511   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 512 }
 513
 514 /* Implementation of the '$_exception' variable.  */
 515
 516 static const struct internalvar_funcs exception_funcs =
 517 {
 518   compute_exception,
 519   NULL,
 520   NULL
 521 };
 522
 523 \f
 524
 525 static void
 526 initialize_throw_catchpoint_ops (void)
 527 {
 528   struct breakpoint_ops *ops;
 529
 530   initialize_breakpoint_ops ();
 531
 532   /* GNU v3 exception catchpoints.  */
 533   ops = &gnu_v3_exception_catchpoint_ops;
 534   *ops = bkpt_breakpoint_ops;
 535   ops->re_set = re_set_exception_catchpoint;
 536   ops->print_it = print_it_exception_catchpoint;
 537   ops->print_one = print_one_exception_catchpoint;
 538   ops->print_mention = print_mention_exception_catchpoint;
 539   ops->print_recreate = print_recreate_exception_catchpoint;
 540   ops->print_one_detail = print_one_detail_exception_catchpoint;
 541   ops->check_status = check_status_exception_catchpoint;
 542 }
 543
 544 initialize_file_ftype _initialize_break_catch_throw;
 545
 546 void
 547 _initialize_break_catch_throw (void)
 548 {
 549   initialize_throw_catchpoint_ops ();
 550
 551   /* Add catch and tcatch sub-commands.  */
 552   add_catch_command ("catch", _("\
 553 Catch an exception, when caught."),
 554                      catch_catch_command,
 555                      NULL,
 556                      CATCH_PERMANENT,
 557                      CATCH_TEMPORARY);
 558   add_catch_command ("throw", _("\
 559 Catch an exception, when thrown."),
 560                      catch_throw_command,
 561                      NULL,
 562                      CATCH_PERMANENT,
 563                      CATCH_TEMPORARY);
 564   add_catch_command ("rethrow", _("\
 565 Catch an exception, when rethrown."),
 566                      catch_rethrow_command,
 567                      NULL,
 568                      CATCH_PERMANENT,
 569                      CATCH_TEMPORARY);
 570
 571   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 572 }