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   ~exception_catchpoint () override;
  80
  81   /* The kind of exception catchpoint.  */
  82
  83   enum exception_event_kind kind;
  84
  85   /* If non-NULL, an xmalloc'd string holding the source form of the
  86      regular expression to match against.  */
  87
  88   char *exception_rx;
  89
  90   /* If non-NULL, an xmalloc'd, compiled regular expression which is
  91      used to determine which exceptions to stop on.  */
  92
  93   regex_t *pattern;
  94 };
  95
  96 \f
  97
  98 /* A helper function that fetches exception probe arguments.  This
  99    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
 100    It will throw an exception on any kind of failure.  */
 101
 102 static void
 103 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 104 {
 105   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 106   CORE_ADDR pc = get_frame_pc (frame);
 107   struct bound_probe pc_probe;
 108   unsigned n_args;
 109
 110   pc_probe = find_probe_by_pc (pc);
 111   if (pc_probe.probe == NULL
 112       || strcmp (pc_probe.probe->provider, "libstdcxx") != 0
 113       || (strcmp (pc_probe.probe->name, "catch") != 0
 114           && strcmp (pc_probe.probe->name, "throw") != 0
 115           && strcmp (pc_probe.probe->name, "rethrow") != 0))
 116     error (_("not stopped at a C++ exception catchpoint"));
 117
 118   n_args = get_probe_argument_count (pc_probe.probe, frame);
 119   if (n_args < 2)
 120     error (_("C++ exception catchpoint has too few arguments"));
 121
 122   if (arg0 != NULL)
 123     *arg0 = evaluate_probe_argument (pc_probe.probe, 0, frame);
 124   *arg1 = evaluate_probe_argument (pc_probe.probe, 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 /* exception_catchpoint destructor.  */
 144
 145 exception_catchpoint::~exception_catchpoint ()
 146 {
 147   xfree (this->exception_rx);
 148   if (this->pattern != NULL)
 149     regfree (this->pattern);
 150 }
 151
 152 /* Implement the 'check_status' method.  */
 153
 154 static void
 155 check_status_exception_catchpoint (struct bpstats *bs)
 156 {
 157   struct exception_catchpoint *self
 158     = (struct exception_catchpoint *) bs->breakpoint_at;
 159   std::string type_name;
 160
 161   bkpt_breakpoint_ops.check_status (bs);
 162   if (bs->stop == 0)
 163     return;
 164
 165   if (self->pattern == NULL)
 166     return;
 167
 168   TRY
 169     {
 170       struct value *typeinfo_arg;
 171       std::string canon;
 172
 173       fetch_probe_arguments (NULL, &typeinfo_arg);
 174       type_name = cplus_typename_from_type_info (typeinfo_arg);
 175
 176       canon = cp_canonicalize_string (type_name.c_str ());
 177       if (!canon.empty ())
 178         std::swap (type_name, canon);
 179     }
 180   CATCH (e, RETURN_MASK_ERROR)
 181     {
 182       exception_print (gdb_stderr, e);
 183     }
 184   END_CATCH
 185
 186   if (!type_name.empty ())
 187     {
 188       if (regexec (self->pattern, type_name.c_str (), 0, NULL, 0) != 0)
 189         bs->stop = 0;
 190     }
 191 }
 192
 193 /* Implement the 're_set' method.  */
 194
 195 static void
 196 re_set_exception_catchpoint (struct breakpoint *self)
 197 {
 198   struct symtabs_and_lines sals = {0};
 199   struct symtabs_and_lines sals_end = {0};
 200   struct cleanup *cleanup;
 201   enum exception_event_kind kind = classify_exception_breakpoint (self);
 202   struct program_space *filter_pspace = current_program_space;
 203
 204   /* We first try to use the probe interface.  */
 205   TRY
 206     {
 207       event_location_up location
 208         = new_probe_location (exception_functions[kind].probe);
 209       sals = parse_probes (location.get (), filter_pspace, NULL);
 210     }
 211   CATCH (e, RETURN_MASK_ERROR)
 212     {
 213       /* Using the probe interface failed.  Let's fallback to the normal
 214          catchpoint mode.  */
 215       TRY
 216         {
 217           struct explicit_location explicit_loc;
 218
 219           initialize_explicit_location (&explicit_loc);
 220           explicit_loc.function_name
 221             = ASTRDUP (exception_functions[kind].function);
 222           event_location_up location = new_explicit_location (&explicit_loc);
 223           self->ops->decode_location (self, location.get (), filter_pspace,
 224                                       &sals);
 225         }
 226       CATCH (ex, RETURN_MASK_ERROR)
 227         {
 228           /* NOT_FOUND_ERROR just means the breakpoint will be
 229              pending, so let it through.  */
 230           if (ex.error != NOT_FOUND_ERROR)
 231             throw_exception (ex);
 232         }
 233       END_CATCH
 234     }
 235   END_CATCH
 236
 237   cleanup = make_cleanup (xfree, sals.sals);
 238   update_breakpoint_locations (self, filter_pspace, sals, sals_end);
 239   do_cleanups (cleanup);
 240 }
 241
 242 static enum print_stop_action
 243 print_it_exception_catchpoint (bpstat bs)
 244 {
 245   struct ui_out *uiout = current_uiout;
 246   struct breakpoint *b = bs->breakpoint_at;
 247   int bp_temp;
 248   enum exception_event_kind kind = classify_exception_breakpoint (b);
 249
 250   annotate_catchpoint (b->number);
 251   maybe_print_thread_hit_breakpoint (uiout);
 252
 253   bp_temp = b->disposition == disp_del;
 254   uiout->text (bp_temp ? "Temporary catchpoint "
 255                        : "Catchpoint ");
 256   if (!uiout->is_mi_like_p ())
 257     uiout->field_int ("bkptno", b->number);
 258   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 259                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 260                    : " (exception rethrown), ")));
 261   if (uiout->is_mi_like_p ())
 262     {
 263       uiout->field_string ("reason",
 264                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 265       uiout->field_string ("disp", bpdisp_text (b->disposition));
 266       uiout->field_int ("bkptno", b->number);
 267     }
 268   return PRINT_SRC_AND_LOC;
 269 }
 270
 271 static void
 272 print_one_exception_catchpoint (struct breakpoint *b,
 273                                 struct bp_location **last_loc)
 274 {
 275   struct value_print_options opts;
 276   struct ui_out *uiout = current_uiout;
 277   enum exception_event_kind kind = classify_exception_breakpoint (b);
 278
 279   get_user_print_options (&opts);
 280   if (opts.addressprint)
 281     {
 282       annotate_field (4);
 283       if (b->loc == NULL || b->loc->shlib_disabled)
 284         uiout->field_string ("addr", "<PENDING>");
 285       else
 286         uiout->field_core_addr ("addr",
 287                                 b->loc->gdbarch, b->loc->address);
 288     }
 289   annotate_field (5);
 290   if (b->loc)
 291     *last_loc = b->loc;
 292
 293   switch (kind)
 294     {
 295     case EX_EVENT_THROW:
 296       uiout->field_string ("what", "exception throw");
 297       if (uiout->is_mi_like_p ())
 298         uiout->field_string ("catch-type", "throw");
 299       break;
 300
 301     case EX_EVENT_RETHROW:
 302       uiout->field_string ("what", "exception rethrow");
 303       if (uiout->is_mi_like_p ())
 304         uiout->field_string ("catch-type", "rethrow");
 305       break;
 306
 307     case EX_EVENT_CATCH:
 308       uiout->field_string ("what", "exception catch");
 309       if (uiout->is_mi_like_p ())
 310         uiout->field_string ("catch-type", "catch");
 311       break;
 312     }
 313 }
 314
 315 /* Implement the 'print_one_detail' method.  */
 316
 317 static void
 318 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 319                                        struct ui_out *uiout)
 320 {
 321   const struct exception_catchpoint *cp
 322     = (const struct exception_catchpoint *) b;
 323
 324   if (cp->exception_rx != NULL)
 325     {
 326       uiout->text (_("\tmatching: "));
 327       uiout->field_string ("regexp", cp->exception_rx);
 328       uiout->text ("\n");
 329     }
 330 }
 331
 332 static void
 333 print_mention_exception_catchpoint (struct breakpoint *b)
 334 {
 335   struct ui_out *uiout = current_uiout;
 336   int bp_temp;
 337   enum exception_event_kind kind = classify_exception_breakpoint (b);
 338
 339   bp_temp = b->disposition == disp_del;
 340   uiout->text (bp_temp ? _("Temporary catchpoint ")
 341                               : _("Catchpoint "));
 342   uiout->field_int ("bkptno", b->number);
 343   uiout->text ((kind == EX_EVENT_THROW ? _(" (throw)")
 344                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 345                           : _(" (rethrow)"))));
 346 }
 347
 348 /* Implement the "print_recreate" breakpoint_ops method for throw and
 349    catch catchpoints.  */
 350
 351 static void
 352 print_recreate_exception_catchpoint (struct breakpoint *b,
 353                                      struct ui_file *fp)
 354 {
 355   int bp_temp;
 356   enum exception_event_kind kind = classify_exception_breakpoint (b);
 357
 358   bp_temp = b->disposition == disp_del;
 359   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 360   switch (kind)
 361     {
 362     case EX_EVENT_THROW:
 363       fprintf_unfiltered (fp, "throw");
 364       break;
 365     case EX_EVENT_CATCH:
 366       fprintf_unfiltered (fp, "catch");
 367       break;
 368     case EX_EVENT_RETHROW:
 369       fprintf_unfiltered (fp, "rethrow");
 370       break;
 371     }
 372   print_recreate_thread (b, fp);
 373 }
 374
 375 static void
 376 handle_gnu_v3_exceptions (int tempflag, char *except_rx,
 377                           const char *cond_string,
 378                           enum exception_event_kind ex_event, int from_tty)
 379 {
 380   regex_t *pattern = NULL;
 381
 382   if (except_rx != NULL)
 383     {
 384       pattern = XNEW (regex_t);
 385       make_cleanup (xfree, pattern);
 386
 387       compile_rx_or_error (pattern, except_rx,
 388                            _("invalid type-matching regexp"));
 389     }
 390
 391   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 392
 393   init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
 394                    &gnu_v3_exception_catchpoint_ops);
 395   /* We need to reset 'type' in order for code in breakpoint.c to do
 396      the right thing.  */
 397   cp->type = bp_breakpoint;
 398   cp->kind = ex_event;
 399   cp->exception_rx = except_rx;
 400   cp->pattern = pattern;
 401
 402   re_set_exception_catchpoint (cp.get ());
 403
 404   install_breakpoint (0, cp.get (), 1);
 405   cp.release ();
 406 }
 407
 408 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 409    by whitespace.
 410
 411    If there is any non-whitespace text between *STRING and the "if"
 412    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 413    this returns NULL.
 414
 415    STRING is updated to point to the "if" token, if it exists, or to
 416    the end of the string.  */
 417
 418 static char *
 419 extract_exception_regexp (const char **string)
 420 {
 421   const char *start;
 422   const char *last, *last_space;
 423
 424   start = skip_spaces_const (*string);
 425
 426   last = start;
 427   last_space = start;
 428   while (*last != '\0')
 429     {
 430       const char *if_token = last;
 431
 432       /* Check for the "if".  */
 433       if (check_for_argument (&if_token, "if", 2))
 434         break;
 435
 436       /* No "if" token here.  Skip to the next word start.  */
 437       last_space = skip_to_space (last);
 438       last = skip_spaces_const (last_space);
 439     }
 440
 441   *string = last;
 442   if (last_space > start)
 443     return savestring (start, last_space - start);
 444   return NULL;
 445 }
 446
 447 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 448    commands.  */
 449
 450 static void
 451 catch_exception_command_1 (enum exception_event_kind ex_event,
 452                            char *arg_entry,
 453                            int tempflag, int from_tty)
 454 {
 455   char *except_rx;
 456   const char *cond_string = NULL;
 457   struct cleanup *cleanup;
 458   const char *arg = arg_entry;
 459
 460   if (!arg)
 461     arg = "";
 462   arg = skip_spaces_const (arg);
 463
 464   except_rx = extract_exception_regexp (&arg);
 465   cleanup = make_cleanup (xfree, except_rx);
 466
 467   cond_string = ep_parse_optional_if_clause (&arg);
 468
 469   if ((*arg != '\0') && !isspace (*arg))
 470     error (_("Junk at end of arguments."));
 471
 472   if (ex_event != EX_EVENT_THROW
 473       && ex_event != EX_EVENT_CATCH
 474       && ex_event != EX_EVENT_RETHROW)
 475     error (_("Unsupported or unknown exception event; cannot catch it"));
 476
 477   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 478                             ex_event, from_tty);
 479
 480   discard_cleanups (cleanup);
 481 }
 482
 483 /* Implementation of "catch catch" command.  */
 484
 485 static void
 486 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 487 {
 488   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 489
 490   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 491 }
 492
 493 /* Implementation of "catch throw" command.  */
 494
 495 static void
 496 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 497 {
 498   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 499
 500   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 501 }
 502
 503 /* Implementation of "catch rethrow" command.  */
 504
 505 static void
 506 catch_rethrow_command (char *arg, int from_tty,
 507                        struct cmd_list_element *command)
 508 {
 509   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 510
 511   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 512 }
 513
 514 \f
 515
 516 /* Implement the 'make_value' method for the $_exception
 517    internalvar.  */
 518
 519 static struct value *
 520 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 521 {
 522   struct value *arg0, *arg1;
 523   struct type *obj_type;
 524
 525   fetch_probe_arguments (&arg0, &arg1);
 526
 527   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 528      the std::type_info for the exception.  Now we find the type from
 529      the type_info and cast the result.  */
 530   obj_type = cplus_type_from_type_info (arg1);
 531   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 532 }
 533
 534 /* Implementation of the '$_exception' variable.  */
 535
 536 static const struct internalvar_funcs exception_funcs =
 537 {
 538   compute_exception,
 539   NULL,
 540   NULL
 541 };
 542
 543 \f
 544
 545 static void
 546 initialize_throw_catchpoint_ops (void)
 547 {
 548   struct breakpoint_ops *ops;
 549
 550   initialize_breakpoint_ops ();
 551
 552   /* GNU v3 exception catchpoints.  */
 553   ops = &gnu_v3_exception_catchpoint_ops;
 554   *ops = bkpt_breakpoint_ops;
 555   ops->re_set = re_set_exception_catchpoint;
 556   ops->print_it = print_it_exception_catchpoint;
 557   ops->print_one = print_one_exception_catchpoint;
 558   ops->print_mention = print_mention_exception_catchpoint;
 559   ops->print_recreate = print_recreate_exception_catchpoint;
 560   ops->print_one_detail = print_one_detail_exception_catchpoint;
 561   ops->check_status = check_status_exception_catchpoint;
 562 }
 563
 564 initialize_file_ftype _initialize_break_catch_throw;
 565
 566 void
 567 _initialize_break_catch_throw (void)
 568 {
 569   initialize_throw_catchpoint_ops ();
 570
 571   /* Add catch and tcatch sub-commands.  */
 572   add_catch_command ("catch", _("\
 573 Catch an exception, when caught."),
 574                      catch_catch_command,
 575                      NULL,
 576                      CATCH_PERMANENT,
 577                      CATCH_TEMPORARY);
 578   add_catch_command ("throw", _("\
 579 Catch an exception, when thrown."),
 580                      catch_throw_command,
 581                      NULL,
 582                      CATCH_PERMANENT,
 583                      CATCH_TEMPORARY);
 584   add_catch_command ("rethrow", _("\
 585 Catch an exception, when rethrown."),
 586                      catch_rethrow_command,
 587                      NULL,
 588                      CATCH_PERMANENT,
 589                      CATCH_TEMPORARY);
 590
 591   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 592 }