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