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
  78 {
  79   /* The base class.  */
  80
  81   struct breakpoint base;
  82
  83   /* The kind of exception catchpoint.  */
  84
  85   enum exception_event_kind kind;
  86
  87   /* If non-NULL, an xmalloc'd string holding the source form of the
  88      regular expression to match against.  */
  89
  90   char *exception_rx;
  91
  92   /* If non-NULL, an xmalloc'd, compiled regular expression which is
  93      used to determine which exceptions to stop on.  */
  94
  95   regex_t *pattern;
  96 };
  97
  98 \f
  99
 100 /* A helper function that fetches exception probe arguments.  This
 101    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
 102    It will throw an exception on any kind of failure.  */
 103
 104 static void
 105 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 106 {
 107   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 108   CORE_ADDR pc = get_frame_pc (frame);
 109   struct bound_probe pc_probe;
 110   unsigned n_args;
 111
 112   pc_probe = find_probe_by_pc (pc);
 113   if (pc_probe.probe == NULL
 114       || strcmp (pc_probe.probe->provider, "libstdcxx") != 0
 115       || (strcmp (pc_probe.probe->name, "catch") != 0
 116           && strcmp (pc_probe.probe->name, "throw") != 0
 117           && strcmp (pc_probe.probe->name, "rethrow") != 0))
 118     error (_("not stopped at a C++ exception catchpoint"));
 119
 120   n_args = get_probe_argument_count (pc_probe.probe, frame);
 121   if (n_args < 2)
 122     error (_("C++ exception catchpoint has too few arguments"));
 123
 124   if (arg0 != NULL)
 125     *arg0 = evaluate_probe_argument (pc_probe.probe, 0, frame);
 126   *arg1 = evaluate_probe_argument (pc_probe.probe, 1, frame);
 127
 128   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 129     error (_("error computing probe argument at c++ exception catchpoint"));
 130 }
 131
 132 \f
 133
 134 /* A helper function that returns a value indicating the kind of the
 135    exception catchpoint B.  */
 136
 137 static enum exception_event_kind
 138 classify_exception_breakpoint (struct breakpoint *b)
 139 {
 140   struct exception_catchpoint *cp = (struct exception_catchpoint *) b;
 141
 142   return cp->kind;
 143 }
 144
 145 /* Implement the 'dtor' method.  */
 146
 147 static void
 148 dtor_exception_catchpoint (struct breakpoint *self)
 149 {
 150   struct exception_catchpoint *cp = (struct exception_catchpoint *) self;
 151
 152   xfree (cp->exception_rx);
 153   if (cp->pattern != NULL)
 154     regfree (cp->pattern);
 155   bkpt_breakpoint_ops.dtor (self);
 156 }
 157
 158 /* Implement the 'check_status' method.  */
 159
 160 static void
 161 check_status_exception_catchpoint (struct bpstats *bs)
 162 {
 163   struct exception_catchpoint *self
 164     = (struct exception_catchpoint *) bs->breakpoint_at;
 165   std::string type_name;
 166
 167   bkpt_breakpoint_ops.check_status (bs);
 168   if (bs->stop == 0)
 169     return;
 170
 171   if (self->pattern == NULL)
 172     return;
 173
 174   TRY
 175     {
 176       struct value *typeinfo_arg;
 177       std::string canon;
 178
 179       fetch_probe_arguments (NULL, &typeinfo_arg);
 180       type_name = cplus_typename_from_type_info (typeinfo_arg);
 181
 182       canon = cp_canonicalize_string (type_name.c_str ());
 183       if (!canon.empty ())
 184         std::swap (type_name, canon);
 185     }
 186   CATCH (e, RETURN_MASK_ERROR)
 187     {
 188       exception_print (gdb_stderr, e);
 189     }
 190   END_CATCH
 191
 192   if (!type_name.empty ())
 193     {
 194       if (regexec (self->pattern, type_name.c_str (), 0, NULL, 0) != 0)
 195         bs->stop = 0;
 196     }
 197 }
 198
 199 /* Implement the 're_set' method.  */
 200
 201 static void
 202 re_set_exception_catchpoint (struct breakpoint *self)
 203 {
 204   struct symtabs_and_lines sals = {0};
 205   struct symtabs_and_lines sals_end = {0};
 206   struct cleanup *cleanup;
 207   enum exception_event_kind kind = classify_exception_breakpoint (self);
 208   struct program_space *filter_pspace = current_program_space;
 209
 210   /* We first try to use the probe interface.  */
 211   TRY
 212     {
 213       event_location_up location
 214         = new_probe_location (exception_functions[kind].probe);
 215       sals = parse_probes (location.get (), filter_pspace, NULL);
 216     }
 217   CATCH (e, RETURN_MASK_ERROR)
 218     {
 219       /* Using the probe interface failed.  Let's fallback to the normal
 220          catchpoint mode.  */
 221       TRY
 222         {
 223           struct explicit_location explicit_loc;
 224
 225           initialize_explicit_location (&explicit_loc);
 226           explicit_loc.function_name
 227             = ASTRDUP (exception_functions[kind].function);
 228           event_location_up location = new_explicit_location (&explicit_loc);
 229           self->ops->decode_location (self, location.get (), filter_pspace,
 230                                       &sals);
 231         }
 232       CATCH (ex, RETURN_MASK_ERROR)
 233         {
 234           /* NOT_FOUND_ERROR just means the breakpoint will be
 235              pending, so let it through.  */
 236           if (ex.error != NOT_FOUND_ERROR)
 237             throw_exception (ex);
 238         }
 239       END_CATCH
 240     }
 241   END_CATCH
 242
 243   cleanup = make_cleanup (xfree, sals.sals);
 244   update_breakpoint_locations (self, filter_pspace, sals, sals_end);
 245   do_cleanups (cleanup);
 246 }
 247
 248 static enum print_stop_action
 249 print_it_exception_catchpoint (bpstat bs)
 250 {
 251   struct ui_out *uiout = current_uiout;
 252   struct breakpoint *b = bs->breakpoint_at;
 253   int bp_temp;
 254   enum exception_event_kind kind = classify_exception_breakpoint (b);
 255
 256   annotate_catchpoint (b->number);
 257   maybe_print_thread_hit_breakpoint (uiout);
 258
 259   bp_temp = b->disposition == disp_del;
 260   uiout->text (bp_temp ? "Temporary catchpoint "
 261                        : "Catchpoint ");
 262   if (!uiout->is_mi_like_p ())
 263     uiout->field_int ("bkptno", b->number);
 264   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 265                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 266                    : " (exception rethrown), ")));
 267   if (uiout->is_mi_like_p ())
 268     {
 269       uiout->field_string ("reason",
 270                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 271       uiout->field_string ("disp", bpdisp_text (b->disposition));
 272       uiout->field_int ("bkptno", b->number);
 273     }
 274   return PRINT_SRC_AND_LOC;
 275 }
 276
 277 static void
 278 print_one_exception_catchpoint (struct breakpoint *b,
 279                                 struct bp_location **last_loc)
 280 {
 281   struct value_print_options opts;
 282   struct ui_out *uiout = current_uiout;
 283   enum exception_event_kind kind = classify_exception_breakpoint (b);
 284
 285   get_user_print_options (&opts);
 286   if (opts.addressprint)
 287     {
 288       annotate_field (4);
 289       if (b->loc == NULL || b->loc->shlib_disabled)
 290         uiout->field_string ("addr", "<PENDING>");
 291       else
 292         uiout->field_core_addr ("addr",
 293                                 b->loc->gdbarch, b->loc->address);
 294     }
 295   annotate_field (5);
 296   if (b->loc)
 297     *last_loc = b->loc;
 298
 299   switch (kind)
 300     {
 301     case EX_EVENT_THROW:
 302       uiout->field_string ("what", "exception throw");
 303       if (uiout->is_mi_like_p ())
 304         uiout->field_string ("catch-type", "throw");
 305       break;
 306
 307     case EX_EVENT_RETHROW:
 308       uiout->field_string ("what", "exception rethrow");
 309       if (uiout->is_mi_like_p ())
 310         uiout->field_string ("catch-type", "rethrow");
 311       break;
 312
 313     case EX_EVENT_CATCH:
 314       uiout->field_string ("what", "exception catch");
 315       if (uiout->is_mi_like_p ())
 316         uiout->field_string ("catch-type", "catch");
 317       break;
 318     }
 319 }
 320
 321 /* Implement the 'print_one_detail' method.  */
 322
 323 static void
 324 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 325                                        struct ui_out *uiout)
 326 {
 327   const struct exception_catchpoint *cp
 328     = (const struct exception_catchpoint *) b;
 329
 330   if (cp->exception_rx != NULL)
 331     {
 332       uiout->text (_("\tmatching: "));
 333       uiout->field_string ("regexp", cp->exception_rx);
 334       uiout->text ("\n");
 335     }
 336 }
 337
 338 static void
 339 print_mention_exception_catchpoint (struct breakpoint *b)
 340 {
 341   struct ui_out *uiout = current_uiout;
 342   int bp_temp;
 343   enum exception_event_kind kind = classify_exception_breakpoint (b);
 344
 345   bp_temp = b->disposition == disp_del;
 346   uiout->text (bp_temp ? _("Temporary catchpoint ")
 347                               : _("Catchpoint "));
 348   uiout->field_int ("bkptno", b->number);
 349   uiout->text ((kind == EX_EVENT_THROW ? _(" (throw)")
 350                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 351                           : _(" (rethrow)"))));
 352 }
 353
 354 /* Implement the "print_recreate" breakpoint_ops method for throw and
 355    catch catchpoints.  */
 356
 357 static void
 358 print_recreate_exception_catchpoint (struct breakpoint *b,
 359                                      struct ui_file *fp)
 360 {
 361   int bp_temp;
 362   enum exception_event_kind kind = classify_exception_breakpoint (b);
 363
 364   bp_temp = b->disposition == disp_del;
 365   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 366   switch (kind)
 367     {
 368     case EX_EVENT_THROW:
 369       fprintf_unfiltered (fp, "throw");
 370       break;
 371     case EX_EVENT_CATCH:
 372       fprintf_unfiltered (fp, "catch");
 373       break;
 374     case EX_EVENT_RETHROW:
 375       fprintf_unfiltered (fp, "rethrow");
 376       break;
 377     }
 378   print_recreate_thread (b, fp);
 379 }
 380
 381 static void
 382 handle_gnu_v3_exceptions (int tempflag, char *except_rx,
 383                           const char *cond_string,
 384                           enum exception_event_kind ex_event, int from_tty)
 385 {
 386   regex_t *pattern = NULL;
 387
 388   if (except_rx != NULL)
 389     {
 390       pattern = XNEW (regex_t);
 391       make_cleanup (xfree, pattern);
 392
 393       compile_rx_or_error (pattern, except_rx,
 394                            _("invalid type-matching regexp"));
 395     }
 396
 397   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 398
 399   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 400                    &gnu_v3_exception_catchpoint_ops);
 401   /* We need to reset 'type' in order for code in breakpoint.c to do
 402      the right thing.  */
 403   cp->base.type = bp_breakpoint;
 404   cp->kind = ex_event;
 405   cp->exception_rx = except_rx;
 406   cp->pattern = pattern;
 407
 408   re_set_exception_catchpoint (&cp->base);
 409
 410   install_breakpoint (0, &cp->base, 1);
 411   cp.release ();
 412 }
 413
 414 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 415    by whitespace.
 416
 417    If there is any non-whitespace text between *STRING and the "if"
 418    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 419    this returns NULL.
 420
 421    STRING is updated to point to the "if" token, if it exists, or to
 422    the end of the string.  */
 423
 424 static char *
 425 extract_exception_regexp (const char **string)
 426 {
 427   const char *start;
 428   const char *last, *last_space;
 429
 430   start = skip_spaces_const (*string);
 431
 432   last = start;
 433   last_space = start;
 434   while (*last != '\0')
 435     {
 436       const char *if_token = last;
 437
 438       /* Check for the "if".  */
 439       if (check_for_argument (&if_token, "if", 2))
 440         break;
 441
 442       /* No "if" token here.  Skip to the next word start.  */
 443       last_space = skip_to_space (last);
 444       last = skip_spaces_const (last_space);
 445     }
 446
 447   *string = last;
 448   if (last_space > start)
 449     return savestring (start, last_space - start);
 450   return NULL;
 451 }
 452
 453 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 454    commands.  */
 455
 456 static void
 457 catch_exception_command_1 (enum exception_event_kind ex_event,
 458                            char *arg_entry,
 459                            int tempflag, int from_tty)
 460 {
 461   char *except_rx;
 462   const char *cond_string = NULL;
 463   struct cleanup *cleanup;
 464   const char *arg = arg_entry;
 465
 466   if (!arg)
 467     arg = "";
 468   arg = skip_spaces_const (arg);
 469
 470   except_rx = extract_exception_regexp (&arg);
 471   cleanup = make_cleanup (xfree, except_rx);
 472
 473   cond_string = ep_parse_optional_if_clause (&arg);
 474
 475   if ((*arg != '\0') && !isspace (*arg))
 476     error (_("Junk at end of arguments."));
 477
 478   if (ex_event != EX_EVENT_THROW
 479       && ex_event != EX_EVENT_CATCH
 480       && ex_event != EX_EVENT_RETHROW)
 481     error (_("Unsupported or unknown exception event; cannot catch it"));
 482
 483   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 484                             ex_event, from_tty);
 485
 486   discard_cleanups (cleanup);
 487 }
 488
 489 /* Implementation of "catch catch" command.  */
 490
 491 static void
 492 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 493 {
 494   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 495
 496   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 497 }
 498
 499 /* Implementation of "catch throw" command.  */
 500
 501 static void
 502 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 503 {
 504   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 505
 506   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 507 }
 508
 509 /* Implementation of "catch rethrow" command.  */
 510
 511 static void
 512 catch_rethrow_command (char *arg, int from_tty,
 513                        struct cmd_list_element *command)
 514 {
 515   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 516
 517   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 518 }
 519
 520 \f
 521
 522 /* Implement the 'make_value' method for the $_exception
 523    internalvar.  */
 524
 525 static struct value *
 526 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 527 {
 528   struct value *arg0, *arg1;
 529   struct type *obj_type;
 530
 531   fetch_probe_arguments (&arg0, &arg1);
 532
 533   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 534      the std::type_info for the exception.  Now we find the type from
 535      the type_info and cast the result.  */
 536   obj_type = cplus_type_from_type_info (arg1);
 537   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 538 }
 539
 540 /* Implementation of the '$_exception' variable.  */
 541
 542 static const struct internalvar_funcs exception_funcs =
 543 {
 544   compute_exception,
 545   NULL,
 546   NULL
 547 };
 548
 549 \f
 550
 551 static void
 552 initialize_throw_catchpoint_ops (void)
 553 {
 554   struct breakpoint_ops *ops;
 555
 556   initialize_breakpoint_ops ();
 557
 558   /* GNU v3 exception catchpoints.  */
 559   ops = &gnu_v3_exception_catchpoint_ops;
 560   *ops = bkpt_breakpoint_ops;
 561   ops->dtor = dtor_exception_catchpoint;
 562   ops->re_set = re_set_exception_catchpoint;
 563   ops->print_it = print_it_exception_catchpoint;
 564   ops->print_one = print_one_exception_catchpoint;
 565   ops->print_mention = print_mention_exception_catchpoint;
 566   ops->print_recreate = print_recreate_exception_catchpoint;
 567   ops->print_one_detail = print_one_detail_exception_catchpoint;
 568   ops->check_status = check_status_exception_catchpoint;
 569 }
 570
 571 initialize_file_ftype _initialize_break_catch_throw;
 572
 573 void
 574 _initialize_break_catch_throw (void)
 575 {
 576   initialize_throw_catchpoint_ops ();
 577
 578   /* Add catch and tcatch sub-commands.  */
 579   add_catch_command ("catch", _("\
 580 Catch an exception, when caught."),
 581                      catch_catch_command,
 582                      NULL,
 583                      CATCH_PERMANENT,
 584                      CATCH_TEMPORARY);
 585   add_catch_command ("throw", _("\
 586 Catch an exception, when thrown."),
 587                      catch_throw_command,
 588                      NULL,
 589                      CATCH_PERMANENT,
 590                      CATCH_TEMPORARY);
 591   add_catch_command ("rethrow", _("\
 592 Catch an exception, when rethrown."),
 593                      catch_rethrow_command,
 594                      NULL,
 595                      CATCH_PERMANENT,
 596                      CATCH_TEMPORARY);
 597
 598   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 599 }