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 event_location *location;
 209   struct program_space *filter_pspace = current_program_space;
 210
 211   /* We first try to use the probe interface.  */
 212   TRY
 213     {
 214       location
 215         = new_probe_location (exception_functions[kind].probe);
 216       cleanup = make_cleanup_delete_event_location (location);
 217       sals = parse_probes (location, filter_pspace, NULL);
 218       do_cleanups (cleanup);
 219     }
 220   CATCH (e, RETURN_MASK_ERROR)
 221     {
 222       /* Using the probe interface failed.  Let's fallback to the normal
 223          catchpoint mode.  */
 224       TRY
 225         {
 226           struct explicit_location explicit_loc;
 227
 228           initialize_explicit_location (&explicit_loc);
 229           explicit_loc.function_name
 230             = ASTRDUP (exception_functions[kind].function);
 231           location = new_explicit_location (&explicit_loc);
 232           cleanup = make_cleanup_delete_event_location (location);
 233           self->ops->decode_location (self, location, filter_pspace, &sals);
 234           do_cleanups (cleanup);
 235         }
 236       CATCH (ex, RETURN_MASK_ERROR)
 237         {
 238           /* NOT_FOUND_ERROR just means the breakpoint will be
 239              pending, so let it through.  */
 240           if (ex.error != NOT_FOUND_ERROR)
 241             throw_exception (ex);
 242         }
 243       END_CATCH
 244     }
 245   END_CATCH
 246
 247   cleanup = make_cleanup (xfree, sals.sals);
 248   update_breakpoint_locations (self, filter_pspace, sals, sals_end);
 249   do_cleanups (cleanup);
 250 }
 251
 252 static enum print_stop_action
 253 print_it_exception_catchpoint (bpstat bs)
 254 {
 255   struct ui_out *uiout = current_uiout;
 256   struct breakpoint *b = bs->breakpoint_at;
 257   int bp_temp;
 258   enum exception_event_kind kind = classify_exception_breakpoint (b);
 259
 260   annotate_catchpoint (b->number);
 261   maybe_print_thread_hit_breakpoint (uiout);
 262
 263   bp_temp = b->disposition == disp_del;
 264   uiout->text (bp_temp ? "Temporary catchpoint "
 265                        : "Catchpoint ");
 266   if (!uiout->is_mi_like_p ())
 267     uiout->field_int ("bkptno", b->number);
 268   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 269                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 270                    : " (exception rethrown), ")));
 271   if (uiout->is_mi_like_p ())
 272     {
 273       uiout->field_string ("reason",
 274                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 275       uiout->field_string ("disp", bpdisp_text (b->disposition));
 276       uiout->field_int ("bkptno", b->number);
 277     }
 278   return PRINT_SRC_AND_LOC;
 279 }
 280
 281 static void
 282 print_one_exception_catchpoint (struct breakpoint *b,
 283                                 struct bp_location **last_loc)
 284 {
 285   struct value_print_options opts;
 286   struct ui_out *uiout = current_uiout;
 287   enum exception_event_kind kind = classify_exception_breakpoint (b);
 288
 289   get_user_print_options (&opts);
 290   if (opts.addressprint)
 291     {
 292       annotate_field (4);
 293       if (b->loc == NULL || b->loc->shlib_disabled)
 294         uiout->field_string ("addr", "<PENDING>");
 295       else
 296         uiout->field_core_addr ("addr",
 297                                 b->loc->gdbarch, b->loc->address);
 298     }
 299   annotate_field (5);
 300   if (b->loc)
 301     *last_loc = b->loc;
 302
 303   switch (kind)
 304     {
 305     case EX_EVENT_THROW:
 306       uiout->field_string ("what", "exception throw");
 307       if (uiout->is_mi_like_p ())
 308         uiout->field_string ("catch-type", "throw");
 309       break;
 310
 311     case EX_EVENT_RETHROW:
 312       uiout->field_string ("what", "exception rethrow");
 313       if (uiout->is_mi_like_p ())
 314         uiout->field_string ("catch-type", "rethrow");
 315       break;
 316
 317     case EX_EVENT_CATCH:
 318       uiout->field_string ("what", "exception catch");
 319       if (uiout->is_mi_like_p ())
 320         uiout->field_string ("catch-type", "catch");
 321       break;
 322     }
 323 }
 324
 325 /* Implement the 'print_one_detail' method.  */
 326
 327 static void
 328 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 329                                        struct ui_out *uiout)
 330 {
 331   const struct exception_catchpoint *cp
 332     = (const struct exception_catchpoint *) b;
 333
 334   if (cp->exception_rx != NULL)
 335     {
 336       uiout->text (_("\tmatching: "));
 337       uiout->field_string ("regexp", cp->exception_rx);
 338       uiout->text ("\n");
 339     }
 340 }
 341
 342 static void
 343 print_mention_exception_catchpoint (struct breakpoint *b)
 344 {
 345   struct ui_out *uiout = current_uiout;
 346   int bp_temp;
 347   enum exception_event_kind kind = classify_exception_breakpoint (b);
 348
 349   bp_temp = b->disposition == disp_del;
 350   uiout->text (bp_temp ? _("Temporary catchpoint ")
 351                               : _("Catchpoint "));
 352   uiout->field_int ("bkptno", b->number);
 353   uiout->text ((kind == EX_EVENT_THROW ? _(" (throw)")
 354                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 355                           : _(" (rethrow)"))));
 356 }
 357
 358 /* Implement the "print_recreate" breakpoint_ops method for throw and
 359    catch catchpoints.  */
 360
 361 static void
 362 print_recreate_exception_catchpoint (struct breakpoint *b,
 363                                      struct ui_file *fp)
 364 {
 365   int bp_temp;
 366   enum exception_event_kind kind = classify_exception_breakpoint (b);
 367
 368   bp_temp = b->disposition == disp_del;
 369   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 370   switch (kind)
 371     {
 372     case EX_EVENT_THROW:
 373       fprintf_unfiltered (fp, "throw");
 374       break;
 375     case EX_EVENT_CATCH:
 376       fprintf_unfiltered (fp, "catch");
 377       break;
 378     case EX_EVENT_RETHROW:
 379       fprintf_unfiltered (fp, "rethrow");
 380       break;
 381     }
 382   print_recreate_thread (b, fp);
 383 }
 384
 385 static void
 386 handle_gnu_v3_exceptions (int tempflag, char *except_rx, char *cond_string,
 387                           enum exception_event_kind ex_event, int from_tty)
 388 {
 389   regex_t *pattern = NULL;
 390
 391   if (except_rx != NULL)
 392     {
 393       pattern = XNEW (regex_t);
 394       make_cleanup (xfree, pattern);
 395
 396       compile_rx_or_error (pattern, except_rx,
 397                            _("invalid type-matching regexp"));
 398     }
 399
 400   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 401
 402   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 403                    &gnu_v3_exception_catchpoint_ops);
 404   /* We need to reset 'type' in order for code in breakpoint.c to do
 405      the right thing.  */
 406   cp->base.type = bp_breakpoint;
 407   cp->kind = ex_event;
 408   cp->exception_rx = except_rx;
 409   cp->pattern = pattern;
 410
 411   re_set_exception_catchpoint (&cp->base);
 412
 413   install_breakpoint (0, &cp->base, 1);
 414   cp.release ();
 415 }
 416
 417 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 418    by whitespace.
 419
 420    If there is any non-whitespace text between *STRING and the "if"
 421    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 422    this returns NULL.
 423
 424    STRING is updated to point to the "if" token, if it exists, or to
 425    the end of the string.  */
 426
 427 static char *
 428 extract_exception_regexp (char **string)
 429 {
 430   char *start;
 431   char *last, *last_space;
 432
 433   start = skip_spaces (*string);
 434
 435   last = start;
 436   last_space = start;
 437   while (*last != '\0')
 438     {
 439       char *if_token = last;
 440
 441       /* Check for the "if".  */
 442       if (check_for_argument (&if_token, "if", 2))
 443         break;
 444
 445       /* No "if" token here.  Skip to the next word start.  */
 446       last_space = skip_to_space (last);
 447       last = skip_spaces (last_space);
 448     }
 449
 450   *string = last;
 451   if (last_space > start)
 452     return savestring (start, last_space - start);
 453   return NULL;
 454 }
 455
 456 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 457    commands.  */
 458
 459 static void
 460 catch_exception_command_1 (enum exception_event_kind ex_event, char *arg,
 461                            int tempflag, int from_tty)
 462 {
 463   char *except_rx;
 464   char *cond_string = NULL;
 465   struct cleanup *cleanup;
 466
 467   if (!arg)
 468     arg = "";
 469   arg = skip_spaces (arg);
 470
 471   except_rx = extract_exception_regexp (&arg);
 472   cleanup = make_cleanup (xfree, except_rx);
 473
 474   cond_string = ep_parse_optional_if_clause (&arg);
 475
 476   if ((*arg != '\0') && !isspace (*arg))
 477     error (_("Junk at end of arguments."));
 478
 479   if (ex_event != EX_EVENT_THROW
 480       && ex_event != EX_EVENT_CATCH
 481       && ex_event != EX_EVENT_RETHROW)
 482     error (_("Unsupported or unknown exception event; cannot catch it"));
 483
 484   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 485                             ex_event, from_tty);
 486
 487   discard_cleanups (cleanup);
 488 }
 489
 490 /* Implementation of "catch catch" command.  */
 491
 492 static void
 493 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 494 {
 495   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 496
 497   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 498 }
 499
 500 /* Implementation of "catch throw" command.  */
 501
 502 static void
 503 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 504 {
 505   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 506
 507   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 508 }
 509
 510 /* Implementation of "catch rethrow" command.  */
 511
 512 static void
 513 catch_rethrow_command (char *arg, int from_tty,
 514                        struct cmd_list_element *command)
 515 {
 516   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 517
 518   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 519 }
 520
 521 \f
 522
 523 /* Implement the 'make_value' method for the $_exception
 524    internalvar.  */
 525
 526 static struct value *
 527 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 528 {
 529   struct value *arg0, *arg1;
 530   struct type *obj_type;
 531
 532   fetch_probe_arguments (&arg0, &arg1);
 533
 534   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 535      the std::type_info for the exception.  Now we find the type from
 536      the type_info and cast the result.  */
 537   obj_type = cplus_type_from_type_info (arg1);
 538   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 539 }
 540
 541 /* Implementation of the '$_exception' variable.  */
 542
 543 static const struct internalvar_funcs exception_funcs =
 544 {
 545   compute_exception,
 546   NULL,
 547   NULL
 548 };
 549
 550 \f
 551
 552 static void
 553 initialize_throw_catchpoint_ops (void)
 554 {
 555   struct breakpoint_ops *ops;
 556
 557   initialize_breakpoint_ops ();
 558
 559   /* GNU v3 exception catchpoints.  */
 560   ops = &gnu_v3_exception_catchpoint_ops;
 561   *ops = bkpt_breakpoint_ops;
 562   ops->dtor = dtor_exception_catchpoint;
 563   ops->re_set = re_set_exception_catchpoint;
 564   ops->print_it = print_it_exception_catchpoint;
 565   ops->print_one = print_one_exception_catchpoint;
 566   ops->print_mention = print_mention_exception_catchpoint;
 567   ops->print_recreate = print_recreate_exception_catchpoint;
 568   ops->print_one_detail = print_one_detail_exception_catchpoint;
 569   ops->check_status = check_status_exception_catchpoint;
 570 }
 571
 572 initialize_file_ftype _initialize_break_catch_throw;
 573
 574 void
 575 _initialize_break_catch_throw (void)
 576 {
 577   initialize_throw_catchpoint_ops ();
 578
 579   /* Add catch and tcatch sub-commands.  */
 580   add_catch_command ("catch", _("\
 581 Catch an exception, when caught."),
 582                      catch_catch_command,
 583                      NULL,
 584                      CATCH_PERMANENT,
 585                      CATCH_TEMPORARY);
 586   add_catch_command ("throw", _("\
 587 Catch an exception, when thrown."),
 588                      catch_throw_command,
 589                      NULL,
 590                      CATCH_PERMANENT,
 591                      CATCH_TEMPORARY);
 592   add_catch_command ("rethrow", _("\
 593 Catch an exception, when rethrown."),
 594                      catch_rethrow_command,
 595                      NULL,
 596                      CATCH_PERMANENT,
 597                      CATCH_TEMPORARY);
 598
 599   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 600 }