gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2019 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
  22 /* Standard C includes.  */
  23 #include <ctype.h>
  24
  25 /* Local non-gdb includes.  */
  26 #include "annotate.h"
  27 #include "arch-utils.h"
  28 #include "breakpoint.h"
  29 #include "cli/cli-utils.h"
  30 #include "completer.h"
  31 #include "cp-abi.h"
  32 #include "cp-support.h"
  33 #include "gdb_obstack.h"
  34 #include "gdb_regex.h"
  35 #include "gdbcmd.h"
  36 #include "inferior.h"
  37 #include "linespec.h"
  38 #include "location.h"
  39 #include "mi/mi-common.h"
  40 #include "objfiles.h"
  41 #include "probe.h"
  42 #include "valprint.h"
  43
  44 /* Enums for exception-handling support.  */
  45 enum exception_event_kind
  46 {
  47   EX_EVENT_THROW,
  48   EX_EVENT_RETHROW,
  49   EX_EVENT_CATCH
  50 };
  51
  52 /* Each spot where we may place an exception-related catchpoint has
  53    two names: the SDT probe point and the function name.  This
  54    structure holds both.  */
  55
  56 struct exception_names
  57 {
  58   /* The name of the probe point to try, in the form accepted by
  59      'parse_probes'.  */
  60
  61   const char *probe;
  62
  63   /* The name of the corresponding function.  */
  64
  65   const char *function;
  66 };
  67
  68 /* Names of the probe points and functions on which to break.  This is
  69    indexed by exception_event_kind.  */
  70 static const struct exception_names exception_functions[] =
  71 {
  72   { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  73   { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  74   { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
  75 };
  76
  77 static struct breakpoint_ops gnu_v3_exception_catchpoint_ops;
  78
  79 /* The type of an exception catchpoint.  */
  80
  81 struct exception_catchpoint : public breakpoint
  82 {
  83   /* The kind of exception catchpoint.  */
  84
  85   enum exception_event_kind kind;
  86
  87   /* If not empty, a string holding the source form of the regular
  88      expression to match against.  */
  89
  90   std::string exception_rx;
  91
  92   /* If non-NULL, a compiled regular expression which is used to
  93      determine which exceptions to stop on.  */
  94
  95   std::unique_ptr<compiled_regex> 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.prob == NULL
 114       || pc_probe.prob->get_provider () != "libstdcxx"
 115       || (pc_probe.prob->get_name () != "catch"
 116           && pc_probe.prob->get_name () != "throw"
 117           && pc_probe.prob->get_name () != "rethrow"))
 118     error (_("not stopped at a C++ exception catchpoint"));
 119
 120   n_args = pc_probe.prob->get_argument_count (frame);
 121   if (n_args < 2)
 122     error (_("C++ exception catchpoint has too few arguments"));
 123
 124   if (arg0 != NULL)
 125     *arg0 = pc_probe.prob->evaluate_argument (0, frame);
 126   *arg1 = pc_probe.prob->evaluate_argument (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 'check_status' method.  */
 146
 147 static void
 148 check_status_exception_catchpoint (struct bpstats *bs)
 149 {
 150   struct exception_catchpoint *self
 151     = (struct exception_catchpoint *) bs->breakpoint_at;
 152   std::string type_name;
 153
 154   bkpt_breakpoint_ops.check_status (bs);
 155   if (bs->stop == 0)
 156     return;
 157
 158   if (self->pattern == NULL)
 159     return;
 160
 161   TRY
 162     {
 163       struct value *typeinfo_arg;
 164       std::string canon;
 165
 166       fetch_probe_arguments (NULL, &typeinfo_arg);
 167       type_name = cplus_typename_from_type_info (typeinfo_arg);
 168
 169       canon = cp_canonicalize_string (type_name.c_str ());
 170       if (!canon.empty ())
 171         std::swap (type_name, canon);
 172     }
 173   CATCH (e, RETURN_MASK_ERROR)
 174     {
 175       exception_print (gdb_stderr, e);
 176     }
 177   END_CATCH
 178
 179   if (!type_name.empty ())
 180     {
 181       if (self->pattern->exec (type_name.c_str (), 0, NULL, 0) != 0)
 182         bs->stop = 0;
 183     }
 184 }
 185
 186 /* Implement the 're_set' method.  */
 187
 188 static void
 189 re_set_exception_catchpoint (struct breakpoint *self)
 190 {
 191   std::vector<symtab_and_line> sals;
 192   enum exception_event_kind kind = classify_exception_breakpoint (self);
 193   struct program_space *filter_pspace = current_program_space;
 194
 195   /* We first try to use the probe interface.  */
 196   TRY
 197     {
 198       event_location_up location
 199         = new_probe_location (exception_functions[kind].probe);
 200       sals = parse_probes (location.get (), filter_pspace, NULL);
 201     }
 202   CATCH (e, RETURN_MASK_ERROR)
 203     {
 204       /* Using the probe interface failed.  Let's fallback to the normal
 205          catchpoint mode.  */
 206       TRY
 207         {
 208           struct explicit_location explicit_loc;
 209
 210           initialize_explicit_location (&explicit_loc);
 211           explicit_loc.function_name
 212             = ASTRDUP (exception_functions[kind].function);
 213           event_location_up location = new_explicit_location (&explicit_loc);
 214           sals = self->ops->decode_location (self, location.get (),
 215                                              filter_pspace);
 216         }
 217       CATCH (ex, RETURN_MASK_ERROR)
 218         {
 219           /* NOT_FOUND_ERROR just means the breakpoint will be
 220              pending, so let it through.  */
 221           if (ex.error != NOT_FOUND_ERROR)
 222             throw_exception (ex);
 223         }
 224       END_CATCH
 225     }
 226   END_CATCH
 227
 228   update_breakpoint_locations (self, filter_pspace, sals, {});
 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   uiout->field_int ("bkptno", b->number);
 246   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 247                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 248                    : " (exception rethrown), ")));
 249   if (uiout->is_mi_like_p ())
 250     {
 251       uiout->field_string ("reason",
 252                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 253       uiout->field_string ("disp", bpdisp_text (b->disposition));
 254     }
 255   return PRINT_SRC_AND_LOC;
 256 }
 257
 258 static void
 259 print_one_exception_catchpoint (struct breakpoint *b,
 260                                 struct bp_location **last_loc)
 261 {
 262   struct value_print_options opts;
 263   struct ui_out *uiout = current_uiout;
 264   enum exception_event_kind kind = classify_exception_breakpoint (b);
 265
 266   get_user_print_options (&opts);
 267   if (opts.addressprint)
 268     {
 269       annotate_field (4);
 270       if (b->loc == NULL || b->loc->shlib_disabled)
 271         uiout->field_string ("addr", "<PENDING>");
 272       else
 273         uiout->field_core_addr ("addr",
 274                                 b->loc->gdbarch, b->loc->address);
 275     }
 276   annotate_field (5);
 277   if (b->loc)
 278     *last_loc = b->loc;
 279
 280   switch (kind)
 281     {
 282     case EX_EVENT_THROW:
 283       uiout->field_string ("what", "exception throw");
 284       if (uiout->is_mi_like_p ())
 285         uiout->field_string ("catch-type", "throw");
 286       break;
 287
 288     case EX_EVENT_RETHROW:
 289       uiout->field_string ("what", "exception rethrow");
 290       if (uiout->is_mi_like_p ())
 291         uiout->field_string ("catch-type", "rethrow");
 292       break;
 293
 294     case EX_EVENT_CATCH:
 295       uiout->field_string ("what", "exception catch");
 296       if (uiout->is_mi_like_p ())
 297         uiout->field_string ("catch-type", "catch");
 298       break;
 299     }
 300 }
 301
 302 /* Implement the 'print_one_detail' method.  */
 303
 304 static void
 305 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 306                                        struct ui_out *uiout)
 307 {
 308   const struct exception_catchpoint *cp
 309     = (const struct exception_catchpoint *) b;
 310
 311   if (!cp->exception_rx.empty ())
 312     {
 313       uiout->text (_("\tmatching: "));
 314       uiout->field_string ("regexp", cp->exception_rx.c_str ());
 315       uiout->text ("\n");
 316     }
 317 }
 318
 319 static void
 320 print_mention_exception_catchpoint (struct breakpoint *b)
 321 {
 322   struct ui_out *uiout = current_uiout;
 323   int bp_temp;
 324   enum exception_event_kind kind = classify_exception_breakpoint (b);
 325
 326   bp_temp = b->disposition == disp_del;
 327   uiout->text (bp_temp ? _("Temporary catchpoint ")
 328                               : _("Catchpoint "));
 329   uiout->field_int ("bkptno", b->number);
 330   uiout->text ((kind == EX_EVENT_THROW ? _(" (throw)")
 331                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 332                           : _(" (rethrow)"))));
 333 }
 334
 335 /* Implement the "print_recreate" breakpoint_ops method for throw and
 336    catch catchpoints.  */
 337
 338 static void
 339 print_recreate_exception_catchpoint (struct breakpoint *b,
 340                                      struct ui_file *fp)
 341 {
 342   int bp_temp;
 343   enum exception_event_kind kind = classify_exception_breakpoint (b);
 344
 345   bp_temp = b->disposition == disp_del;
 346   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 347   switch (kind)
 348     {
 349     case EX_EVENT_THROW:
 350       fprintf_unfiltered (fp, "throw");
 351       break;
 352     case EX_EVENT_CATCH:
 353       fprintf_unfiltered (fp, "catch");
 354       break;
 355     case EX_EVENT_RETHROW:
 356       fprintf_unfiltered (fp, "rethrow");
 357       break;
 358     }
 359   print_recreate_thread (b, fp);
 360 }
 361
 362 static void
 363 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 364                           const char *cond_string,
 365                           enum exception_event_kind ex_event, int from_tty)
 366 {
 367   std::unique_ptr<compiled_regex> pattern;
 368
 369   if (!except_rx.empty ())
 370     {
 371       pattern.reset (new compiled_regex (except_rx.c_str (), REG_NOSUB,
 372                                          _("invalid type-matching regexp")));
 373     }
 374
 375   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 376
 377   init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
 378                    &gnu_v3_exception_catchpoint_ops);
 379   /* We need to reset 'type' in order for code in breakpoint.c to do
 380      the right thing.  */
 381   cp->type = bp_breakpoint;
 382   cp->kind = ex_event;
 383   cp->exception_rx = std::move (except_rx);
 384   cp->pattern = std::move (pattern);
 385
 386   re_set_exception_catchpoint (cp.get ());
 387
 388   install_breakpoint (0, std::move (cp), 1);
 389 }
 390
 391 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 392    by whitespace.
 393
 394    If there is any non-whitespace text between *STRING and the "if"
 395    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 396    this returns NULL.
 397
 398    STRING is updated to point to the "if" token, if it exists, or to
 399    the end of the string.  */
 400
 401 static std::string
 402 extract_exception_regexp (const char **string)
 403 {
 404   const char *start;
 405   const char *last, *last_space;
 406
 407   start = skip_spaces (*string);
 408
 409   last = start;
 410   last_space = start;
 411   while (*last != '\0')
 412     {
 413       const char *if_token = last;
 414
 415       /* Check for the "if".  */
 416       if (check_for_argument (&if_token, "if", 2))
 417         break;
 418
 419       /* No "if" token here.  Skip to the next word start.  */
 420       last_space = skip_to_space (last);
 421       last = skip_spaces (last_space);
 422     }
 423
 424   *string = last;
 425   if (last_space > start)
 426     return std::string (start, last_space - start);
 427   return std::string ();
 428 }
 429
 430 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 431    commands.  */
 432
 433 static void
 434 catch_exception_command_1 (enum exception_event_kind ex_event,
 435                            const char *arg,
 436                            int tempflag, int from_tty)
 437 {
 438   const char *cond_string = NULL;
 439
 440   if (!arg)
 441     arg = "";
 442   arg = skip_spaces (arg);
 443
 444   std::string except_rx = extract_exception_regexp (&arg);
 445
 446   cond_string = ep_parse_optional_if_clause (&arg);
 447
 448   if ((*arg != '\0') && !isspace (*arg))
 449     error (_("Junk at end of arguments."));
 450
 451   if (ex_event != EX_EVENT_THROW
 452       && ex_event != EX_EVENT_CATCH
 453       && ex_event != EX_EVENT_RETHROW)
 454     error (_("Unsupported or unknown exception event; cannot catch it"));
 455
 456   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 457                             ex_event, from_tty);
 458 }
 459
 460 /* Implementation of "catch catch" command.  */
 461
 462 static void
 463 catch_catch_command (const char *arg, int from_tty,
 464                      struct cmd_list_element *command)
 465 {
 466   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 467
 468   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 469 }
 470
 471 /* Implementation of "catch throw" command.  */
 472
 473 static void
 474 catch_throw_command (const char *arg, int from_tty,
 475                      struct cmd_list_element *command)
 476 {
 477   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 478
 479   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 480 }
 481
 482 /* Implementation of "catch rethrow" command.  */
 483
 484 static void
 485 catch_rethrow_command (const char *arg, int from_tty,
 486                        struct cmd_list_element *command)
 487 {
 488   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 489
 490   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 491 }
 492
 493 \f
 494
 495 /* Implement the 'make_value' method for the $_exception
 496    internalvar.  */
 497
 498 static struct value *
 499 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 500 {
 501   struct value *arg0, *arg1;
 502   struct type *obj_type;
 503
 504   fetch_probe_arguments (&arg0, &arg1);
 505
 506   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 507      the std::type_info for the exception.  Now we find the type from
 508      the type_info and cast the result.  */
 509   obj_type = cplus_type_from_type_info (arg1);
 510   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 511 }
 512
 513 /* Implementation of the '$_exception' variable.  */
 514
 515 static const struct internalvar_funcs exception_funcs =
 516 {
 517   compute_exception,
 518   NULL,
 519   NULL
 520 };
 521
 522 \f
 523
 524 static void
 525 initialize_throw_catchpoint_ops (void)
 526 {
 527   struct breakpoint_ops *ops;
 528
 529   initialize_breakpoint_ops ();
 530
 531   /* GNU v3 exception catchpoints.  */
 532   ops = &gnu_v3_exception_catchpoint_ops;
 533   *ops = bkpt_breakpoint_ops;
 534   ops->re_set = re_set_exception_catchpoint;
 535   ops->print_it = print_it_exception_catchpoint;
 536   ops->print_one = print_one_exception_catchpoint;
 537   ops->print_mention = print_mention_exception_catchpoint;
 538   ops->print_recreate = print_recreate_exception_catchpoint;
 539   ops->print_one_detail = print_one_detail_exception_catchpoint;
 540   ops->check_status = check_status_exception_catchpoint;
 541 }
 542
 543 void
 544 _initialize_break_catch_throw (void)
 545 {
 546   initialize_throw_catchpoint_ops ();
 547
 548   /* Add catch and tcatch sub-commands.  */
 549   add_catch_command ("catch", _("\
 550 Catch an exception, when caught."),
 551                      catch_catch_command,
 552                      NULL,
 553                      CATCH_PERMANENT,
 554                      CATCH_TEMPORARY);
 555   add_catch_command ("throw", _("\
 556 Catch an exception, when thrown."),
 557                      catch_throw_command,
 558                      NULL,
 559                      CATCH_PERMANENT,
 560                      CATCH_TEMPORARY);
 561   add_catch_command ("rethrow", _("\
 562 Catch an exception, when rethrown."),
 563                      catch_rethrow_command,
 564                      NULL,
 565                      CATCH_PERMANENT,
 566                      CATCH_TEMPORARY);
 567
 568   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 569 }