gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2020 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 /* Each spot where we may place an exception-related catchpoint has
  41    two names: the SDT probe point and the function name.  This
  42    structure holds both.  */
  43
  44 struct exception_names
  45 {
  46   /* The name of the probe point to try, in the form accepted by
  47      'parse_probes'.  */
  48
  49   const char *probe;
  50
  51   /* The name of the corresponding function.  */
  52
  53   const char *function;
  54 };
  55
  56 /* Names of the probe points and functions on which to break.  This is
  57    indexed by exception_event_kind.  */
  58 static const struct exception_names exception_functions[] =
  59 {
  60   { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  61   { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  62   { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
  63 };
  64
  65 static struct breakpoint_ops gnu_v3_exception_catchpoint_ops;
  66
  67 /* The type of an exception catchpoint.  */
  68
  69 struct exception_catchpoint : public breakpoint
  70 {
  71   /* The kind of exception catchpoint.  */
  72
  73   enum exception_event_kind kind;
  74
  75   /* If not empty, a string holding the source form of the regular
  76      expression to match against.  */
  77
  78   std::string exception_rx;
  79
  80   /* If non-NULL, a compiled regular expression which is used to
  81      determine which exceptions to stop on.  */
  82
  83   std::unique_ptr<compiled_regex> pattern;
  84 };
  85
  86 /* See breakpoint.h.  */
  87
  88 bool
  89 is_exception_catchpoint (breakpoint *bp)
  90 {
  91   return bp->ops == &gnu_v3_exception_catchpoint_ops;
  92 }
  93
  94 \f
  95
  96 /* A helper function that fetches exception probe arguments.  This
  97    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
  98    It will throw an exception on any kind of failure.  */
  99
 100 static void
 101 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 102 {
 103   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 104   CORE_ADDR pc = get_frame_pc (frame);
 105   struct bound_probe pc_probe;
 106   unsigned n_args;
 107
 108   pc_probe = find_probe_by_pc (pc);
 109   if (pc_probe.prob == NULL)
 110     error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
 111
 112   if (pc_probe.prob->get_provider () != "libstdcxx"
 113       || (pc_probe.prob->get_name () != "catch"
 114           && pc_probe.prob->get_name () != "throw"
 115           && pc_probe.prob->get_name () != "rethrow"))
 116     error (_("not stopped at a C++ exception catchpoint"));
 117
 118   n_args = pc_probe.prob->get_argument_count (get_frame_arch (frame));
 119   if (n_args < 2)
 120     error (_("C++ exception catchpoint has too few arguments"));
 121
 122   if (arg0 != NULL)
 123     *arg0 = pc_probe.prob->evaluate_argument (0, frame);
 124   *arg1 = pc_probe.prob->evaluate_argument (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 /* Implement the 'check_status' method.  */
 144
 145 static void
 146 check_status_exception_catchpoint (struct bpstats *bs)
 147 {
 148   struct exception_catchpoint *self
 149     = (struct exception_catchpoint *) bs->breakpoint_at;
 150   std::string type_name;
 151
 152   bkpt_breakpoint_ops.check_status (bs);
 153   if (bs->stop == 0)
 154     return;
 155
 156   if (self->pattern == NULL)
 157     return;
 158
 159   const char *name = nullptr;
 160   gdb::unique_xmalloc_ptr<char> canon;
 161   try
 162     {
 163       struct value *typeinfo_arg;
 164
 165       fetch_probe_arguments (NULL, &typeinfo_arg);
 166       type_name = cplus_typename_from_type_info (typeinfo_arg);
 167
 168       canon = cp_canonicalize_string (type_name.c_str ());
 169       name = (canon != nullptr
 170               ? canon.get ()
 171               : type_name.c_str ());
 172     }
 173   catch (const gdb_exception_error &e)
 174     {
 175       exception_print (gdb_stderr, e);
 176     }
 177
 178   if (name != nullptr)
 179     {
 180       if (self->pattern->exec (name, 0, NULL, 0) != 0)
 181         bs->stop = 0;
 182     }
 183 }
 184
 185 /* Implement the 're_set' method.  */
 186
 187 static void
 188 re_set_exception_catchpoint (struct breakpoint *self)
 189 {
 190   std::vector<symtab_and_line> sals;
 191   enum exception_event_kind kind = classify_exception_breakpoint (self);
 192   struct program_space *filter_pspace = current_program_space;
 193
 194   /* We first try to use the probe interface.  */
 195   try
 196     {
 197       event_location_up location
 198         = new_probe_location (exception_functions[kind].probe);
 199       sals = parse_probes (location.get (), filter_pspace, NULL);
 200     }
 201   catch (const gdb_exception_error &e)
 202     {
 203       /* Using the probe interface failed.  Let's fallback to the normal
 204          catchpoint mode.  */
 205       try
 206         {
 207           struct explicit_location explicit_loc;
 208
 209           initialize_explicit_location (&explicit_loc);
 210           explicit_loc.function_name
 211             = ASTRDUP (exception_functions[kind].function);
 212           event_location_up location = new_explicit_location (&explicit_loc);
 213           sals = self->ops->decode_location (self, location.get (),
 214                                              filter_pspace);
 215         }
 216       catch (const gdb_exception_error &ex)
 217         {
 218           /* NOT_FOUND_ERROR just means the breakpoint will be
 219              pending, so let it through.  */
 220           if (ex.error != NOT_FOUND_ERROR)
 221             throw;
 222         }
 223     }
 224
 225   update_breakpoint_locations (self, filter_pspace, sals, {});
 226 }
 227
 228 static enum print_stop_action
 229 print_it_exception_catchpoint (bpstat bs)
 230 {
 231   struct ui_out *uiout = current_uiout;
 232   struct breakpoint *b = bs->breakpoint_at;
 233   int bp_temp;
 234   enum exception_event_kind kind = classify_exception_breakpoint (b);
 235
 236   annotate_catchpoint (b->number);
 237   maybe_print_thread_hit_breakpoint (uiout);
 238
 239   bp_temp = b->disposition == disp_del;
 240   uiout->text (bp_temp ? "Temporary catchpoint "
 241                        : "Catchpoint ");
 242   uiout->field_signed ("bkptno", b->number);
 243   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 244                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 245                    : " (exception rethrown), ")));
 246   if (uiout->is_mi_like_p ())
 247     {
 248       uiout->field_string ("reason",
 249                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 250       uiout->field_string ("disp", bpdisp_text (b->disposition));
 251     }
 252   return PRINT_SRC_AND_LOC;
 253 }
 254
 255 static void
 256 print_one_exception_catchpoint (struct breakpoint *b,
 257                                 struct bp_location **last_loc)
 258 {
 259   struct value_print_options opts;
 260   struct ui_out *uiout = current_uiout;
 261   enum exception_event_kind kind = classify_exception_breakpoint (b);
 262
 263   get_user_print_options (&opts);
 264
 265   if (opts.addressprint)
 266     uiout->field_skip ("addr");
 267   annotate_field (5);
 268
 269   switch (kind)
 270     {
 271     case EX_EVENT_THROW:
 272       uiout->field_string ("what", "exception throw");
 273       if (uiout->is_mi_like_p ())
 274         uiout->field_string ("catch-type", "throw");
 275       break;
 276
 277     case EX_EVENT_RETHROW:
 278       uiout->field_string ("what", "exception rethrow");
 279       if (uiout->is_mi_like_p ())
 280         uiout->field_string ("catch-type", "rethrow");
 281       break;
 282
 283     case EX_EVENT_CATCH:
 284       uiout->field_string ("what", "exception catch");
 285       if (uiout->is_mi_like_p ())
 286         uiout->field_string ("catch-type", "catch");
 287       break;
 288     }
 289 }
 290
 291 /* Implement the 'print_one_detail' method.  */
 292
 293 static void
 294 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 295                                        struct ui_out *uiout)
 296 {
 297   const struct exception_catchpoint *cp
 298     = (const struct exception_catchpoint *) b;
 299
 300   if (!cp->exception_rx.empty ())
 301     {
 302       uiout->text (_("\tmatching: "));
 303       uiout->field_string ("regexp", cp->exception_rx.c_str ());
 304       uiout->text ("\n");
 305     }
 306 }
 307
 308 static void
 309 print_mention_exception_catchpoint (struct breakpoint *b)
 310 {
 311   struct ui_out *uiout = current_uiout;
 312   int bp_temp;
 313   enum exception_event_kind kind = classify_exception_breakpoint (b);
 314
 315   bp_temp = b->disposition == disp_del;
 316   uiout->message ("%s %d %s",
 317                   (bp_temp ? _("Temporary catchpoint ") : _("Catchpoint")),
 318                   b->number,
 319                   (kind == EX_EVENT_THROW
 320                    ? _("(throw)") : (kind == EX_EVENT_CATCH
 321                                      ? _("(catch)") : _("(rethrow)"))));
 322 }
 323
 324 /* Implement the "print_recreate" breakpoint_ops method for throw and
 325    catch catchpoints.  */
 326
 327 static void
 328 print_recreate_exception_catchpoint (struct breakpoint *b,
 329                                      struct ui_file *fp)
 330 {
 331   int bp_temp;
 332   enum exception_event_kind kind = classify_exception_breakpoint (b);
 333
 334   bp_temp = b->disposition == disp_del;
 335   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 336   switch (kind)
 337     {
 338     case EX_EVENT_THROW:
 339       fprintf_unfiltered (fp, "throw");
 340       break;
 341     case EX_EVENT_CATCH:
 342       fprintf_unfiltered (fp, "catch");
 343       break;
 344     case EX_EVENT_RETHROW:
 345       fprintf_unfiltered (fp, "rethrow");
 346       break;
 347     }
 348   print_recreate_thread (b, fp);
 349 }
 350
 351 /* Implement the "allocate_location" breakpoint_ops method for throw
 352    and catch catchpoints.  */
 353
 354 static bp_location *
 355 allocate_location_exception_catchpoint (breakpoint *self)
 356 {
 357   return new bp_location (self, bp_loc_software_breakpoint);
 358 }
 359
 360 static void
 361 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 362                           const char *cond_string,
 363                           enum exception_event_kind ex_event, int from_tty)
 364 {
 365   std::unique_ptr<compiled_regex> pattern;
 366
 367   if (!except_rx.empty ())
 368     {
 369       pattern.reset (new compiled_regex (except_rx.c_str (), REG_NOSUB,
 370                                          _("invalid type-matching regexp")));
 371     }
 372
 373   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 374
 375   init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
 376                    &gnu_v3_exception_catchpoint_ops);
 377   cp->kind = ex_event;
 378   cp->exception_rx = std::move (except_rx);
 379   cp->pattern = std::move (pattern);
 380
 381   re_set_exception_catchpoint (cp.get ());
 382
 383   install_breakpoint (0, std::move (cp), 1);
 384 }
 385
 386 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 387    by whitespace.
 388
 389    If there is any non-whitespace text between *STRING and the "if"
 390    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 391    this returns NULL.
 392
 393    STRING is updated to point to the "if" token, if it exists, or to
 394    the end of the string.  */
 395
 396 static std::string
 397 extract_exception_regexp (const char **string)
 398 {
 399   const char *start;
 400   const char *last, *last_space;
 401
 402   start = skip_spaces (*string);
 403
 404   last = start;
 405   last_space = start;
 406   while (*last != '\0')
 407     {
 408       const char *if_token = last;
 409
 410       /* Check for the "if".  */
 411       if (check_for_argument (&if_token, "if", 2))
 412         break;
 413
 414       /* No "if" token here.  Skip to the next word start.  */
 415       last_space = skip_to_space (last);
 416       last = skip_spaces (last_space);
 417     }
 418
 419   *string = last;
 420   if (last_space > start)
 421     return std::string (start, last_space - start);
 422   return std::string ();
 423 }
 424
 425 /* See breakpoint.h.  */
 426
 427 void
 428 catch_exception_event (enum exception_event_kind ex_event,
 429                        const char *arg, bool tempflag, int from_tty)
 430 {
 431   const char *cond_string = NULL;
 432
 433   if (!arg)
 434     arg = "";
 435   arg = skip_spaces (arg);
 436
 437   std::string except_rx = extract_exception_regexp (&arg);
 438
 439   cond_string = ep_parse_optional_if_clause (&arg);
 440
 441   if ((*arg != '\0') && !isspace (*arg))
 442     error (_("Junk at end of arguments."));
 443
 444   if (ex_event != EX_EVENT_THROW
 445       && ex_event != EX_EVENT_CATCH
 446       && ex_event != EX_EVENT_RETHROW)
 447     error (_("Unsupported or unknown exception event; cannot catch it"));
 448
 449   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 450                             ex_event, from_tty);
 451 }
 452
 453 /* Implementation of "catch catch" command.  */
 454
 455 static void
 456 catch_catch_command (const char *arg, int from_tty,
 457                      struct cmd_list_element *command)
 458 {
 459   bool tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 460
 461   catch_exception_event (EX_EVENT_CATCH, arg, tempflag, from_tty);
 462 }
 463
 464 /* Implementation of "catch throw" command.  */
 465
 466 static void
 467 catch_throw_command (const char *arg, int from_tty,
 468                      struct cmd_list_element *command)
 469 {
 470   bool tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 471
 472   catch_exception_event (EX_EVENT_THROW, arg, tempflag, from_tty);
 473 }
 474
 475 /* Implementation of "catch rethrow" command.  */
 476
 477 static void
 478 catch_rethrow_command (const char *arg, int from_tty,
 479                        struct cmd_list_element *command)
 480 {
 481   bool tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 482
 483   catch_exception_event (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 484 }
 485
 486 \f
 487
 488 /* Implement the 'make_value' method for the $_exception
 489    internalvar.  */
 490
 491 static struct value *
 492 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 493 {
 494   struct value *arg0, *arg1;
 495   struct type *obj_type;
 496
 497   fetch_probe_arguments (&arg0, &arg1);
 498
 499   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 500      the std::type_info for the exception.  Now we find the type from
 501      the type_info and cast the result.  */
 502   obj_type = cplus_type_from_type_info (arg1);
 503   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 504 }
 505
 506 /* Implementation of the '$_exception' variable.  */
 507
 508 static const struct internalvar_funcs exception_funcs =
 509 {
 510   compute_exception,
 511   NULL,
 512   NULL
 513 };
 514
 515 \f
 516
 517 static void
 518 initialize_throw_catchpoint_ops (void)
 519 {
 520   struct breakpoint_ops *ops;
 521
 522   initialize_breakpoint_ops ();
 523
 524   /* GNU v3 exception catchpoints.  */
 525   ops = &gnu_v3_exception_catchpoint_ops;
 526   *ops = bkpt_breakpoint_ops;
 527   ops->re_set = re_set_exception_catchpoint;
 528   ops->print_it = print_it_exception_catchpoint;
 529   ops->print_one = print_one_exception_catchpoint;
 530   ops->print_mention = print_mention_exception_catchpoint;
 531   ops->print_recreate = print_recreate_exception_catchpoint;
 532   ops->print_one_detail = print_one_detail_exception_catchpoint;
 533   ops->check_status = check_status_exception_catchpoint;
 534   ops->allocate_location = allocate_location_exception_catchpoint;
 535 }
 536
 537 void _initialize_break_catch_throw ();
 538 void
 539 _initialize_break_catch_throw ()
 540 {
 541   initialize_throw_catchpoint_ops ();
 542
 543   /* Add catch and tcatch sub-commands.  */
 544   add_catch_command ("catch", _("\
 545 Catch an exception, when caught."),
 546                      catch_catch_command,
 547                      NULL,
 548                      CATCH_PERMANENT,
 549                      CATCH_TEMPORARY);
 550   add_catch_command ("throw", _("\
 551 Catch an exception, when thrown."),
 552                      catch_throw_command,
 553                      NULL,
 554                      CATCH_PERMANENT,
 555                      CATCH_TEMPORARY);
 556   add_catch_command ("rethrow", _("\
 557 Catch an exception, when rethrown."),
 558                      catch_rethrow_command,
 559                      NULL,
 560                      CATCH_PERMANENT,
 561                      CATCH_TEMPORARY);
 562
 563   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 564 }