gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2022 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 "gdbsupport/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 "gdbsupport/gdb_regex.h"
  37 #include "cp-support.h"
  38 #include "location.h"
  39 #include "cli/cli-decode.h"
  40
  41 /* Each spot where we may place an exception-related catchpoint has
  42    two names: the SDT probe point and the function name.  This
  43    structure holds both.  */
  44
  45 struct exception_names
  46 {
  47   /* The name of the probe point to try, in the form accepted by
  48      'parse_probes'.  */
  49
  50   const char *probe;
  51
  52   /* The name of the corresponding function.  */
  53
  54   const char *function;
  55 };
  56
  57 /* Names of the probe points and functions on which to break.  This is
  58    indexed by exception_event_kind.  */
  59 static const struct exception_names exception_functions[] =
  60 {
  61   { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  62   { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  63   { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
  64 };
  65
  66 /* The type of an exception catchpoint.  */
  67
  68 struct exception_catchpoint : public catchpoint
  69 {
  70   exception_catchpoint (struct gdbarch *gdbarch,
  71                         bool temp, const char *cond_string,
  72                         enum exception_event_kind kind_,
  73                         std::string &&except_rx)
  74     : catchpoint (gdbarch, temp, cond_string),
  75       kind (kind_),
  76       exception_rx (std::move (except_rx)),
  77       pattern (exception_rx.empty ()
  78                ? nullptr
  79                : new compiled_regex (exception_rx.c_str (), REG_NOSUB,
  80                                      _("invalid type-matching regexp")))
  81   {
  82   }
  83
  84   void re_set () override;
  85   enum print_stop_action print_it (const bpstat *bs) const override;
  86   bool print_one (bp_location **) const override;
  87   void print_mention () const override;
  88   void print_recreate (struct ui_file *fp) const override;
  89   void print_one_detail (struct ui_out *) const override;
  90   void check_status (struct bpstat *bs) override;
  91   struct bp_location *allocate_location () override;
  92
  93   /* FIXME this is temporary - until ordinary breakpoints have been
  94      converted.  */
  95   int resources_needed (const struct bp_location *) override
  96   {
  97     return 1;
  98   }
  99
 100   /* The kind of exception catchpoint.  */
 101
 102   enum exception_event_kind kind;
 103
 104   /* If not empty, a string holding the source form of the regular
 105      expression to match against.  */
 106
 107   std::string exception_rx;
 108
 109   /* If non-NULL, a compiled regular expression which is used to
 110      determine which exceptions to stop on.  */
 111
 112   std::unique_ptr<compiled_regex> pattern;
 113 };
 114
 115 /* See breakpoint.h.  */
 116
 117 bool
 118 is_exception_catchpoint (breakpoint *bp)
 119 {
 120   return dynamic_cast<exception_catchpoint *> (bp) != nullptr;
 121 }
 122
 123 \f
 124
 125 /* A helper function that fetches exception probe arguments.  This
 126    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
 127    It will throw an exception on any kind of failure.  */
 128
 129 static void
 130 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 131 {
 132   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 133   CORE_ADDR pc = get_frame_pc (frame);
 134   struct bound_probe pc_probe;
 135   unsigned n_args;
 136
 137   pc_probe = find_probe_by_pc (pc);
 138   if (pc_probe.prob == NULL)
 139     error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
 140
 141   if (pc_probe.prob->get_provider () != "libstdcxx"
 142       || (pc_probe.prob->get_name () != "catch"
 143           && pc_probe.prob->get_name () != "throw"
 144           && pc_probe.prob->get_name () != "rethrow"))
 145     error (_("not stopped at a C++ exception catchpoint"));
 146
 147   n_args = pc_probe.prob->get_argument_count (get_frame_arch (frame));
 148   if (n_args < 2)
 149     error (_("C++ exception catchpoint has too few arguments"));
 150
 151   if (arg0 != NULL)
 152     *arg0 = pc_probe.prob->evaluate_argument (0, frame);
 153   *arg1 = pc_probe.prob->evaluate_argument (1, frame);
 154
 155   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 156     error (_("error computing probe argument at c++ exception catchpoint"));
 157 }
 158
 159 \f
 160
 161 /* Implement the 'check_status' method.  */
 162
 163 void
 164 exception_catchpoint::check_status (struct bpstat *bs)
 165 {
 166   struct exception_catchpoint *self
 167     = (struct exception_catchpoint *) bs->breakpoint_at;
 168   std::string type_name;
 169
 170   this->breakpoint::check_status (bs);
 171   if (bs->stop == 0)
 172     return;
 173
 174   if (self->pattern == NULL)
 175     return;
 176
 177   const char *name = nullptr;
 178   gdb::unique_xmalloc_ptr<char> canon;
 179   try
 180     {
 181       struct value *typeinfo_arg;
 182
 183       fetch_probe_arguments (NULL, &typeinfo_arg);
 184       type_name = cplus_typename_from_type_info (typeinfo_arg);
 185
 186       canon = cp_canonicalize_string (type_name.c_str ());
 187       name = (canon != nullptr
 188               ? canon.get ()
 189               : type_name.c_str ());
 190     }
 191   catch (const gdb_exception_error &e)
 192     {
 193       exception_print (gdb_stderr, e);
 194     }
 195
 196   if (name != nullptr)
 197     {
 198       if (self->pattern->exec (name, 0, NULL, 0) != 0)
 199         bs->stop = 0;
 200     }
 201 }
 202
 203 /* Implement the 're_set' method.  */
 204
 205 void
 206 exception_catchpoint::re_set ()
 207 {
 208   std::vector<symtab_and_line> sals;
 209   struct program_space *filter_pspace = current_program_space;
 210
 211   /* We first try to use the probe interface.  */
 212   try
 213     {
 214       event_location_up location
 215         = new_probe_location (exception_functions[kind].probe);
 216       sals = parse_probes (location.get (), filter_pspace, NULL);
 217     }
 218   catch (const gdb_exception_error &e)
 219     {
 220       /* Using the probe interface failed.  Let's fallback to the normal
 221          catchpoint mode.  */
 222       try
 223         {
 224           struct explicit_location explicit_loc;
 225
 226           initialize_explicit_location (&explicit_loc);
 227           explicit_loc.function_name
 228             = ASTRDUP (exception_functions[kind].function);
 229           event_location_up location = new_explicit_location (&explicit_loc);
 230           sals = this->decode_location (location.get (), filter_pspace);
 231         }
 232       catch (const gdb_exception_error &ex)
 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;
 238         }
 239     }
 240
 241   update_breakpoint_locations (this, filter_pspace, sals, {});
 242 }
 243
 244 enum print_stop_action
 245 exception_catchpoint::print_it (const bpstat *bs) const
 246 {
 247   struct ui_out *uiout = current_uiout;
 248   int bp_temp;
 249
 250   annotate_catchpoint (number);
 251   maybe_print_thread_hit_breakpoint (uiout);
 252
 253   bp_temp = disposition == disp_del;
 254   uiout->text (bp_temp ? "Temporary catchpoint "
 255                        : "Catchpoint ");
 256   uiout->field_signed ("bkptno", number);
 257   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 258                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 259                    : " (exception rethrown), ")));
 260   if (uiout->is_mi_like_p ())
 261     {
 262       uiout->field_string ("reason",
 263                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 264       uiout->field_string ("disp", bpdisp_text (disposition));
 265     }
 266   return PRINT_SRC_AND_LOC;
 267 }
 268
 269 bool
 270 exception_catchpoint::print_one (bp_location **last_loc) const
 271 {
 272   struct value_print_options opts;
 273   struct ui_out *uiout = current_uiout;
 274
 275   get_user_print_options (&opts);
 276
 277   if (opts.addressprint)
 278     uiout->field_skip ("addr");
 279   annotate_field (5);
 280
 281   switch (kind)
 282     {
 283     case EX_EVENT_THROW:
 284       uiout->field_string ("what", "exception throw");
 285       if (uiout->is_mi_like_p ())
 286         uiout->field_string ("catch-type", "throw");
 287       break;
 288
 289     case EX_EVENT_RETHROW:
 290       uiout->field_string ("what", "exception rethrow");
 291       if (uiout->is_mi_like_p ())
 292         uiout->field_string ("catch-type", "rethrow");
 293       break;
 294
 295     case EX_EVENT_CATCH:
 296       uiout->field_string ("what", "exception catch");
 297       if (uiout->is_mi_like_p ())
 298         uiout->field_string ("catch-type", "catch");
 299       break;
 300     }
 301
 302   return true;
 303 }
 304
 305 /* Implement the 'print_one_detail' method.  */
 306
 307 void
 308 exception_catchpoint::print_one_detail (struct ui_out *uiout) const
 309 {
 310   if (!exception_rx.empty ())
 311     {
 312       uiout->text (_("\tmatching: "));
 313       uiout->field_string ("regexp", exception_rx);
 314       uiout->text ("\n");
 315     }
 316 }
 317
 318 void
 319 exception_catchpoint::print_mention () const
 320 {
 321   struct ui_out *uiout = current_uiout;
 322   int bp_temp;
 323
 324   bp_temp = disposition == disp_del;
 325   uiout->message ("%s %d %s",
 326                   (bp_temp ? _("Temporary catchpoint ") : _("Catchpoint")),
 327                   number,
 328                   (kind == EX_EVENT_THROW
 329                    ? _("(throw)") : (kind == EX_EVENT_CATCH
 330                                      ? _("(catch)") : _("(rethrow)"))));
 331 }
 332
 333 /* Implement the "print_recreate" method for throw and catch
 334    catchpoints.  */
 335
 336 void
 337 exception_catchpoint::print_recreate (struct ui_file *fp) const
 338 {
 339   int bp_temp;
 340
 341   bp_temp = disposition == disp_del;
 342   gdb_printf (fp, bp_temp ? "tcatch " : "catch ");
 343   switch (kind)
 344     {
 345     case EX_EVENT_THROW:
 346       gdb_printf (fp, "throw");
 347       break;
 348     case EX_EVENT_CATCH:
 349       gdb_printf (fp, "catch");
 350       break;
 351     case EX_EVENT_RETHROW:
 352       gdb_printf (fp, "rethrow");
 353       break;
 354     }
 355   print_recreate_thread (fp);
 356 }
 357
 358 /* Implement the "allocate_location" method for throw and catch
 359    catchpoints.  */
 360
 361 bp_location *
 362 exception_catchpoint::allocate_location ()
 363 {
 364   return new bp_location (this, bp_loc_software_breakpoint);
 365 }
 366
 367 static void
 368 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 369                           const char *cond_string,
 370                           enum exception_event_kind ex_event, int from_tty)
 371 {
 372   struct gdbarch *gdbarch = get_current_arch ();
 373
 374   std::unique_ptr<exception_catchpoint> cp
 375     (new exception_catchpoint (gdbarch, tempflag, cond_string,
 376                                ex_event, std::move (except_rx)));
 377
 378   cp->re_set ();
 379
 380   install_breakpoint (0, std::move (cp), 1);
 381 }
 382
 383 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 384    by whitespace.
 385
 386    If there is any non-whitespace text between *STRING and the "if"
 387    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 388    this returns NULL.
 389
 390    STRING is updated to point to the "if" token, if it exists, or to
 391    the end of the string.  */
 392
 393 static std::string
 394 extract_exception_regexp (const char **string)
 395 {
 396   const char *start;
 397   const char *last, *last_space;
 398
 399   start = skip_spaces (*string);
 400
 401   last = start;
 402   last_space = start;
 403   while (*last != '\0')
 404     {
 405       const char *if_token = last;
 406
 407       /* Check for the "if".  */
 408       if (check_for_argument (&if_token, "if", 2))
 409         break;
 410
 411       /* No "if" token here.  Skip to the next word start.  */
 412       last_space = skip_to_space (last);
 413       last = skip_spaces (last_space);
 414     }
 415
 416   *string = last;
 417   if (last_space > start)
 418     return std::string (start, last_space - start);
 419   return std::string ();
 420 }
 421
 422 /* See breakpoint.h.  */
 423
 424 void
 425 catch_exception_event (enum exception_event_kind ex_event,
 426                        const char *arg, bool tempflag, int from_tty)
 427 {
 428   const char *cond_string = NULL;
 429
 430   if (!arg)
 431     arg = "";
 432   arg = skip_spaces (arg);
 433
 434   std::string except_rx = extract_exception_regexp (&arg);
 435
 436   cond_string = ep_parse_optional_if_clause (&arg);
 437
 438   if ((*arg != '\0') && !isspace (*arg))
 439     error (_("Junk at end of arguments."));
 440
 441   if (ex_event != EX_EVENT_THROW
 442       && ex_event != EX_EVENT_CATCH
 443       && ex_event != EX_EVENT_RETHROW)
 444     error (_("Unsupported or unknown exception event; cannot catch it"));
 445
 446   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 447                             ex_event, from_tty);
 448 }
 449
 450 /* Implementation of "catch catch" command.  */
 451
 452 static void
 453 catch_catch_command (const char *arg, int from_tty,
 454                      struct cmd_list_element *command)
 455 {
 456   bool tempflag = command->context () == CATCH_TEMPORARY;
 457
 458   catch_exception_event (EX_EVENT_CATCH, arg, tempflag, from_tty);
 459 }
 460
 461 /* Implementation of "catch throw" command.  */
 462
 463 static void
 464 catch_throw_command (const char *arg, int from_tty,
 465                      struct cmd_list_element *command)
 466 {
 467   bool tempflag = command->context () == CATCH_TEMPORARY;
 468
 469   catch_exception_event (EX_EVENT_THROW, arg, tempflag, from_tty);
 470 }
 471
 472 /* Implementation of "catch rethrow" command.  */
 473
 474 static void
 475 catch_rethrow_command (const char *arg, int from_tty,
 476                        struct cmd_list_element *command)
 477 {
 478   bool tempflag = command->context () == CATCH_TEMPORARY;
 479
 480   catch_exception_event (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 481 }
 482
 483 \f
 484
 485 /* Implement the 'make_value' method for the $_exception
 486    internalvar.  */
 487
 488 static struct value *
 489 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 490 {
 491   struct value *arg0, *arg1;
 492   struct type *obj_type;
 493
 494   fetch_probe_arguments (&arg0, &arg1);
 495
 496   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 497      the std::type_info for the exception.  Now we find the type from
 498      the type_info and cast the result.  */
 499   obj_type = cplus_type_from_type_info (arg1);
 500   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 501 }
 502
 503 /* Implementation of the '$_exception' variable.  */
 504
 505 static const struct internalvar_funcs exception_funcs =
 506 {
 507   compute_exception,
 508   NULL,
 509 };
 510
 511 \f
 512
 513 void _initialize_break_catch_throw ();
 514 void
 515 _initialize_break_catch_throw ()
 516 {
 517   /* Add catch and tcatch sub-commands.  */
 518   add_catch_command ("catch", _("\
 519 Catch an exception, when caught."),
 520                      catch_catch_command,
 521                      NULL,
 522                      CATCH_PERMANENT,
 523                      CATCH_TEMPORARY);
 524   add_catch_command ("throw", _("\
 525 Catch an exception, when thrown."),
 526                      catch_throw_command,
 527                      NULL,
 528                      CATCH_PERMANENT,
 529                      CATCH_TEMPORARY);
 530   add_catch_command ("rethrow", _("\
 531 Catch an exception, when rethrown."),
 532                      catch_rethrow_command,
 533                      NULL,
 534                      CATCH_PERMANENT,
 535                      CATCH_TEMPORARY);
 536
 537   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 538 }