gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2024 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 "arch-utils.h"
  21 #include <ctype.h>
  22 #include "breakpoint.h"
  23 #include "cli/cli-cmds.h"
  24 #include "inferior.h"
  25 #include "annotate.h"
  26 #include "valprint.h"
  27 #include "cli/cli-utils.h"
  28 #include "completer.h"
  29 #include "gdbsupport/gdb_obstack.h"
  30 #include "mi/mi-common.h"
  31 #include "linespec.h"
  32 #include "probe.h"
  33 #include "objfiles.h"
  34 #include "cp-abi.h"
  35 #include "gdbsupport/gdb_regex.h"
  36 #include "cp-support.h"
  37 #include "location.h"
  38 #include "cli/cli-decode.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 /* The type of an exception catchpoint.  Unlike most catchpoints, this
  66    one is implemented with code breakpoints, so it inherits struct
  67    code_breakpoint, not struct catchpoint.  */
  68
  69 struct exception_catchpoint : public code_breakpoint
  70 {
  71   exception_catchpoint (struct gdbarch *gdbarch,
  72                         bool temp, const char *cond_string_,
  73                         enum exception_event_kind kind_,
  74                         std::string &&except_rx)
  75     : code_breakpoint (gdbarch, bp_catchpoint, temp, cond_string_),
  76       kind (kind_),
  77       exception_rx (std::move (except_rx)),
  78       pattern (exception_rx.empty ()
  79                ? nullptr
  80                : new compiled_regex (exception_rx.c_str (), REG_NOSUB,
  81                                      _("invalid type-matching regexp")))
  82   {
  83     pspace = current_program_space;
  84     re_set ();
  85   }
  86
  87   void re_set () override;
  88   enum print_stop_action print_it (const bpstat *bs) const override;
  89   bool print_one (const bp_location **) const override;
  90   void print_mention () const override;
  91   void print_recreate (struct ui_file *fp) const override;
  92   void print_one_detail (struct ui_out *) const override;
  93   void check_status (struct bpstat *bs) override;
  94   struct bp_location *allocate_location () override;
  95
  96   /* The kind of exception catchpoint.  */
  97
  98   enum exception_event_kind kind;
  99
 100   /* If not empty, a string holding the source form of the regular
 101      expression to match against.  */
 102
 103   std::string exception_rx;
 104
 105   /* If non-NULL, a compiled regular expression which is used to
 106      determine which exceptions to stop on.  */
 107
 108   std::unique_ptr<compiled_regex> pattern;
 109 };
 110
 111 /* See breakpoint.h.  */
 112
 113 bool
 114 is_exception_catchpoint (breakpoint *bp)
 115 {
 116   return dynamic_cast<exception_catchpoint *> (bp) != nullptr;
 117 }
 118
 119 \f
 120
 121 /* A helper function that fetches exception probe arguments.  This
 122    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
 123    It will throw an exception on any kind of failure.  */
 124
 125 static void
 126 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 127 {
 128   frame_info_ptr frame = get_selected_frame (_("No frame selected"));
 129   CORE_ADDR pc = get_frame_pc (frame);
 130   struct bound_probe pc_probe;
 131   unsigned n_args;
 132
 133   pc_probe = find_probe_by_pc (pc);
 134   if (pc_probe.prob == NULL)
 135     error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
 136
 137   if (pc_probe.prob->get_provider () != "libstdcxx"
 138       || (pc_probe.prob->get_name () != "catch"
 139           && pc_probe.prob->get_name () != "throw"
 140           && pc_probe.prob->get_name () != "rethrow"))
 141     error (_("not stopped at a C++ exception catchpoint"));
 142
 143   n_args = pc_probe.prob->get_argument_count (get_frame_arch (frame));
 144   if (n_args < 2)
 145     error (_("C++ exception catchpoint has too few arguments"));
 146
 147   if (arg0 != NULL)
 148     *arg0 = pc_probe.prob->evaluate_argument (0, frame);
 149   *arg1 = pc_probe.prob->evaluate_argument (1, frame);
 150
 151   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 152     error (_("error computing probe argument at c++ exception catchpoint"));
 153 }
 154
 155 \f
 156
 157 /* Implement the 'check_status' method.  */
 158
 159 void
 160 exception_catchpoint::check_status (struct bpstat *bs)
 161 {
 162   std::string type_name;
 163
 164   this->breakpoint::check_status (bs);
 165   if (!bs->stop)
 166     return;
 167
 168   if (this->pattern == NULL)
 169     return;
 170
 171   const char *name = nullptr;
 172   gdb::unique_xmalloc_ptr<char> canon;
 173   try
 174     {
 175       struct value *typeinfo_arg;
 176
 177       fetch_probe_arguments (NULL, &typeinfo_arg);
 178       type_name = cplus_typename_from_type_info (typeinfo_arg);
 179
 180       canon = cp_canonicalize_string (type_name.c_str ());
 181       name = (canon != nullptr
 182               ? canon.get ()
 183               : type_name.c_str ());
 184     }
 185   catch (const gdb_exception_error &e)
 186     {
 187       exception_print (gdb_stderr, e);
 188     }
 189
 190   if (name != nullptr)
 191     {
 192       if (this->pattern->exec (name, 0, NULL, 0) != 0)
 193         bs->stop = false;
 194     }
 195 }
 196
 197 /* Implement the 're_set' method.  */
 198
 199 void
 200 exception_catchpoint::re_set ()
 201 {
 202   std::vector<symtab_and_line> sals;
 203   struct program_space *filter_pspace = current_program_space;
 204
 205   /* We first try to use the probe interface.  */
 206   try
 207     {
 208       location_spec_up locspec
 209         = new_probe_location_spec (exception_functions[kind].probe);
 210       sals = parse_probes (locspec.get (), filter_pspace, NULL);
 211     }
 212   catch (const gdb_exception_error &e)
 213     {
 214       /* Using the probe interface failed.  Let's fallback to the normal
 215          catchpoint mode.  */
 216       try
 217         {
 218           location_spec_up locspec
 219             = (new_explicit_location_spec_function
 220                (exception_functions[kind].function));
 221           sals = this->decode_location_spec (locspec.get (), filter_pspace);
 222         }
 223       catch (const gdb_exception_error &ex)
 224         {
 225           /* NOT_FOUND_ERROR just means the breakpoint will be
 226              pending, so let it through.  */
 227           if (ex.error != NOT_FOUND_ERROR)
 228             throw;
 229         }
 230     }
 231
 232   update_breakpoint_locations (this, filter_pspace, sals, {});
 233 }
 234
 235 enum print_stop_action
 236 exception_catchpoint::print_it (const bpstat *bs) const
 237 {
 238   struct ui_out *uiout = current_uiout;
 239   int bp_temp;
 240
 241   annotate_catchpoint (number);
 242   maybe_print_thread_hit_breakpoint (uiout);
 243
 244   bp_temp = disposition == disp_del;
 245   uiout->text (bp_temp ? "Temporary catchpoint "
 246                        : "Catchpoint ");
 247   print_num_locno (bs, uiout);
 248   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 249                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 250                    : " (exception rethrown), ")));
 251   if (uiout->is_mi_like_p ())
 252     {
 253       uiout->field_string ("reason",
 254                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 255       uiout->field_string ("disp", bpdisp_text (disposition));
 256     }
 257   return PRINT_SRC_AND_LOC;
 258 }
 259
 260 bool
 261 exception_catchpoint::print_one (const bp_location **last_loc) const
 262 {
 263   struct value_print_options opts;
 264   struct ui_out *uiout = current_uiout;
 265
 266   get_user_print_options (&opts);
 267
 268   if (opts.addressprint)
 269     uiout->field_skip ("addr");
 270   annotate_field (5);
 271
 272   switch (kind)
 273     {
 274     case EX_EVENT_THROW:
 275       uiout->field_string ("what", "exception throw");
 276       if (uiout->is_mi_like_p ())
 277         uiout->field_string ("catch-type", "throw");
 278       break;
 279
 280     case EX_EVENT_RETHROW:
 281       uiout->field_string ("what", "exception rethrow");
 282       if (uiout->is_mi_like_p ())
 283         uiout->field_string ("catch-type", "rethrow");
 284       break;
 285
 286     case EX_EVENT_CATCH:
 287       uiout->field_string ("what", "exception catch");
 288       if (uiout->is_mi_like_p ())
 289         uiout->field_string ("catch-type", "catch");
 290       break;
 291     }
 292
 293   return true;
 294 }
 295
 296 /* Implement the 'print_one_detail' method.  */
 297
 298 void
 299 exception_catchpoint::print_one_detail (struct ui_out *uiout) const
 300 {
 301   if (!exception_rx.empty ())
 302     {
 303       uiout->text (_("\tmatching: "));
 304       uiout->field_string ("regexp", exception_rx);
 305       uiout->text ("\n");
 306     }
 307 }
 308
 309 void
 310 exception_catchpoint::print_mention () const
 311 {
 312   struct ui_out *uiout = current_uiout;
 313   int bp_temp;
 314
 315   bp_temp = disposition == disp_del;
 316   uiout->message ("%s %d %s",
 317                   (bp_temp ? _("Temporary catchpoint ") : _("Catchpoint")),
 318                   number,
 319                   (kind == EX_EVENT_THROW
 320                    ? _("(throw)") : (kind == EX_EVENT_CATCH
 321                                      ? _("(catch)") : _("(rethrow)"))));
 322 }
 323
 324 /* Implement the "print_recreate" method for throw and catch
 325    catchpoints.  */
 326
 327 void
 328 exception_catchpoint::print_recreate (struct ui_file *fp) const
 329 {
 330   int bp_temp;
 331
 332   bp_temp = disposition == disp_del;
 333   gdb_printf (fp, bp_temp ? "tcatch " : "catch ");
 334   switch (kind)
 335     {
 336     case EX_EVENT_THROW:
 337       gdb_printf (fp, "throw");
 338       break;
 339     case EX_EVENT_CATCH:
 340       gdb_printf (fp, "catch");
 341       break;
 342     case EX_EVENT_RETHROW:
 343       gdb_printf (fp, "rethrow");
 344       break;
 345     }
 346   print_recreate_thread (fp);
 347 }
 348
 349 /* Implement the "allocate_location" method for throw and catch
 350    catchpoints.  */
 351
 352 bp_location *
 353 exception_catchpoint::allocate_location ()
 354 {
 355   return new bp_location (this, bp_loc_software_breakpoint);
 356 }
 357
 358 static void
 359 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 360                           const char *cond_string,
 361                           enum exception_event_kind ex_event, int from_tty)
 362 {
 363   struct gdbarch *gdbarch = get_current_arch ();
 364
 365   std::unique_ptr<exception_catchpoint> cp
 366     (new exception_catchpoint (gdbarch, tempflag, cond_string,
 367                                ex_event, std::move (except_rx)));
 368
 369   install_breakpoint (0, std::move (cp), 1);
 370 }
 371
 372 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 373    by whitespace.
 374
 375    If there is any non-whitespace text between *STRING and the "if"
 376    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 377    this returns NULL.
 378
 379    STRING is updated to point to the "if" token, if it exists, or to
 380    the end of the string.  */
 381
 382 static std::string
 383 extract_exception_regexp (const char **string)
 384 {
 385   const char *start;
 386   const char *last, *last_space;
 387
 388   start = skip_spaces (*string);
 389
 390   last = start;
 391   last_space = start;
 392   while (*last != '\0')
 393     {
 394       const char *if_token = last;
 395
 396       /* Check for the "if".  */
 397       if (check_for_argument (&if_token, "if", 2))
 398         break;
 399
 400       /* No "if" token here.  Skip to the next word start.  */
 401       last_space = skip_to_space (last);
 402       last = skip_spaces (last_space);
 403     }
 404
 405   *string = last;
 406   if (last_space > start)
 407     return std::string (start, last_space - start);
 408   return std::string ();
 409 }
 410
 411 /* See breakpoint.h.  */
 412
 413 void
 414 catch_exception_event (enum exception_event_kind ex_event,
 415                        const char *arg, bool tempflag, int from_tty)
 416 {
 417   const char *cond_string = NULL;
 418
 419   if (!arg)
 420     arg = "";
 421   arg = skip_spaces (arg);
 422
 423   std::string except_rx = extract_exception_regexp (&arg);
 424
 425   cond_string = ep_parse_optional_if_clause (&arg);
 426
 427   if ((*arg != '\0') && !isspace (*arg))
 428     error (_("Junk at end of arguments."));
 429
 430   if (ex_event != EX_EVENT_THROW
 431       && ex_event != EX_EVENT_CATCH
 432       && ex_event != EX_EVENT_RETHROW)
 433     error (_("Unsupported or unknown exception event; cannot catch it"));
 434
 435   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 436                             ex_event, from_tty);
 437 }
 438
 439 /* Implementation of "catch catch" command.  */
 440
 441 static void
 442 catch_catch_command (const char *arg, int from_tty,
 443                      struct cmd_list_element *command)
 444 {
 445   bool tempflag = command->context () == CATCH_TEMPORARY;
 446
 447   catch_exception_event (EX_EVENT_CATCH, arg, tempflag, from_tty);
 448 }
 449
 450 /* Implementation of "catch throw" command.  */
 451
 452 static void
 453 catch_throw_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_THROW, arg, tempflag, from_tty);
 459 }
 460
 461 /* Implementation of "catch rethrow" command.  */
 462
 463 static void
 464 catch_rethrow_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_RETHROW, arg, tempflag, from_tty);
 470 }
 471
 472 \f
 473
 474 /* Implement the 'make_value' method for the $_exception
 475    internalvar.  */
 476
 477 static struct value *
 478 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 479 {
 480   struct value *arg0, *arg1;
 481   struct type *obj_type;
 482
 483   fetch_probe_arguments (&arg0, &arg1);
 484
 485   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 486      the std::type_info for the exception.  Now we find the type from
 487      the type_info and cast the result.  */
 488   obj_type = cplus_type_from_type_info (arg1);
 489   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 490 }
 491
 492 /* Implementation of the '$_exception' variable.  */
 493
 494 static const struct internalvar_funcs exception_funcs =
 495 {
 496   compute_exception,
 497   NULL,
 498 };
 499
 500 \f
 501
 502 void _initialize_break_catch_throw ();
 503 void
 504 _initialize_break_catch_throw ()
 505 {
 506   /* Add catch and tcatch sub-commands.  */
 507   add_catch_command ("catch", _("\
 508 Catch an exception, when caught."),
 509                      catch_catch_command,
 510                      NULL,
 511                      CATCH_PERMANENT,
 512                      CATCH_TEMPORARY);
 513   add_catch_command ("throw", _("\
 514 Catch an exception, when thrown."),
 515                      catch_throw_command,
 516                      NULL,
 517                      CATCH_PERMANENT,
 518                      CATCH_TEMPORARY);
 519   add_catch_command ("rethrow", _("\
 520 Catch an exception, when rethrown."),
 521                      catch_rethrow_command,
 522                      NULL,
 523                      CATCH_PERMANENT,
 524                      CATCH_TEMPORARY);
 525
 526   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 527 }