gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2023 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.  Unlike most catchpoints, this
  67    one is implemented with code breakpoints, so it inherits struct
  68    code_breakpoint, not struct catchpoint.  */
  69
  70 struct exception_catchpoint : public code_breakpoint
  71 {
  72   exception_catchpoint (struct gdbarch *gdbarch,
  73                         bool temp, const char *cond_string_,
  74                         enum exception_event_kind kind_,
  75                         std::string &&except_rx)
  76     : code_breakpoint (gdbarch, bp_catchpoint, temp, cond_string_),
  77       kind (kind_),
  78       exception_rx (std::move (except_rx)),
  79       pattern (exception_rx.empty ()
  80                ? nullptr
  81                : new compiled_regex (exception_rx.c_str (), REG_NOSUB,
  82                                      _("invalid type-matching regexp")))
  83   {
  84     pspace = current_program_space;
  85     re_set ();
  86   }
  87
  88   void re_set () override;
  89   enum print_stop_action print_it (const bpstat *bs) const override;
  90   bool print_one (const bp_location **) const override;
  91   void print_mention () const override;
  92   void print_recreate (struct ui_file *fp) const override;
  93   void print_one_detail (struct ui_out *) const override;
  94   void check_status (struct bpstat *bs) override;
  95   struct bp_location *allocate_location () override;
  96
  97   /* The kind of exception catchpoint.  */
  98
  99   enum exception_event_kind kind;
 100
 101   /* If not empty, a string holding the source form of the regular
 102      expression to match against.  */
 103
 104   std::string exception_rx;
 105
 106   /* If non-NULL, a compiled regular expression which is used to
 107      determine which exceptions to stop on.  */
 108
 109   std::unique_ptr<compiled_regex> pattern;
 110 };
 111
 112 /* See breakpoint.h.  */
 113
 114 bool
 115 is_exception_catchpoint (breakpoint *bp)
 116 {
 117   return dynamic_cast<exception_catchpoint *> (bp) != nullptr;
 118 }
 119
 120 \f
 121
 122 /* A helper function that fetches exception probe arguments.  This
 123    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
 124    It will throw an exception on any kind of failure.  */
 125
 126 static void
 127 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 128 {
 129   frame_info_ptr frame = get_selected_frame (_("No frame selected"));
 130   CORE_ADDR pc = get_frame_pc (frame);
 131   struct bound_probe pc_probe;
 132   unsigned n_args;
 133
 134   pc_probe = find_probe_by_pc (pc);
 135   if (pc_probe.prob == NULL)
 136     error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
 137
 138   if (pc_probe.prob->get_provider () != "libstdcxx"
 139       || (pc_probe.prob->get_name () != "catch"
 140           && pc_probe.prob->get_name () != "throw"
 141           && pc_probe.prob->get_name () != "rethrow"))
 142     error (_("not stopped at a C++ exception catchpoint"));
 143
 144   n_args = pc_probe.prob->get_argument_count (get_frame_arch (frame));
 145   if (n_args < 2)
 146     error (_("C++ exception catchpoint has too few arguments"));
 147
 148   if (arg0 != NULL)
 149     *arg0 = pc_probe.prob->evaluate_argument (0, frame);
 150   *arg1 = pc_probe.prob->evaluate_argument (1, frame);
 151
 152   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 153     error (_("error computing probe argument at c++ exception catchpoint"));
 154 }
 155
 156 \f
 157
 158 /* Implement the 'check_status' method.  */
 159
 160 void
 161 exception_catchpoint::check_status (struct bpstat *bs)
 162 {
 163   std::string type_name;
 164
 165   this->breakpoint::check_status (bs);
 166   if (!bs->stop)
 167     return;
 168
 169   if (this->pattern == NULL)
 170     return;
 171
 172   const char *name = nullptr;
 173   gdb::unique_xmalloc_ptr<char> canon;
 174   try
 175     {
 176       struct value *typeinfo_arg;
 177
 178       fetch_probe_arguments (NULL, &typeinfo_arg);
 179       type_name = cplus_typename_from_type_info (typeinfo_arg);
 180
 181       canon = cp_canonicalize_string (type_name.c_str ());
 182       name = (canon != nullptr
 183               ? canon.get ()
 184               : type_name.c_str ());
 185     }
 186   catch (const gdb_exception_error &e)
 187     {
 188       exception_print (gdb_stderr, e);
 189     }
 190
 191   if (name != nullptr)
 192     {
 193       if (this->pattern->exec (name, 0, NULL, 0) != 0)
 194         bs->stop = false;
 195     }
 196 }
 197
 198 /* Implement the 're_set' method.  */
 199
 200 void
 201 exception_catchpoint::re_set ()
 202 {
 203   std::vector<symtab_and_line> sals;
 204   struct program_space *filter_pspace = current_program_space;
 205
 206   /* We first try to use the probe interface.  */
 207   try
 208     {
 209       location_spec_up locspec
 210         = new_probe_location_spec (exception_functions[kind].probe);
 211       sals = parse_probes (locspec.get (), filter_pspace, NULL);
 212     }
 213   catch (const gdb_exception_error &e)
 214     {
 215       /* Using the probe interface failed.  Let's fallback to the normal
 216          catchpoint mode.  */
 217       try
 218         {
 219           location_spec_up locspec
 220             = (new_explicit_location_spec_function
 221                (exception_functions[kind].function));
 222           sals = this->decode_location_spec (locspec.get (), filter_pspace);
 223         }
 224       catch (const gdb_exception_error &ex)
 225         {
 226           /* NOT_FOUND_ERROR just means the breakpoint will be
 227              pending, so let it through.  */
 228           if (ex.error != NOT_FOUND_ERROR)
 229             throw;
 230         }
 231     }
 232
 233   update_breakpoint_locations (this, filter_pspace, sals, {});
 234 }
 235
 236 enum print_stop_action
 237 exception_catchpoint::print_it (const bpstat *bs) const
 238 {
 239   struct ui_out *uiout = current_uiout;
 240   int bp_temp;
 241
 242   annotate_catchpoint (number);
 243   maybe_print_thread_hit_breakpoint (uiout);
 244
 245   bp_temp = disposition == disp_del;
 246   uiout->text (bp_temp ? "Temporary catchpoint "
 247                        : "Catchpoint ");
 248   print_num_locno (bs, uiout);
 249   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 250                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 251                    : " (exception rethrown), ")));
 252   if (uiout->is_mi_like_p ())
 253     {
 254       uiout->field_string ("reason",
 255                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 256       uiout->field_string ("disp", bpdisp_text (disposition));
 257     }
 258   return PRINT_SRC_AND_LOC;
 259 }
 260
 261 bool
 262 exception_catchpoint::print_one (const bp_location **last_loc) const
 263 {
 264   struct value_print_options opts;
 265   struct ui_out *uiout = current_uiout;
 266
 267   get_user_print_options (&opts);
 268
 269   if (opts.addressprint)
 270     uiout->field_skip ("addr");
 271   annotate_field (5);
 272
 273   switch (kind)
 274     {
 275     case EX_EVENT_THROW:
 276       uiout->field_string ("what", "exception throw");
 277       if (uiout->is_mi_like_p ())
 278         uiout->field_string ("catch-type", "throw");
 279       break;
 280
 281     case EX_EVENT_RETHROW:
 282       uiout->field_string ("what", "exception rethrow");
 283       if (uiout->is_mi_like_p ())
 284         uiout->field_string ("catch-type", "rethrow");
 285       break;
 286
 287     case EX_EVENT_CATCH:
 288       uiout->field_string ("what", "exception catch");
 289       if (uiout->is_mi_like_p ())
 290         uiout->field_string ("catch-type", "catch");
 291       break;
 292     }
 293
 294   return true;
 295 }
 296
 297 /* Implement the 'print_one_detail' method.  */
 298
 299 void
 300 exception_catchpoint::print_one_detail (struct ui_out *uiout) const
 301 {
 302   if (!exception_rx.empty ())
 303     {
 304       uiout->text (_("\tmatching: "));
 305       uiout->field_string ("regexp", exception_rx);
 306       uiout->text ("\n");
 307     }
 308 }
 309
 310 void
 311 exception_catchpoint::print_mention () const
 312 {
 313   struct ui_out *uiout = current_uiout;
 314   int bp_temp;
 315
 316   bp_temp = disposition == disp_del;
 317   uiout->message ("%s %d %s",
 318                   (bp_temp ? _("Temporary catchpoint ") : _("Catchpoint")),
 319                   number,
 320                   (kind == EX_EVENT_THROW
 321                    ? _("(throw)") : (kind == EX_EVENT_CATCH
 322                                      ? _("(catch)") : _("(rethrow)"))));
 323 }
 324
 325 /* Implement the "print_recreate" method for throw and catch
 326    catchpoints.  */
 327
 328 void
 329 exception_catchpoint::print_recreate (struct ui_file *fp) const
 330 {
 331   int bp_temp;
 332
 333   bp_temp = disposition == disp_del;
 334   gdb_printf (fp, bp_temp ? "tcatch " : "catch ");
 335   switch (kind)
 336     {
 337     case EX_EVENT_THROW:
 338       gdb_printf (fp, "throw");
 339       break;
 340     case EX_EVENT_CATCH:
 341       gdb_printf (fp, "catch");
 342       break;
 343     case EX_EVENT_RETHROW:
 344       gdb_printf (fp, "rethrow");
 345       break;
 346     }
 347   print_recreate_thread (fp);
 348 }
 349
 350 /* Implement the "allocate_location" method for throw and catch
 351    catchpoints.  */
 352
 353 bp_location *
 354 exception_catchpoint::allocate_location ()
 355 {
 356   return new bp_location (this, bp_loc_software_breakpoint);
 357 }
 358
 359 static void
 360 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 361                           const char *cond_string,
 362                           enum exception_event_kind ex_event, int from_tty)
 363 {
 364   struct gdbarch *gdbarch = get_current_arch ();
 365
 366   std::unique_ptr<exception_catchpoint> cp
 367     (new exception_catchpoint (gdbarch, tempflag, cond_string,
 368                                ex_event, std::move (except_rx)));
 369
 370   install_breakpoint (0, std::move (cp), 1);
 371 }
 372
 373 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 374    by whitespace.
 375
 376    If there is any non-whitespace text between *STRING and the "if"
 377    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 378    this returns NULL.
 379
 380    STRING is updated to point to the "if" token, if it exists, or to
 381    the end of the string.  */
 382
 383 static std::string
 384 extract_exception_regexp (const char **string)
 385 {
 386   const char *start;
 387   const char *last, *last_space;
 388
 389   start = skip_spaces (*string);
 390
 391   last = start;
 392   last_space = start;
 393   while (*last != '\0')
 394     {
 395       const char *if_token = last;
 396
 397       /* Check for the "if".  */
 398       if (check_for_argument (&if_token, "if", 2))
 399         break;
 400
 401       /* No "if" token here.  Skip to the next word start.  */
 402       last_space = skip_to_space (last);
 403       last = skip_spaces (last_space);
 404     }
 405
 406   *string = last;
 407   if (last_space > start)
 408     return std::string (start, last_space - start);
 409   return std::string ();
 410 }
 411
 412 /* See breakpoint.h.  */
 413
 414 void
 415 catch_exception_event (enum exception_event_kind ex_event,
 416                        const char *arg, bool tempflag, int from_tty)
 417 {
 418   const char *cond_string = NULL;
 419
 420   if (!arg)
 421     arg = "";
 422   arg = skip_spaces (arg);
 423
 424   std::string except_rx = extract_exception_regexp (&arg);
 425
 426   cond_string = ep_parse_optional_if_clause (&arg);
 427
 428   if ((*arg != '\0') && !isspace (*arg))
 429     error (_("Junk at end of arguments."));
 430
 431   if (ex_event != EX_EVENT_THROW
 432       && ex_event != EX_EVENT_CATCH
 433       && ex_event != EX_EVENT_RETHROW)
 434     error (_("Unsupported or unknown exception event; cannot catch it"));
 435
 436   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 437                             ex_event, from_tty);
 438 }
 439
 440 /* Implementation of "catch catch" command.  */
 441
 442 static void
 443 catch_catch_command (const char *arg, int from_tty,
 444                      struct cmd_list_element *command)
 445 {
 446   bool tempflag = command->context () == CATCH_TEMPORARY;
 447
 448   catch_exception_event (EX_EVENT_CATCH, arg, tempflag, from_tty);
 449 }
 450
 451 /* Implementation of "catch throw" command.  */
 452
 453 static void
 454 catch_throw_command (const char *arg, int from_tty,
 455                      struct cmd_list_element *command)
 456 {
 457   bool tempflag = command->context () == CATCH_TEMPORARY;
 458
 459   catch_exception_event (EX_EVENT_THROW, arg, tempflag, from_tty);
 460 }
 461
 462 /* Implementation of "catch rethrow" command.  */
 463
 464 static void
 465 catch_rethrow_command (const char *arg, int from_tty,
 466                        struct cmd_list_element *command)
 467 {
 468   bool tempflag = command->context () == CATCH_TEMPORARY;
 469
 470   catch_exception_event (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 471 }
 472
 473 \f
 474
 475 /* Implement the 'make_value' method for the $_exception
 476    internalvar.  */
 477
 478 static struct value *
 479 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 480 {
 481   struct value *arg0, *arg1;
 482   struct type *obj_type;
 483
 484   fetch_probe_arguments (&arg0, &arg1);
 485
 486   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 487      the std::type_info for the exception.  Now we find the type from
 488      the type_info and cast the result.  */
 489   obj_type = cplus_type_from_type_info (arg1);
 490   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 491 }
 492
 493 /* Implementation of the '$_exception' variable.  */
 494
 495 static const struct internalvar_funcs exception_funcs =
 496 {
 497   compute_exception,
 498   NULL,
 499 };
 500
 501 \f
 502
 503 void _initialize_break_catch_throw ();
 504 void
 505 _initialize_break_catch_throw ()
 506 {
 507   /* Add catch and tcatch sub-commands.  */
 508   add_catch_command ("catch", _("\
 509 Catch an exception, when caught."),
 510                      catch_catch_command,
 511                      NULL,
 512                      CATCH_PERMANENT,
 513                      CATCH_TEMPORARY);
 514   add_catch_command ("throw", _("\
 515 Catch an exception, when thrown."),
 516                      catch_throw_command,
 517                      NULL,
 518                      CATCH_PERMANENT,
 519                      CATCH_TEMPORARY);
 520   add_catch_command ("rethrow", _("\
 521 Catch an exception, when rethrown."),
 522                      catch_rethrow_command,
 523                      NULL,
 524                      CATCH_PERMANENT,
 525                      CATCH_TEMPORARY);
 526
 527   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 528 }