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 #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 \f
  87
  88 /* A helper function that fetches exception probe arguments.  This
  89    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
  90    It will throw an exception on any kind of failure.  */
  91
  92 static void
  93 fetch_probe_arguments (struct value **arg0, struct value **arg1)
  94 {
  95   struct frame_info *frame = get_selected_frame (_("No frame selected"));
  96   CORE_ADDR pc = get_frame_pc (frame);
  97   struct bound_probe pc_probe;
  98   unsigned n_args;
  99
 100   pc_probe = find_probe_by_pc (pc);
 101   if (pc_probe.prob == NULL
 102       || pc_probe.prob->get_provider () != "libstdcxx"
 103       || (pc_probe.prob->get_name () != "catch"
 104           && pc_probe.prob->get_name () != "throw"
 105           && pc_probe.prob->get_name () != "rethrow"))
 106     error (_("not stopped at a C++ exception catchpoint"));
 107
 108   n_args = pc_probe.prob->get_argument_count (frame);
 109   if (n_args < 2)
 110     error (_("C++ exception catchpoint has too few arguments"));
 111
 112   if (arg0 != NULL)
 113     *arg0 = pc_probe.prob->evaluate_argument (0, frame);
 114   *arg1 = pc_probe.prob->evaluate_argument (1, frame);
 115
 116   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 117     error (_("error computing probe argument at c++ exception catchpoint"));
 118 }
 119
 120 \f
 121
 122 /* A helper function that returns a value indicating the kind of the
 123    exception catchpoint B.  */
 124
 125 static enum exception_event_kind
 126 classify_exception_breakpoint (struct breakpoint *b)
 127 {
 128   struct exception_catchpoint *cp = (struct exception_catchpoint *) b;
 129
 130   return cp->kind;
 131 }
 132
 133 /* Implement the 'check_status' method.  */
 134
 135 static void
 136 check_status_exception_catchpoint (struct bpstats *bs)
 137 {
 138   struct exception_catchpoint *self
 139     = (struct exception_catchpoint *) bs->breakpoint_at;
 140   std::string type_name;
 141
 142   bkpt_breakpoint_ops.check_status (bs);
 143   if (bs->stop == 0)
 144     return;
 145
 146   if (self->pattern == NULL)
 147     return;
 148
 149   try
 150     {
 151       struct value *typeinfo_arg;
 152       std::string canon;
 153
 154       fetch_probe_arguments (NULL, &typeinfo_arg);
 155       type_name = cplus_typename_from_type_info (typeinfo_arg);
 156
 157       canon = cp_canonicalize_string (type_name.c_str ());
 158       if (!canon.empty ())
 159         std::swap (type_name, canon);
 160     }
 161   catch (const gdb_exception_error &e)
 162     {
 163       exception_print (gdb_stderr, e);
 164     }
 165
 166   if (!type_name.empty ())
 167     {
 168       if (self->pattern->exec (type_name.c_str (), 0, NULL, 0) != 0)
 169         bs->stop = 0;
 170     }
 171 }
 172
 173 /* Implement the 're_set' method.  */
 174
 175 static void
 176 re_set_exception_catchpoint (struct breakpoint *self)
 177 {
 178   std::vector<symtab_and_line> sals;
 179   enum exception_event_kind kind = classify_exception_breakpoint (self);
 180   struct program_space *filter_pspace = current_program_space;
 181
 182   /* We first try to use the probe interface.  */
 183   try
 184     {
 185       event_location_up location
 186         = new_probe_location (exception_functions[kind].probe);
 187       sals = parse_probes (location.get (), filter_pspace, NULL);
 188     }
 189   catch (const gdb_exception_error &e)
 190     {
 191       /* Using the probe interface failed.  Let's fallback to the normal
 192          catchpoint mode.  */
 193       try
 194         {
 195           struct explicit_location explicit_loc;
 196
 197           initialize_explicit_location (&explicit_loc);
 198           explicit_loc.function_name
 199             = ASTRDUP (exception_functions[kind].function);
 200           event_location_up location = new_explicit_location (&explicit_loc);
 201           sals = self->ops->decode_location (self, location.get (),
 202                                              filter_pspace);
 203         }
 204       catch (const gdb_exception_error &ex)
 205         {
 206           /* NOT_FOUND_ERROR just means the breakpoint will be
 207              pending, so let it through.  */
 208           if (ex.error != NOT_FOUND_ERROR)
 209             throw;
 210         }
 211     }
 212
 213   update_breakpoint_locations (self, filter_pspace, sals, {});
 214 }
 215
 216 static enum print_stop_action
 217 print_it_exception_catchpoint (bpstat bs)
 218 {
 219   struct ui_out *uiout = current_uiout;
 220   struct breakpoint *b = bs->breakpoint_at;
 221   int bp_temp;
 222   enum exception_event_kind kind = classify_exception_breakpoint (b);
 223
 224   annotate_catchpoint (b->number);
 225   maybe_print_thread_hit_breakpoint (uiout);
 226
 227   bp_temp = b->disposition == disp_del;
 228   uiout->text (bp_temp ? "Temporary catchpoint "
 229                        : "Catchpoint ");
 230   uiout->field_int ("bkptno", b->number);
 231   uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
 232                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 233                    : " (exception rethrown), ")));
 234   if (uiout->is_mi_like_p ())
 235     {
 236       uiout->field_string ("reason",
 237                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 238       uiout->field_string ("disp", bpdisp_text (b->disposition));
 239     }
 240   return PRINT_SRC_AND_LOC;
 241 }
 242
 243 static void
 244 print_one_exception_catchpoint (struct breakpoint *b,
 245                                 struct bp_location **last_loc)
 246 {
 247   struct value_print_options opts;
 248   struct ui_out *uiout = current_uiout;
 249   enum exception_event_kind kind = classify_exception_breakpoint (b);
 250
 251   get_user_print_options (&opts);
 252   if (opts.addressprint)
 253     {
 254       annotate_field (4);
 255       if (b->loc == NULL || b->loc->shlib_disabled)
 256         uiout->field_string ("addr", "<PENDING>");
 257       else
 258         uiout->field_core_addr ("addr",
 259                                 b->loc->gdbarch, b->loc->address);
 260     }
 261   annotate_field (5);
 262   if (b->loc)
 263     *last_loc = b->loc;
 264
 265   switch (kind)
 266     {
 267     case EX_EVENT_THROW:
 268       uiout->field_string ("what", "exception throw");
 269       if (uiout->is_mi_like_p ())
 270         uiout->field_string ("catch-type", "throw");
 271       break;
 272
 273     case EX_EVENT_RETHROW:
 274       uiout->field_string ("what", "exception rethrow");
 275       if (uiout->is_mi_like_p ())
 276         uiout->field_string ("catch-type", "rethrow");
 277       break;
 278
 279     case EX_EVENT_CATCH:
 280       uiout->field_string ("what", "exception catch");
 281       if (uiout->is_mi_like_p ())
 282         uiout->field_string ("catch-type", "catch");
 283       break;
 284     }
 285 }
 286
 287 /* Implement the 'print_one_detail' method.  */
 288
 289 static void
 290 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 291                                        struct ui_out *uiout)
 292 {
 293   const struct exception_catchpoint *cp
 294     = (const struct exception_catchpoint *) b;
 295
 296   if (!cp->exception_rx.empty ())
 297     {
 298       uiout->text (_("\tmatching: "));
 299       uiout->field_string ("regexp", cp->exception_rx.c_str ());
 300       uiout->text ("\n");
 301     }
 302 }
 303
 304 static void
 305 print_mention_exception_catchpoint (struct breakpoint *b)
 306 {
 307   struct ui_out *uiout = current_uiout;
 308   int bp_temp;
 309   enum exception_event_kind kind = classify_exception_breakpoint (b);
 310
 311   bp_temp = b->disposition == disp_del;
 312   uiout->message ("%s %d %s",
 313                   (bp_temp ? _("Temporary catchpoint ") : _("Catchpoint")),
 314                   b->number,
 315                   (kind == EX_EVENT_THROW
 316                    ? _("(throw)") : (kind == EX_EVENT_CATCH
 317                                      ? _("(catch)") : _("(rethrow)"))));
 318 }
 319
 320 /* Implement the "print_recreate" breakpoint_ops method for throw and
 321    catch catchpoints.  */
 322
 323 static void
 324 print_recreate_exception_catchpoint (struct breakpoint *b,
 325                                      struct ui_file *fp)
 326 {
 327   int bp_temp;
 328   enum exception_event_kind kind = classify_exception_breakpoint (b);
 329
 330   bp_temp = b->disposition == disp_del;
 331   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 332   switch (kind)
 333     {
 334     case EX_EVENT_THROW:
 335       fprintf_unfiltered (fp, "throw");
 336       break;
 337     case EX_EVENT_CATCH:
 338       fprintf_unfiltered (fp, "catch");
 339       break;
 340     case EX_EVENT_RETHROW:
 341       fprintf_unfiltered (fp, "rethrow");
 342       break;
 343     }
 344   print_recreate_thread (b, fp);
 345 }
 346
 347 static void
 348 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
 349                           const char *cond_string,
 350                           enum exception_event_kind ex_event, int from_tty)
 351 {
 352   std::unique_ptr<compiled_regex> pattern;
 353
 354   if (!except_rx.empty ())
 355     {
 356       pattern.reset (new compiled_regex (except_rx.c_str (), REG_NOSUB,
 357                                          _("invalid type-matching regexp")));
 358     }
 359
 360   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 361
 362   init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
 363                    &gnu_v3_exception_catchpoint_ops);
 364   /* We need to reset 'type' in order for code in breakpoint.c to do
 365      the right thing.  */
 366   cp->type = bp_breakpoint;
 367   cp->kind = ex_event;
 368   cp->exception_rx = std::move (except_rx);
 369   cp->pattern = std::move (pattern);
 370
 371   re_set_exception_catchpoint (cp.get ());
 372
 373   install_breakpoint (0, std::move (cp), 1);
 374 }
 375
 376 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 377    by whitespace.
 378
 379    If there is any non-whitespace text between *STRING and the "if"
 380    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 381    this returns NULL.
 382
 383    STRING is updated to point to the "if" token, if it exists, or to
 384    the end of the string.  */
 385
 386 static std::string
 387 extract_exception_regexp (const char **string)
 388 {
 389   const char *start;
 390   const char *last, *last_space;
 391
 392   start = skip_spaces (*string);
 393
 394   last = start;
 395   last_space = start;
 396   while (*last != '\0')
 397     {
 398       const char *if_token = last;
 399
 400       /* Check for the "if".  */
 401       if (check_for_argument (&if_token, "if", 2))
 402         break;
 403
 404       /* No "if" token here.  Skip to the next word start.  */
 405       last_space = skip_to_space (last);
 406       last = skip_spaces (last_space);
 407     }
 408
 409   *string = last;
 410   if (last_space > start)
 411     return std::string (start, last_space - start);
 412   return std::string ();
 413 }
 414
 415 /* See breakpoint.h.  */
 416
 417 void
 418 catch_exception_event (enum exception_event_kind ex_event,
 419                        const char *arg, bool tempflag, int from_tty)
 420 {
 421   const char *cond_string = NULL;
 422
 423   if (!arg)
 424     arg = "";
 425   arg = skip_spaces (arg);
 426
 427   std::string except_rx = extract_exception_regexp (&arg);
 428
 429   cond_string = ep_parse_optional_if_clause (&arg);
 430
 431   if ((*arg != '\0') && !isspace (*arg))
 432     error (_("Junk at end of arguments."));
 433
 434   if (ex_event != EX_EVENT_THROW
 435       && ex_event != EX_EVENT_CATCH
 436       && ex_event != EX_EVENT_RETHROW)
 437     error (_("Unsupported or unknown exception event; cannot catch it"));
 438
 439   handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
 440                             ex_event, from_tty);
 441 }
 442
 443 /* Implementation of "catch catch" command.  */
 444
 445 static void
 446 catch_catch_command (const char *arg, int from_tty,
 447                      struct cmd_list_element *command)
 448 {
 449   bool tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 450
 451   catch_exception_event (EX_EVENT_CATCH, arg, tempflag, from_tty);
 452 }
 453
 454 /* Implementation of "catch throw" command.  */
 455
 456 static void
 457 catch_throw_command (const char *arg, int from_tty,
 458                      struct cmd_list_element *command)
 459 {
 460   bool tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 461
 462   catch_exception_event (EX_EVENT_THROW, arg, tempflag, from_tty);
 463 }
 464
 465 /* Implementation of "catch rethrow" command.  */
 466
 467 static void
 468 catch_rethrow_command (const char *arg, int from_tty,
 469                        struct cmd_list_element *command)
 470 {
 471   bool tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 472
 473   catch_exception_event (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 474 }
 475
 476 \f
 477
 478 /* Implement the 'make_value' method for the $_exception
 479    internalvar.  */
 480
 481 static struct value *
 482 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 483 {
 484   struct value *arg0, *arg1;
 485   struct type *obj_type;
 486
 487   fetch_probe_arguments (&arg0, &arg1);
 488
 489   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 490      the std::type_info for the exception.  Now we find the type from
 491      the type_info and cast the result.  */
 492   obj_type = cplus_type_from_type_info (arg1);
 493   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 494 }
 495
 496 /* Implementation of the '$_exception' variable.  */
 497
 498 static const struct internalvar_funcs exception_funcs =
 499 {
 500   compute_exception,
 501   NULL,
 502   NULL
 503 };
 504
 505 \f
 506
 507 static void
 508 initialize_throw_catchpoint_ops (void)
 509 {
 510   struct breakpoint_ops *ops;
 511
 512   initialize_breakpoint_ops ();
 513
 514   /* GNU v3 exception catchpoints.  */
 515   ops = &gnu_v3_exception_catchpoint_ops;
 516   *ops = bkpt_breakpoint_ops;
 517   ops->re_set = re_set_exception_catchpoint;
 518   ops->print_it = print_it_exception_catchpoint;
 519   ops->print_one = print_one_exception_catchpoint;
 520   ops->print_mention = print_mention_exception_catchpoint;
 521   ops->print_recreate = print_recreate_exception_catchpoint;
 522   ops->print_one_detail = print_one_detail_exception_catchpoint;
 523   ops->check_status = check_status_exception_catchpoint;
 524 }
 525
 526 void
 527 _initialize_break_catch_throw (void)
 528 {
 529   initialize_throw_catchpoint_ops ();
 530
 531   /* Add catch and tcatch sub-commands.  */
 532   add_catch_command ("catch", _("\
 533 Catch an exception, when caught."),
 534                      catch_catch_command,
 535                      NULL,
 536                      CATCH_PERMANENT,
 537                      CATCH_TEMPORARY);
 538   add_catch_command ("throw", _("\
 539 Catch an exception, when thrown."),
 540                      catch_throw_command,
 541                      NULL,
 542                      CATCH_PERMANENT,
 543                      CATCH_TEMPORARY);
 544   add_catch_command ("rethrow", _("\
 545 Catch an exception, when rethrown."),
 546                      catch_rethrow_command,
 547                      NULL,
 548                      CATCH_PERMANENT,
 549                      CATCH_TEMPORARY);
 550
 551   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 552 }