gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2015 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 /* Enums for exception-handling support.  */
  41 enum exception_event_kind
  42 {
  43   EX_EVENT_THROW,
  44   EX_EVENT_RETHROW,
  45   EX_EVENT_CATCH
  46 };
  47
  48 /* Each spot where we may place an exception-related catchpoint has
  49    two names: the SDT probe point and the function name.  This
  50    structure holds both.  */
  51
  52 struct exception_names
  53 {
  54   /* The name of the probe point to try, in the form accepted by
  55      'parse_probes'.  */
  56
  57   const char *probe;
  58
  59   /* The name of the corresponding function.  */
  60
  61   const char *function;
  62 };
  63
  64 /* Names of the probe points and functions on which to break.  This is
  65    indexed by exception_event_kind.  */
  66 static const struct exception_names exception_functions[] =
  67 {
  68   { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  69   { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  70   { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
  71 };
  72
  73 static struct breakpoint_ops gnu_v3_exception_catchpoint_ops;
  74
  75 /* The type of an exception catchpoint.  */
  76
  77 struct exception_catchpoint
  78 {
  79   /* The base class.  */
  80
  81   struct breakpoint base;
  82
  83   /* The kind of exception catchpoint.  */
  84
  85   enum exception_event_kind kind;
  86
  87   /* If non-NULL, an xmalloc'd string holding the source form of the
  88      regular expression to match against.  */
  89
  90   char *exception_rx;
  91
  92   /* If non-NULL, an xmalloc'd, compiled regular expression which is
  93      used to determine which exceptions to stop on.  */
  94
  95   regex_t *pattern;
  96 };
  97
  98 \f
  99
 100 /* A helper function that fetches exception probe arguments.  This
 101    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
 102    It will throw an exception on any kind of failure.  */
 103
 104 static void
 105 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 106 {
 107   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 108   CORE_ADDR pc = get_frame_pc (frame);
 109   struct bound_probe pc_probe;
 110   const struct sym_probe_fns *pc_probe_fns;
 111   unsigned n_args;
 112
 113   pc_probe = find_probe_by_pc (pc);
 114   if (pc_probe.probe == NULL
 115       || strcmp (pc_probe.probe->provider, "libstdcxx") != 0
 116       || (strcmp (pc_probe.probe->name, "catch") != 0
 117           && strcmp (pc_probe.probe->name, "throw") != 0
 118           && strcmp (pc_probe.probe->name, "rethrow") != 0))
 119     error (_("not stopped at a C++ exception catchpoint"));
 120
 121   n_args = get_probe_argument_count (pc_probe.probe, frame);
 122   if (n_args < 2)
 123     error (_("C++ exception catchpoint has too few arguments"));
 124
 125   if (arg0 != NULL)
 126     *arg0 = evaluate_probe_argument (pc_probe.probe, 0, frame);
 127   *arg1 = evaluate_probe_argument (pc_probe.probe, 1, frame);
 128
 129   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 130     error (_("error computing probe argument at c++ exception catchpoint"));
 131 }
 132
 133 \f
 134
 135 /* A helper function that returns a value indicating the kind of the
 136    exception catchpoint B.  */
 137
 138 static enum exception_event_kind
 139 classify_exception_breakpoint (struct breakpoint *b)
 140 {
 141   struct exception_catchpoint *cp = (struct exception_catchpoint *) b;
 142
 143   return cp->kind;
 144 }
 145
 146 /* Implement the 'dtor' method.  */
 147
 148 static void
 149 dtor_exception_catchpoint (struct breakpoint *self)
 150 {
 151   struct exception_catchpoint *cp = (struct exception_catchpoint *) self;
 152
 153   xfree (cp->exception_rx);
 154   if (cp->pattern != NULL)
 155     regfree (cp->pattern);
 156   bkpt_breakpoint_ops.dtor (self);
 157 }
 158
 159 /* Implement the 'check_status' method.  */
 160
 161 static void
 162 check_status_exception_catchpoint (struct bpstats *bs)
 163 {
 164   struct exception_catchpoint *self
 165     = (struct exception_catchpoint *) bs->breakpoint_at;
 166   char *type_name = NULL;
 167
 168   bkpt_breakpoint_ops.check_status (bs);
 169   if (bs->stop == 0)
 170     return;
 171
 172   if (self->pattern == NULL)
 173     return;
 174
 175   TRY
 176     {
 177       struct value *typeinfo_arg;
 178       char *canon;
 179
 180       fetch_probe_arguments (NULL, &typeinfo_arg);
 181       type_name = cplus_typename_from_type_info (typeinfo_arg);
 182
 183       canon = cp_canonicalize_string (type_name);
 184       if (canon != NULL)
 185         {
 186           xfree (type_name);
 187           type_name = canon;
 188         }
 189     }
 190   CATCH (e, RETURN_MASK_ERROR)
 191     {
 192       exception_print (gdb_stderr, e);
 193     }
 194   END_CATCH
 195
 196   if (type_name != NULL)
 197     {
 198       if (regexec (self->pattern, type_name, 0, NULL, 0) != 0)
 199         bs->stop = 0;
 200
 201       xfree (type_name);
 202     }
 203 }
 204
 205 /* Implement the 're_set' method.  */
 206
 207 static void
 208 re_set_exception_catchpoint (struct breakpoint *self)
 209 {
 210   struct symtabs_and_lines sals = {0};
 211   struct symtabs_and_lines sals_end = {0};
 212   struct cleanup *cleanup;
 213   enum exception_event_kind kind = classify_exception_breakpoint (self);
 214   struct event_location *location;
 215
 216   /* We first try to use the probe interface.  */
 217   TRY
 218     {
 219       location
 220         = new_probe_location (exception_functions[kind].probe);
 221       cleanup = make_cleanup_delete_event_location (location);
 222       sals = parse_probes (location, NULL);
 223       do_cleanups (cleanup);
 224     }
 225
 226   CATCH (e, RETURN_MASK_ERROR)
 227     {
 228       /* Using the probe interface failed.  Let's fallback to the normal
 229          catchpoint mode.  */
 230       TRY
 231         {
 232           struct explicit_location explicit_loc;
 233
 234           initialize_explicit_location (&explicit_loc);
 235           explicit_loc.function_name
 236             = ASTRDUP (exception_functions[kind].function);
 237           location = new_explicit_location (&explicit_loc);
 238           cleanup = make_cleanup_delete_event_location (location);
 239           self->ops->decode_location (self, location, &sals);
 240           do_cleanups (cleanup);
 241         }
 242       CATCH (ex, RETURN_MASK_ERROR)
 243         {
 244           /* NOT_FOUND_ERROR just means the breakpoint will be
 245              pending, so let it through.  */
 246           if (ex.error != NOT_FOUND_ERROR)
 247             throw_exception (ex);
 248         }
 249       END_CATCH
 250     }
 251   END_CATCH
 252
 253   cleanup = make_cleanup (xfree, sals.sals);
 254   update_breakpoint_locations (self, sals, sals_end);
 255   do_cleanups (cleanup);
 256 }
 257
 258 static enum print_stop_action
 259 print_it_exception_catchpoint (bpstat bs)
 260 {
 261   struct ui_out *uiout = current_uiout;
 262   struct breakpoint *b = bs->breakpoint_at;
 263   int bp_temp;
 264   enum exception_event_kind kind = classify_exception_breakpoint (b);
 265
 266   annotate_catchpoint (b->number);
 267
 268   bp_temp = b->disposition == disp_del;
 269   ui_out_text (uiout,
 270                bp_temp ? "Temporary catchpoint "
 271                        : "Catchpoint ");
 272   if (!ui_out_is_mi_like_p (uiout))
 273     ui_out_field_int (uiout, "bkptno", b->number);
 274   ui_out_text (uiout,
 275                (kind == EX_EVENT_THROW ? " (exception thrown), "
 276                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 277                    : " (exception rethrown), ")));
 278   if (ui_out_is_mi_like_p (uiout))
 279     {
 280       ui_out_field_string (uiout, "reason",
 281                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 282       ui_out_field_string (uiout, "disp", bpdisp_text (b->disposition));
 283       ui_out_field_int (uiout, "bkptno", b->number);
 284     }
 285   return PRINT_SRC_AND_LOC;
 286 }
 287
 288 static void
 289 print_one_exception_catchpoint (struct breakpoint *b,
 290                                 struct bp_location **last_loc)
 291 {
 292   struct value_print_options opts;
 293   struct ui_out *uiout = current_uiout;
 294   enum exception_event_kind kind = classify_exception_breakpoint (b);
 295
 296   get_user_print_options (&opts);
 297   if (opts.addressprint)
 298     {
 299       annotate_field (4);
 300       if (b->loc == NULL || b->loc->shlib_disabled)
 301         ui_out_field_string (uiout, "addr", "<PENDING>");
 302       else
 303         ui_out_field_core_addr (uiout, "addr",
 304                                 b->loc->gdbarch, b->loc->address);
 305     }
 306   annotate_field (5);
 307   if (b->loc)
 308     *last_loc = b->loc;
 309
 310   switch (kind)
 311     {
 312     case EX_EVENT_THROW:
 313       ui_out_field_string (uiout, "what", "exception throw");
 314       if (ui_out_is_mi_like_p (uiout))
 315         ui_out_field_string (uiout, "catch-type", "throw");
 316       break;
 317
 318     case EX_EVENT_RETHROW:
 319       ui_out_field_string (uiout, "what", "exception rethrow");
 320       if (ui_out_is_mi_like_p (uiout))
 321         ui_out_field_string (uiout, "catch-type", "rethrow");
 322       break;
 323
 324     case EX_EVENT_CATCH:
 325       ui_out_field_string (uiout, "what", "exception catch");
 326       if (ui_out_is_mi_like_p (uiout))
 327         ui_out_field_string (uiout, "catch-type", "catch");
 328       break;
 329     }
 330 }
 331
 332 /* Implement the 'print_one_detail' method.  */
 333
 334 static void
 335 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 336                                        struct ui_out *uiout)
 337 {
 338   const struct exception_catchpoint *cp
 339     = (const struct exception_catchpoint *) b;
 340
 341   if (cp->exception_rx != NULL)
 342     {
 343       ui_out_text (uiout, _("\tmatching: "));
 344       ui_out_field_string (uiout, "regexp", cp->exception_rx);
 345       ui_out_text (uiout, "\n");
 346     }
 347 }
 348
 349 static void
 350 print_mention_exception_catchpoint (struct breakpoint *b)
 351 {
 352   struct ui_out *uiout = current_uiout;
 353   int bp_temp;
 354   enum exception_event_kind kind = classify_exception_breakpoint (b);
 355
 356   bp_temp = b->disposition == disp_del;
 357   ui_out_text (uiout, bp_temp ? _("Temporary catchpoint ")
 358                               : _("Catchpoint "));
 359   ui_out_field_int (uiout, "bkptno", b->number);
 360   ui_out_text (uiout, (kind == EX_EVENT_THROW ? _(" (throw)")
 361                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 362                           : _(" (rethrow)"))));
 363 }
 364
 365 /* Implement the "print_recreate" breakpoint_ops method for throw and
 366    catch catchpoints.  */
 367
 368 static void
 369 print_recreate_exception_catchpoint (struct breakpoint *b,
 370                                      struct ui_file *fp)
 371 {
 372   int bp_temp;
 373   enum exception_event_kind kind = classify_exception_breakpoint (b);
 374
 375   bp_temp = b->disposition == disp_del;
 376   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 377   switch (kind)
 378     {
 379     case EX_EVENT_THROW:
 380       fprintf_unfiltered (fp, "throw");
 381       break;
 382     case EX_EVENT_CATCH:
 383       fprintf_unfiltered (fp, "catch");
 384       break;
 385     case EX_EVENT_RETHROW:
 386       fprintf_unfiltered (fp, "rethrow");
 387       break;
 388     }
 389   print_recreate_thread (b, fp);
 390 }
 391
 392 static void
 393 handle_gnu_v3_exceptions (int tempflag, char *except_rx, char *cond_string,
 394                           enum exception_event_kind ex_event, int from_tty)
 395 {
 396   struct exception_catchpoint *cp;
 397   struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
 398   regex_t *pattern = NULL;
 399
 400   if (except_rx != NULL)
 401     {
 402       pattern = XNEW (regex_t);
 403       make_cleanup (xfree, pattern);
 404
 405       compile_rx_or_error (pattern, except_rx,
 406                            _("invalid type-matching regexp"));
 407     }
 408
 409   cp = XCNEW (struct exception_catchpoint);
 410   make_cleanup (xfree, cp);
 411
 412   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 413                    &gnu_v3_exception_catchpoint_ops);
 414   /* We need to reset 'type' in order for code in breakpoint.c to do
 415      the right thing.  */
 416   cp->base.type = bp_breakpoint;
 417   cp->kind = ex_event;
 418   cp->exception_rx = except_rx;
 419   cp->pattern = pattern;
 420
 421   re_set_exception_catchpoint (&cp->base);
 422
 423   install_breakpoint (0, &cp->base, 1);
 424   discard_cleanups (cleanup);
 425 }
 426
 427 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 428    by whitespace.
 429
 430    If there is any non-whitespace text between *STRING and the "if"
 431    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 432    this returns NULL.
 433
 434    STRING is updated to point to the "if" token, if it exists, or to
 435    the end of the string.  */
 436
 437 static char *
 438 extract_exception_regexp (char **string)
 439 {
 440   char *start;
 441   char *last, *last_space;
 442
 443   start = skip_spaces (*string);
 444
 445   last = start;
 446   last_space = start;
 447   while (*last != '\0')
 448     {
 449       char *if_token = last;
 450
 451       /* Check for the "if".  */
 452       if (check_for_argument (&if_token, "if", 2))
 453         break;
 454
 455       /* No "if" token here.  Skip to the next word start.  */
 456       last_space = skip_to_space (last);
 457       last = skip_spaces (last_space);
 458     }
 459
 460   *string = last;
 461   if (last_space > start)
 462     return savestring (start, last_space - start);
 463   return NULL;
 464 }
 465
 466 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 467    commands.  */
 468
 469 static void
 470 catch_exception_command_1 (enum exception_event_kind ex_event, char *arg,
 471                            int tempflag, int from_tty)
 472 {
 473   char *except_rx;
 474   char *cond_string = NULL;
 475   struct cleanup *cleanup;
 476
 477   if (!arg)
 478     arg = "";
 479   arg = skip_spaces (arg);
 480
 481   except_rx = extract_exception_regexp (&arg);
 482   cleanup = make_cleanup (xfree, except_rx);
 483
 484   cond_string = ep_parse_optional_if_clause (&arg);
 485
 486   if ((*arg != '\0') && !isspace (*arg))
 487     error (_("Junk at end of arguments."));
 488
 489   if (ex_event != EX_EVENT_THROW
 490       && ex_event != EX_EVENT_CATCH
 491       && ex_event != EX_EVENT_RETHROW)
 492     error (_("Unsupported or unknown exception event; cannot catch it"));
 493
 494   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 495                             ex_event, from_tty);
 496
 497   discard_cleanups (cleanup);
 498 }
 499
 500 /* Implementation of "catch catch" command.  */
 501
 502 static void
 503 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 504 {
 505   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 506
 507   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 508 }
 509
 510 /* Implementation of "catch throw" command.  */
 511
 512 static void
 513 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 514 {
 515   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 516
 517   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 518 }
 519
 520 /* Implementation of "catch rethrow" command.  */
 521
 522 static void
 523 catch_rethrow_command (char *arg, int from_tty,
 524                        struct cmd_list_element *command)
 525 {
 526   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 527
 528   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 529 }
 530
 531 \f
 532
 533 /* Implement the 'make_value' method for the $_exception
 534    internalvar.  */
 535
 536 static struct value *
 537 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 538 {
 539   struct value *arg0, *arg1;
 540   struct type *obj_type;
 541
 542   fetch_probe_arguments (&arg0, &arg1);
 543
 544   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 545      the std::type_info for the exception.  Now we find the type from
 546      the type_info and cast the result.  */
 547   obj_type = cplus_type_from_type_info (arg1);
 548   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 549 }
 550
 551 /* Implementation of the '$_exception' variable.  */
 552
 553 static const struct internalvar_funcs exception_funcs =
 554 {
 555   compute_exception,
 556   NULL,
 557   NULL
 558 };
 559
 560 \f
 561
 562 static void
 563 initialize_throw_catchpoint_ops (void)
 564 {
 565   struct breakpoint_ops *ops;
 566
 567   initialize_breakpoint_ops ();
 568
 569   /* GNU v3 exception catchpoints.  */
 570   ops = &gnu_v3_exception_catchpoint_ops;
 571   *ops = bkpt_breakpoint_ops;
 572   ops->dtor = dtor_exception_catchpoint;
 573   ops->re_set = re_set_exception_catchpoint;
 574   ops->print_it = print_it_exception_catchpoint;
 575   ops->print_one = print_one_exception_catchpoint;
 576   ops->print_mention = print_mention_exception_catchpoint;
 577   ops->print_recreate = print_recreate_exception_catchpoint;
 578   ops->print_one_detail = print_one_detail_exception_catchpoint;
 579   ops->check_status = check_status_exception_catchpoint;
 580 }
 581
 582 initialize_file_ftype _initialize_break_catch_throw;
 583
 584 void
 585 _initialize_break_catch_throw (void)
 586 {
 587   initialize_throw_catchpoint_ops ();
 588
 589   /* Add catch and tcatch sub-commands.  */
 590   add_catch_command ("catch", _("\
 591 Catch an exception, when caught."),
 592                      catch_catch_command,
 593                      NULL,
 594                      CATCH_PERMANENT,
 595                      CATCH_TEMPORARY);
 596   add_catch_command ("throw", _("\
 597 Catch an exception, when thrown."),
 598                      catch_throw_command,
 599                      NULL,
 600                      CATCH_PERMANENT,
 601                      CATCH_TEMPORARY);
 602   add_catch_command ("rethrow", _("\
 603 Catch an exception, when rethrown."),
 604                      catch_rethrow_command,
 605                      NULL,
 606                      CATCH_PERMANENT,
 607                      CATCH_TEMPORARY);
 608
 609   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 610 }