gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2014 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
  39 /* Enums for exception-handling support.  */
  40 enum exception_event_kind
  41 {
  42   EX_EVENT_THROW,
  43   EX_EVENT_RETHROW,
  44   EX_EVENT_CATCH
  45 };
  46
  47 /* Each spot where we may place an exception-related catchpoint has
  48    two names: the SDT probe point and the function name.  This
  49    structure holds both.  */
  50
  51 struct exception_names
  52 {
  53   /* The name of the probe point to try, in the form accepted by
  54      'parse_probes'.  */
  55
  56   const char *probe;
  57
  58   /* The name of the corresponding function.  */
  59
  60   const char *function;
  61 };
  62
  63 /* Names of the probe points and functions on which to break.  This is
  64    indexed by exception_event_kind.  */
  65 static const struct exception_names exception_functions[] =
  66 {
  67   { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  68   { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  69   { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
  70 };
  71
  72 static struct breakpoint_ops gnu_v3_exception_catchpoint_ops;
  73
  74 /* The type of an exception catchpoint.  */
  75
  76 struct exception_catchpoint
  77 {
  78   /* The base class.  */
  79
  80   struct breakpoint base;
  81
  82   /* The kind of exception catchpoint.  */
  83
  84   enum exception_event_kind kind;
  85
  86   /* If non-NULL, an xmalloc'd string holding the source form of the
  87      regular expression to match against.  */
  88
  89   char *exception_rx;
  90
  91   /* If non-NULL, an xmalloc'd, compiled regular expression which is
  92      used to determine which exceptions to stop on.  */
  93
  94   regex_t *pattern;
  95 };
  96
  97 \f
  98
  99 /* A helper function that fetches exception probe arguments.  This
 100    fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
 101    It will throw an exception on any kind of failure.  */
 102
 103 static void
 104 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 105 {
 106   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 107   CORE_ADDR pc = get_frame_pc (frame);
 108   struct bound_probe pc_probe;
 109   const struct sym_probe_fns *pc_probe_fns;
 110   unsigned n_args;
 111
 112   pc_probe = find_probe_by_pc (pc);
 113   if (pc_probe.probe == NULL
 114       || strcmp (pc_probe.probe->provider, "libstdcxx") != 0
 115       || (strcmp (pc_probe.probe->name, "catch") != 0
 116           && strcmp (pc_probe.probe->name, "throw") != 0
 117           && strcmp (pc_probe.probe->name, "rethrow") != 0))
 118     error (_("not stopped at a C++ exception catchpoint"));
 119
 120   n_args = get_probe_argument_count (pc_probe.probe, frame);
 121   if (n_args < 2)
 122     error (_("C++ exception catchpoint has too few arguments"));
 123
 124   if (arg0 != NULL)
 125     *arg0 = evaluate_probe_argument (pc_probe.probe, 0, frame);
 126   *arg1 = evaluate_probe_argument (pc_probe.probe, 1, frame);
 127
 128   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
 129     error (_("error computing probe argument at c++ exception catchpoint"));
 130 }
 131
 132 \f
 133
 134 /* A helper function that returns a value indicating the kind of the
 135    exception catchpoint B.  */
 136
 137 static enum exception_event_kind
 138 classify_exception_breakpoint (struct breakpoint *b)
 139 {
 140   struct exception_catchpoint *cp = (struct exception_catchpoint *) b;
 141
 142   return cp->kind;
 143 }
 144
 145 /* Implement the 'dtor' method.  */
 146
 147 static void
 148 dtor_exception_catchpoint (struct breakpoint *self)
 149 {
 150   struct exception_catchpoint *cp = (struct exception_catchpoint *) self;
 151
 152   xfree (cp->exception_rx);
 153   if (cp->pattern != NULL)
 154     regfree (cp->pattern);
 155   bkpt_breakpoint_ops.dtor (self);
 156 }
 157
 158 /* Implement the 'check_status' method.  */
 159
 160 static void
 161 check_status_exception_catchpoint (struct bpstats *bs)
 162 {
 163   struct exception_catchpoint *self
 164     = (struct exception_catchpoint *) bs->breakpoint_at;
 165   char *typename = NULL;
 166   volatile struct gdb_exception e;
 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_CATCH (e, RETURN_MASK_ERROR)
 176     {
 177       struct value *typeinfo_arg;
 178       char *canon;
 179
 180       fetch_probe_arguments (NULL, &typeinfo_arg);
 181       typename = cplus_typename_from_type_info (typeinfo_arg);
 182
 183       canon = cp_canonicalize_string (typename);
 184       if (canon != NULL)
 185         {
 186           xfree (typename);
 187           typename = canon;
 188         }
 189     }
 190
 191   if (e.reason < 0)
 192     exception_print (gdb_stderr, e);
 193   else if (regexec (self->pattern, typename, 0, NULL, 0) != 0)
 194     bs->stop = 0;
 195
 196   xfree (typename);
 197 }
 198
 199 /* Implement the 're_set' method.  */
 200
 201 static void
 202 re_set_exception_catchpoint (struct breakpoint *self)
 203 {
 204   struct symtabs_and_lines sals = {0};
 205   struct symtabs_and_lines sals_end = {0};
 206   volatile struct gdb_exception e;
 207   struct cleanup *cleanup;
 208   enum exception_event_kind kind = classify_exception_breakpoint (self);
 209
 210   /* We first try to use the probe interface.  */
 211   TRY_CATCH (e, RETURN_MASK_ERROR)
 212     {
 213       char *spec = ASTRDUP (exception_functions[kind].probe);
 214
 215       sals = parse_probes (&spec, NULL);
 216     }
 217
 218   if (e.reason < 0)
 219     {
 220       volatile struct gdb_exception ex;
 221
 222       /* Using the probe interface failed.  Let's fallback to the normal
 223          catchpoint mode.  */
 224       TRY_CATCH (ex, RETURN_MASK_ERROR)
 225         {
 226           char *spec = ASTRDUP (exception_functions[kind].function);
 227
 228           self->ops->decode_linespec (self, &spec, &sals);
 229         }
 230
 231       /* NOT_FOUND_ERROR just means the breakpoint will be pending, so
 232          let it through.  */
 233       if (ex.reason < 0 && ex.error != NOT_FOUND_ERROR)
 234         throw_exception (ex);
 235     }
 236
 237   cleanup = make_cleanup (xfree, sals.sals);
 238   update_breakpoint_locations (self, sals, sals_end);
 239   do_cleanups (cleanup);
 240 }
 241
 242 static enum print_stop_action
 243 print_it_exception_catchpoint (bpstat bs)
 244 {
 245   struct ui_out *uiout = current_uiout;
 246   struct breakpoint *b = bs->breakpoint_at;
 247   int bp_temp;
 248   enum exception_event_kind kind = classify_exception_breakpoint (b);
 249
 250   annotate_catchpoint (b->number);
 251
 252   bp_temp = b->disposition == disp_del;
 253   ui_out_text (uiout,
 254                bp_temp ? "Temporary catchpoint "
 255                        : "Catchpoint ");
 256   if (!ui_out_is_mi_like_p (uiout))
 257     ui_out_field_int (uiout, "bkptno", b->number);
 258   ui_out_text (uiout,
 259                (kind == EX_EVENT_THROW ? " (exception thrown), "
 260                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 261                    : " (exception rethrown), ")));
 262   if (ui_out_is_mi_like_p (uiout))
 263     {
 264       ui_out_field_string (uiout, "reason",
 265                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 266       ui_out_field_string (uiout, "disp", bpdisp_text (b->disposition));
 267       ui_out_field_int (uiout, "bkptno", b->number);
 268     }
 269   return PRINT_SRC_AND_LOC;
 270 }
 271
 272 static void
 273 print_one_exception_catchpoint (struct breakpoint *b,
 274                                 struct bp_location **last_loc)
 275 {
 276   struct value_print_options opts;
 277   struct ui_out *uiout = current_uiout;
 278   enum exception_event_kind kind = classify_exception_breakpoint (b);
 279
 280   get_user_print_options (&opts);
 281   if (opts.addressprint)
 282     {
 283       annotate_field (4);
 284       if (b->loc == NULL || b->loc->shlib_disabled)
 285         ui_out_field_string (uiout, "addr", "<PENDING>");
 286       else
 287         ui_out_field_core_addr (uiout, "addr",
 288                                 b->loc->gdbarch, b->loc->address);
 289     }
 290   annotate_field (5);
 291   if (b->loc)
 292     *last_loc = b->loc;
 293
 294   switch (kind)
 295     {
 296     case EX_EVENT_THROW:
 297       ui_out_field_string (uiout, "what", "exception throw");
 298       if (ui_out_is_mi_like_p (uiout))
 299         ui_out_field_string (uiout, "catch-type", "throw");
 300       break;
 301
 302     case EX_EVENT_RETHROW:
 303       ui_out_field_string (uiout, "what", "exception rethrow");
 304       if (ui_out_is_mi_like_p (uiout))
 305         ui_out_field_string (uiout, "catch-type", "rethrow");
 306       break;
 307
 308     case EX_EVENT_CATCH:
 309       ui_out_field_string (uiout, "what", "exception catch");
 310       if (ui_out_is_mi_like_p (uiout))
 311         ui_out_field_string (uiout, "catch-type", "catch");
 312       break;
 313     }
 314 }
 315
 316 /* Implement the 'print_one_detail' method.  */
 317
 318 static void
 319 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 320                                        struct ui_out *uiout)
 321 {
 322   const struct exception_catchpoint *cp
 323     = (const struct exception_catchpoint *) b;
 324
 325   if (cp->exception_rx != NULL)
 326     {
 327       ui_out_text (uiout, _("\tmatching: "));
 328       ui_out_field_string (uiout, "regexp", cp->exception_rx);
 329       ui_out_text (uiout, "\n");
 330     }
 331 }
 332
 333 static void
 334 print_mention_exception_catchpoint (struct breakpoint *b)
 335 {
 336   struct ui_out *uiout = current_uiout;
 337   int bp_temp;
 338   enum exception_event_kind kind = classify_exception_breakpoint (b);
 339
 340   bp_temp = b->disposition == disp_del;
 341   ui_out_text (uiout, bp_temp ? _("Temporary catchpoint ")
 342                               : _("Catchpoint "));
 343   ui_out_field_int (uiout, "bkptno", b->number);
 344   ui_out_text (uiout, (kind == EX_EVENT_THROW ? _(" (throw)")
 345                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 346                           : _(" (rethrow)"))));
 347 }
 348
 349 /* Implement the "print_recreate" breakpoint_ops method for throw and
 350    catch catchpoints.  */
 351
 352 static void
 353 print_recreate_exception_catchpoint (struct breakpoint *b,
 354                                      struct ui_file *fp)
 355 {
 356   int bp_temp;
 357   enum exception_event_kind kind = classify_exception_breakpoint (b);
 358
 359   bp_temp = b->disposition == disp_del;
 360   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 361   switch (kind)
 362     {
 363     case EX_EVENT_THROW:
 364       fprintf_unfiltered (fp, "throw");
 365       break;
 366     case EX_EVENT_CATCH:
 367       fprintf_unfiltered (fp, "catch");
 368       break;
 369     case EX_EVENT_RETHROW:
 370       fprintf_unfiltered (fp, "rethrow");
 371       break;
 372     }
 373   print_recreate_thread (b, fp);
 374 }
 375
 376 static void
 377 handle_gnu_v3_exceptions (int tempflag, char *except_rx, char *cond_string,
 378                           enum exception_event_kind ex_event, int from_tty)
 379 {
 380   struct exception_catchpoint *cp;
 381   struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
 382   regex_t *pattern = NULL;
 383
 384   if (except_rx != NULL)
 385     {
 386       pattern = XNEW (regex_t);
 387       make_cleanup (xfree, pattern);
 388
 389       compile_rx_or_error (pattern, except_rx,
 390                            _("invalid type-matching regexp"));
 391     }
 392
 393   cp = XCNEW (struct exception_catchpoint);
 394   make_cleanup (xfree, cp);
 395
 396   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 397                    &gnu_v3_exception_catchpoint_ops);
 398   /* We need to reset 'type' in order for code in breakpoint.c to do
 399      the right thing.  */
 400   cp->base.type = bp_breakpoint;
 401   cp->kind = ex_event;
 402   cp->exception_rx = except_rx;
 403   cp->pattern = pattern;
 404
 405   re_set_exception_catchpoint (&cp->base);
 406
 407   install_breakpoint (0, &cp->base, 1);
 408   discard_cleanups (cleanup);
 409 }
 410
 411 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 412    by whitespace.
 413
 414    If there is any non-whitespace text between *STRING and the "if"
 415    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 416    this returns NULL.
 417
 418    STRING is updated to point to the "if" token, if it exists, or to
 419    the end of the string.  */
 420
 421 static char *
 422 extract_exception_regexp (char **string)
 423 {
 424   char *start;
 425   char *last, *last_space;
 426
 427   start = skip_spaces (*string);
 428
 429   last = start;
 430   last_space = start;
 431   while (*last != '\0')
 432     {
 433       char *if_token = last;
 434
 435       /* Check for the "if".  */
 436       if (check_for_argument (&if_token, "if", 2))
 437         break;
 438
 439       /* No "if" token here.  Skip to the next word start.  */
 440       last_space = skip_to_space (last);
 441       last = skip_spaces (last_space);
 442     }
 443
 444   *string = last;
 445   if (last_space > start)
 446     return savestring (start, last_space - start);
 447   return NULL;
 448 }
 449
 450 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 451    commands.  */
 452
 453 static void
 454 catch_exception_command_1 (enum exception_event_kind ex_event, char *arg,
 455                            int tempflag, int from_tty)
 456 {
 457   char *except_rx;
 458   char *cond_string = NULL;
 459   struct cleanup *cleanup;
 460
 461   if (!arg)
 462     arg = "";
 463   arg = skip_spaces (arg);
 464
 465   except_rx = extract_exception_regexp (&arg);
 466   cleanup = make_cleanup (xfree, except_rx);
 467
 468   cond_string = ep_parse_optional_if_clause (&arg);
 469
 470   if ((*arg != '\0') && !isspace (*arg))
 471     error (_("Junk at end of arguments."));
 472
 473   if (ex_event != EX_EVENT_THROW
 474       && ex_event != EX_EVENT_CATCH
 475       && ex_event != EX_EVENT_RETHROW)
 476     error (_("Unsupported or unknown exception event; cannot catch it"));
 477
 478   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 479                             ex_event, from_tty);
 480
 481   discard_cleanups (cleanup);
 482 }
 483
 484 /* Implementation of "catch catch" command.  */
 485
 486 static void
 487 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 488 {
 489   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 490
 491   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 492 }
 493
 494 /* Implementation of "catch throw" command.  */
 495
 496 static void
 497 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 498 {
 499   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 500
 501   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 502 }
 503
 504 /* Implementation of "catch rethrow" command.  */
 505
 506 static void
 507 catch_rethrow_command (char *arg, int from_tty,
 508                        struct cmd_list_element *command)
 509 {
 510   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 511
 512   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 513 }
 514
 515 \f
 516
 517 /* Implement the 'make_value' method for the $_exception
 518    internalvar.  */
 519
 520 static struct value *
 521 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 522 {
 523   struct value *arg0, *arg1;
 524   struct type *obj_type;
 525
 526   fetch_probe_arguments (&arg0, &arg1);
 527
 528   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 529      the std::type_info for the exception.  Now we find the type from
 530      the type_info and cast the result.  */
 531   obj_type = cplus_type_from_type_info (arg1);
 532   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 533 }
 534
 535 /* Implementation of the '$_exception' variable.  */
 536
 537 static const struct internalvar_funcs exception_funcs =
 538 {
 539   compute_exception,
 540   NULL,
 541   NULL
 542 };
 543
 544 \f
 545
 546 static void
 547 initialize_throw_catchpoint_ops (void)
 548 {
 549   struct breakpoint_ops *ops;
 550
 551   initialize_breakpoint_ops ();
 552
 553   /* GNU v3 exception catchpoints.  */
 554   ops = &gnu_v3_exception_catchpoint_ops;
 555   *ops = bkpt_breakpoint_ops;
 556   ops->dtor = dtor_exception_catchpoint;
 557   ops->re_set = re_set_exception_catchpoint;
 558   ops->print_it = print_it_exception_catchpoint;
 559   ops->print_one = print_one_exception_catchpoint;
 560   ops->print_mention = print_mention_exception_catchpoint;
 561   ops->print_recreate = print_recreate_exception_catchpoint;
 562   ops->print_one_detail = print_one_detail_exception_catchpoint;
 563   ops->check_status = check_status_exception_catchpoint;
 564 }
 565
 566 initialize_file_ftype _initialize_break_catch_throw;
 567
 568 void
 569 _initialize_break_catch_throw (void)
 570 {
 571   initialize_throw_catchpoint_ops ();
 572
 573   /* Add catch and tcatch sub-commands.  */
 574   add_catch_command ("catch", _("\
 575 Catch an exception, when caught."),
 576                      catch_catch_command,
 577                      NULL,
 578                      CATCH_PERMANENT,
 579                      CATCH_TEMPORARY);
 580   add_catch_command ("throw", _("\
 581 Catch an exception, when thrown."),
 582                      catch_throw_command,
 583                      NULL,
 584                      CATCH_PERMANENT,
 585                      CATCH_TEMPORARY);
 586   add_catch_command ("rethrow", _("\
 587 Catch an exception, when rethrown."),
 588                      catch_rethrow_command,
 589                      NULL,
 590                      CATCH_PERMANENT,
 591                      CATCH_TEMPORARY);
 592
 593   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 594 }