gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2013 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 "exceptions.h"
  33 #include "linespec.h"
  34 #include "probe.h"
  35 #include "objfiles.h"
  36 #include "cp-abi.h"
  37 #include "gdb_regex.h"
  38 #include "cp-support.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 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 == NULL
 115       || strcmp (pc_probe->provider, "libstdcxx") != 0
 116       || (strcmp (pc_probe->name, "catch") != 0
 117           && strcmp (pc_probe->name, "throw") != 0
 118           && strcmp (pc_probe->name, "rethrow") != 0))
 119     error (_("not stopped at a C++ exception catchpoint"));
 120
 121   n_args = get_probe_argument_count (pc_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, 0, frame);
 127   *arg1 = evaluate_probe_argument (pc_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 *typename = NULL;
 167   volatile struct gdb_exception e;
 168
 169   bkpt_breakpoint_ops.check_status (bs);
 170   if (bs->stop == 0)
 171     return;
 172
 173   if (self->pattern == NULL)
 174     return;
 175
 176   TRY_CATCH (e, RETURN_MASK_ERROR)
 177     {
 178       struct value *typeinfo_arg;
 179       char *canon;
 180
 181       fetch_probe_arguments (NULL, &typeinfo_arg);
 182       typename = cplus_typename_from_type_info (typeinfo_arg);
 183
 184       canon = cp_canonicalize_string (typename);
 185       if (canon != NULL)
 186         {
 187           xfree (typename);
 188           typename = canon;
 189         }
 190     }
 191
 192   if (e.reason < 0)
 193     exception_print (gdb_stderr, e);
 194   else if (regexec (self->pattern, typename, 0, NULL, 0) != 0)
 195     bs->stop = 0;
 196
 197   xfree (typename);
 198 }
 199
 200 /* Implement the 're_set' method.  */
 201
 202 static void
 203 re_set_exception_catchpoint (struct breakpoint *self)
 204 {
 205   struct symtabs_and_lines sals = {0};
 206   struct symtabs_and_lines sals_end = {0};
 207   volatile struct gdb_exception e;
 208   struct cleanup *cleanup;
 209   enum exception_event_kind kind = classify_exception_breakpoint (self);
 210   int pass;
 211
 212   for (pass = 0; sals.sals == NULL && pass < 2; ++pass)
 213     {
 214       TRY_CATCH (e, RETURN_MASK_ERROR)
 215         {
 216           char *spec;
 217
 218           if (pass == 0)
 219             {
 220               spec = ASTRDUP (exception_functions[kind].probe);
 221               sals = parse_probes (&spec, NULL);
 222             }
 223           else
 224             {
 225               spec = ASTRDUP (exception_functions[kind].function);
 226               self->ops->decode_linespec (self, &spec, &sals);
 227             }
 228         }
 229       /* NOT_FOUND_ERROR just means the breakpoint will be pending, so
 230          let it through.  */
 231       if (e.reason < 0 && e.error != NOT_FOUND_ERROR)
 232         throw_exception (e);
 233     }
 234
 235   cleanup = make_cleanup (xfree, sals.sals);
 236   update_breakpoint_locations (self, sals, sals_end);
 237   do_cleanups (cleanup);
 238 }
 239
 240 static enum print_stop_action
 241 print_it_exception_catchpoint (bpstat bs)
 242 {
 243   struct ui_out *uiout = current_uiout;
 244   struct breakpoint *b = bs->breakpoint_at;
 245   int bp_temp;
 246   enum exception_event_kind kind = classify_exception_breakpoint (b);
 247
 248   annotate_catchpoint (b->number);
 249
 250   bp_temp = b->disposition == disp_del;
 251   ui_out_text (uiout,
 252                bp_temp ? "Temporary catchpoint "
 253                        : "Catchpoint ");
 254   if (!ui_out_is_mi_like_p (uiout))
 255     ui_out_field_int (uiout, "bkptno", b->number);
 256   ui_out_text (uiout,
 257                (kind == EX_EVENT_THROW ? " (exception thrown), "
 258                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 259                    : " (exception rethrown), ")));
 260   if (ui_out_is_mi_like_p (uiout))
 261     {
 262       ui_out_field_string (uiout, "reason",
 263                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 264       ui_out_field_string (uiout, "disp", bpdisp_text (b->disposition));
 265       ui_out_field_int (uiout, "bkptno", b->number);
 266     }
 267   return PRINT_SRC_AND_LOC;
 268 }
 269
 270 static void
 271 print_one_exception_catchpoint (struct breakpoint *b,
 272                                 struct bp_location **last_loc)
 273 {
 274   struct value_print_options opts;
 275   struct ui_out *uiout = current_uiout;
 276   enum exception_event_kind kind = classify_exception_breakpoint (b);
 277
 278   get_user_print_options (&opts);
 279   if (opts.addressprint)
 280     {
 281       annotate_field (4);
 282       if (b->loc == NULL || b->loc->shlib_disabled)
 283         ui_out_field_string (uiout, "addr", "<PENDING>");
 284       else
 285         ui_out_field_core_addr (uiout, "addr",
 286                                 b->loc->gdbarch, b->loc->address);
 287     }
 288   annotate_field (5);
 289   if (b->loc)
 290     *last_loc = b->loc;
 291
 292   switch (kind)
 293     {
 294     case EX_EVENT_THROW:
 295       ui_out_field_string (uiout, "what", "exception throw");
 296       if (ui_out_is_mi_like_p (uiout))
 297         ui_out_field_string (uiout, "catch-type", "throw");
 298       break;
 299
 300     case EX_EVENT_RETHROW:
 301       ui_out_field_string (uiout, "what", "exception rethrow");
 302       if (ui_out_is_mi_like_p (uiout))
 303         ui_out_field_string (uiout, "catch-type", "rethrow");
 304       break;
 305
 306     case EX_EVENT_CATCH:
 307       ui_out_field_string (uiout, "what", "exception catch");
 308       if (ui_out_is_mi_like_p (uiout))
 309         ui_out_field_string (uiout, "catch-type", "catch");
 310       break;
 311     }
 312 }
 313
 314 /* Implement the 'print_one_detail' method.  */
 315
 316 static void
 317 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 318                                        struct ui_out *uiout)
 319 {
 320   const struct exception_catchpoint *cp
 321     = (const struct exception_catchpoint *) b;
 322
 323   if (cp->exception_rx != NULL)
 324     {
 325       ui_out_text (uiout, _("\tmatching: "));
 326       ui_out_field_string (uiout, "regexp", cp->exception_rx);
 327       ui_out_text (uiout, "\n");
 328     }
 329 }
 330
 331 static void
 332 print_mention_exception_catchpoint (struct breakpoint *b)
 333 {
 334   struct ui_out *uiout = current_uiout;
 335   int bp_temp;
 336   enum exception_event_kind kind = classify_exception_breakpoint (b);
 337
 338   bp_temp = b->disposition == disp_del;
 339   ui_out_text (uiout, bp_temp ? _("Temporary catchpoint ")
 340                               : _("Catchpoint "));
 341   ui_out_field_int (uiout, "bkptno", b->number);
 342   ui_out_text (uiout, (kind == EX_EVENT_THROW ? _(" (throw)")
 343                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 344                           : _(" (rethrow)"))));
 345 }
 346
 347 /* Implement the "print_recreate" breakpoint_ops method for throw and
 348    catch catchpoints.  */
 349
 350 static void
 351 print_recreate_exception_catchpoint (struct breakpoint *b,
 352                                      struct ui_file *fp)
 353 {
 354   int bp_temp;
 355   enum exception_event_kind kind = classify_exception_breakpoint (b);
 356
 357   bp_temp = b->disposition == disp_del;
 358   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 359   switch (kind)
 360     {
 361     case EX_EVENT_THROW:
 362       fprintf_unfiltered (fp, "throw");
 363       break;
 364     case EX_EVENT_CATCH:
 365       fprintf_unfiltered (fp, "catch");
 366       break;
 367     case EX_EVENT_RETHROW:
 368       fprintf_unfiltered (fp, "rethrow");
 369       break;
 370     }
 371   print_recreate_thread (b, fp);
 372 }
 373
 374 static void
 375 handle_gnu_v3_exceptions (int tempflag, char *except_rx, char *cond_string,
 376                           enum exception_event_kind ex_event, int from_tty)
 377 {
 378   struct exception_catchpoint *cp;
 379   struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
 380   regex_t *pattern = NULL;
 381
 382   if (except_rx != NULL)
 383     {
 384       pattern = XNEW (regex_t);
 385       make_cleanup (xfree, pattern);
 386
 387       compile_rx_or_error (pattern, except_rx,
 388                            _("invalid type-matching regexp"));
 389     }
 390
 391   cp = XCNEW (struct exception_catchpoint);
 392   make_cleanup (xfree, cp);
 393
 394   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 395                    &gnu_v3_exception_catchpoint_ops);
 396   /* We need to reset 'type' in order for code in breakpoint.c to do
 397      the right thing.  */
 398   cp->base.type = bp_breakpoint;
 399   cp->kind = ex_event;
 400   cp->exception_rx = except_rx;
 401   cp->pattern = pattern;
 402
 403   re_set_exception_catchpoint (&cp->base);
 404
 405   install_breakpoint (0, &cp->base, 1);
 406   discard_cleanups (cleanup);
 407 }
 408
 409 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 410    by whitespace.
 411
 412    If there is any non-whitespace text between *STRING and the "if"
 413    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 414    this returns NULL.
 415
 416    STRING is updated to point to the "if" token, if it exists, or to
 417    the end of the string.  */
 418
 419 static char *
 420 extract_exception_regexp (char **string)
 421 {
 422   char *start;
 423   char *last, *last_space;
 424
 425   start = skip_spaces (*string);
 426
 427   last = start;
 428   last_space = start;
 429   while (*last != '\0')
 430     {
 431       char *if_token = last;
 432
 433       /* Check for the "if".  */
 434       if (check_for_argument (&if_token, "if", 2))
 435         break;
 436
 437       /* No "if" token here.  Skip to the next word start.  */
 438       last_space = skip_to_space (last);
 439       last = skip_spaces (last_space);
 440     }
 441
 442   *string = last;
 443   if (last_space > start)
 444     return savestring (start, last_space - start);
 445   return NULL;
 446 }
 447
 448 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 449    commands.  */
 450
 451 static void
 452 catch_exception_command_1 (enum exception_event_kind ex_event, char *arg,
 453                            int tempflag, int from_tty)
 454 {
 455   char *except_rx;
 456   char *cond_string = NULL;
 457   struct cleanup *cleanup;
 458
 459   if (!arg)
 460     arg = "";
 461   arg = skip_spaces (arg);
 462
 463   except_rx = extract_exception_regexp (&arg);
 464   cleanup = make_cleanup (xfree, except_rx);
 465
 466   cond_string = ep_parse_optional_if_clause (&arg);
 467
 468   if ((*arg != '\0') && !isspace (*arg))
 469     error (_("Junk at end of arguments."));
 470
 471   if (ex_event != EX_EVENT_THROW
 472       && ex_event != EX_EVENT_CATCH
 473       && ex_event != EX_EVENT_RETHROW)
 474     error (_("Unsupported or unknown exception event; cannot catch it"));
 475
 476   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 477                             ex_event, from_tty);
 478
 479   discard_cleanups (cleanup);
 480 }
 481
 482 /* Implementation of "catch catch" command.  */
 483
 484 static void
 485 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 486 {
 487   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 488
 489   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 490 }
 491
 492 /* Implementation of "catch throw" command.  */
 493
 494 static void
 495 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 496 {
 497   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 498
 499   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 500 }
 501
 502 /* Implementation of "catch rethrow" command.  */
 503
 504 static void
 505 catch_rethrow_command (char *arg, int from_tty,
 506                        struct cmd_list_element *command)
 507 {
 508   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 509
 510   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 511 }
 512
 513 \f
 514
 515 /* Implement the 'make_value' method for the $_exception
 516    internalvar.  */
 517
 518 static struct value *
 519 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 520 {
 521   struct value *arg0, *arg1;
 522   struct type *obj_type;
 523
 524   fetch_probe_arguments (&arg0, &arg1);
 525
 526   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 527      the std::type_info for the exception.  Now we find the type from
 528      the type_info and cast the result.  */
 529   obj_type = cplus_type_from_type_info (arg1);
 530   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 531 }
 532
 533 /* Implementation of the '$_exception' variable.  */
 534
 535 static const struct internalvar_funcs exception_funcs =
 536 {
 537   compute_exception,
 538   NULL,
 539   NULL
 540 };
 541
 542 \f
 543
 544 static void
 545 initialize_throw_catchpoint_ops (void)
 546 {
 547   struct breakpoint_ops *ops;
 548
 549   initialize_breakpoint_ops ();
 550
 551   /* GNU v3 exception catchpoints.  */
 552   ops = &gnu_v3_exception_catchpoint_ops;
 553   *ops = bkpt_breakpoint_ops;
 554   ops->dtor = dtor_exception_catchpoint;
 555   ops->re_set = re_set_exception_catchpoint;
 556   ops->print_it = print_it_exception_catchpoint;
 557   ops->print_one = print_one_exception_catchpoint;
 558   ops->print_mention = print_mention_exception_catchpoint;
 559   ops->print_recreate = print_recreate_exception_catchpoint;
 560   ops->print_one_detail = print_one_detail_exception_catchpoint;
 561   ops->check_status = check_status_exception_catchpoint;
 562 }
 563
 564 initialize_file_ftype _initialize_break_catch_throw;
 565
 566 void
 567 _initialize_break_catch_throw (void)
 568 {
 569   initialize_throw_catchpoint_ops ();
 570
 571   /* Add catch and tcatch sub-commands.  */
 572   add_catch_command ("catch", _("\
 573 Catch an exception, when caught."),
 574                      catch_catch_command,
 575                      NULL,
 576                      CATCH_PERMANENT,
 577                      CATCH_TEMPORARY);
 578   add_catch_command ("throw", _("\
 579 Catch an exception, when thrown."),
 580                      catch_throw_command,
 581                      NULL,
 582                      CATCH_PERMANENT,
 583                      CATCH_TEMPORARY);
 584   add_catch_command ("rethrow", _("\
 585 Catch an exception, when rethrown."),
 586                      catch_rethrow_command,
 587                      NULL,
 588                      CATCH_PERMANENT,
 589                      CATCH_TEMPORARY);
 590
 591   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 592 }