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       char *spec = ASTRDUP (exception_functions[kind].probe);
 220
 221       location = new_linespec_location (&spec);
 222       cleanup = make_cleanup_delete_event_location (location);
 223       sals = parse_probes (location, NULL);
 224       do_cleanups (cleanup);
 225     }
 226
 227   CATCH (e, RETURN_MASK_ERROR)
 228     {
 229       /* Using the probe interface failed.  Let's fallback to the normal
 230          catchpoint mode.  */
 231       TRY
 232         {
 233           char *spec = ASTRDUP (exception_functions[kind].function);
 234
 235           location = new_linespec_location (&spec);
 236           cleanup = make_cleanup_delete_event_location (location);
 237           self->ops->decode_location (self, location, &sals);
 238           do_cleanups (cleanup);
 239         }
 240       CATCH (ex, RETURN_MASK_ERROR)
 241         {
 242           /* NOT_FOUND_ERROR just means the breakpoint will be
 243              pending, so let it through.  */
 244           if (ex.error != NOT_FOUND_ERROR)
 245             throw_exception (ex);
 246         }
 247       END_CATCH
 248     }
 249   END_CATCH
 250
 251   cleanup = make_cleanup (xfree, sals.sals);
 252   update_breakpoint_locations (self, sals, sals_end);
 253   do_cleanups (cleanup);
 254 }
 255
 256 static enum print_stop_action
 257 print_it_exception_catchpoint (bpstat bs)
 258 {
 259   struct ui_out *uiout = current_uiout;
 260   struct breakpoint *b = bs->breakpoint_at;
 261   int bp_temp;
 262   enum exception_event_kind kind = classify_exception_breakpoint (b);
 263
 264   annotate_catchpoint (b->number);
 265
 266   bp_temp = b->disposition == disp_del;
 267   ui_out_text (uiout,
 268                bp_temp ? "Temporary catchpoint "
 269                        : "Catchpoint ");
 270   if (!ui_out_is_mi_like_p (uiout))
 271     ui_out_field_int (uiout, "bkptno", b->number);
 272   ui_out_text (uiout,
 273                (kind == EX_EVENT_THROW ? " (exception thrown), "
 274                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 275                    : " (exception rethrown), ")));
 276   if (ui_out_is_mi_like_p (uiout))
 277     {
 278       ui_out_field_string (uiout, "reason",
 279                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 280       ui_out_field_string (uiout, "disp", bpdisp_text (b->disposition));
 281       ui_out_field_int (uiout, "bkptno", b->number);
 282     }
 283   return PRINT_SRC_AND_LOC;
 284 }
 285
 286 static void
 287 print_one_exception_catchpoint (struct breakpoint *b,
 288                                 struct bp_location **last_loc)
 289 {
 290   struct value_print_options opts;
 291   struct ui_out *uiout = current_uiout;
 292   enum exception_event_kind kind = classify_exception_breakpoint (b);
 293
 294   get_user_print_options (&opts);
 295   if (opts.addressprint)
 296     {
 297       annotate_field (4);
 298       if (b->loc == NULL || b->loc->shlib_disabled)
 299         ui_out_field_string (uiout, "addr", "<PENDING>");
 300       else
 301         ui_out_field_core_addr (uiout, "addr",
 302                                 b->loc->gdbarch, b->loc->address);
 303     }
 304   annotate_field (5);
 305   if (b->loc)
 306     *last_loc = b->loc;
 307
 308   switch (kind)
 309     {
 310     case EX_EVENT_THROW:
 311       ui_out_field_string (uiout, "what", "exception throw");
 312       if (ui_out_is_mi_like_p (uiout))
 313         ui_out_field_string (uiout, "catch-type", "throw");
 314       break;
 315
 316     case EX_EVENT_RETHROW:
 317       ui_out_field_string (uiout, "what", "exception rethrow");
 318       if (ui_out_is_mi_like_p (uiout))
 319         ui_out_field_string (uiout, "catch-type", "rethrow");
 320       break;
 321
 322     case EX_EVENT_CATCH:
 323       ui_out_field_string (uiout, "what", "exception catch");
 324       if (ui_out_is_mi_like_p (uiout))
 325         ui_out_field_string (uiout, "catch-type", "catch");
 326       break;
 327     }
 328 }
 329
 330 /* Implement the 'print_one_detail' method.  */
 331
 332 static void
 333 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 334                                        struct ui_out *uiout)
 335 {
 336   const struct exception_catchpoint *cp
 337     = (const struct exception_catchpoint *) b;
 338
 339   if (cp->exception_rx != NULL)
 340     {
 341       ui_out_text (uiout, _("\tmatching: "));
 342       ui_out_field_string (uiout, "regexp", cp->exception_rx);
 343       ui_out_text (uiout, "\n");
 344     }
 345 }
 346
 347 static void
 348 print_mention_exception_catchpoint (struct breakpoint *b)
 349 {
 350   struct ui_out *uiout = current_uiout;
 351   int bp_temp;
 352   enum exception_event_kind kind = classify_exception_breakpoint (b);
 353
 354   bp_temp = b->disposition == disp_del;
 355   ui_out_text (uiout, bp_temp ? _("Temporary catchpoint ")
 356                               : _("Catchpoint "));
 357   ui_out_field_int (uiout, "bkptno", b->number);
 358   ui_out_text (uiout, (kind == EX_EVENT_THROW ? _(" (throw)")
 359                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 360                           : _(" (rethrow)"))));
 361 }
 362
 363 /* Implement the "print_recreate" breakpoint_ops method for throw and
 364    catch catchpoints.  */
 365
 366 static void
 367 print_recreate_exception_catchpoint (struct breakpoint *b,
 368                                      struct ui_file *fp)
 369 {
 370   int bp_temp;
 371   enum exception_event_kind kind = classify_exception_breakpoint (b);
 372
 373   bp_temp = b->disposition == disp_del;
 374   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 375   switch (kind)
 376     {
 377     case EX_EVENT_THROW:
 378       fprintf_unfiltered (fp, "throw");
 379       break;
 380     case EX_EVENT_CATCH:
 381       fprintf_unfiltered (fp, "catch");
 382       break;
 383     case EX_EVENT_RETHROW:
 384       fprintf_unfiltered (fp, "rethrow");
 385       break;
 386     }
 387   print_recreate_thread (b, fp);
 388 }
 389
 390 static void
 391 handle_gnu_v3_exceptions (int tempflag, char *except_rx, char *cond_string,
 392                           enum exception_event_kind ex_event, int from_tty)
 393 {
 394   struct exception_catchpoint *cp;
 395   struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
 396   regex_t *pattern = NULL;
 397
 398   if (except_rx != NULL)
 399     {
 400       pattern = XNEW (regex_t);
 401       make_cleanup (xfree, pattern);
 402
 403       compile_rx_or_error (pattern, except_rx,
 404                            _("invalid type-matching regexp"));
 405     }
 406
 407   cp = XCNEW (struct exception_catchpoint);
 408   make_cleanup (xfree, cp);
 409
 410   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 411                    &gnu_v3_exception_catchpoint_ops);
 412   /* We need to reset 'type' in order for code in breakpoint.c to do
 413      the right thing.  */
 414   cp->base.type = bp_breakpoint;
 415   cp->kind = ex_event;
 416   cp->exception_rx = except_rx;
 417   cp->pattern = pattern;
 418
 419   re_set_exception_catchpoint (&cp->base);
 420
 421   install_breakpoint (0, &cp->base, 1);
 422   discard_cleanups (cleanup);
 423 }
 424
 425 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 426    by whitespace.
 427
 428    If there is any non-whitespace text between *STRING and the "if"
 429    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 430    this returns NULL.
 431
 432    STRING is updated to point to the "if" token, if it exists, or to
 433    the end of the string.  */
 434
 435 static char *
 436 extract_exception_regexp (char **string)
 437 {
 438   char *start;
 439   char *last, *last_space;
 440
 441   start = skip_spaces (*string);
 442
 443   last = start;
 444   last_space = start;
 445   while (*last != '\0')
 446     {
 447       char *if_token = last;
 448
 449       /* Check for the "if".  */
 450       if (check_for_argument (&if_token, "if", 2))
 451         break;
 452
 453       /* No "if" token here.  Skip to the next word start.  */
 454       last_space = skip_to_space (last);
 455       last = skip_spaces (last_space);
 456     }
 457
 458   *string = last;
 459   if (last_space > start)
 460     return savestring (start, last_space - start);
 461   return NULL;
 462 }
 463
 464 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 465    commands.  */
 466
 467 static void
 468 catch_exception_command_1 (enum exception_event_kind ex_event, char *arg,
 469                            int tempflag, int from_tty)
 470 {
 471   char *except_rx;
 472   char *cond_string = NULL;
 473   struct cleanup *cleanup;
 474
 475   if (!arg)
 476     arg = "";
 477   arg = skip_spaces (arg);
 478
 479   except_rx = extract_exception_regexp (&arg);
 480   cleanup = make_cleanup (xfree, except_rx);
 481
 482   cond_string = ep_parse_optional_if_clause (&arg);
 483
 484   if ((*arg != '\0') && !isspace (*arg))
 485     error (_("Junk at end of arguments."));
 486
 487   if (ex_event != EX_EVENT_THROW
 488       && ex_event != EX_EVENT_CATCH
 489       && ex_event != EX_EVENT_RETHROW)
 490     error (_("Unsupported or unknown exception event; cannot catch it"));
 491
 492   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 493                             ex_event, from_tty);
 494
 495   discard_cleanups (cleanup);
 496 }
 497
 498 /* Implementation of "catch catch" command.  */
 499
 500 static void
 501 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 502 {
 503   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 504
 505   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 506 }
 507
 508 /* Implementation of "catch throw" command.  */
 509
 510 static void
 511 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 512 {
 513   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 514
 515   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 516 }
 517
 518 /* Implementation of "catch rethrow" command.  */
 519
 520 static void
 521 catch_rethrow_command (char *arg, int from_tty,
 522                        struct cmd_list_element *command)
 523 {
 524   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 525
 526   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 527 }
 528
 529 \f
 530
 531 /* Implement the 'make_value' method for the $_exception
 532    internalvar.  */
 533
 534 static struct value *
 535 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 536 {
 537   struct value *arg0, *arg1;
 538   struct type *obj_type;
 539
 540   fetch_probe_arguments (&arg0, &arg1);
 541
 542   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 543      the std::type_info for the exception.  Now we find the type from
 544      the type_info and cast the result.  */
 545   obj_type = cplus_type_from_type_info (arg1);
 546   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 547 }
 548
 549 /* Implementation of the '$_exception' variable.  */
 550
 551 static const struct internalvar_funcs exception_funcs =
 552 {
 553   compute_exception,
 554   NULL,
 555   NULL
 556 };
 557
 558 \f
 559
 560 static void
 561 initialize_throw_catchpoint_ops (void)
 562 {
 563   struct breakpoint_ops *ops;
 564
 565   initialize_breakpoint_ops ();
 566
 567   /* GNU v3 exception catchpoints.  */
 568   ops = &gnu_v3_exception_catchpoint_ops;
 569   *ops = bkpt_breakpoint_ops;
 570   ops->dtor = dtor_exception_catchpoint;
 571   ops->re_set = re_set_exception_catchpoint;
 572   ops->print_it = print_it_exception_catchpoint;
 573   ops->print_one = print_one_exception_catchpoint;
 574   ops->print_mention = print_mention_exception_catchpoint;
 575   ops->print_recreate = print_recreate_exception_catchpoint;
 576   ops->print_one_detail = print_one_detail_exception_catchpoint;
 577   ops->check_status = check_status_exception_catchpoint;
 578 }
 579
 580 initialize_file_ftype _initialize_break_catch_throw;
 581
 582 void
 583 _initialize_break_catch_throw (void)
 584 {
 585   initialize_throw_catchpoint_ops ();
 586
 587   /* Add catch and tcatch sub-commands.  */
 588   add_catch_command ("catch", _("\
 589 Catch an exception, when caught."),
 590                      catch_catch_command,
 591                      NULL,
 592                      CATCH_PERMANENT,
 593                      CATCH_TEMPORARY);
 594   add_catch_command ("throw", _("\
 595 Catch an exception, when thrown."),
 596                      catch_throw_command,
 597                      NULL,
 598                      CATCH_PERMANENT,
 599                      CATCH_TEMPORARY);
 600   add_catch_command ("rethrow", _("\
 601 Catch an exception, when rethrown."),
 602                      catch_rethrow_command,
 603                      NULL,
 604                      CATCH_PERMANENT,
 605                      CATCH_TEMPORARY);
 606
 607   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 608 }