gdb/break-catch-throw.c

   1 /* Everything about catch/throw catchpoints, for GDB.
   2
   3    Copyright (C) 1986-2016 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   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   std::string type_name;
 166
 167   bkpt_breakpoint_ops.check_status (bs);
 168   if (bs->stop == 0)
 169     return;
 170
 171   if (self->pattern == NULL)
 172     return;
 173
 174   TRY
 175     {
 176       struct value *typeinfo_arg;
 177       std::string canon;
 178
 179       fetch_probe_arguments (NULL, &typeinfo_arg);
 180       type_name = cplus_typename_from_type_info (typeinfo_arg);
 181
 182       canon = cp_canonicalize_string (type_name.c_str ());
 183       if (!canon.empty ())
 184         std::swap (type_name, canon);
 185     }
 186   CATCH (e, RETURN_MASK_ERROR)
 187     {
 188       exception_print (gdb_stderr, e);
 189     }
 190   END_CATCH
 191
 192   if (!type_name.empty ())
 193     {
 194       if (regexec (self->pattern, type_name.c_str (), 0, NULL, 0) != 0)
 195         bs->stop = 0;
 196     }
 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   struct cleanup *cleanup;
 207   enum exception_event_kind kind = classify_exception_breakpoint (self);
 208   struct event_location *location;
 209   struct program_space *filter_pspace = current_program_space;
 210
 211   /* We first try to use the probe interface.  */
 212   TRY
 213     {
 214       location
 215         = new_probe_location (exception_functions[kind].probe);
 216       cleanup = make_cleanup_delete_event_location (location);
 217       sals = parse_probes (location, filter_pspace, NULL);
 218       do_cleanups (cleanup);
 219     }
 220   CATCH (e, RETURN_MASK_ERROR)
 221     {
 222       /* Using the probe interface failed.  Let's fallback to the normal
 223          catchpoint mode.  */
 224       TRY
 225         {
 226           struct explicit_location explicit_loc;
 227
 228           initialize_explicit_location (&explicit_loc);
 229           explicit_loc.function_name
 230             = ASTRDUP (exception_functions[kind].function);
 231           location = new_explicit_location (&explicit_loc);
 232           cleanup = make_cleanup_delete_event_location (location);
 233           self->ops->decode_location (self, location, filter_pspace, &sals);
 234           do_cleanups (cleanup);
 235         }
 236       CATCH (ex, RETURN_MASK_ERROR)
 237         {
 238           /* NOT_FOUND_ERROR just means the breakpoint will be
 239              pending, so let it through.  */
 240           if (ex.error != NOT_FOUND_ERROR)
 241             throw_exception (ex);
 242         }
 243       END_CATCH
 244     }
 245   END_CATCH
 246
 247   cleanup = make_cleanup (xfree, sals.sals);
 248   update_breakpoint_locations (self, filter_pspace, sals, sals_end);
 249   do_cleanups (cleanup);
 250 }
 251
 252 static enum print_stop_action
 253 print_it_exception_catchpoint (bpstat bs)
 254 {
 255   struct ui_out *uiout = current_uiout;
 256   struct breakpoint *b = bs->breakpoint_at;
 257   int bp_temp;
 258   enum exception_event_kind kind = classify_exception_breakpoint (b);
 259
 260   annotate_catchpoint (b->number);
 261   maybe_print_thread_hit_breakpoint (uiout);
 262
 263   bp_temp = b->disposition == disp_del;
 264   ui_out_text (uiout,
 265                bp_temp ? "Temporary catchpoint "
 266                        : "Catchpoint ");
 267   if (!ui_out_is_mi_like_p (uiout))
 268     ui_out_field_int (uiout, "bkptno", b->number);
 269   ui_out_text (uiout,
 270                (kind == EX_EVENT_THROW ? " (exception thrown), "
 271                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 272                    : " (exception rethrown), ")));
 273   if (ui_out_is_mi_like_p (uiout))
 274     {
 275       ui_out_field_string (uiout, "reason",
 276                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 277       ui_out_field_string (uiout, "disp", bpdisp_text (b->disposition));
 278       ui_out_field_int (uiout, "bkptno", b->number);
 279     }
 280   return PRINT_SRC_AND_LOC;
 281 }
 282
 283 static void
 284 print_one_exception_catchpoint (struct breakpoint *b,
 285                                 struct bp_location **last_loc)
 286 {
 287   struct value_print_options opts;
 288   struct ui_out *uiout = current_uiout;
 289   enum exception_event_kind kind = classify_exception_breakpoint (b);
 290
 291   get_user_print_options (&opts);
 292   if (opts.addressprint)
 293     {
 294       annotate_field (4);
 295       if (b->loc == NULL || b->loc->shlib_disabled)
 296         ui_out_field_string (uiout, "addr", "<PENDING>");
 297       else
 298         ui_out_field_core_addr (uiout, "addr",
 299                                 b->loc->gdbarch, b->loc->address);
 300     }
 301   annotate_field (5);
 302   if (b->loc)
 303     *last_loc = b->loc;
 304
 305   switch (kind)
 306     {
 307     case EX_EVENT_THROW:
 308       ui_out_field_string (uiout, "what", "exception throw");
 309       if (ui_out_is_mi_like_p (uiout))
 310         ui_out_field_string (uiout, "catch-type", "throw");
 311       break;
 312
 313     case EX_EVENT_RETHROW:
 314       ui_out_field_string (uiout, "what", "exception rethrow");
 315       if (ui_out_is_mi_like_p (uiout))
 316         ui_out_field_string (uiout, "catch-type", "rethrow");
 317       break;
 318
 319     case EX_EVENT_CATCH:
 320       ui_out_field_string (uiout, "what", "exception catch");
 321       if (ui_out_is_mi_like_p (uiout))
 322         ui_out_field_string (uiout, "catch-type", "catch");
 323       break;
 324     }
 325 }
 326
 327 /* Implement the 'print_one_detail' method.  */
 328
 329 static void
 330 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 331                                        struct ui_out *uiout)
 332 {
 333   const struct exception_catchpoint *cp
 334     = (const struct exception_catchpoint *) b;
 335
 336   if (cp->exception_rx != NULL)
 337     {
 338       ui_out_text (uiout, _("\tmatching: "));
 339       ui_out_field_string (uiout, "regexp", cp->exception_rx);
 340       ui_out_text (uiout, "\n");
 341     }
 342 }
 343
 344 static void
 345 print_mention_exception_catchpoint (struct breakpoint *b)
 346 {
 347   struct ui_out *uiout = current_uiout;
 348   int bp_temp;
 349   enum exception_event_kind kind = classify_exception_breakpoint (b);
 350
 351   bp_temp = b->disposition == disp_del;
 352   ui_out_text (uiout, bp_temp ? _("Temporary catchpoint ")
 353                               : _("Catchpoint "));
 354   ui_out_field_int (uiout, "bkptno", b->number);
 355   ui_out_text (uiout, (kind == EX_EVENT_THROW ? _(" (throw)")
 356                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 357                           : _(" (rethrow)"))));
 358 }
 359
 360 /* Implement the "print_recreate" breakpoint_ops method for throw and
 361    catch catchpoints.  */
 362
 363 static void
 364 print_recreate_exception_catchpoint (struct breakpoint *b,
 365                                      struct ui_file *fp)
 366 {
 367   int bp_temp;
 368   enum exception_event_kind kind = classify_exception_breakpoint (b);
 369
 370   bp_temp = b->disposition == disp_del;
 371   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 372   switch (kind)
 373     {
 374     case EX_EVENT_THROW:
 375       fprintf_unfiltered (fp, "throw");
 376       break;
 377     case EX_EVENT_CATCH:
 378       fprintf_unfiltered (fp, "catch");
 379       break;
 380     case EX_EVENT_RETHROW:
 381       fprintf_unfiltered (fp, "rethrow");
 382       break;
 383     }
 384   print_recreate_thread (b, fp);
 385 }
 386
 387 static void
 388 handle_gnu_v3_exceptions (int tempflag, char *except_rx, char *cond_string,
 389                           enum exception_event_kind ex_event, int from_tty)
 390 {
 391   regex_t *pattern = NULL;
 392
 393   if (except_rx != NULL)
 394     {
 395       pattern = XNEW (regex_t);
 396       make_cleanup (xfree, pattern);
 397
 398       compile_rx_or_error (pattern, except_rx,
 399                            _("invalid type-matching regexp"));
 400     }
 401
 402   std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
 403
 404   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 405                    &gnu_v3_exception_catchpoint_ops);
 406   /* We need to reset 'type' in order for code in breakpoint.c to do
 407      the right thing.  */
 408   cp->base.type = bp_breakpoint;
 409   cp->kind = ex_event;
 410   cp->exception_rx = except_rx;
 411   cp->pattern = pattern;
 412
 413   re_set_exception_catchpoint (&cp->base);
 414
 415   install_breakpoint (0, &cp->base, 1);
 416   cp.release ();
 417 }
 418
 419 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 420    by whitespace.
 421
 422    If there is any non-whitespace text between *STRING and the "if"
 423    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 424    this returns NULL.
 425
 426    STRING is updated to point to the "if" token, if it exists, or to
 427    the end of the string.  */
 428
 429 static char *
 430 extract_exception_regexp (char **string)
 431 {
 432   char *start;
 433   char *last, *last_space;
 434
 435   start = skip_spaces (*string);
 436
 437   last = start;
 438   last_space = start;
 439   while (*last != '\0')
 440     {
 441       char *if_token = last;
 442
 443       /* Check for the "if".  */
 444       if (check_for_argument (&if_token, "if", 2))
 445         break;
 446
 447       /* No "if" token here.  Skip to the next word start.  */
 448       last_space = skip_to_space (last);
 449       last = skip_spaces (last_space);
 450     }
 451
 452   *string = last;
 453   if (last_space > start)
 454     return savestring (start, last_space - start);
 455   return NULL;
 456 }
 457
 458 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 459    commands.  */
 460
 461 static void
 462 catch_exception_command_1 (enum exception_event_kind ex_event, char *arg,
 463                            int tempflag, int from_tty)
 464 {
 465   char *except_rx;
 466   char *cond_string = NULL;
 467   struct cleanup *cleanup;
 468
 469   if (!arg)
 470     arg = "";
 471   arg = skip_spaces (arg);
 472
 473   except_rx = extract_exception_regexp (&arg);
 474   cleanup = make_cleanup (xfree, except_rx);
 475
 476   cond_string = ep_parse_optional_if_clause (&arg);
 477
 478   if ((*arg != '\0') && !isspace (*arg))
 479     error (_("Junk at end of arguments."));
 480
 481   if (ex_event != EX_EVENT_THROW
 482       && ex_event != EX_EVENT_CATCH
 483       && ex_event != EX_EVENT_RETHROW)
 484     error (_("Unsupported or unknown exception event; cannot catch it"));
 485
 486   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 487                             ex_event, from_tty);
 488
 489   discard_cleanups (cleanup);
 490 }
 491
 492 /* Implementation of "catch catch" command.  */
 493
 494 static void
 495 catch_catch_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_CATCH, arg, tempflag, from_tty);
 500 }
 501
 502 /* Implementation of "catch throw" command.  */
 503
 504 static void
 505 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 506 {
 507   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 508
 509   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 510 }
 511
 512 /* Implementation of "catch rethrow" command.  */
 513
 514 static void
 515 catch_rethrow_command (char *arg, int from_tty,
 516                        struct cmd_list_element *command)
 517 {
 518   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 519
 520   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 521 }
 522
 523 \f
 524
 525 /* Implement the 'make_value' method for the $_exception
 526    internalvar.  */
 527
 528 static struct value *
 529 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 530 {
 531   struct value *arg0, *arg1;
 532   struct type *obj_type;
 533
 534   fetch_probe_arguments (&arg0, &arg1);
 535
 536   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 537      the std::type_info for the exception.  Now we find the type from
 538      the type_info and cast the result.  */
 539   obj_type = cplus_type_from_type_info (arg1);
 540   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 541 }
 542
 543 /* Implementation of the '$_exception' variable.  */
 544
 545 static const struct internalvar_funcs exception_funcs =
 546 {
 547   compute_exception,
 548   NULL,
 549   NULL
 550 };
 551
 552 \f
 553
 554 static void
 555 initialize_throw_catchpoint_ops (void)
 556 {
 557   struct breakpoint_ops *ops;
 558
 559   initialize_breakpoint_ops ();
 560
 561   /* GNU v3 exception catchpoints.  */
 562   ops = &gnu_v3_exception_catchpoint_ops;
 563   *ops = bkpt_breakpoint_ops;
 564   ops->dtor = dtor_exception_catchpoint;
 565   ops->re_set = re_set_exception_catchpoint;
 566   ops->print_it = print_it_exception_catchpoint;
 567   ops->print_one = print_one_exception_catchpoint;
 568   ops->print_mention = print_mention_exception_catchpoint;
 569   ops->print_recreate = print_recreate_exception_catchpoint;
 570   ops->print_one_detail = print_one_detail_exception_catchpoint;
 571   ops->check_status = check_status_exception_catchpoint;
 572 }
 573
 574 initialize_file_ftype _initialize_break_catch_throw;
 575
 576 void
 577 _initialize_break_catch_throw (void)
 578 {
 579   initialize_throw_catchpoint_ops ();
 580
 581   /* Add catch and tcatch sub-commands.  */
 582   add_catch_command ("catch", _("\
 583 Catch an exception, when caught."),
 584                      catch_catch_command,
 585                      NULL,
 586                      CATCH_PERMANENT,
 587                      CATCH_TEMPORARY);
 588   add_catch_command ("throw", _("\
 589 Catch an exception, when thrown."),
 590                      catch_throw_command,
 591                      NULL,
 592                      CATCH_PERMANENT,
 593                      CATCH_TEMPORARY);
 594   add_catch_command ("rethrow", _("\
 595 Catch an exception, when rethrown."),
 596                      catch_rethrow_command,
 597                      NULL,
 598                      CATCH_PERMANENT,
 599                      CATCH_TEMPORARY);
 600
 601   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 602 }