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   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   maybe_print_thread_hit_breakpoint (uiout);
 268
 269   bp_temp = b->disposition == disp_del;
 270   ui_out_text (uiout,
 271                bp_temp ? "Temporary catchpoint "
 272                        : "Catchpoint ");
 273   if (!ui_out_is_mi_like_p (uiout))
 274     ui_out_field_int (uiout, "bkptno", b->number);
 275   ui_out_text (uiout,
 276                (kind == EX_EVENT_THROW ? " (exception thrown), "
 277                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 278                    : " (exception rethrown), ")));
 279   if (ui_out_is_mi_like_p (uiout))
 280     {
 281       ui_out_field_string (uiout, "reason",
 282                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 283       ui_out_field_string (uiout, "disp", bpdisp_text (b->disposition));
 284       ui_out_field_int (uiout, "bkptno", b->number);
 285     }
 286   return PRINT_SRC_AND_LOC;
 287 }
 288
 289 static void
 290 print_one_exception_catchpoint (struct breakpoint *b,
 291                                 struct bp_location **last_loc)
 292 {
 293   struct value_print_options opts;
 294   struct ui_out *uiout = current_uiout;
 295   enum exception_event_kind kind = classify_exception_breakpoint (b);
 296
 297   get_user_print_options (&opts);
 298   if (opts.addressprint)
 299     {
 300       annotate_field (4);
 301       if (b->loc == NULL || b->loc->shlib_disabled)
 302         ui_out_field_string (uiout, "addr", "<PENDING>");
 303       else
 304         ui_out_field_core_addr (uiout, "addr",
 305                                 b->loc->gdbarch, b->loc->address);
 306     }
 307   annotate_field (5);
 308   if (b->loc)
 309     *last_loc = b->loc;
 310
 311   switch (kind)
 312     {
 313     case EX_EVENT_THROW:
 314       ui_out_field_string (uiout, "what", "exception throw");
 315       if (ui_out_is_mi_like_p (uiout))
 316         ui_out_field_string (uiout, "catch-type", "throw");
 317       break;
 318
 319     case EX_EVENT_RETHROW:
 320       ui_out_field_string (uiout, "what", "exception rethrow");
 321       if (ui_out_is_mi_like_p (uiout))
 322         ui_out_field_string (uiout, "catch-type", "rethrow");
 323       break;
 324
 325     case EX_EVENT_CATCH:
 326       ui_out_field_string (uiout, "what", "exception catch");
 327       if (ui_out_is_mi_like_p (uiout))
 328         ui_out_field_string (uiout, "catch-type", "catch");
 329       break;
 330     }
 331 }
 332
 333 /* Implement the 'print_one_detail' method.  */
 334
 335 static void
 336 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 337                                        struct ui_out *uiout)
 338 {
 339   const struct exception_catchpoint *cp
 340     = (const struct exception_catchpoint *) b;
 341
 342   if (cp->exception_rx != NULL)
 343     {
 344       ui_out_text (uiout, _("\tmatching: "));
 345       ui_out_field_string (uiout, "regexp", cp->exception_rx);
 346       ui_out_text (uiout, "\n");
 347     }
 348 }
 349
 350 static void
 351 print_mention_exception_catchpoint (struct breakpoint *b)
 352 {
 353   struct ui_out *uiout = current_uiout;
 354   int bp_temp;
 355   enum exception_event_kind kind = classify_exception_breakpoint (b);
 356
 357   bp_temp = b->disposition == disp_del;
 358   ui_out_text (uiout, bp_temp ? _("Temporary catchpoint ")
 359                               : _("Catchpoint "));
 360   ui_out_field_int (uiout, "bkptno", b->number);
 361   ui_out_text (uiout, (kind == EX_EVENT_THROW ? _(" (throw)")
 362                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 363                           : _(" (rethrow)"))));
 364 }
 365
 366 /* Implement the "print_recreate" breakpoint_ops method for throw and
 367    catch catchpoints.  */
 368
 369 static void
 370 print_recreate_exception_catchpoint (struct breakpoint *b,
 371                                      struct ui_file *fp)
 372 {
 373   int bp_temp;
 374   enum exception_event_kind kind = classify_exception_breakpoint (b);
 375
 376   bp_temp = b->disposition == disp_del;
 377   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 378   switch (kind)
 379     {
 380     case EX_EVENT_THROW:
 381       fprintf_unfiltered (fp, "throw");
 382       break;
 383     case EX_EVENT_CATCH:
 384       fprintf_unfiltered (fp, "catch");
 385       break;
 386     case EX_EVENT_RETHROW:
 387       fprintf_unfiltered (fp, "rethrow");
 388       break;
 389     }
 390   print_recreate_thread (b, fp);
 391 }
 392
 393 static void
 394 handle_gnu_v3_exceptions (int tempflag, char *except_rx, char *cond_string,
 395                           enum exception_event_kind ex_event, int from_tty)
 396 {
 397   struct exception_catchpoint *cp;
 398   struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
 399   regex_t *pattern = NULL;
 400
 401   if (except_rx != NULL)
 402     {
 403       pattern = XNEW (regex_t);
 404       make_cleanup (xfree, pattern);
 405
 406       compile_rx_or_error (pattern, except_rx,
 407                            _("invalid type-matching regexp"));
 408     }
 409
 410   cp = XCNEW (struct exception_catchpoint);
 411   make_cleanup (xfree, cp);
 412
 413   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 414                    &gnu_v3_exception_catchpoint_ops);
 415   /* We need to reset 'type' in order for code in breakpoint.c to do
 416      the right thing.  */
 417   cp->base.type = bp_breakpoint;
 418   cp->kind = ex_event;
 419   cp->exception_rx = except_rx;
 420   cp->pattern = pattern;
 421
 422   re_set_exception_catchpoint (&cp->base);
 423
 424   install_breakpoint (0, &cp->base, 1);
 425   discard_cleanups (cleanup);
 426 }
 427
 428 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 429    by whitespace.
 430
 431    If there is any non-whitespace text between *STRING and the "if"
 432    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 433    this returns NULL.
 434
 435    STRING is updated to point to the "if" token, if it exists, or to
 436    the end of the string.  */
 437
 438 static char *
 439 extract_exception_regexp (char **string)
 440 {
 441   char *start;
 442   char *last, *last_space;
 443
 444   start = skip_spaces (*string);
 445
 446   last = start;
 447   last_space = start;
 448   while (*last != '\0')
 449     {
 450       char *if_token = last;
 451
 452       /* Check for the "if".  */
 453       if (check_for_argument (&if_token, "if", 2))
 454         break;
 455
 456       /* No "if" token here.  Skip to the next word start.  */
 457       last_space = skip_to_space (last);
 458       last = skip_spaces (last_space);
 459     }
 460
 461   *string = last;
 462   if (last_space > start)
 463     return savestring (start, last_space - start);
 464   return NULL;
 465 }
 466
 467 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 468    commands.  */
 469
 470 static void
 471 catch_exception_command_1 (enum exception_event_kind ex_event, char *arg,
 472                            int tempflag, int from_tty)
 473 {
 474   char *except_rx;
 475   char *cond_string = NULL;
 476   struct cleanup *cleanup;
 477
 478   if (!arg)
 479     arg = "";
 480   arg = skip_spaces (arg);
 481
 482   except_rx = extract_exception_regexp (&arg);
 483   cleanup = make_cleanup (xfree, except_rx);
 484
 485   cond_string = ep_parse_optional_if_clause (&arg);
 486
 487   if ((*arg != '\0') && !isspace (*arg))
 488     error (_("Junk at end of arguments."));
 489
 490   if (ex_event != EX_EVENT_THROW
 491       && ex_event != EX_EVENT_CATCH
 492       && ex_event != EX_EVENT_RETHROW)
 493     error (_("Unsupported or unknown exception event; cannot catch it"));
 494
 495   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 496                             ex_event, from_tty);
 497
 498   discard_cleanups (cleanup);
 499 }
 500
 501 /* Implementation of "catch catch" command.  */
 502
 503 static void
 504 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 505 {
 506   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 507
 508   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 509 }
 510
 511 /* Implementation of "catch throw" command.  */
 512
 513 static void
 514 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 515 {
 516   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 517
 518   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 519 }
 520
 521 /* Implementation of "catch rethrow" command.  */
 522
 523 static void
 524 catch_rethrow_command (char *arg, int from_tty,
 525                        struct cmd_list_element *command)
 526 {
 527   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 528
 529   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 530 }
 531
 532 \f
 533
 534 /* Implement the 'make_value' method for the $_exception
 535    internalvar.  */
 536
 537 static struct value *
 538 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 539 {
 540   struct value *arg0, *arg1;
 541   struct type *obj_type;
 542
 543   fetch_probe_arguments (&arg0, &arg1);
 544
 545   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 546      the std::type_info for the exception.  Now we find the type from
 547      the type_info and cast the result.  */
 548   obj_type = cplus_type_from_type_info (arg1);
 549   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 550 }
 551
 552 /* Implementation of the '$_exception' variable.  */
 553
 554 static const struct internalvar_funcs exception_funcs =
 555 {
 556   compute_exception,
 557   NULL,
 558   NULL
 559 };
 560
 561 \f
 562
 563 static void
 564 initialize_throw_catchpoint_ops (void)
 565 {
 566   struct breakpoint_ops *ops;
 567
 568   initialize_breakpoint_ops ();
 569
 570   /* GNU v3 exception catchpoints.  */
 571   ops = &gnu_v3_exception_catchpoint_ops;
 572   *ops = bkpt_breakpoint_ops;
 573   ops->dtor = dtor_exception_catchpoint;
 574   ops->re_set = re_set_exception_catchpoint;
 575   ops->print_it = print_it_exception_catchpoint;
 576   ops->print_one = print_one_exception_catchpoint;
 577   ops->print_mention = print_mention_exception_catchpoint;
 578   ops->print_recreate = print_recreate_exception_catchpoint;
 579   ops->print_one_detail = print_one_detail_exception_catchpoint;
 580   ops->check_status = check_status_exception_catchpoint;
 581 }
 582
 583 initialize_file_ftype _initialize_break_catch_throw;
 584
 585 void
 586 _initialize_break_catch_throw (void)
 587 {
 588   initialize_throw_catchpoint_ops ();
 589
 590   /* Add catch and tcatch sub-commands.  */
 591   add_catch_command ("catch", _("\
 592 Catch an exception, when caught."),
 593                      catch_catch_command,
 594                      NULL,
 595                      CATCH_PERMANENT,
 596                      CATCH_TEMPORARY);
 597   add_catch_command ("throw", _("\
 598 Catch an exception, when thrown."),
 599                      catch_throw_command,
 600                      NULL,
 601                      CATCH_PERMANENT,
 602                      CATCH_TEMPORARY);
 603   add_catch_command ("rethrow", _("\
 604 Catch an exception, when rethrown."),
 605                      catch_rethrow_command,
 606                      NULL,
 607                      CATCH_PERMANENT,
 608                      CATCH_TEMPORARY);
 609
 610   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 611 }