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 "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 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 *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
 211   /* We first try to use the probe interface.  */
 212   TRY_CATCH (e, RETURN_MASK_ERROR)
 213     {
 214       char *spec = ASTRDUP (exception_functions[kind].probe);
 215
 216       sals = parse_probes (&spec, NULL);
 217     }
 218
 219   if (e.reason < 0)
 220     {
 221       volatile struct gdb_exception ex;
 222
 223       /* Using the probe interface failed.  Let's fallback to the normal
 224          catchpoint mode.  */
 225       TRY_CATCH (ex, RETURN_MASK_ERROR)
 226         {
 227           char *spec = ASTRDUP (exception_functions[kind].function);
 228
 229           self->ops->decode_linespec (self, &spec, &sals);
 230         }
 231
 232       /* NOT_FOUND_ERROR just means the breakpoint will be pending, so
 233          let it through.  */
 234       if (ex.reason < 0 && ex.error != NOT_FOUND_ERROR)
 235         throw_exception (ex);
 236     }
 237
 238   cleanup = make_cleanup (xfree, sals.sals);
 239   update_breakpoint_locations (self, sals, sals_end);
 240   do_cleanups (cleanup);
 241 }
 242
 243 static enum print_stop_action
 244 print_it_exception_catchpoint (bpstat bs)
 245 {
 246   struct ui_out *uiout = current_uiout;
 247   struct breakpoint *b = bs->breakpoint_at;
 248   int bp_temp;
 249   enum exception_event_kind kind = classify_exception_breakpoint (b);
 250
 251   annotate_catchpoint (b->number);
 252
 253   bp_temp = b->disposition == disp_del;
 254   ui_out_text (uiout,
 255                bp_temp ? "Temporary catchpoint "
 256                        : "Catchpoint ");
 257   if (!ui_out_is_mi_like_p (uiout))
 258     ui_out_field_int (uiout, "bkptno", b->number);
 259   ui_out_text (uiout,
 260                (kind == EX_EVENT_THROW ? " (exception thrown), "
 261                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 262                    : " (exception rethrown), ")));
 263   if (ui_out_is_mi_like_p (uiout))
 264     {
 265       ui_out_field_string (uiout, "reason",
 266                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 267       ui_out_field_string (uiout, "disp", bpdisp_text (b->disposition));
 268       ui_out_field_int (uiout, "bkptno", b->number);
 269     }
 270   return PRINT_SRC_AND_LOC;
 271 }
 272
 273 static void
 274 print_one_exception_catchpoint (struct breakpoint *b,
 275                                 struct bp_location **last_loc)
 276 {
 277   struct value_print_options opts;
 278   struct ui_out *uiout = current_uiout;
 279   enum exception_event_kind kind = classify_exception_breakpoint (b);
 280
 281   get_user_print_options (&opts);
 282   if (opts.addressprint)
 283     {
 284       annotate_field (4);
 285       if (b->loc == NULL || b->loc->shlib_disabled)
 286         ui_out_field_string (uiout, "addr", "<PENDING>");
 287       else
 288         ui_out_field_core_addr (uiout, "addr",
 289                                 b->loc->gdbarch, b->loc->address);
 290     }
 291   annotate_field (5);
 292   if (b->loc)
 293     *last_loc = b->loc;
 294
 295   switch (kind)
 296     {
 297     case EX_EVENT_THROW:
 298       ui_out_field_string (uiout, "what", "exception throw");
 299       if (ui_out_is_mi_like_p (uiout))
 300         ui_out_field_string (uiout, "catch-type", "throw");
 301       break;
 302
 303     case EX_EVENT_RETHROW:
 304       ui_out_field_string (uiout, "what", "exception rethrow");
 305       if (ui_out_is_mi_like_p (uiout))
 306         ui_out_field_string (uiout, "catch-type", "rethrow");
 307       break;
 308
 309     case EX_EVENT_CATCH:
 310       ui_out_field_string (uiout, "what", "exception catch");
 311       if (ui_out_is_mi_like_p (uiout))
 312         ui_out_field_string (uiout, "catch-type", "catch");
 313       break;
 314     }
 315 }
 316
 317 /* Implement the 'print_one_detail' method.  */
 318
 319 static void
 320 print_one_detail_exception_catchpoint (const struct breakpoint *b,
 321                                        struct ui_out *uiout)
 322 {
 323   const struct exception_catchpoint *cp
 324     = (const struct exception_catchpoint *) b;
 325
 326   if (cp->exception_rx != NULL)
 327     {
 328       ui_out_text (uiout, _("\tmatching: "));
 329       ui_out_field_string (uiout, "regexp", cp->exception_rx);
 330       ui_out_text (uiout, "\n");
 331     }
 332 }
 333
 334 static void
 335 print_mention_exception_catchpoint (struct breakpoint *b)
 336 {
 337   struct ui_out *uiout = current_uiout;
 338   int bp_temp;
 339   enum exception_event_kind kind = classify_exception_breakpoint (b);
 340
 341   bp_temp = b->disposition == disp_del;
 342   ui_out_text (uiout, bp_temp ? _("Temporary catchpoint ")
 343                               : _("Catchpoint "));
 344   ui_out_field_int (uiout, "bkptno", b->number);
 345   ui_out_text (uiout, (kind == EX_EVENT_THROW ? _(" (throw)")
 346                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 347                           : _(" (rethrow)"))));
 348 }
 349
 350 /* Implement the "print_recreate" breakpoint_ops method for throw and
 351    catch catchpoints.  */
 352
 353 static void
 354 print_recreate_exception_catchpoint (struct breakpoint *b,
 355                                      struct ui_file *fp)
 356 {
 357   int bp_temp;
 358   enum exception_event_kind kind = classify_exception_breakpoint (b);
 359
 360   bp_temp = b->disposition == disp_del;
 361   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 362   switch (kind)
 363     {
 364     case EX_EVENT_THROW:
 365       fprintf_unfiltered (fp, "throw");
 366       break;
 367     case EX_EVENT_CATCH:
 368       fprintf_unfiltered (fp, "catch");
 369       break;
 370     case EX_EVENT_RETHROW:
 371       fprintf_unfiltered (fp, "rethrow");
 372       break;
 373     }
 374   print_recreate_thread (b, fp);
 375 }
 376
 377 static void
 378 handle_gnu_v3_exceptions (int tempflag, char *except_rx, char *cond_string,
 379                           enum exception_event_kind ex_event, int from_tty)
 380 {
 381   struct exception_catchpoint *cp;
 382   struct cleanup *cleanup = make_cleanup (null_cleanup, NULL);
 383   regex_t *pattern = NULL;
 384
 385   if (except_rx != NULL)
 386     {
 387       pattern = XNEW (regex_t);
 388       make_cleanup (xfree, pattern);
 389
 390       compile_rx_or_error (pattern, except_rx,
 391                            _("invalid type-matching regexp"));
 392     }
 393
 394   cp = XCNEW (struct exception_catchpoint);
 395   make_cleanup (xfree, cp);
 396
 397   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 398                    &gnu_v3_exception_catchpoint_ops);
 399   /* We need to reset 'type' in order for code in breakpoint.c to do
 400      the right thing.  */
 401   cp->base.type = bp_breakpoint;
 402   cp->kind = ex_event;
 403   cp->exception_rx = except_rx;
 404   cp->pattern = pattern;
 405
 406   re_set_exception_catchpoint (&cp->base);
 407
 408   install_breakpoint (0, &cp->base, 1);
 409   discard_cleanups (cleanup);
 410 }
 411
 412 /* Look for an "if" token in *STRING.  The "if" token must be preceded
 413    by whitespace.
 414
 415    If there is any non-whitespace text between *STRING and the "if"
 416    token, then it is returned in a newly-xmalloc'd string.  Otherwise,
 417    this returns NULL.
 418
 419    STRING is updated to point to the "if" token, if it exists, or to
 420    the end of the string.  */
 421
 422 static char *
 423 extract_exception_regexp (char **string)
 424 {
 425   char *start;
 426   char *last, *last_space;
 427
 428   start = skip_spaces (*string);
 429
 430   last = start;
 431   last_space = start;
 432   while (*last != '\0')
 433     {
 434       char *if_token = last;
 435
 436       /* Check for the "if".  */
 437       if (check_for_argument (&if_token, "if", 2))
 438         break;
 439
 440       /* No "if" token here.  Skip to the next word start.  */
 441       last_space = skip_to_space (last);
 442       last = skip_spaces (last_space);
 443     }
 444
 445   *string = last;
 446   if (last_space > start)
 447     return savestring (start, last_space - start);
 448   return NULL;
 449 }
 450
 451 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 452    commands.  */
 453
 454 static void
 455 catch_exception_command_1 (enum exception_event_kind ex_event, char *arg,
 456                            int tempflag, int from_tty)
 457 {
 458   char *except_rx;
 459   char *cond_string = NULL;
 460   struct cleanup *cleanup;
 461
 462   if (!arg)
 463     arg = "";
 464   arg = skip_spaces (arg);
 465
 466   except_rx = extract_exception_regexp (&arg);
 467   cleanup = make_cleanup (xfree, except_rx);
 468
 469   cond_string = ep_parse_optional_if_clause (&arg);
 470
 471   if ((*arg != '\0') && !isspace (*arg))
 472     error (_("Junk at end of arguments."));
 473
 474   if (ex_event != EX_EVENT_THROW
 475       && ex_event != EX_EVENT_CATCH
 476       && ex_event != EX_EVENT_RETHROW)
 477     error (_("Unsupported or unknown exception event; cannot catch it"));
 478
 479   handle_gnu_v3_exceptions (tempflag, except_rx, cond_string,
 480                             ex_event, from_tty);
 481
 482   discard_cleanups (cleanup);
 483 }
 484
 485 /* Implementation of "catch catch" command.  */
 486
 487 static void
 488 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 489 {
 490   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 491
 492   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 493 }
 494
 495 /* Implementation of "catch throw" command.  */
 496
 497 static void
 498 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 499 {
 500   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 501
 502   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 503 }
 504
 505 /* Implementation of "catch rethrow" command.  */
 506
 507 static void
 508 catch_rethrow_command (char *arg, int from_tty,
 509                        struct cmd_list_element *command)
 510 {
 511   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 512
 513   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 514 }
 515
 516 \f
 517
 518 /* Implement the 'make_value' method for the $_exception
 519    internalvar.  */
 520
 521 static struct value *
 522 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 523 {
 524   struct value *arg0, *arg1;
 525   struct type *obj_type;
 526
 527   fetch_probe_arguments (&arg0, &arg1);
 528
 529   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 530      the std::type_info for the exception.  Now we find the type from
 531      the type_info and cast the result.  */
 532   obj_type = cplus_type_from_type_info (arg1);
 533   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 534 }
 535
 536 /* Implementation of the '$_exception' variable.  */
 537
 538 static const struct internalvar_funcs exception_funcs =
 539 {
 540   compute_exception,
 541   NULL,
 542   NULL
 543 };
 544
 545 \f
 546
 547 static void
 548 initialize_throw_catchpoint_ops (void)
 549 {
 550   struct breakpoint_ops *ops;
 551
 552   initialize_breakpoint_ops ();
 553
 554   /* GNU v3 exception catchpoints.  */
 555   ops = &gnu_v3_exception_catchpoint_ops;
 556   *ops = bkpt_breakpoint_ops;
 557   ops->dtor = dtor_exception_catchpoint;
 558   ops->re_set = re_set_exception_catchpoint;
 559   ops->print_it = print_it_exception_catchpoint;
 560   ops->print_one = print_one_exception_catchpoint;
 561   ops->print_mention = print_mention_exception_catchpoint;
 562   ops->print_recreate = print_recreate_exception_catchpoint;
 563   ops->print_one_detail = print_one_detail_exception_catchpoint;
 564   ops->check_status = check_status_exception_catchpoint;
 565 }
 566
 567 initialize_file_ftype _initialize_break_catch_throw;
 568
 569 void
 570 _initialize_break_catch_throw (void)
 571 {
 572   initialize_throw_catchpoint_ops ();
 573
 574   /* Add catch and tcatch sub-commands.  */
 575   add_catch_command ("catch", _("\
 576 Catch an exception, when caught."),
 577                      catch_catch_command,
 578                      NULL,
 579                      CATCH_PERMANENT,
 580                      CATCH_TEMPORARY);
 581   add_catch_command ("throw", _("\
 582 Catch an exception, when thrown."),
 583                      catch_throw_command,
 584                      NULL,
 585                      CATCH_PERMANENT,
 586                      CATCH_TEMPORARY);
 587   add_catch_command ("rethrow", _("\
 588 Catch an exception, when rethrown."),
 589                      catch_rethrow_command,
 590                      NULL,
 591                      CATCH_PERMANENT,
 592                      CATCH_TEMPORARY);
 593
 594   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 595 }