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
  38 /* Enums for exception-handling support.  */
  39 enum exception_event_kind
  40 {
  41   EX_EVENT_THROW,
  42   EX_EVENT_RETHROW,
  43   EX_EVENT_CATCH
  44 };
  45
  46 /* Each spot where we may place an exception-related catchpoint has
  47    two names: the SDT probe point and the function name.  This
  48    structure holds both.  */
  49
  50 struct exception_names
  51 {
  52   /* The name of the probe point to try, in the form accepted by
  53      'parse_probes'.  */
  54
  55   const char *probe;
  56
  57   /* The name of the corresponding function.  */
  58
  59   const char *function;
  60 };
  61
  62 /* Names of the probe points and functions on which to break.  This is
  63    indexed by exception_event_kind.  */
  64 static const struct exception_names exception_functions[] =
  65 {
  66   { "-probe-stap libstdcxx:throw", "__cxa_throw" },
  67   { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
  68   { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
  69 };
  70
  71 static struct breakpoint_ops gnu_v3_exception_catchpoint_ops;
  72
  73 /* The type of an exception catchpoint.  */
  74
  75 struct exception_catchpoint
  76 {
  77   /* The base class.  */
  78
  79   struct breakpoint base;
  80
  81   /* The kind of exception catchpoint.  */
  82
  83   enum exception_event_kind kind;
  84 };
  85
  86 /* A helper function that returns a value indicating the kind of the
  87    exception catchpoint B.  */
  88
  89 static enum exception_event_kind
  90 classify_exception_breakpoint (struct breakpoint *b)
  91 {
  92   struct exception_catchpoint *cp = (struct exception_catchpoint *) b;
  93
  94   return cp->kind;
  95 }
  96
  97 /* Implement the 're_set' method.  */
  98
  99 static void
 100 re_set_exception_catchpoint (struct breakpoint *self)
 101 {
 102   struct symtabs_and_lines sals = {0};
 103   struct symtabs_and_lines sals_end = {0};
 104   volatile struct gdb_exception e;
 105   struct cleanup *cleanup;
 106   enum exception_event_kind kind = classify_exception_breakpoint (self);
 107   int pass;
 108
 109   for (pass = 0; sals.sals == NULL && pass < 2; ++pass)
 110     {
 111       TRY_CATCH (e, RETURN_MASK_ERROR)
 112         {
 113           char *spec;
 114
 115           if (pass == 0)
 116             {
 117               spec = ASTRDUP (exception_functions[kind].probe);
 118               sals = parse_probes (&spec, NULL);
 119             }
 120           else
 121             {
 122               spec = ASTRDUP (exception_functions[kind].function);
 123               self->ops->decode_linespec (self, &spec, &sals);
 124             }
 125         }
 126       /* NOT_FOUND_ERROR just means the breakpoint will be pending, so
 127          let it through.  */
 128       if (e.reason < 0 && e.error != NOT_FOUND_ERROR)
 129         throw_exception (e);
 130     }
 131
 132   cleanup = make_cleanup (xfree, sals.sals);
 133   update_breakpoint_locations (self, sals, sals_end);
 134   do_cleanups (cleanup);
 135 }
 136
 137 static enum print_stop_action
 138 print_it_exception_catchpoint (bpstat bs)
 139 {
 140   struct ui_out *uiout = current_uiout;
 141   struct breakpoint *b = bs->breakpoint_at;
 142   int bp_temp;
 143   enum exception_event_kind kind = classify_exception_breakpoint (b);
 144
 145   annotate_catchpoint (b->number);
 146
 147   bp_temp = b->disposition == disp_del;
 148   ui_out_text (uiout,
 149                bp_temp ? "Temporary catchpoint "
 150                        : "Catchpoint ");
 151   if (!ui_out_is_mi_like_p (uiout))
 152     ui_out_field_int (uiout, "bkptno", b->number);
 153   ui_out_text (uiout,
 154                (kind == EX_EVENT_THROW ? " (exception thrown), "
 155                 : (kind == EX_EVENT_CATCH ? " (exception caught), "
 156                    : " (exception rethrown), ")));
 157   if (ui_out_is_mi_like_p (uiout))
 158     {
 159       ui_out_field_string (uiout, "reason",
 160                            async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
 161       ui_out_field_string (uiout, "disp", bpdisp_text (b->disposition));
 162       ui_out_field_int (uiout, "bkptno", b->number);
 163     }
 164   return PRINT_SRC_AND_LOC;
 165 }
 166
 167 static void
 168 print_one_exception_catchpoint (struct breakpoint *b,
 169                                 struct bp_location **last_loc)
 170 {
 171   struct value_print_options opts;
 172   struct ui_out *uiout = current_uiout;
 173   enum exception_event_kind kind = classify_exception_breakpoint (b);
 174
 175   get_user_print_options (&opts);
 176   if (opts.addressprint)
 177     {
 178       annotate_field (4);
 179       if (b->loc == NULL || b->loc->shlib_disabled)
 180         ui_out_field_string (uiout, "addr", "<PENDING>");
 181       else
 182         ui_out_field_core_addr (uiout, "addr",
 183                                 b->loc->gdbarch, b->loc->address);
 184     }
 185   annotate_field (5);
 186   if (b->loc)
 187     *last_loc = b->loc;
 188
 189   switch (kind)
 190     {
 191     case EX_EVENT_THROW:
 192       ui_out_field_string (uiout, "what", "exception throw");
 193       if (ui_out_is_mi_like_p (uiout))
 194         ui_out_field_string (uiout, "catch-type", "throw");
 195       break;
 196
 197     case EX_EVENT_RETHROW:
 198       ui_out_field_string (uiout, "what", "exception rethrow");
 199       if (ui_out_is_mi_like_p (uiout))
 200         ui_out_field_string (uiout, "catch-type", "rethrow");
 201       break;
 202
 203     case EX_EVENT_CATCH:
 204       ui_out_field_string (uiout, "what", "exception catch");
 205       if (ui_out_is_mi_like_p (uiout))
 206         ui_out_field_string (uiout, "catch-type", "catch");
 207       break;
 208     }
 209 }
 210
 211 static void
 212 print_mention_exception_catchpoint (struct breakpoint *b)
 213 {
 214   struct ui_out *uiout = current_uiout;
 215   int bp_temp;
 216   enum exception_event_kind kind = classify_exception_breakpoint (b);
 217
 218   bp_temp = b->disposition == disp_del;
 219   ui_out_text (uiout, bp_temp ? _("Temporary catchpoint ")
 220                               : _("Catchpoint "));
 221   ui_out_field_int (uiout, "bkptno", b->number);
 222   ui_out_text (uiout, (kind == EX_EVENT_THROW ? _(" (throw)")
 223                        : (kind == EX_EVENT_CATCH ? _(" (catch)")
 224                           : _(" (rethrow)"))));
 225 }
 226
 227 /* Implement the "print_recreate" breakpoint_ops method for throw and
 228    catch catchpoints.  */
 229
 230 static void
 231 print_recreate_exception_catchpoint (struct breakpoint *b,
 232                                      struct ui_file *fp)
 233 {
 234   int bp_temp;
 235   enum exception_event_kind kind = classify_exception_breakpoint (b);
 236
 237   bp_temp = b->disposition == disp_del;
 238   fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
 239   switch (kind)
 240     {
 241     case EX_EVENT_THROW:
 242       fprintf_unfiltered (fp, "throw");
 243       break;
 244     case EX_EVENT_CATCH:
 245       fprintf_unfiltered (fp, "catch");
 246       break;
 247     case EX_EVENT_RETHROW:
 248       fprintf_unfiltered (fp, "rethrow");
 249       break;
 250     }
 251   print_recreate_thread (b, fp);
 252 }
 253
 254 static void
 255 handle_gnu_v3_exceptions (int tempflag, char *cond_string,
 256                           enum exception_event_kind ex_event, int from_tty)
 257 {
 258   struct exception_catchpoint *cp;
 259
 260   cp = XCNEW (struct exception_catchpoint);
 261   init_catchpoint (&cp->base, get_current_arch (), tempflag, cond_string,
 262                    &gnu_v3_exception_catchpoint_ops);
 263   /* We need to reset 'type' in order for code in breakpoint.c to do
 264      the right thing.  */
 265   cp->base.type = bp_breakpoint;
 266   cp->kind = ex_event;
 267
 268   re_set_exception_catchpoint (&cp->base);
 269
 270   install_breakpoint (0, &cp->base, 1);
 271 }
 272
 273 /* Deal with "catch catch", "catch throw", and "catch rethrow"
 274    commands.  */
 275
 276 static void
 277 catch_exception_command_1 (enum exception_event_kind ex_event, char *arg,
 278                            int tempflag, int from_tty)
 279 {
 280   char *cond_string = NULL;
 281
 282   if (!arg)
 283     arg = "";
 284   arg = skip_spaces (arg);
 285
 286   cond_string = ep_parse_optional_if_clause (&arg);
 287
 288   if ((*arg != '\0') && !isspace (*arg))
 289     error (_("Junk at end of arguments."));
 290
 291   if (ex_event != EX_EVENT_THROW
 292       && ex_event != EX_EVENT_CATCH
 293       && ex_event != EX_EVENT_RETHROW)
 294     error (_("Unsupported or unknown exception event; cannot catch it"));
 295
 296   handle_gnu_v3_exceptions (tempflag, cond_string, ex_event, from_tty);
 297 }
 298
 299 /* Implementation of "catch catch" command.  */
 300
 301 static void
 302 catch_catch_command (char *arg, int from_tty, struct cmd_list_element *command)
 303 {
 304   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 305
 306   catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
 307 }
 308
 309 /* Implementation of "catch throw" command.  */
 310
 311 static void
 312 catch_throw_command (char *arg, int from_tty, struct cmd_list_element *command)
 313 {
 314   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 315
 316   catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
 317 }
 318
 319 /* Implementation of "catch rethrow" command.  */
 320
 321 static void
 322 catch_rethrow_command (char *arg, int from_tty,
 323                        struct cmd_list_element *command)
 324 {
 325   int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
 326
 327   catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
 328 }
 329
 330 \f
 331
 332 /* Implement the 'make_value' method for the $_exception
 333    internalvar.  */
 334
 335 static struct value *
 336 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
 337 {
 338   struct frame_info *frame = get_selected_frame (_("No frame selected"));
 339   CORE_ADDR pc = get_frame_pc (frame);
 340   struct probe *pc_probe;
 341   const struct sym_probe_fns *pc_probe_fns;
 342   unsigned n_args;
 343   struct value *arg0, *arg1;
 344   struct type *obj_type;
 345
 346   pc_probe = find_probe_by_pc (pc);
 347   if (pc_probe == NULL
 348       || strcmp (pc_probe->provider, "libstdcxx") != 0
 349       || (strcmp (pc_probe->name, "catch") != 0
 350           && strcmp (pc_probe->name, "throw") != 0
 351           && strcmp (pc_probe->name, "rethrow") != 0))
 352     error (_("not stopped at a C++ exception catchpoint"));
 353
 354   gdb_assert (pc_probe->objfile != NULL);
 355   gdb_assert (pc_probe->objfile->sf != NULL);
 356   gdb_assert (pc_probe->objfile->sf->sym_probe_fns != NULL);
 357
 358   pc_probe_fns = pc_probe->objfile->sf->sym_probe_fns;
 359   n_args = pc_probe_fns->sym_get_probe_argument_count (pc_probe);
 360   if (n_args < 2)
 361     error (_("C++ exception catchpoint has too few arguments"));
 362
 363   arg0 = pc_probe_fns->sym_evaluate_probe_argument (pc_probe, 0);
 364   arg1 = pc_probe_fns->sym_evaluate_probe_argument (pc_probe, 1);
 365
 366   if (arg0 == NULL || arg1 == NULL)
 367     error (_("error computing probe argument at c++ exception catchpoint"));
 368
 369   /* ARG0 is a pointer to the exception object.  ARG1 is a pointer to
 370      the std::type_info for the exception.  Now we find the type from
 371      the type_info and cast the result.  */
 372   obj_type = cplus_type_from_type_info (arg1);
 373   return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
 374 }
 375
 376 /* Implementation of the '$_exception' variable.  */
 377
 378 static const struct internalvar_funcs exception_funcs =
 379 {
 380   compute_exception,
 381   NULL,
 382   NULL
 383 };
 384
 385 \f
 386
 387 static void
 388 initialize_throw_catchpoint_ops (void)
 389 {
 390   struct breakpoint_ops *ops;
 391
 392   initialize_breakpoint_ops ();
 393
 394   /* GNU v3 exception catchpoints.  */
 395   ops = &gnu_v3_exception_catchpoint_ops;
 396   *ops = bkpt_breakpoint_ops;
 397   ops->re_set = re_set_exception_catchpoint;
 398   ops->print_it = print_it_exception_catchpoint;
 399   ops->print_one = print_one_exception_catchpoint;
 400   ops->print_mention = print_mention_exception_catchpoint;
 401   ops->print_recreate = print_recreate_exception_catchpoint;
 402 }
 403
 404 initialize_file_ftype _initialize_break_catch_throw;
 405
 406 void
 407 _initialize_break_catch_throw (void)
 408 {
 409   initialize_throw_catchpoint_ops ();
 410
 411   /* Add catch and tcatch sub-commands.  */
 412   add_catch_command ("catch", _("\
 413 Catch an exception, when caught."),
 414                      catch_catch_command,
 415                      NULL,
 416                      CATCH_PERMANENT,
 417                      CATCH_TEMPORARY);
 418   add_catch_command ("throw", _("\
 419 Catch an exception, when thrown."),
 420                      catch_throw_command,
 421                      NULL,
 422                      CATCH_PERMANENT,
 423                      CATCH_TEMPORARY);
 424   add_catch_command ("rethrow", _("\
 425 Catch an exception, when rethrown."),
 426                      catch_rethrow_command,
 427                      NULL,
 428                      CATCH_PERMANENT,
 429                      CATCH_TEMPORARY);
 430
 431   create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
 432 }