1 /* Everything about catch/throw catchpoints, for GDB.
3 Copyright (C) 1986-2019 Free Software Foundation, Inc.
5 This file is part of GDB.
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.
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.
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/>. */
21 #include "arch-utils.h"
23 #include "breakpoint.h"
28 #include "cli/cli-utils.h"
29 #include "completer.h"
30 #include "gdb_obstack.h"
31 #include "mi/mi-common.h"
36 #include "gdb_regex.h"
37 #include "cp-support.h"
40 /* Enums for exception-handling support. */
41 enum exception_event_kind
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. */
52 struct exception_names
54 /* The name of the probe point to try, in the form accepted by
59 /* The name of the corresponding function. */
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[] =
68 { "-probe-stap libstdcxx:throw", "__cxa_throw" },
69 { "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
70 { "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
73 static struct breakpoint_ops gnu_v3_exception_catchpoint_ops;
75 /* The type of an exception catchpoint. */
77 struct exception_catchpoint : public breakpoint
79 /* The kind of exception catchpoint. */
81 enum exception_event_kind kind;
83 /* If not empty, a string holding the source form of the regular
84 expression to match against. */
86 std::string exception_rx;
88 /* If non-NULL, a compiled regular expression which is used to
89 determine which exceptions to stop on. */
91 std::unique_ptr<compiled_regex> pattern;
96 /* A helper function that fetches exception probe arguments. This
97 fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
98 It will throw an exception on any kind of failure. */
101 fetch_probe_arguments (struct value **arg0, struct value **arg1)
103 struct frame_info *frame = get_selected_frame (_("No frame selected"));
104 CORE_ADDR pc = get_frame_pc (frame);
105 struct bound_probe pc_probe;
108 pc_probe = find_probe_by_pc (pc);
109 if (pc_probe.prob == NULL
110 || pc_probe.prob->get_provider () != "libstdcxx"
111 || (pc_probe.prob->get_name () != "catch"
112 && pc_probe.prob->get_name () != "throw"
113 && pc_probe.prob->get_name () != "rethrow"))
114 error (_("not stopped at a C++ exception catchpoint"));
116 n_args = pc_probe.prob->get_argument_count (frame);
118 error (_("C++ exception catchpoint has too few arguments"));
121 *arg0 = pc_probe.prob->evaluate_argument (0, frame);
122 *arg1 = pc_probe.prob->evaluate_argument (1, frame);
124 if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
125 error (_("error computing probe argument at c++ exception catchpoint"));
130 /* A helper function that returns a value indicating the kind of the
131 exception catchpoint B. */
133 static enum exception_event_kind
134 classify_exception_breakpoint (struct breakpoint *b)
136 struct exception_catchpoint *cp = (struct exception_catchpoint *) b;
141 /* Implement the 'check_status' method. */
144 check_status_exception_catchpoint (struct bpstats *bs)
146 struct exception_catchpoint *self
147 = (struct exception_catchpoint *) bs->breakpoint_at;
148 std::string type_name;
150 bkpt_breakpoint_ops.check_status (bs);
154 if (self->pattern == NULL)
159 struct value *typeinfo_arg;
162 fetch_probe_arguments (NULL, &typeinfo_arg);
163 type_name = cplus_typename_from_type_info (typeinfo_arg);
165 canon = cp_canonicalize_string (type_name.c_str ());
167 std::swap (type_name, canon);
169 catch (const gdb_exception_RETURN_MASK_ERROR &e)
171 exception_print (gdb_stderr, e);
174 if (!type_name.empty ())
176 if (self->pattern->exec (type_name.c_str (), 0, NULL, 0) != 0)
181 /* Implement the 're_set' method. */
184 re_set_exception_catchpoint (struct breakpoint *self)
186 std::vector<symtab_and_line> sals;
187 enum exception_event_kind kind = classify_exception_breakpoint (self);
188 struct program_space *filter_pspace = current_program_space;
190 /* We first try to use the probe interface. */
193 event_location_up location
194 = new_probe_location (exception_functions[kind].probe);
195 sals = parse_probes (location.get (), filter_pspace, NULL);
197 catch (const gdb_exception_RETURN_MASK_ERROR &e)
199 /* Using the probe interface failed. Let's fallback to the normal
203 struct explicit_location explicit_loc;
205 initialize_explicit_location (&explicit_loc);
206 explicit_loc.function_name
207 = ASTRDUP (exception_functions[kind].function);
208 event_location_up location = new_explicit_location (&explicit_loc);
209 sals = self->ops->decode_location (self, location.get (),
212 catch (const gdb_exception_RETURN_MASK_ERROR &ex)
214 /* NOT_FOUND_ERROR just means the breakpoint will be
215 pending, so let it through. */
216 if (ex.error != NOT_FOUND_ERROR)
217 throw_exception (ex);
221 update_breakpoint_locations (self, filter_pspace, sals, {});
224 static enum print_stop_action
225 print_it_exception_catchpoint (bpstat bs)
227 struct ui_out *uiout = current_uiout;
228 struct breakpoint *b = bs->breakpoint_at;
230 enum exception_event_kind kind = classify_exception_breakpoint (b);
232 annotate_catchpoint (b->number);
233 maybe_print_thread_hit_breakpoint (uiout);
235 bp_temp = b->disposition == disp_del;
236 uiout->text (bp_temp ? "Temporary catchpoint "
238 uiout->field_int ("bkptno", b->number);
239 uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
240 : (kind == EX_EVENT_CATCH ? " (exception caught), "
241 : " (exception rethrown), ")));
242 if (uiout->is_mi_like_p ())
244 uiout->field_string ("reason",
245 async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
246 uiout->field_string ("disp", bpdisp_text (b->disposition));
248 return PRINT_SRC_AND_LOC;
252 print_one_exception_catchpoint (struct breakpoint *b,
253 struct bp_location **last_loc)
255 struct value_print_options opts;
256 struct ui_out *uiout = current_uiout;
257 enum exception_event_kind kind = classify_exception_breakpoint (b);
259 get_user_print_options (&opts);
260 if (opts.addressprint)
263 if (b->loc == NULL || b->loc->shlib_disabled)
264 uiout->field_string ("addr", "<PENDING>");
266 uiout->field_core_addr ("addr",
267 b->loc->gdbarch, b->loc->address);
276 uiout->field_string ("what", "exception throw");
277 if (uiout->is_mi_like_p ())
278 uiout->field_string ("catch-type", "throw");
281 case EX_EVENT_RETHROW:
282 uiout->field_string ("what", "exception rethrow");
283 if (uiout->is_mi_like_p ())
284 uiout->field_string ("catch-type", "rethrow");
288 uiout->field_string ("what", "exception catch");
289 if (uiout->is_mi_like_p ())
290 uiout->field_string ("catch-type", "catch");
295 /* Implement the 'print_one_detail' method. */
298 print_one_detail_exception_catchpoint (const struct breakpoint *b,
299 struct ui_out *uiout)
301 const struct exception_catchpoint *cp
302 = (const struct exception_catchpoint *) b;
304 if (!cp->exception_rx.empty ())
306 uiout->text (_("\tmatching: "));
307 uiout->field_string ("regexp", cp->exception_rx.c_str ());
313 print_mention_exception_catchpoint (struct breakpoint *b)
315 struct ui_out *uiout = current_uiout;
317 enum exception_event_kind kind = classify_exception_breakpoint (b);
319 bp_temp = b->disposition == disp_del;
320 uiout->text (bp_temp ? _("Temporary catchpoint ")
322 uiout->field_int ("bkptno", b->number);
323 uiout->text ((kind == EX_EVENT_THROW ? _(" (throw)")
324 : (kind == EX_EVENT_CATCH ? _(" (catch)")
325 : _(" (rethrow)"))));
328 /* Implement the "print_recreate" breakpoint_ops method for throw and
329 catch catchpoints. */
332 print_recreate_exception_catchpoint (struct breakpoint *b,
336 enum exception_event_kind kind = classify_exception_breakpoint (b);
338 bp_temp = b->disposition == disp_del;
339 fprintf_unfiltered (fp, bp_temp ? "tcatch " : "catch ");
343 fprintf_unfiltered (fp, "throw");
346 fprintf_unfiltered (fp, "catch");
348 case EX_EVENT_RETHROW:
349 fprintf_unfiltered (fp, "rethrow");
352 print_recreate_thread (b, fp);
356 handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
357 const char *cond_string,
358 enum exception_event_kind ex_event, int from_tty)
360 std::unique_ptr<compiled_regex> pattern;
362 if (!except_rx.empty ())
364 pattern.reset (new compiled_regex (except_rx.c_str (), REG_NOSUB,
365 _("invalid type-matching regexp")));
368 std::unique_ptr<exception_catchpoint> cp (new exception_catchpoint ());
370 init_catchpoint (cp.get (), get_current_arch (), tempflag, cond_string,
371 &gnu_v3_exception_catchpoint_ops);
372 /* We need to reset 'type' in order for code in breakpoint.c to do
374 cp->type = bp_breakpoint;
376 cp->exception_rx = std::move (except_rx);
377 cp->pattern = std::move (pattern);
379 re_set_exception_catchpoint (cp.get ());
381 install_breakpoint (0, std::move (cp), 1);
384 /* Look for an "if" token in *STRING. The "if" token must be preceded
387 If there is any non-whitespace text between *STRING and the "if"
388 token, then it is returned in a newly-xmalloc'd string. Otherwise,
391 STRING is updated to point to the "if" token, if it exists, or to
392 the end of the string. */
395 extract_exception_regexp (const char **string)
398 const char *last, *last_space;
400 start = skip_spaces (*string);
404 while (*last != '\0')
406 const char *if_token = last;
408 /* Check for the "if". */
409 if (check_for_argument (&if_token, "if", 2))
412 /* No "if" token here. Skip to the next word start. */
413 last_space = skip_to_space (last);
414 last = skip_spaces (last_space);
418 if (last_space > start)
419 return std::string (start, last_space - start);
420 return std::string ();
423 /* Deal with "catch catch", "catch throw", and "catch rethrow"
427 catch_exception_command_1 (enum exception_event_kind ex_event,
429 int tempflag, int from_tty)
431 const char *cond_string = NULL;
435 arg = skip_spaces (arg);
437 std::string except_rx = extract_exception_regexp (&arg);
439 cond_string = ep_parse_optional_if_clause (&arg);
441 if ((*arg != '\0') && !isspace (*arg))
442 error (_("Junk at end of arguments."));
444 if (ex_event != EX_EVENT_THROW
445 && ex_event != EX_EVENT_CATCH
446 && ex_event != EX_EVENT_RETHROW)
447 error (_("Unsupported or unknown exception event; cannot catch it"));
449 handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
453 /* Implementation of "catch catch" command. */
456 catch_catch_command (const char *arg, int from_tty,
457 struct cmd_list_element *command)
459 int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
461 catch_exception_command_1 (EX_EVENT_CATCH, arg, tempflag, from_tty);
464 /* Implementation of "catch throw" command. */
467 catch_throw_command (const char *arg, int from_tty,
468 struct cmd_list_element *command)
470 int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
472 catch_exception_command_1 (EX_EVENT_THROW, arg, tempflag, from_tty);
475 /* Implementation of "catch rethrow" command. */
478 catch_rethrow_command (const char *arg, int from_tty,
479 struct cmd_list_element *command)
481 int tempflag = get_cmd_context (command) == CATCH_TEMPORARY;
483 catch_exception_command_1 (EX_EVENT_RETHROW, arg, tempflag, from_tty);
488 /* Implement the 'make_value' method for the $_exception
491 static struct value *
492 compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
494 struct value *arg0, *arg1;
495 struct type *obj_type;
497 fetch_probe_arguments (&arg0, &arg1);
499 /* ARG0 is a pointer to the exception object. ARG1 is a pointer to
500 the std::type_info for the exception. Now we find the type from
501 the type_info and cast the result. */
502 obj_type = cplus_type_from_type_info (arg1);
503 return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
506 /* Implementation of the '$_exception' variable. */
508 static const struct internalvar_funcs exception_funcs =
518 initialize_throw_catchpoint_ops (void)
520 struct breakpoint_ops *ops;
522 initialize_breakpoint_ops ();
524 /* GNU v3 exception catchpoints. */
525 ops = &gnu_v3_exception_catchpoint_ops;
526 *ops = bkpt_breakpoint_ops;
527 ops->re_set = re_set_exception_catchpoint;
528 ops->print_it = print_it_exception_catchpoint;
529 ops->print_one = print_one_exception_catchpoint;
530 ops->print_mention = print_mention_exception_catchpoint;
531 ops->print_recreate = print_recreate_exception_catchpoint;
532 ops->print_one_detail = print_one_detail_exception_catchpoint;
533 ops->check_status = check_status_exception_catchpoint;
537 _initialize_break_catch_throw (void)
539 initialize_throw_catchpoint_ops ();
541 /* Add catch and tcatch sub-commands. */
542 add_catch_command ("catch", _("\
543 Catch an exception, when caught."),
548 add_catch_command ("throw", _("\
549 Catch an exception, when thrown."),
554 add_catch_command ("rethrow", _("\
555 Catch an exception, when rethrown."),
556 catch_rethrow_command,
561 create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);