/* Everything about catch/throw catchpoints, for GDB.
Copyright (C) 1986-2023 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see . */
#include "defs.h"
#include "arch-utils.h"
#include
#include "breakpoint.h"
#include "gdbcmd.h"
#include "inferior.h"
#include "annotate.h"
#include "valprint.h"
#include "cli/cli-utils.h"
#include "completer.h"
#include "gdbsupport/gdb_obstack.h"
#include "mi/mi-common.h"
#include "linespec.h"
#include "probe.h"
#include "objfiles.h"
#include "cp-abi.h"
#include "gdbsupport/gdb_regex.h"
#include "cp-support.h"
#include "location.h"
#include "cli/cli-decode.h"
/* Each spot where we may place an exception-related catchpoint has
two names: the SDT probe point and the function name. This
structure holds both. */
struct exception_names
{
/* The name of the probe point to try, in the form accepted by
'parse_probes'. */
const char *probe;
/* The name of the corresponding function. */
const char *function;
};
/* Names of the probe points and functions on which to break. This is
indexed by exception_event_kind. */
static const struct exception_names exception_functions[] =
{
{ "-probe-stap libstdcxx:throw", "__cxa_throw" },
{ "-probe-stap libstdcxx:rethrow", "__cxa_rethrow" },
{ "-probe-stap libstdcxx:catch", "__cxa_begin_catch" }
};
/* The type of an exception catchpoint. Unlike most catchpoints, this
one is implemented with code breakpoints, so it inherits struct
code_breakpoint, not struct catchpoint. */
struct exception_catchpoint : public code_breakpoint
{
exception_catchpoint (struct gdbarch *gdbarch,
bool temp, const char *cond_string_,
enum exception_event_kind kind_,
std::string &&except_rx)
: code_breakpoint (gdbarch, bp_catchpoint, temp, cond_string_),
kind (kind_),
exception_rx (std::move (except_rx)),
pattern (exception_rx.empty ()
? nullptr
: new compiled_regex (exception_rx.c_str (), REG_NOSUB,
_("invalid type-matching regexp")))
{
pspace = current_program_space;
re_set ();
}
void re_set () override;
enum print_stop_action print_it (const bpstat *bs) const override;
bool print_one (bp_location **) const override;
void print_mention () const override;
void print_recreate (struct ui_file *fp) const override;
void print_one_detail (struct ui_out *) const override;
void check_status (struct bpstat *bs) override;
struct bp_location *allocate_location () override;
/* FIXME this is temporary - until ordinary breakpoints have been
converted. */
int resources_needed (const struct bp_location *) override
{
return 1;
}
/* The kind of exception catchpoint. */
enum exception_event_kind kind;
/* If not empty, a string holding the source form of the regular
expression to match against. */
std::string exception_rx;
/* If non-NULL, a compiled regular expression which is used to
determine which exceptions to stop on. */
std::unique_ptr pattern;
};
/* See breakpoint.h. */
bool
is_exception_catchpoint (breakpoint *bp)
{
return dynamic_cast (bp) != nullptr;
}
/* A helper function that fetches exception probe arguments. This
fills in *ARG0 (if non-NULL) and *ARG1 (which must be non-NULL).
It will throw an exception on any kind of failure. */
static void
fetch_probe_arguments (struct value **arg0, struct value **arg1)
{
frame_info_ptr frame = get_selected_frame (_("No frame selected"));
CORE_ADDR pc = get_frame_pc (frame);
struct bound_probe pc_probe;
unsigned n_args;
pc_probe = find_probe_by_pc (pc);
if (pc_probe.prob == NULL)
error (_("did not find exception probe (does libstdcxx have SDT probes?)"));
if (pc_probe.prob->get_provider () != "libstdcxx"
|| (pc_probe.prob->get_name () != "catch"
&& pc_probe.prob->get_name () != "throw"
&& pc_probe.prob->get_name () != "rethrow"))
error (_("not stopped at a C++ exception catchpoint"));
n_args = pc_probe.prob->get_argument_count (get_frame_arch (frame));
if (n_args < 2)
error (_("C++ exception catchpoint has too few arguments"));
if (arg0 != NULL)
*arg0 = pc_probe.prob->evaluate_argument (0, frame);
*arg1 = pc_probe.prob->evaluate_argument (1, frame);
if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
error (_("error computing probe argument at c++ exception catchpoint"));
}
/* Implement the 'check_status' method. */
void
exception_catchpoint::check_status (struct bpstat *bs)
{
struct exception_catchpoint *self
= (struct exception_catchpoint *) bs->breakpoint_at;
std::string type_name;
this->breakpoint::check_status (bs);
if (bs->stop == 0)
return;
if (self->pattern == NULL)
return;
const char *name = nullptr;
gdb::unique_xmalloc_ptr canon;
try
{
struct value *typeinfo_arg;
fetch_probe_arguments (NULL, &typeinfo_arg);
type_name = cplus_typename_from_type_info (typeinfo_arg);
canon = cp_canonicalize_string (type_name.c_str ());
name = (canon != nullptr
? canon.get ()
: type_name.c_str ());
}
catch (const gdb_exception_error &e)
{
exception_print (gdb_stderr, e);
}
if (name != nullptr)
{
if (self->pattern->exec (name, 0, NULL, 0) != 0)
bs->stop = 0;
}
}
/* Implement the 're_set' method. */
void
exception_catchpoint::re_set ()
{
std::vector sals;
struct program_space *filter_pspace = current_program_space;
/* We first try to use the probe interface. */
try
{
location_spec_up locspec
= new_probe_location_spec (exception_functions[kind].probe);
sals = parse_probes (locspec.get (), filter_pspace, NULL);
}
catch (const gdb_exception_error &e)
{
/* Using the probe interface failed. Let's fallback to the normal
catchpoint mode. */
try
{
location_spec_up locspec
= (new_explicit_location_spec_function
(exception_functions[kind].function));
sals = this->decode_location_spec (locspec.get (), filter_pspace);
}
catch (const gdb_exception_error &ex)
{
/* NOT_FOUND_ERROR just means the breakpoint will be
pending, so let it through. */
if (ex.error != NOT_FOUND_ERROR)
throw;
}
}
update_breakpoint_locations (this, filter_pspace, sals, {});
}
enum print_stop_action
exception_catchpoint::print_it (const bpstat *bs) const
{
struct ui_out *uiout = current_uiout;
int bp_temp;
annotate_catchpoint (number);
maybe_print_thread_hit_breakpoint (uiout);
bp_temp = disposition == disp_del;
uiout->text (bp_temp ? "Temporary catchpoint "
: "Catchpoint ");
print_num_locno (bs, uiout);
uiout->text ((kind == EX_EVENT_THROW ? " (exception thrown), "
: (kind == EX_EVENT_CATCH ? " (exception caught), "
: " (exception rethrown), ")));
if (uiout->is_mi_like_p ())
{
uiout->field_string ("reason",
async_reason_lookup (EXEC_ASYNC_BREAKPOINT_HIT));
uiout->field_string ("disp", bpdisp_text (disposition));
}
return PRINT_SRC_AND_LOC;
}
bool
exception_catchpoint::print_one (bp_location **last_loc) const
{
struct value_print_options opts;
struct ui_out *uiout = current_uiout;
get_user_print_options (&opts);
if (opts.addressprint)
uiout->field_skip ("addr");
annotate_field (5);
switch (kind)
{
case EX_EVENT_THROW:
uiout->field_string ("what", "exception throw");
if (uiout->is_mi_like_p ())
uiout->field_string ("catch-type", "throw");
break;
case EX_EVENT_RETHROW:
uiout->field_string ("what", "exception rethrow");
if (uiout->is_mi_like_p ())
uiout->field_string ("catch-type", "rethrow");
break;
case EX_EVENT_CATCH:
uiout->field_string ("what", "exception catch");
if (uiout->is_mi_like_p ())
uiout->field_string ("catch-type", "catch");
break;
}
return true;
}
/* Implement the 'print_one_detail' method. */
void
exception_catchpoint::print_one_detail (struct ui_out *uiout) const
{
if (!exception_rx.empty ())
{
uiout->text (_("\tmatching: "));
uiout->field_string ("regexp", exception_rx);
uiout->text ("\n");
}
}
void
exception_catchpoint::print_mention () const
{
struct ui_out *uiout = current_uiout;
int bp_temp;
bp_temp = disposition == disp_del;
uiout->message ("%s %d %s",
(bp_temp ? _("Temporary catchpoint ") : _("Catchpoint")),
number,
(kind == EX_EVENT_THROW
? _("(throw)") : (kind == EX_EVENT_CATCH
? _("(catch)") : _("(rethrow)"))));
}
/* Implement the "print_recreate" method for throw and catch
catchpoints. */
void
exception_catchpoint::print_recreate (struct ui_file *fp) const
{
int bp_temp;
bp_temp = disposition == disp_del;
gdb_printf (fp, bp_temp ? "tcatch " : "catch ");
switch (kind)
{
case EX_EVENT_THROW:
gdb_printf (fp, "throw");
break;
case EX_EVENT_CATCH:
gdb_printf (fp, "catch");
break;
case EX_EVENT_RETHROW:
gdb_printf (fp, "rethrow");
break;
}
print_recreate_thread (fp);
}
/* Implement the "allocate_location" method for throw and catch
catchpoints. */
bp_location *
exception_catchpoint::allocate_location ()
{
return new bp_location (this, bp_loc_software_breakpoint);
}
static void
handle_gnu_v3_exceptions (int tempflag, std::string &&except_rx,
const char *cond_string,
enum exception_event_kind ex_event, int from_tty)
{
struct gdbarch *gdbarch = get_current_arch ();
std::unique_ptr cp
(new exception_catchpoint (gdbarch, tempflag, cond_string,
ex_event, std::move (except_rx)));
install_breakpoint (0, std::move (cp), 1);
}
/* Look for an "if" token in *STRING. The "if" token must be preceded
by whitespace.
If there is any non-whitespace text between *STRING and the "if"
token, then it is returned in a newly-xmalloc'd string. Otherwise,
this returns NULL.
STRING is updated to point to the "if" token, if it exists, or to
the end of the string. */
static std::string
extract_exception_regexp (const char **string)
{
const char *start;
const char *last, *last_space;
start = skip_spaces (*string);
last = start;
last_space = start;
while (*last != '\0')
{
const char *if_token = last;
/* Check for the "if". */
if (check_for_argument (&if_token, "if", 2))
break;
/* No "if" token here. Skip to the next word start. */
last_space = skip_to_space (last);
last = skip_spaces (last_space);
}
*string = last;
if (last_space > start)
return std::string (start, last_space - start);
return std::string ();
}
/* See breakpoint.h. */
void
catch_exception_event (enum exception_event_kind ex_event,
const char *arg, bool tempflag, int from_tty)
{
const char *cond_string = NULL;
if (!arg)
arg = "";
arg = skip_spaces (arg);
std::string except_rx = extract_exception_regexp (&arg);
cond_string = ep_parse_optional_if_clause (&arg);
if ((*arg != '\0') && !isspace (*arg))
error (_("Junk at end of arguments."));
if (ex_event != EX_EVENT_THROW
&& ex_event != EX_EVENT_CATCH
&& ex_event != EX_EVENT_RETHROW)
error (_("Unsupported or unknown exception event; cannot catch it"));
handle_gnu_v3_exceptions (tempflag, std::move (except_rx), cond_string,
ex_event, from_tty);
}
/* Implementation of "catch catch" command. */
static void
catch_catch_command (const char *arg, int from_tty,
struct cmd_list_element *command)
{
bool tempflag = command->context () == CATCH_TEMPORARY;
catch_exception_event (EX_EVENT_CATCH, arg, tempflag, from_tty);
}
/* Implementation of "catch throw" command. */
static void
catch_throw_command (const char *arg, int from_tty,
struct cmd_list_element *command)
{
bool tempflag = command->context () == CATCH_TEMPORARY;
catch_exception_event (EX_EVENT_THROW, arg, tempflag, from_tty);
}
/* Implementation of "catch rethrow" command. */
static void
catch_rethrow_command (const char *arg, int from_tty,
struct cmd_list_element *command)
{
bool tempflag = command->context () == CATCH_TEMPORARY;
catch_exception_event (EX_EVENT_RETHROW, arg, tempflag, from_tty);
}
/* Implement the 'make_value' method for the $_exception
internalvar. */
static struct value *
compute_exception (struct gdbarch *argc, struct internalvar *var, void *ignore)
{
struct value *arg0, *arg1;
struct type *obj_type;
fetch_probe_arguments (&arg0, &arg1);
/* ARG0 is a pointer to the exception object. ARG1 is a pointer to
the std::type_info for the exception. Now we find the type from
the type_info and cast the result. */
obj_type = cplus_type_from_type_info (arg1);
return value_ind (value_cast (make_pointer_type (obj_type, NULL), arg0));
}
/* Implementation of the '$_exception' variable. */
static const struct internalvar_funcs exception_funcs =
{
compute_exception,
NULL,
};
void _initialize_break_catch_throw ();
void
_initialize_break_catch_throw ()
{
/* Add catch and tcatch sub-commands. */
add_catch_command ("catch", _("\
Catch an exception, when caught."),
catch_catch_command,
NULL,
CATCH_PERMANENT,
CATCH_TEMPORARY);
add_catch_command ("throw", _("\
Catch an exception, when thrown."),
catch_throw_command,
NULL,
CATCH_PERMANENT,
CATCH_TEMPORARY);
add_catch_command ("rethrow", _("\
Catch an exception, when rethrown."),
catch_rethrow_command,
NULL,
CATCH_PERMANENT,
CATCH_TEMPORARY);
create_internalvar_type_lazy ("_exception", &exception_funcs, NULL);
}