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/* Exception (throw catch) mechanism, for GDB, the GNU debugger.
Copyright (C) 1986-2015 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 <http://www.gnu.org/licenses/>. */
#include "common-defs.h"
#include "common-exceptions.h"
const struct gdb_exception exception_none = { (enum return_reason) 0, GDB_NO_ERROR, NULL };
#ifndef __cplusplus
/* Possible catcher states. */
enum catcher_state {
/* Initial state, a new catcher has just been created. */
CATCHER_CREATED,
/* The catch code is running. */
CATCHER_RUNNING,
CATCHER_RUNNING_1,
/* The catch code threw an exception. */
CATCHER_ABORTING
};
/* Possible catcher actions. */
enum catcher_action {
CATCH_ITER,
CATCH_ITER_1,
CATCH_THROWING
};
struct catcher
{
enum catcher_state state;
/* Jump buffer pointing back at the exception handler. */
SIGJMP_BUF buf;
/* Status buffer belonging to the exception handler. */
struct gdb_exception exception;
struct cleanup *saved_cleanup_chain;
/* Back link. */
struct catcher *prev;
};
/* Where to go for throw_exception(). */
static struct catcher *current_catcher;
/* Return length of current_catcher list. */
static int
catcher_list_size (void)
{
int size;
struct catcher *catcher;
for (size = 0, catcher = current_catcher;
catcher != NULL;
catcher = catcher->prev)
++size;
return size;
}
SIGJMP_BUF *
exceptions_state_mc_init (void)
{
struct catcher *new_catcher = XCNEW (struct catcher);
/* Start with no exception. */
new_catcher->exception = exception_none;
/* Prevent error/quit during FUNC from calling cleanups established
prior to here. */
new_catcher->saved_cleanup_chain = save_cleanups ();
/* Push this new catcher on the top. */
new_catcher->prev = current_catcher;
current_catcher = new_catcher;
new_catcher->state = CATCHER_CREATED;
return &new_catcher->buf;
}
static void
catcher_pop (void)
{
struct catcher *old_catcher = current_catcher;
current_catcher = old_catcher->prev;
/* Restore the cleanup chain, the error/quit messages, and the uiout
builder, to their original states. */
restore_cleanups (old_catcher->saved_cleanup_chain);
xfree (old_catcher);
}
/* Catcher state machine. Returns non-zero if the m/c should be run
again, zero if it should abort. */
static int
exceptions_state_mc (enum catcher_action action)
{
switch (current_catcher->state)
{
case CATCHER_CREATED:
switch (action)
{
case CATCH_ITER:
/* Allow the code to run the catcher. */
current_catcher->state = CATCHER_RUNNING;
return 1;
default:
internal_error (__FILE__, __LINE__, _("bad state"));
}
case CATCHER_RUNNING:
switch (action)
{
case CATCH_ITER:
/* No error/quit has occured. */
return 0;
case CATCH_ITER_1:
current_catcher->state = CATCHER_RUNNING_1;
return 1;
case CATCH_THROWING:
current_catcher->state = CATCHER_ABORTING;
/* See also throw_exception. */
return 1;
default:
internal_error (__FILE__, __LINE__, _("bad switch"));
}
case CATCHER_RUNNING_1:
switch (action)
{
case CATCH_ITER:
/* The did a "break" from the inner while loop. */
return 0;
case CATCH_ITER_1:
current_catcher->state = CATCHER_RUNNING;
return 0;
case CATCH_THROWING:
current_catcher->state = CATCHER_ABORTING;
/* See also throw_exception. */
return 1;
default:
internal_error (__FILE__, __LINE__, _("bad switch"));
}
case CATCHER_ABORTING:
switch (action)
{
case CATCH_ITER:
{
/* Exit normally if this catcher can handle this
exception. The caller analyses the func return
values. */
return 0;
}
default:
internal_error (__FILE__, __LINE__, _("bad state"));
}
default:
internal_error (__FILE__, __LINE__, _("bad switch"));
}
}
int
exceptions_state_mc_catch (struct gdb_exception *exception,
int mask)
{
*exception = current_catcher->exception;
catcher_pop ();
if (exception->reason < 0)
{
if (mask & RETURN_MASK (exception->reason))
{
/* Exit normally and let the caller handle the
exception. */
return 1;
}
/* The caller didn't request that the event be caught, relay the
event to the next exception_catch/CATCH. */
throw_exception (*exception);
}
/* No exception was thrown. */
return 0;
}
int
exceptions_state_mc_action_iter (void)
{
return exceptions_state_mc (CATCH_ITER);
}
int
exceptions_state_mc_action_iter_1 (void)
{
return exceptions_state_mc (CATCH_ITER_1);
}
#else /* !__cplusplus */
/* How many nested TRY blocks we have. See exception_messages and
throw_it. */
static int try_scope_depth;
/* Called on entry to a TRY scope. */
void *
exception_try_scope_entry (void)
{
++try_scope_depth;
return (void *) save_cleanups ();
}
/* Called on exit of a TRY scope, either normal exit or exception
exit. */
void
exception_try_scope_exit (void *saved_state)
{
restore_cleanups ((struct cleanup *) saved_state);
--try_scope_depth;
}
/* Called by the default catch block. IOW, we'll get here before
jumping out to the next outermost scope an exception if a GDB
exception is not caught. */
void
exception_rethrow (void)
{
/* Run this scope's cleanups before re-throwing to the next
outermost scope. */
prepare_to_throw_exception ();
do_cleanups (all_cleanups ());
throw;
}
/* Copy the 'gdb_exception' portion of FROM to TO. */
static void
gdb_exception_sliced_copy (struct gdb_exception *to, const struct gdb_exception *from)
{
*to = *from;
}
#endif /* !__cplusplus */
/* Return EXCEPTION to the nearest containing catch_errors(). */
void
throw_exception (struct gdb_exception exception)
{
prepare_to_throw_exception ();
do_cleanups (all_cleanups ());
#ifndef __cplusplus
/* Jump to the containing catch_errors() call, communicating REASON
to that call via setjmp's return value. Note that REASON can't
be zero, by definition in defs.h. */
exceptions_state_mc (CATCH_THROWING);
current_catcher->exception = exception;
SIGLONGJMP (current_catcher->buf, exception.reason);
#else
if (exception.reason == RETURN_QUIT)
{
gdb_exception_RETURN_MASK_QUIT ex;
gdb_exception_sliced_copy (&ex, &exception);
throw ex;
}
else if (exception.reason == RETURN_ERROR)
{
gdb_exception_RETURN_MASK_ERROR ex;
gdb_exception_sliced_copy (&ex, &exception);
throw ex;
}
else
gdb_assert_not_reached ("invalid return reason");
#endif
}
/* A stack of exception messages.
This is needed to handle nested calls to throw_it: we don't want to
xfree space for a message before it's used.
This can happen if we throw an exception during a cleanup:
An outer TRY_CATCH may have an exception message it wants to print,
but while doing cleanups further calls to throw_it are made.
This is indexed by the size of the current_catcher list.
It is a dynamically allocated array so that we don't care how deeply
GDB nests its TRY_CATCHs. */
static char **exception_messages;
/* The number of currently allocated entries in exception_messages. */
static int exception_messages_size;
static void ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (3, 0)
throw_it (enum return_reason reason, enum errors error, const char *fmt,
va_list ap)
{
struct gdb_exception e;
char *new_message;
#ifndef __cplusplus
int depth = catcher_list_size ();
#else
int depth = try_scope_depth;
#endif
gdb_assert (depth > 0);
/* Note: The new message may use an old message's text. */
new_message = xstrvprintf (fmt, ap);
if (depth > exception_messages_size)
{
int old_size = exception_messages_size;
exception_messages_size = depth + 10;
exception_messages = XRESIZEVEC (char *, exception_messages,
exception_messages_size);
memset (exception_messages + old_size, 0,
(exception_messages_size - old_size) * sizeof (char *));
}
xfree (exception_messages[depth - 1]);
exception_messages[depth - 1] = new_message;
/* Create the exception. */
e.reason = reason;
e.error = error;
e.message = new_message;
/* Throw the exception. */
throw_exception (e);
}
void
throw_verror (enum errors error, const char *fmt, va_list ap)
{
throw_it (RETURN_ERROR, error, fmt, ap);
}
void
throw_vquit (const char *fmt, va_list ap)
{
throw_it (RETURN_QUIT, GDB_NO_ERROR, fmt, ap);
}
void
throw_error (enum errors error, const char *fmt, ...)
{
va_list args;
va_start (args, fmt);
throw_verror (error, fmt, args);
va_end (args);
}
void
throw_quit (const char *fmt, ...)
{
va_list args;
va_start (args, fmt);
throw_vquit (fmt, args);
va_end (args);
}
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