407 lines
9.5 KiB
C
407 lines
9.5 KiB
C
/* Exception (throw catch) mechanism, for GDB, the GNU debugger.
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Copyright (C) 1986-2016 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "common-defs.h"
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#include "common-exceptions.h"
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const struct gdb_exception exception_none = { (enum return_reason) 0, GDB_NO_ERROR, NULL };
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/* Possible catcher states. */
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enum catcher_state {
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/* Initial state, a new catcher has just been created. */
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CATCHER_CREATED,
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/* The catch code is running. */
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CATCHER_RUNNING,
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CATCHER_RUNNING_1,
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/* The catch code threw an exception. */
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CATCHER_ABORTING
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};
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/* Possible catcher actions. */
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enum catcher_action {
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CATCH_ITER,
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CATCH_ITER_1,
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CATCH_THROWING
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};
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struct catcher
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{
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enum catcher_state state;
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/* Jump buffer pointing back at the exception handler. */
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jmp_buf buf;
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/* Status buffer belonging to the exception handler. */
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struct gdb_exception exception;
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struct cleanup *saved_cleanup_chain;
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/* Back link. */
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struct catcher *prev;
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};
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/* Where to go for throw_exception(). */
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static struct catcher *current_catcher;
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#if GDB_XCPT == GDB_XCPT_SJMP
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/* Return length of current_catcher list. */
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static int
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catcher_list_size (void)
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{
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int size;
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struct catcher *catcher;
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for (size = 0, catcher = current_catcher;
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catcher != NULL;
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catcher = catcher->prev)
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++size;
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return size;
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}
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#endif
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jmp_buf *
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exceptions_state_mc_init (void)
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{
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struct catcher *new_catcher = XCNEW (struct catcher);
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/* Start with no exception. */
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new_catcher->exception = exception_none;
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/* Prevent error/quit during FUNC from calling cleanups established
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prior to here. */
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new_catcher->saved_cleanup_chain = save_cleanups ();
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/* Push this new catcher on the top. */
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new_catcher->prev = current_catcher;
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current_catcher = new_catcher;
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new_catcher->state = CATCHER_CREATED;
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return &new_catcher->buf;
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}
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static void
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catcher_pop (void)
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{
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struct catcher *old_catcher = current_catcher;
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current_catcher = old_catcher->prev;
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/* Restore the cleanup chain, the error/quit messages, and the uiout
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builder, to their original states. */
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restore_cleanups (old_catcher->saved_cleanup_chain);
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xfree (old_catcher);
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}
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/* Catcher state machine. Returns non-zero if the m/c should be run
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again, zero if it should abort. */
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static int
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exceptions_state_mc (enum catcher_action action)
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{
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switch (current_catcher->state)
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{
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case CATCHER_CREATED:
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switch (action)
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{
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case CATCH_ITER:
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/* Allow the code to run the catcher. */
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current_catcher->state = CATCHER_RUNNING;
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return 1;
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default:
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internal_error (__FILE__, __LINE__, _("bad state"));
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}
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case CATCHER_RUNNING:
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switch (action)
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{
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case CATCH_ITER:
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/* No error/quit has occured. */
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return 0;
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case CATCH_ITER_1:
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current_catcher->state = CATCHER_RUNNING_1;
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return 1;
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case CATCH_THROWING:
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current_catcher->state = CATCHER_ABORTING;
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/* See also throw_exception. */
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return 1;
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default:
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internal_error (__FILE__, __LINE__, _("bad switch"));
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}
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case CATCHER_RUNNING_1:
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switch (action)
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{
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case CATCH_ITER:
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/* The did a "break" from the inner while loop. */
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return 0;
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case CATCH_ITER_1:
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current_catcher->state = CATCHER_RUNNING;
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return 0;
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case CATCH_THROWING:
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current_catcher->state = CATCHER_ABORTING;
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/* See also throw_exception. */
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return 1;
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default:
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internal_error (__FILE__, __LINE__, _("bad switch"));
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}
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case CATCHER_ABORTING:
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switch (action)
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{
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case CATCH_ITER:
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{
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/* Exit normally if this catcher can handle this
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exception. The caller analyses the func return
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values. */
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return 0;
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}
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default:
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internal_error (__FILE__, __LINE__, _("bad state"));
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}
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default:
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internal_error (__FILE__, __LINE__, _("bad switch"));
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}
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}
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int
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exceptions_state_mc_catch (struct gdb_exception *exception,
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int mask)
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{
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*exception = current_catcher->exception;
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catcher_pop ();
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if (exception->reason < 0)
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{
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if (mask & RETURN_MASK (exception->reason))
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{
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/* Exit normally and let the caller handle the
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exception. */
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return 1;
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}
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/* The caller didn't request that the event be caught, relay the
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event to the next exception_catch/CATCH_SJLJ. */
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throw_exception_sjlj (*exception);
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}
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/* No exception was thrown. */
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return 0;
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}
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int
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exceptions_state_mc_action_iter (void)
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{
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return exceptions_state_mc (CATCH_ITER);
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}
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int
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exceptions_state_mc_action_iter_1 (void)
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{
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return exceptions_state_mc (CATCH_ITER_1);
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}
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#if GDB_XCPT != GDB_XCPT_SJMP
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/* How many nested TRY blocks we have. See exception_messages and
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throw_it. */
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static int try_scope_depth;
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/* Called on entry to a TRY scope. */
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void *
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exception_try_scope_entry (void)
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{
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++try_scope_depth;
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return (void *) save_cleanups ();
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}
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/* Called on exit of a TRY scope, either normal exit or exception
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exit. */
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void
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exception_try_scope_exit (void *saved_state)
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{
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restore_cleanups ((struct cleanup *) saved_state);
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--try_scope_depth;
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}
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/* Called by the default catch block. IOW, we'll get here before
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jumping out to the next outermost scope an exception if a GDB
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exception is not caught. */
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void
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exception_rethrow (void)
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{
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/* Run this scope's cleanups before re-throwing to the next
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outermost scope. */
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do_cleanups (all_cleanups ());
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throw;
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}
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/* Copy the 'gdb_exception' portion of FROM to TO. */
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static void
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gdb_exception_sliced_copy (struct gdb_exception *to, const struct gdb_exception *from)
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{
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*to = *from;
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}
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#endif /* !GDB_XCPT_SJMP */
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/* Return EXCEPTION to the nearest containing catch_errors(). */
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void
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throw_exception_sjlj (struct gdb_exception exception)
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{
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do_cleanups (all_cleanups ());
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/* Jump to the containing catch_errors() call, communicating REASON
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to that call via setjmp's return value. Note that REASON can't
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be zero, by definition in defs.h. */
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exceptions_state_mc (CATCH_THROWING);
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current_catcher->exception = exception;
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longjmp (current_catcher->buf, exception.reason);
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}
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#if GDB_XCPT != GDB_XCPT_SJMP
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/* Implementation of throw_exception that uses C++ try/catch. */
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static ATTRIBUTE_NORETURN void
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throw_exception_cxx (struct gdb_exception exception)
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{
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do_cleanups (all_cleanups ());
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if (exception.reason == RETURN_QUIT)
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{
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gdb_exception_RETURN_MASK_QUIT ex;
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gdb_exception_sliced_copy (&ex, &exception);
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throw ex;
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}
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else if (exception.reason == RETURN_ERROR)
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{
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gdb_exception_RETURN_MASK_ERROR ex;
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gdb_exception_sliced_copy (&ex, &exception);
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throw ex;
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}
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else
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gdb_assert_not_reached ("invalid return reason");
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}
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#endif
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void
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throw_exception (struct gdb_exception exception)
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{
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#if GDB_XCPT == GDB_XCPT_SJMP
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throw_exception_sjlj (exception);
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#else
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throw_exception_cxx (exception);
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#endif
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}
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/* A stack of exception messages.
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This is needed to handle nested calls to throw_it: we don't want to
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xfree space for a message before it's used.
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This can happen if we throw an exception during a cleanup:
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An outer TRY_CATCH may have an exception message it wants to print,
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but while doing cleanups further calls to throw_it are made.
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This is indexed by the size of the current_catcher list.
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It is a dynamically allocated array so that we don't care how deeply
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GDB nests its TRY_CATCHs. */
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static char **exception_messages;
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/* The number of currently allocated entries in exception_messages. */
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static int exception_messages_size;
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static void ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (3, 0)
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throw_it (enum return_reason reason, enum errors error, const char *fmt,
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va_list ap)
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{
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struct gdb_exception e;
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char *new_message;
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#if GDB_XCPT == GDB_XCPT_SJMP
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int depth = catcher_list_size ();
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#else
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int depth = try_scope_depth;
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#endif
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gdb_assert (depth > 0);
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/* Note: The new message may use an old message's text. */
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new_message = xstrvprintf (fmt, ap);
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if (depth > exception_messages_size)
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{
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int old_size = exception_messages_size;
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exception_messages_size = depth + 10;
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exception_messages = XRESIZEVEC (char *, exception_messages,
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exception_messages_size);
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memset (exception_messages + old_size, 0,
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(exception_messages_size - old_size) * sizeof (char *));
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}
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xfree (exception_messages[depth - 1]);
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exception_messages[depth - 1] = new_message;
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/* Create the exception. */
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e.reason = reason;
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e.error = error;
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e.message = new_message;
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/* Throw the exception. */
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throw_exception (e);
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}
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void
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throw_verror (enum errors error, const char *fmt, va_list ap)
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{
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throw_it (RETURN_ERROR, error, fmt, ap);
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}
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void
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throw_vquit (const char *fmt, va_list ap)
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{
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throw_it (RETURN_QUIT, GDB_NO_ERROR, fmt, ap);
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}
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void
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throw_error (enum errors error, const char *fmt, ...)
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{
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va_list args;
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va_start (args, fmt);
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throw_verror (error, fmt, args);
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va_end (args);
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}
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void
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throw_quit (const char *fmt, ...)
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{
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va_list args;
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va_start (args, fmt);
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throw_vquit (fmt, args);
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va_end (args);
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}
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