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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 8 -*-
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* Copyright (C) 2006 Red Hat, Inc.
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* Copyright (C) 2007 William Jon McCann <mccann@jhu.edu>
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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 2 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, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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#include <glib/gi18n.h>
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#include <glib/gstdio.h>
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#include <glib-object.h>
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#include "gdm-signal-handler.h"
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#define GDM_SIGNAL_HANDLER_GET_PRIVATE(o) (G_TYPE_INSTANCE_GET_PRIVATE ((o), GDM_TYPE_SIGNAL_HANDLER, GdmSignalHandlerPrivate))
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GdmSignalHandlerFunc func;
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struct GdmSignalHandlerPrivate
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GHashTable *id_lookup;
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GHashTable *action_lookup;
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GDestroyNotify fatal_func;
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static void gdm_signal_handler_class_init (GdmSignalHandlerClass *klass);
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static void gdm_signal_handler_init (GdmSignalHandler *signal_handler);
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static void gdm_signal_handler_finalize (GObject *object);
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static gpointer signal_handler_object = NULL;
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static int signal_pipes[2];
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static int signals_blocked = 0;
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static sigset_t signals_block_mask;
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static sigset_t signals_oldmask;
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G_DEFINE_TYPE (GdmSignalHandler, gdm_signal_handler, G_TYPE_OBJECT)
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block_signals_push (void)
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if (signals_blocked == 1) {
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sigemptyset (&signals_block_mask);
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sigfillset (&signals_block_mask);
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sigprocmask (SIG_BLOCK, &signals_block_mask, &signals_oldmask);
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block_signals_pop (void)
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if (signals_blocked == 0) {
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sigprocmask (SIG_SETMASK, &signals_oldmask, NULL);
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signal_io_watch (GIOChannel *ioc,
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GIOCondition condition,
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GdmSignalHandler *handler)
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block_signals_push ();
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g_io_channel_read_chars (ioc, buf, sizeof (buf), &bytes_read, NULL);
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for (i = 0; i < bytes_read; i++) {
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signum = (gint32)buf[i];
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g_debug ("GdmSignalHandler: handling signal %d", signum);
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handlers = g_hash_table_lookup (handler->priv->lookup, GINT_TO_POINTER (signum));
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g_debug ("GdmSignalHandler: Found %u callbacks", g_slist_length (handlers));
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for (l = handlers; l != NULL; l = l->next) {
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data = g_hash_table_lookup (handler->priv->id_lookup, l->data);
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if (data->func != NULL) {
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g_debug ("GdmSignalHandler: running %d handler: %p", signum, data->func);
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res = data->func (signum, data->data);
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block_signals_pop ();
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if (handler->priv->fatal_func != NULL) {
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g_debug ("GdmSignalHandler: Caught termination signal - calling fatal func");
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handler->priv->fatal_func (handler->priv->fatal_data);
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g_debug ("GdmSignalHandler: Caught termination signal - exiting");
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g_debug ("GdmSignalHandler: Done handling signals");
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fallback_get_backtrace (void)
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#ifdef HAVE_EXECINFO_H
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size = backtrace (frames, G_N_ELEMENTS (frames));
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if ((strings = backtrace_symbols (frames, size))) {
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syslog (LOG_CRIT, "******************* START ********************************");
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for (i = 0; i < size; i++) {
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syslog (LOG_CRIT, "Frame %zd: %s", i, strings[i]);
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syslog (LOG_CRIT, "******************* END **********************************");
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g_warning ("GDM crashed, but symbols couldn't be retrieved.");
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crashlogger_get_backtrace (void)
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gboolean success = FALSE;
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/* Wait for the child to finish */
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if (waitpid (pid, &estatus, 0) != -1) {
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/* Only succeed if the crashlogger succeeded */
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if (WIFEXITED (estatus) && (WEXITSTATUS (estatus) == 0)) {
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} else if (pid == 0) {
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execl (LIBEXECDIR "/gdm-crash-logger",
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LIBEXECDIR "/gdm-crash-logger", NULL);
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gdm_signal_handler_backtrace (void)
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gboolean fallback = TRUE;
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/* Try to use gdb via gdm-crash-logger if it exists, since
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* we get much better information out of it. Otherwise
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* fall back to execinfo.
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if (g_stat (LIBEXECDIR "/gdm-crash-logger", &s) == 0) {
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fallback = crashlogger_get_backtrace () ? FALSE : TRUE;
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fallback_get_backtrace ();
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signal_handler (int signo)
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static int in_fatal = 0;
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guchar signo_byte = signo;
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gdm_signal_handler_backtrace ();
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/* let the fatal signals interrupt us */
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gdm_signal_handler_backtrace ();
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ignore = write (signal_pipes [1], &signo_byte, 1);
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ignore = write (signal_pipes [1], &signo_byte, 1);
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catch_signal (GdmSignalHandler *handler,
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struct sigaction action;
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struct sigaction *old_action;
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g_debug ("GdmSignalHandler: Registering for %d signals", signal_number);
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action.sa_handler = signal_handler;
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sigemptyset (&action.sa_mask);
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old_action = g_new0 (struct sigaction, 1);
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sigaction (signal_number, &action, old_action);
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g_hash_table_insert (handler->priv->action_lookup,
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GINT_TO_POINTER (signal_number),
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uncatch_signal (GdmSignalHandler *handler,
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struct sigaction *old_action;
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g_debug ("GdmSignalHandler: Unregistering for %d signals", signal_number);
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old_action = g_hash_table_lookup (handler->priv->action_lookup,
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GINT_TO_POINTER (signal_number));
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g_hash_table_remove (handler->priv->action_lookup,
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GINT_TO_POINTER (signal_number));
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sigaction (signal_number, old_action, NULL);
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gdm_signal_handler_add (GdmSignalHandler *handler,
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GdmSignalHandlerFunc callback,
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g_return_val_if_fail (GDM_IS_SIGNAL_HANDLER (handler), 0);
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cdata = g_new0 (CallbackData, 1);
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cdata->signal_number = signal_number;
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cdata->func = callback;
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cdata->id = handler->priv->next_id++;
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g_debug ("GdmSignalHandler: Adding handler %u: signum=%d %p", cdata->id, cdata->signal_number, cdata->func);
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if (g_hash_table_lookup (handler->priv->action_lookup, GINT_TO_POINTER (signal_number)) == NULL) {
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catch_signal (handler, signal_number);
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/* ID lookup owns the CallbackData */
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g_hash_table_insert (handler->priv->id_lookup, GUINT_TO_POINTER (cdata->id), cdata);
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list = g_hash_table_lookup (handler->priv->lookup, GINT_TO_POINTER (signal_number));
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list = g_slist_prepend (list, GUINT_TO_POINTER (cdata->id));
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g_hash_table_insert (handler->priv->lookup, GINT_TO_POINTER (signal_number), list);
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gdm_signal_handler_add_fatal (GdmSignalHandler *handler)
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g_return_if_fail (GDM_IS_SIGNAL_HANDLER (handler));
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gdm_signal_handler_add (handler, SIGILL, NULL, NULL);
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gdm_signal_handler_add (handler, SIGBUS, NULL, NULL);
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gdm_signal_handler_add (handler, SIGSEGV, NULL, NULL);
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gdm_signal_handler_add (handler, SIGABRT, NULL, NULL);
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gdm_signal_handler_add (handler, SIGTRAP, NULL, NULL);
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callback_data_free (CallbackData *d)
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gdm_signal_handler_remove_and_free_data (GdmSignalHandler *handler,
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g_return_if_fail (GDM_IS_SIGNAL_HANDLER (handler));
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list = g_hash_table_lookup (handler->priv->lookup, GINT_TO_POINTER (cdata->signal_number));
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list = g_slist_remove_all (list, GUINT_TO_POINTER (cdata->id));
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uncatch_signal (handler, cdata->signal_number);
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g_debug ("GdmSignalHandler: Removing handler %u: signum=%d %p", cdata->signal_number, cdata->id, cdata->func);
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/* put changed list back in */
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g_hash_table_insert (handler->priv->lookup, GINT_TO_POINTER (cdata->signal_number), list);
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g_hash_table_remove (handler->priv->id_lookup, GUINT_TO_POINTER (cdata->id));
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gdm_signal_handler_remove (GdmSignalHandler *handler,
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g_return_if_fail (GDM_IS_SIGNAL_HANDLER (handler));
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found = g_hash_table_lookup (handler->priv->id_lookup, GUINT_TO_POINTER (id));
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gdm_signal_handler_remove_and_free_data (handler, found);
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static CallbackData *
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find_callback_data_by_func (GdmSignalHandler *handler,
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GdmSignalHandlerFunc callback,
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list = g_hash_table_lookup (handler->priv->lookup, GINT_TO_POINTER (signal_number));
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for (l = list; l != NULL; l = l->next) {
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id = GPOINTER_TO_UINT (l->data);
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d = g_hash_table_lookup (handler->priv->id_lookup, GUINT_TO_POINTER (id));
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&& d->func == callback
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&& d->data == data) {
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gdm_signal_handler_remove_func (GdmSignalHandler *handler,
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GdmSignalHandlerFunc callback,
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g_return_if_fail (GDM_IS_SIGNAL_HANDLER (handler));
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found = find_callback_data_by_func (handler, signal_number, callback, data);
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gdm_signal_handler_remove_and_free_data (handler, found);
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/* FIXME: once all handlers are removed deregister signum handler */
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gdm_signal_handler_class_init (GdmSignalHandlerClass *klass)
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GObjectClass *object_class = G_OBJECT_CLASS (klass);
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object_class->finalize = gdm_signal_handler_finalize;
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g_type_class_add_private (klass, sizeof (GdmSignalHandlerPrivate));
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signal_list_free (GSList *list)
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gdm_signal_handler_set_fatal_func (GdmSignalHandler *handler,
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g_return_if_fail (GDM_IS_SIGNAL_HANDLER (handler));
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handler->priv->fatal_func = func;
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handler->priv->fatal_data = user_data;
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gdm_signal_handler_init (GdmSignalHandler *handler)
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handler->priv = GDM_SIGNAL_HANDLER_GET_PRIVATE (handler);
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handler->priv->next_id = 1;
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handler->priv->lookup = g_hash_table_new (NULL, NULL);
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handler->priv->id_lookup = g_hash_table_new (NULL, NULL);
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handler->priv->action_lookup = g_hash_table_new (NULL, NULL);
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if (pipe (signal_pipes) == -1) {
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g_error ("Could not create pipe() for signal handling");
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fcntl(signal_pipes[0], F_SETFD, FD_CLOEXEC);
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fcntl(signal_pipes[1], F_SETFD, FD_CLOEXEC);
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ioc = g_io_channel_unix_new (signal_pipes[0]);
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g_io_channel_set_flags (ioc, G_IO_FLAG_NONBLOCK, NULL);
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g_io_add_watch (ioc, G_IO_IN, (GIOFunc)signal_io_watch, handler);
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g_io_channel_set_close_on_unref (ioc, TRUE);
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g_io_channel_unref (ioc);
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gdm_signal_handler_finalize (GObject *object)
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GdmSignalHandler *handler;
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g_return_if_fail (object != NULL);
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g_return_if_fail (GDM_IS_SIGNAL_HANDLER (object));
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handler = GDM_SIGNAL_HANDLER (object);
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g_debug ("GdmSignalHandler: Finalizing signal handler");
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g_return_if_fail (handler->priv != NULL);
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for (l = g_hash_table_get_values (handler->priv->lookup);
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l != NULL; l = l->next) {
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signal_list_free ((GSList *) l->data);
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g_hash_table_destroy (handler->priv->lookup);
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for (l = g_hash_table_get_values (handler->priv->id_lookup);
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l != NULL; l = l->next) {
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callback_data_free ((CallbackData *) l->data);
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g_hash_table_destroy (handler->priv->id_lookup);
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for (l = g_hash_table_get_values (handler->priv->action_lookup);
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l != NULL; l = l->next) {
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g_hash_table_destroy (handler->priv->action_lookup);
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close (signal_pipes [0]);
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close (signal_pipes [1]);
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G_OBJECT_CLASS (gdm_signal_handler_parent_class)->finalize (object);
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gdm_signal_handler_new (void)
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if (signal_handler_object != NULL) {
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g_object_ref (signal_handler_object);
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signal_handler_object = g_object_new (GDM_TYPE_SIGNAL_HANDLER, NULL);
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g_object_add_weak_pointer (signal_handler_object,
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(gpointer *) &signal_handler_object);
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return GDM_SIGNAL_HANDLER (signal_handler_object);
added
removed
.pc/ubuntu_dont_catch_sigsegv.patch/common/gdm-signal-handler.c
