Commit 956d7d1c authored by Jasper St. Pierre's avatar Jasper St. Pierre

server: Process SIGUSR1 more carefully

If the slave is removed as a separate process, it means that we need
to be more careful with our handling of SIGUSR1. If multiple X servers
are launched at once, we need to use siginfo_t to get the PID of the
thing that sent the user signal, and make sure we signal the correct

glib doesn't have native siginfo support, so do it ourselves by using
a worker thread that spins around waiting for sigwaitinfo.
parent 98a32e4f
......@@ -94,7 +94,6 @@ struct GdmServerPrivate
char *auth_file;
guint child_watch_id;
guint sigusr1_id;
gboolean is_initial;
......@@ -180,16 +179,77 @@ gdm_server_get_display_device (GdmServer *server)
return g_strdup (server->priv->display_device);
static void
gdm_server_ready (GdmServer *server)
g_debug ("GdmServer: Got USR1 from X server - emitting READY");
g_signal_emit (server, signals[READY], 0);
static GSList *active_servers;
static gboolean sigusr1_thread_running;
static GCond sigusr1_thread_cond;
static GMutex sigusr1_thread_mutex;
static gboolean
on_sigusr1 (gpointer user_data)
got_sigusr1 (gpointer user_data)
GPid pid = GPOINTER_TO_UINT (user_data);
GSList *l;
g_debug ("GdmServer: got SIGUSR1 from PID %d", pid);
for (l = active_servers; l; l = l->next) {
GdmServer *server = l->data;
if (server->priv->pid == pid)
gdm_server_ready (server);
static gpointer
sigusr1_thread_main (gpointer user_data)
GdmServer *server = user_data;
sigset_t sigusr1_mask;
g_debug ("GdmServer: Got USR1 from X server - emitting READY");
/* Handle only SIGUSR1 */
sigemptyset (&sigusr1_mask);
sigaddset (&sigusr1_mask, SIGUSR1);
sigprocmask (SIG_SETMASK, &sigusr1_mask, NULL);
g_signal_emit (server, signals[READY], 0);
return FALSE;
g_mutex_lock (&sigusr1_thread_mutex);
sigusr1_thread_running = TRUE;
g_cond_signal (&sigusr1_thread_cond);
g_mutex_unlock (&sigusr1_thread_mutex);
/* Spin waiting for a SIGUSR1 */
while (TRUE) {
siginfo_t info;
if (sigwaitinfo (&sigusr1_mask, &info) == -1)
g_idle_add (got_sigusr1, GUINT_TO_POINTER (info.si_pid));
return NULL;
static void
gdm_server_launch_sigusr1_thread_if_needed (void)
static GThread *sigusr1_thread;
if (sigusr1_thread == NULL) {
sigusr1_thread = g_thread_new ("gdm SIGUSR1 catcher", sigusr1_thread_main, NULL);
g_mutex_lock (&sigusr1_thread_mutex);
while (!sigusr1_thread_running)
g_cond_wait (&sigusr1_thread_cond, &sigusr1_thread_mutex);
g_mutex_unlock (&sigusr1_thread_mutex);
/* We keep a connection (parent_dsp) open with the parent X server
......@@ -676,6 +736,8 @@ server_child_watch (GPid pid,
g_signal_emit (server, signals [DIED], 0, num);
active_servers = g_slist_remove (active_servers, server);
g_spawn_close_pid (server->priv->pid);
server->priv->pid = -1;
......@@ -719,6 +781,10 @@ gdm_server_spawn (GdmServer *server,
g_debug ("GdmServer: Starting X server process: %s", freeme);
g_free (freeme);
active_servers = g_slist_append (active_servers, server);
gdm_server_launch_sigusr1_thread_if_needed ();
if (!g_spawn_async_with_pipes (NULL,
(char **)env->pdata,
......@@ -1063,16 +1129,11 @@ gdm_server_class_init (GdmServerClass *klass)
static void
gdm_server_init (GdmServer *server)
server->priv = GDM_SERVER_GET_PRIVATE (server);
server->priv->pid = -1;
server->priv->log_dir = g_strdup (LOGDIR);
server->priv->sigusr1_id = g_unix_signal_add (SIGUSR1,
static void
......@@ -1087,9 +1148,6 @@ gdm_server_finalize (GObject *object)
g_return_if_fail (server->priv != NULL);
if (server->priv->sigusr1_id > 0)
g_source_remove (server->priv->sigusr1_id);
gdm_server_stop (server);
g_free (server->priv->command);
......@@ -295,6 +295,19 @@ is_debug_set (void)
return debug;
/* SIGUSR1 is used by the X server to tell us that we're ready, so
* block it. We'll unblock it in the worker thread in gdm-server.c
static void
block_sigusr1 (void)
sigset_t mask;
sigemptyset (&mask);
sigaddset (&mask, SIGUSR1);
sigprocmask (SIG_BLOCK, &mask, NULL);
main (int argc,
char **argv)
......@@ -315,6 +328,8 @@ main (int argc,
{ NULL }
block_sigusr1 ();
textdomain (GETTEXT_PACKAGE);
setlocale (LC_ALL, "");
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