xsettings: flush Xlib output so settings reach X11/XWayland clients

2 files changed, 36 insertions, 0 deletions

diff --git a/plugins/xsettings/msd-xsettings-manager.c b/plugins/xsettings/msd-xsettings-manager.c
index 6656ccb..879aa81 100644
--- a/plugins/xsettings/msd-xsettings-manager.c
+++ b/plugins/xsettings/msd-xsettings-manager.c
@@ -39,6 +39,9 @@
 #ifdef GDK_WINDOWING_X11
 #include <gdk/gdkx.h>
 #endif /* GDK_WINDOWING_X11 */
+#ifdef GDK_WINDOWING_WAYLAND
+#include <gdk/gdkwayland.h>
+#endif /* GDK_WINDOWING_WAYLAND */
 #include <gtk/gtk.h>
 #include <gio/gio.h>
 
@@ -879,6 +882,19 @@ terminate_cb (void *data)
         gtk_main_quit ();
 }
 
+#ifdef GDK_WINDOWING_WAYLAND
+/* No-op Xlib IO error handler used when running on Wayland: the X connection
+ * only serves XSettings on XWayland, so the daemon should survive an
+ * XWayland restart instead of exiting. */
+static int
+wayland_x_io_error_handler (Display *display)
+{
+        g_warning ("Connection to the XWayland display lost; XSettings for "
+                   "X11 applications disabled");
+        return 0;
+}
+#endif /* GDK_WINDOWING_WAYLAND */
+
 static gboolean
 setup_xsettings_managers (MateXSettingsManager *manager)
 {
@@ -892,6 +908,16 @@ setup_xsettings_managers (MateXSettingsManager *manager)
                 return FALSE;
         }
 
+#ifdef GDK_WINDOWING_WAYLAND
+        /* When running on Wayland the XSETTINGS manager uses its own Xlib
+         * connection to XWayland, which nothing else watches.  Now that we
+         * explicitly flush it, a disappearing XWayland would otherwise kill
+         * the whole daemon through the default Xlib IO error handler. */
+        if (GDK_IS_WAYLAND_DISPLAY (gdk_display_get_default ())) {
+                XSetIOErrorHandler (wayland_x_io_error_handler);
+        }
+#endif /* GDK_WINDOWING_WAYLAND */
+
         res = xsettings_manager_check_running (xdisplay, DefaultScreen (xdisplay));
         if (res) {
                 g_warning ("You can only run one xsettings manager at a time; exiting");
diff --git a/plugins/xsettings/xsettings-manager.c b/plugins/xsettings/xsettings-manager.c
index d8f5dd5..3aeffa6 100644
--- a/plugins/xsettings/xsettings-manager.c
+++ b/plugins/xsettings/xsettings-manager.c
@@ -188,6 +188,11 @@ xsettings_manager_new (Display                *display,
       manager->terminate (manager->cb_data);
     }
 
+  /* The display may not be watched by the main loop (e.g. when running on
+   * Wayland the XSettings manager uses its own connection to XWayland), so
+   * make sure the MANAGER message actually reaches the server. */
+  XFlush (manager->display);
+
   return manager;
 }
 
@@ -428,6 +433,11 @@ xsettings_manager_notify (XSettingsManager *manager)
 
   free (buffer.data);
 
+  /* See the note in xsettings_manager_new(): on Wayland nothing else
+   * flushes this connection, so without this clients never see the
+   * property and none of the settings are applied. */
+  XFlush (manager->display);
+
   return XSETTINGS_SUCCESS;
 }