wayland: Add a prepare-shutdown signal

This allows moving the xwayland shutdown logic to the xwayland
implementation

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2399>

src/wayland/meta-wayland-private.h

@@ -62,6 +62,8 @@ struct _MetaXWaylandManager
   guint abstract_fd_watch_id;
   guint unix_fd_watch_id;
 
+  gulong prepare_shutdown_id;
+
   struct wl_display *wayland_display;
   struct wl_client *client;
   struct wl_resource *xserver_resource;

src/wayland/meta-wayland.c

@@ -61,6 +61,15 @@
 #include "backends/native/meta-renderer-native.h"
 #endif
 
+enum
+{
+  PREPARE_SHUTDOWN,
+
+  N_SIGNALS
+};
+
+static guint signals[N_SIGNALS];
+
 static char *_display_name_override;
 
 typedef struct _MetaWaylandCompositorPrivate
@@ -431,14 +440,7 @@ meta_wayland_log_func (const char *fmt,
 void
 meta_wayland_compositor_prepare_shutdown (MetaWaylandCompositor *compositor)
 {
-#ifdef HAVE_XWAYLAND
+  g_signal_emit (compositor, signals[PREPARE_SHUTDOWN], 0, NULL);
-  MetaX11DisplayPolicy x11_display_policy;
-
-  x11_display_policy =
-    meta_context_get_x11_display_policy (compositor->context);
-  if (x11_display_policy != META_X11_DISPLAY_POLICY_DISABLED)
-    meta_xwayland_shutdown (&compositor->xwayland_manager);
-#endif
 
   if (compositor->wayland_display)
     wl_display_destroy_clients (compositor->wayland_display);
@@ -492,6 +494,14 @@ meta_wayland_compositor_class_init (MetaWaylandCompositorClass *klass)
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
   object_class->finalize = meta_wayland_compositor_finalize;
+
+  signals[PREPARE_SHUTDOWN] =
+    g_signal_new ("prepare-shutdown",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  0,
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
 }
 
 #ifdef HAVE_XWAYLAND

src/wayland/meta-xwayland-private.h

@@ -38,9 +38,6 @@ void
 meta_xwayland_setup_xdisplay (MetaXWaylandManager *manager,
                               Display             *xdisplay);
 
-void
-meta_xwayland_shutdown (MetaXWaylandManager *manager);
-
 gboolean
 meta_xwayland_handle_xevent (XEvent *event);
 

src/wayland/meta-xwayland.c

@@ -468,6 +468,7 @@ meta_xwayland_terminate (MetaXWaylandManager *manager)
 
   meta_display_shutdown_x11 (display);
   meta_xwayland_stop_xserver (manager);
+  g_clear_signal_handler (&manager->prepare_shutdown_id, manager->compositor);
 }
 
 static int
@@ -510,11 +511,13 @@ x_io_error_exit (Display *display,
     }
 }
 
+#ifdef HAVE_XSETIOERROREXITHANDLER
 static void
 x_io_error_exit_noop (Display *display,
                       void    *data)
 {
 }
+#endif
 
 void
 meta_xwayland_override_display_number (int number)
@@ -995,6 +998,63 @@ meta_xwayland_stop_xserver (MetaXWaylandManager *manager)
   g_clear_object (&manager->proc);
 }
 
+static void
+meta_xwayland_connection_release (MetaXWaylandConnection *connection)
+{
+  unlink (connection->lock_file);
+  g_clear_pointer (&connection->lock_file, g_free);
+}
+
+static void
+meta_xwayland_shutdown (MetaWaylandCompositor *compositor)
+{
+  MetaXWaylandManager *manager = &compositor->xwayland_manager;
+#ifdef HAVE_XSETIOERROREXITHANDLER
+  MetaDisplay *display = meta_get_display ();
+  MetaX11Display *x11_display;
+#endif
+  char path[256];
+
+  g_cancellable_cancel (manager->xserver_died_cancellable);
+
+  XSetIOErrorHandler (x_io_error_noop);
+#ifdef HAVE_XSETIOERROREXITHANDLER
+  x11_display = display->x11_display;
+  if (x11_display)
+    {
+      XSetIOErrorExitHandler (meta_x11_display_get_xdisplay (x11_display),
+                              x_io_error_exit_noop, NULL);
+    }
+#endif
+
+  meta_xwayland_terminate (manager);
+
+  if (manager->public_connection.name)
+    {
+      snprintf (path, sizeof path, "%s%d", X11_TMP_UNIX_PATH,
+                manager->public_connection.display_index);
+      unlink (path);
+      g_clear_pointer (&manager->public_connection.name, g_free);
+    }
+
+  if (manager->private_connection.name)
+    {
+      snprintf (path, sizeof path, "%s%d", X11_TMP_UNIX_PATH,
+                manager->private_connection.display_index);
+      unlink (path);
+      g_clear_pointer (&manager->private_connection.name, g_free);
+    }
+
+  meta_xwayland_connection_release (&manager->public_connection);
+  meta_xwayland_connection_release (&manager->private_connection);
+
+  if (manager->auth_file)
+    {
+      unlink (manager->auth_file);
+      g_clear_pointer (&manager->auth_file, g_free);
+    }
+}
+
 gboolean
 meta_xwayland_init (MetaXWaylandManager    *manager,
                     MetaWaylandCompositor  *compositor,
@@ -1057,6 +1117,11 @@ meta_xwayland_init (MetaXWaylandManager    *manager,
                        xdisplay_connection_activity_cb, manager);
     }
 
+  if (policy != META_X11_DISPLAY_POLICY_DISABLED)
+    manager->prepare_shutdown_id = g_signal_connect (compositor, "prepare-shutdown",
+                                                     G_CALLBACK (meta_xwayland_shutdown), 
+                                                     NULL);
+
   return TRUE;
 }
 
@@ -1145,60 +1210,6 @@ meta_xwayland_setup_xdisplay (MetaXWaylandManager *manager,
   XFixesSetClientDisconnectMode (xdisplay, XFixesClientDisconnectFlagTerminate);
 }
 
-static void
-meta_xwayland_connection_release (MetaXWaylandConnection *connection)
-{
-  unlink (connection->lock_file);
-  g_clear_pointer (&connection->lock_file, g_free);
-}
-
-void
-meta_xwayland_shutdown (MetaXWaylandManager *manager)
-{
-  MetaContext *context =
-    meta_wayland_compositor_get_context (manager->compositor);
-  MetaDisplay *display = meta_context_get_display (context);
-  MetaX11Display *x11_display;
-  char path[256];
-
-  g_cancellable_cancel (manager->xserver_died_cancellable);
-
-  XSetIOErrorHandler (x_io_error_noop);
-  x11_display = display->x11_display;
-  if (x11_display)
-    {
-      XSetIOErrorExitHandler (meta_x11_display_get_xdisplay (x11_display),
-                              x_io_error_exit_noop, NULL);
-    }
-
-  meta_xwayland_terminate (manager);
-
-  if (manager->public_connection.name)
-    {
-      snprintf (path, sizeof path, "%s%d", X11_TMP_UNIX_PATH,
-                manager->public_connection.display_index);
-      unlink (path);
-      g_clear_pointer (&manager->public_connection.name, g_free);
-    }
-
-  if (manager->private_connection.name)
-    {
-      snprintf (path, sizeof path, "%s%d", X11_TMP_UNIX_PATH,
-                manager->private_connection.display_index);
-      unlink (path);
-      g_clear_pointer (&manager->private_connection.name, g_free);
-    }
-
-  meta_xwayland_connection_release (&manager->public_connection);
-  meta_xwayland_connection_release (&manager->private_connection);
-
-  if (manager->auth_file)
-    {
-      unlink (manager->auth_file);
-      g_clear_pointer (&manager->auth_file, g_free);
-    }
-}
-
 static void
 meta_xwayland_set_primary_output (MetaX11Display *x11_display)
 {