mutter/mutter-xwayland-use-gdm-auth-file.patch

Index: mutter-3.28.0/src/wayland/meta-xwayland.c
===================================================================
--- mutter-3.28.0.orig/src/wayland/meta-xwayland.c
+++ mutter-3.28.0/src/wayland/meta-xwayland.c
@@ -32,6 +32,12 @@
 #include <sys/socket.h>
 #include <sys/un.h>
 
+/* For g_open() */
+#include <glib/gstdio.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
 #include "compositor/meta-surface-actor-wayland.h"
 #include "wayland/meta-wayland-actor-surface.h"
 
@@ -508,6 +514,37 @@ on_displayfd_ready (int          fd,
   return G_SOURCE_REMOVE;
 }
 
+/* Look for an Xauthority file that may have been created by gdm */
+static char *
+find_auth_file (void)
+{
+  char *auth_dir = NULL;
+  char *auth_file = NULL;
+  int fd;
+
+  auth_dir = g_build_filename (g_get_user_runtime_dir (),
+                               "gdm",
+                               NULL);
+
+  auth_file = g_build_filename (auth_dir, "Xauthority", NULL);
+  g_clear_pointer (&auth_dir, g_free);
+
+  /* Check that we can open the file. In theory it could still go away before
+   * Xwayland gets a chance to run, but at least we can be fairly sure. */
+
+  fd = g_open (auth_file, O_RDWR, 0700);
+
+  if (fd < 0) {
+    g_clear_pointer (&auth_file, g_free);
+    goto out;
+  }
+
+  g_close (fd, NULL);
+
+out:
+  return auth_file;
+}
+
 gboolean
 meta_xwayland_start (MetaXWaylandManager *manager,
                      struct wl_display   *wl_display)
@@ -517,11 +554,14 @@ meta_xwayland_start (MetaXWaylandManager
   gboolean started = FALSE;
   g_autoptr(GSubprocessLauncher) launcher = NULL;
   GSubprocessFlags flags;
+  gchar *auth_file = NULL;
   GError *error = NULL;
 
   if (!choose_xdisplay (manager))
     goto out;
 
+  auth_file = find_auth_file ();
+
   /* We want xwayland to be a wayland client so we make a socketpair to setup a
    * wayland protocol connection. */
   if (socketpair (AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, xwayland_client_fd) < 0)
@@ -560,16 +600,34 @@ meta_xwayland_start (MetaXWaylandManager
    * won't try to reconnect and crash, leaving uninteresting core dumps. We do
    * want core dumps from Xwayland but only if a real bug occurs...
    */
-  manager->proc = g_subprocess_launcher_spawn (launcher, &error,
-                                               XWAYLAND_PATH, manager->display_name,
-                                               "-rootless",
-                                               "-terminate",
-                                               "-accessx",
-                                               "-core",
-                                               "-listen", "4",
-                                               "-listen", "5",
-                                               "-displayfd", "6",
-                                               NULL);
+  if (auth_file)
+    {
+      manager->proc = g_subprocess_launcher_spawn (launcher, &error,
+                                                   XWAYLAND_PATH, manager->display_name,
+                                                   "-rootless",
+                                                   "-terminate",
+                                                   "-accessx",
+                                                   "-core",
+                                                   "-auth", auth_file,
+                                                   "-listen", "4",
+                                                   "-listen", "5",
+                                                   "-displayfd", "6",
+                                                   NULL);
+    }
+  else
+    {
+      manager->proc = g_subprocess_launcher_spawn (launcher, &error,
+                                                   XWAYLAND_PATH, manager->display_name,
+                                                   "-rootless",
+                                                   "-terminate",
+                                                   "-accessx",
+                                                   "-core",
+                                                   "-listen", "4",
+                                                   "-listen", "5",
+                                                   "-displayfd", "6",
+                                                   NULL);
+    }
+
   if (!manager->proc)
     {
       g_error ("Failed to spawn Xwayland: %s", error->message);
@@ -591,6 +649,7 @@ meta_xwayland_start (MetaXWaylandManager
   started = TRUE;
 
 out:
+  g_free (auth_file);
   if (!started)
     {
       unlink (manager->lock_file);