[mutter/gnome-3-38] xwayland: Make sure /tmp/.X11-unix/ exists

[Marge Bot <marge-bot src gnome org>]

commit d5bc6891ba4a5d6be946f7f3cc882e2583893465
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Dec 9 15:04:56 2020 +0100

    xwayland: Make sure /tmp/.X11-unix/ exists
    
    When we're running under a polyinstantiated SELinux environment, we'll
    likely start with an isolated and empty /tmp, meannig no /tmp/.X11-unix
    directory to add things to. To make it possible to still function in
    this kind of setup, make sure said directory exists.
    
    (cherry picked from commit 357f3250cbc09c9b4c4064fa2bccfbc9a076a7c8)
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1788>

 src/wayland/meta-xwayland.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
---
diff --git a/src/wayland/meta-xwayland.c b/src/wayland/meta-xwayland.c
index cd95d6886a..a69624ba5d 100644
--- a/src/wayland/meta-xwayland.c
+++ b/src/wayland/meta-xwayland.c
@@ -30,6 +30,7 @@
 #include <glib-unix.h>
 #include <glib.h>
 #include <sys/socket.h>
+#include <sys/stat.h>
 #include <sys/un.h>
 #if defined(HAVE_SYS_RANDOM)
 #include <sys/random.h>
@@ -413,10 +414,28 @@ open_display_sockets (MetaXWaylandManager *manager,
   return TRUE;
 }
 
+static gboolean
+ensure_x11_unix_dir (GError **error)
+{
+  if (mkdir ("/tmp/.X11-unix", 01777) != 0)
+    {
+      if (errno == EEXIST)
+        return TRUE;
+
+      g_set_error (error, G_IO_ERROR, g_io_error_from_errno (errno),
+                   "Failed to create directory \"/tmp/.X11-unix\": %s",
+                   g_strerror (errno));
+      return FALSE;
+    }
+
+  return TRUE;
+}
+
 static gboolean
 choose_xdisplay (MetaXWaylandManager    *manager,
                  MetaXWaylandConnection *connection)
 {
+  g_autoptr (GError) error = NULL;
   int display = 0;
   char *lock_file = NULL;
   gboolean fatal = FALSE;
@@ -426,6 +445,13 @@ choose_xdisplay (MetaXWaylandManager    *manager,
   else if (g_getenv ("RUNNING_UNDER_GDM"))
     display = 1024;
 
+  if (!ensure_x11_unix_dir (&error))
+    {
+      g_warning ("Failed to ensure X11 socket directory: %s",
+                 error->message);
+      return FALSE;
+    }
+
   do
     {
       lock_file = create_lock_file (display, &display);