gnu: Add x11-socket-directory-service.

* gnu/services/desktop.scm (x11-socket-directory-service): New
variable.
(%desktop-services): Add it.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/services/desktop.scm

@@ -94,6 +94,8 @@
             xfce-desktop-service
             xfce-desktop-service-type
 
+            x11-socket-directory-service
+
             %desktop-services))
 
 ;;; Commentary:
@@ -880,6 +882,24 @@ system as root from within a user session, after the user has authenticated
 with the administrator's password."
   (service xfce-desktop-service-type config))
 
+
+;;;
+;;; X11 socket directory service
+;;;
+
+(define x11-socket-directory-service
+  ;; Return a service that creates /tmp/.X11-unix.  When using X11, libxcb
+  ;; takes care of creating that directory.  However, when using XWayland, we
+  ;; need to create beforehand.  Thus, create it unconditionally here.
+  (simple-service 'x11-socket-directory
+                  activation-service-type
+                  (with-imported-modules '((guix build utils))
+                    #~(begin
+                        (use-modules (guix build utils))
+                        (let ((directory "/tmp/.X11-unix"))
+                          (mkdir-p directory)
+                          (chmod directory #o777))))))
+
 
 ;;;
 ;;; The default set of desktop services.
@@ -912,6 +932,8 @@ with the administrator's password."
 
          (ntp-service)
 
+         x11-socket-directory-service
+
          %base-services))
 
 ;;; desktop.scm ends here