[bug#73391] [PATCH v2 2/2] services: sane-service-type: create lock path for plustek backend

[neox]

From: Adrien 'neox' Bourmault <neox@gnu.org>

* gnu/services/desktop.scm (sane-service-type): extend with an activation
 service to create the lockpath and give the right permissions

Change-Id: I187886d12b5f0b4fe21b03de178ea2187205387a
Signed-off-by: Adrien 'neox' Bourmault <neox@gnu.org>
---
 gnu/services/desktop.scm | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/gnu/services/desktop.scm b/gnu/services/desktop.scm
index 274aeeef9b..500527cb50 100644
--- a/gnu/services/desktop.scm
+++ b/gnu/services/desktop.scm
@@ -17,6 +17,7 @@
 ;;; Copyright © 2021, 2022 muradm <mail@muradm.net>
 ;;; Copyright © 2023 Bruno Victal <mirai@makinata.eu>
 ;;; Copyright © 2023 Zheng Junjie <873216071@qq.com>
+;;; Copyright © 2024 Adrien Bourmault <neox@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -1408,6 +1409,17 @@ (define %sane-accounts
   ;; The '60-libsane.rules' udev rules refers to the "scanner" group.
   (list (user-group (name "scanner") (system? #t))))
 
+(define %sane-activation
+  #~(begin
+      (use-modules (guix build utils))
+      (let ((lockpath "/var/lock/sane")
+            (gid (vector-ref (getgrnam "scanner") 2)))
+        ;; Create the lock directory at runtime and give right perms
+        (mkdir-p lockpath)
+        (chown lockpath -1 gid)
+        (chmod lockpath #o770))
+      #t))
+
 (define sane-service-type
   (service-type
    (name 'sane)
@@ -1418,6 +1430,8 @@ (define sane-service-type
    (default-value sane-backends-minimal)
    (extensions
     (list (service-extension udev-service-type list)
+          (service-extension activation-service-type
+                             (const %sane-activation))
           (service-extension account-service-type
                              (const %sane-accounts))))))
 
-- 
2.46.0