services: elogind: Support hook directories.

Allow the user to specify scripts to be added into Elogind's hook
directories. These scripts will be run before/after
suspend/hibernate/poweroff/reboot.

Also allow setting the associated config options.

* gnu/services/desktop.scm (elogind-configuration): add
`system-sleep-hook-files`, `system-shutdown-hook-files`,
and 4 new config options.
(elogind-configuration-file): Add entries for the new config options
under the `[Sleep]` section.
(elogind-etc-directory): New procedure.
(elogind-service-type): Extend `etc-service-type` using `/etc/elogind`.
* doc/guix.texi (Desktop Services): Document the new options.

Change-Id: I7e22cbaa9d031049b9d085ba0ce4cc8a8b4f16ff
Reviewed-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

doc/guix.texi

@@ -134,6 +134,7 @@ Copyright @copyright{} 2024 Arnaud Daby-Seesaram@*
 Copyright @copyright{} 2024 Nigko Yerden@*
 Copyright @copyright{} 2024 Troy Figiel@*
 Copyright @copyright{} 2024 Sharlatan Hellseher@*
+Copyright @copyright{} 2024 45mg@*
 
 Permission is granted to copy, distribute and/or modify this document
 under the terms of the GNU Free Documentation License, Version 1.3 or
@@ -25374,6 +25375,32 @@ Data type representing the configuration of @command{elogind}.
 @item @code{suspend-estimation-seconds} (default: @code{*unspecified*}) (type: integer)
 ...
 
+@item @code{system-sleep-hook-files} (default: @code{'()}) (type: list)
+A list of executables (file-like objects) that will be installed into
+the @file{/etc/elogind/system-sleep/} hook directory. For example:
+
+@lisp
+(elogind-configuration
+ (system-sleep-hook-files
+  (list (local-file "sleep-script"))))
+@end lisp
+
+See `Hook directories' in the @code{loginctl(1)} man page for more information.
+
+@item @code{system-shutdown-hook-files} (default: @code{'()}) (type: list)
+A list of executables (file-like objects) that will be installed into
+the @file{/etc/elogind/system-shutdown/} hook directory.
+
+@item @code{allow-power-off-interrupts?} (default: @code{#f}) (type: boolean)
+@itemx @code{allow-suspend-interrupts?} (default: @code{#f}) (type: boolean)
+Whether the executables in elogind's hook directories (see above) can
+cause a power-off or suspend action to be cancelled (interrupted) by
+printing an appropriate error message to stdout.
+
+@item @code{broadcast-power-off-interrupts?} (default: @code{#t}) (type: boolean)
+@itemx @code{broadcast-suspend-interrupts?} (default: @code{#t}) (type: boolean)
+Whether an interrupt of a power-off or suspend action is broadcasted.
+
 @end table
 @end deftp
 

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 45mg <45mg.writes@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -1084,7 +1085,19 @@ and many other) available for GIO applications.")
   (hibernate-delay-seconds          elogind-hibernate-delay-seconds
                                     (default *unspecified*))
   (suspend-estimation-seconds       elogind-suspend-estimation-seconds
-                                    (default *unspecified*)))
+                                    (default *unspecified*))
+  (system-sleep-hook-files          elogind-system-sleep-hook-files
+                                    (default '()))
+  (system-shutdown-hook-files       elogind-system-shutdown-hook-files
+                                    (default '()))
+  (allow-power-off-interrupts?      elogind-allow-power-off-interrupts?
+                                    (default #f))
+  (allow-suspend-interrupts?        elogind-allow-suspend-interrupts?
+                                    (default #f))
+  (broadcast-power-off-interrupts?  elogind-broadcast-power-off-interrupts?
+                                    (default #t))
+  (broadcast-suspend-interrupts?    elogind-broadcast-suspend-interrupts?
+                                    (default #t)))
 
 (define (elogind-configuration-file config)
   (define (yesno x)
@@ -1172,7 +1185,38 @@ and many other) available for GIO applications.")
    ("HybridSleepState" (sleep-list elogind-hybrid-sleep-state))
    ("HybridSleepMode" (sleep-list elogind-hybrid-sleep-mode))
    ("HibernateDelaySec" (maybe-non-negative-integer elogind-hibernate-delay-seconds))
-   ("SuspendEstimationSec" (maybe-non-negative-integer elogind-suspend-estimation-seconds))))
+   ("SuspendEstimationSec" (maybe-non-negative-integer elogind-suspend-estimation-seconds))
+   ("AllowPowerOffInterrupts" (yesno elogind-allow-power-off-interrupts?))
+   ("AllowSuspendInterrupts" (yesno elogind-allow-suspend-interrupts?))
+   ("BroadcastPowerOffInterrupts" (yesno elogind-broadcast-power-off-interrupts?))
+   ("BroadcastSuspendInterrupts" (yesno elogind-broadcast-suspend-interrupts?))))
+
+(define (elogind-etc-directory config)
+  "Return the /etc/elogind directory for CONFIG."
+  (with-imported-modules (source-module-closure '((guix build utils)))
+    (computed-file
+     "etc-elogind"
+
+     #~(begin
+         (use-modules (guix build utils))
+
+         (define sleep-directory (string-append #$output "/system-sleep/"))
+         (define shutdown-directory (string-append #$output "/system-shutdown/"))
+
+         (define (copy-script file directory)
+           "Copy FILE into DIRECTORY, giving rx (500) permissions."
+           (let ((dest (string-append directory "/" (basename file))))
+             (mkdir-p directory)
+             (copy-file file dest)
+             (chmod dest #o500)))
+
+         (mkdir-p #$output)            ;in case neither directory gets created
+         (for-each (lambda (f)
+                     (copy-script f sleep-directory))
+                   '#$(elogind-system-sleep-hook-files config))
+         (for-each (lambda (f)
+                     (copy-script f shutdown-directory))
+                   '#$(elogind-system-shutdown-hook-files config))))))
 
 (define (elogind-dbus-service config)
   "Return a @file{org.freedesktop.login1.service} file that tells D-Bus how to
@@ -1294,6 +1338,12 @@ seats.)"
                        (service-extension pam-root-service-type
                                           pam-extension-procedure)
 
+                       ;; Install sleep/shutdown hook files.
+                       (service-extension etc-service-type
+                                          (lambda (config)
+                                            `(("elogind"
+                                               ,(elogind-etc-directory config)))))
+
                        ;; We need /run/user, /run/systemd, etc.
                        (service-extension file-system-service-type
                                           (const %elogind-file-systems))))