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+;;; gnus-dbus.el --- DBUS integration for Gnus       -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2020  Free Software Foundation, Inc.
+
+;; Author: Eric Abrahamsen <eric@ericabrahamsen.net>
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; This library contains some Gnus integration for systems using DBUS.
+;; At present it registers a signal to close all Gnus servers before
+;; system sleep or hibernation.
+
+;;; Code:
+
+(require 'gnus)
+(require 'dbus)
+(declare-function gnus-close-all-servers "gnus-start")
+
+(defcustom gnus-dbus-close-on-sleep nil
+  "When non-nil, close Gnus servers on system sleep."
+  :group 'gnus-dbus
+  :type 'boolean)
+
+(defvar gnus-dbus-sleep-registration-object nil
+  "Object returned from `dbus-register-signal'.
+Used to unregister the signal.")
+
+(defun gnus-dbus-register-sleep-signal ()
+  "Use `dbus-register-signal' to close servers on sleep."
+  (when (featurep 'dbusbind)
+    (setq gnus-dbus-sleep-registration-object
+	  (dbus-register-signal :system
+				"org.freedesktop.login1"
+				"/org/freedesktop/login1"
+				"org.freedesktop.login1.Manager"
+				"PrepareForSleep"
+				#'gnus-dbus-sleep-handler))
+    (gnus-add-shutdown #'gnus-dbus-unregister-sleep-signal 'gnus)))
+
+(defun gnus-dbus-sleep-handler (sleep-start)
+  ;; Sleep-start is t before sleeping.
+  (when (and sleep-start
+	     (gnus-alive-p))
+    (condition-case nil
+	(gnus-close-all-servers)
+      (error nil))))
+
+(defun gnus-dbus-unregister-sleep-signal ()
+  (condition-case nil
+      (dbus-unregister-object
+       gnus-dbus-sleep-registration-object)
+    (wrong-type-argument nil)))
+
+(provide 'gnus-dbus)
+;;; gnus-dbus.el ends here