importd: properly support operation in per-user mode

units/user/systemd-importd.socket

@@ -0,0 +1,18 @@
+#  SPDX-License-Identifier: LGPL-2.1-or-later
+#
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Disk Image Download Service Socket
+Documentation=man:systemd-importd.service(8)
+Documentation=man:org.freedesktop.import1(5)
+
+[Socket]
+ListenStream=%t/systemd/io.systemd.Import
+FileDescriptorName=varlink
+SocketMode=0600