restart create_ap after suspend-and-resume

Uses the /lib/systemd/system-sleep mechanism.
See https://www.freedesktop.org/software/systemd/man/systemd-suspend.service.html for how this works.

For unclear reasons, this only works in /lib/systemd/system-sleep, not in /usr/lib/systemd/system-sleep.

(ping #153, #167)

Makefile

@@ -10,6 +10,7 @@ install:
 	install -Dm755 create_ap $(DESTDIR)$(BINDIR)/create_ap
 	install -Dm644 create_ap.conf $(DESTDIR)/etc/create_ap.conf
 	[ ! -d /lib/systemd/system ] || install -Dm644 create_ap.service $(DESTDIR)$(PREFIX)/lib/systemd/system/create_ap.service
+	[ ! -d /lib/systemd/system-sleep ] || install -Dm755 create_ap.resume $(DESTDIR)/lib/systemd/system-sleep/create_ap.resume
 	[ ! -e /sbin/openrc-run ] || install -Dm755 create_ap.openrc $(DESTDIR)/etc/init.d/create_ap
 	install -Dm644 bash_completion $(DESTDIR)$(PREFIX)/share/bash-completion/completions/create_ap
 	install -Dm644 README.md $(DESTDIR)$(PREFIX)/share/doc/create_ap/README.md
@@ -18,6 +19,7 @@ uninstall:
 	rm -f $(DESTDIR)$(BINDIR)/create_ap
 	rm -f $(DESTDIR)/etc/create_ap.conf
 	[ ! -f /lib/systemd/system/create_ap.service ] || rm -f $(DESTDIR)$(PREFIX)/lib/systemd/system/create_ap.service
+	[ ! -f /lib/systemd/system-sleep/create_ap.resume ] || rm -f $(DESTDIR)$(PREFIX)/lib/systemd/system/create_ap.resume
 	[ ! -e /sbin/openrc-run ] || rm -f $(DESTDIR)/etc/init.d/create_ap
 	rm -f $(DESTDIR)$(PREFIX)/share/bash-completion/completions/create_ap
 	rm -f $(DESTDIR)$(PREFIX)/share/doc/create_ap/README.md

create_ap.resume

@@ -0,0 +1,11 @@
+#!/bin/sh
+set -e
+
+# After resume, restart create_ap service (if it was already running)
+# See:
+#   https://www.freedesktop.org/software/systemd/man/systemd-suspend.service.html
+
+case "$1" in
+    pre) ;;
+    post) /bin/systemctl try-restart create_ap.service ;;
+esac