systemd: Intermediate --chroot fix with the new sd_notify() implementation

systemd: Intermediate --chroot fix with the new sd_notify() implementation

Commit c5931897ae8d663e7e introduced support for talking directly
to the systemd service manager about the situation for the OpenVPN
tunnel. This approach makes a lot of sense and is mostly the proper
way to do it.  But it was discovered that it breaks OpenVPN
configurations using --chroot.

The reason sd_notify() calls fails when using chroot() is that
sd_notify() expects to have access to a file as declared in the
$NOTIFY_SOCKET environment variable.  It is the main systemd
instance which is responsible to provide both the environment variable
as well as the socket file sd_nodify() should use.  When --chroot
comes into play, the $NOTIFY_SOCKET file will not be available
for OpenVPN any more.

As things are getting close to the 2.4_rc2 release we will not dare
to bring a too invasive fix.  As well we need some time to discuss
an approrpriate solution.  So this intermediate fix will only
provide a "successful start" message to the systemd service manager
right before chroot() happens.  This will at least resolve the issue
in a safe and non-intrusive way.

Signed-off-by: David Sommerseth <davids@openvpn.net>
Acked-by: Christian Hesse <mail@eworm.de>
Message-Id: <1481079112-22990-1-git-send-email-davids@openvpn.net>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg13416.html