Bug#768456: Version 3 including ansgar's and pitti's feedback

[Didier Roche]

Here is the v3 of the patch, which includes ansgar's and pitti's 
feedback. Thanks to them!

The only suggestion I couldn't integrate is Martin's system vs exec one. 
I had to change keep it as system() call as we are evaluating one unit 
after another as the scripts can accepts multiple units, and so exec 
would prefer the evaluation and inclusion of other units passed as 
parameters.
Does this make sense? The downside is that we loose the return code, 
indeed (we could concatenate it if needed).

Cheers,
Didier
diff -Nru init-system-helpers-1.21/debian/changelog 
init-system-helpers-1.22/debian/changelog
--- init-system-helpers-1.21/debian/changelog   2014-08-21 07:40:58.000000000 
+0200
+++ init-system-helpers-1.22/debian/changelog   2014-11-07 15:13:08.000000000 
+0100
@@ -1,3 +1,16 @@
+init-system-helpers (1.22) UNRELEASED; urgency=medium
+
+  * deb-system-invoke: don't start disabled systemd services (in case
+    of systemd only services), when there is no init script.
+    Add some conditions to start the job on deb-system-invoke [restart|start],
+    during package upgrade: (Closes: #768456)
+    - deb-system-invoke start <unit> don't do anything on systemd if the
+      service is disabled.
+    - deb-system-invoke restart <unit> only restart a disabled service if
+      if the daemon was already running (forced by the admin).
+
+ -- Didier Roche <didro...@ubuntu.com>  Fri, 07 Nov 2014 15:01:27 +0100
+
 init-system-helpers (1.21) unstable; urgency=medium
 
   * Demote augeas-tools to Suggests and let the systemd2init tool error out
diff -Nru init-system-helpers-1.21/script/deb-systemd-invoke 
init-system-helpers-1.22/script/deb-systemd-invoke
--- init-system-helpers-1.21/script/deb-systemd-invoke  2014-08-21 
07:40:58.000000000 +0200
+++ init-system-helpers-1.22/script/deb-systemd-invoke  2014-11-07 
17:08:10.000000000 +0100
@@ -77,4 +77,24 @@
     }
 }
 
-exec '/bin/systemctl', @ARGV;
+# If the job is disabled and is not currently running, the job is not started 
or restarted.
+# However, if the job is disabled but has been forced into the running state, 
we *do* stop
+# and restart it since this is expected behaviour for the admin who forced the 
start.
+if ($action eq "start" || $action eq "restart") {
+    for my $unit (@units) {
+        system('/bin/systemctl', '--quiet', 'is-enabled', '--', $unit);
+        my $unit_enabled = $?>>8 == 0 ? 1 : 0;
+        system('/bin/systemctl', '--quiet', 'is-active', '--', $unit);
+        my $unit_active = $?>>8 == 0 ? 1 : 0;
+        if (!$unit_enabled && $action eq "start") {
+            print STDERR "$unit is disabled, not starting it.\n";
+        } elsif (!$unit_enabled && !$unit_active && $action eq "restart") {
+            print STDERR "$unit is disabled and not running, not starting 
it.\n";
+        }
+        else {
+            system('/bin/systemctl', "$action", "$unit");
+        }
+    }
+} else {
+    exec '/bin/systemctl', @ARGV;
+}