Add scriptlets for migration away from systemd-timedated-ntp.target

F17 had systemd-timedated-ntp.target. The target is gone in F18.
We want to ensure that users who had their NTP services enabled
indirectly via the target in F17 will still have them enabled after
upgrading to F18.

We use the %pretrans step to record which NTP services to enable.
Doing it in %pre would be too late. %pretrans has to be in lua.
The actual enabling of the NTP services is done in %post.

systemd.spec

@@ -22,7 +22,7 @@ Url:            http://www.freedesktop.org/wiki/Software/systemd
 # THIS PACKAGE FOR A NON-RAWHIDE DEVELOPMENT DISTRIBUTION!
 
 Version:        194
-Release:        1%{?gitcommit:.git%{gitcommit}}%{?dist}
+Release:        2%{?gitcommit:.git%{gitcommit}}%{?dist}
 # For a breakdown of the licensing, see README
 License:        LGPLv2+ and MIT and GPLv2+
 Summary:        A System and Service Manager
@@ -293,6 +293,42 @@ glib-based applications using libudev functionality.
 /usr/bin/mv -n %{_sysconfdir}/systemd/systemd-logind.conf %{_sysconfdir}/systemd/logind.conf >/dev/null 2>&1 || :
 /usr/bin/mv -n %{_sysconfdir}/systemd/systemd-journald.conf %{_sysconfdir}/systemd/journald.conf >/dev/null 2>&1 || :
 
+%pretrans -p <lua>
+--# Migrate away from systemd-timedated-ntp.target.
+--# Take note which ntp services, if any, were pulled in by it.
+--# We'll enable them the usual way in %%post.
+--# Remove this after upgrades from F17 are no longer supported.
+function migrate_ntp()
+    --# Are we upgrading from a version that had systemd-timedated-ntp.target?
+    t = posix.stat("/usr/lib/systemd/system/systemd-timedated-ntp.target", "type")
+    if t ~= "regular" then return end
+
+    --# Was the target enabled?
+    t = posix.stat("/etc/systemd/system/multi-user.target.wants/systemd-timedated-ntp.target", "type")
+    if t ~= "link" then return end
+
+    --# filesystem provides /var/lib/rpm-state since F17 GA
+    r,msg,errno = posix.mkdir("/var/lib/rpm-state/systemd")
+    if r == nil and errno ~= 17 then return end  --# EEXIST is fine.
+
+    --# Save the list of ntp services pulled by the target.
+    f = io.open("/var/lib/rpm-state/systemd/ntp-units", "w")
+    if f == nil then return end
+
+    files = posix.dir("/usr/lib/systemd/system/systemd-timedated-ntp.target.wants")
+    for i,name in ipairs(files) do
+        if name ~= "." and name ~= ".." then
+            s = string.format("%s\n", name)
+            f:write(s)
+        end
+    end
+
+    f:close()
+end
+
+migrate_ntp()
+return 0
+
 %post
 /usr/bin/systemd-machine-id-setup > /dev/null 2>&1 || :
 /usr/lib/systemd/systemd-random-seed save > /dev/null 2>&1 || :
@@ -325,6 +361,18 @@ else
         # This systemd service does not exist anymore, we now do it
         # internally in PID 1
         /usr/bin/rm -f /etc/systemd/system/sysinit.target.wants/hwclock-load.service >/dev/null 2>&1 || :
+
+        # This systemd target does not exist anymore. It's been replaced
+        # by ntp-units.d.
+        /usr/bin/rm -f /etc/systemd/system/multi-user.target.wants/systemd-timedated-ntp.target >/dev/null 2>&1 || :
+
+        # Enable the units recorded by %%pretrans
+        if [ -e /var/lib/rpm-state/systemd/ntp-units ] ; then
+                while read service; do
+                        /usr/bin/systemctl enable "$service" >/dev/null 2>&1 || :
+                done < /var/lib/rpm-state/systemd/ntp-units
+                /usr/bin/rm -r /var/lib/rpm-state/systemd/ntp-units
+	fi
 fi
 
 # Migrate /etc/sysconfig/clock
@@ -582,6 +630,9 @@ fi
 %{_libdir}/pkgconfig/gudev-1.0*
 
 %changelog
+* Wed Oct 10 2012 Michal Schmidt <mschmidt@redhat.com> - 194-2
+- Add scriptlets for migration away from systemd-timedated-ntp.target
+
 * Wed Oct  3 2012 Lennart Poettering <lpoetter@redhat.com> - 194-1
 - New upstream release
 - https://bugzilla.redhat.com/show_bug.cgi?id=859614