Convert file trigger scripts to lua

At least the %filetriggerpostun script can be invoked hundreds of
times during an upgrade, so it makes sense to optimize it a bit.

assert(exec(...)) is used because of https://bugzilla.redhat.com/show_bug.cgi?id=1094072.

Add -P (--priority) to have %filetriggerpostun run as early as
possible (before any reload/stop actions), and %transfiletriggerin as
late as possible (after any enable/disable/preset actions).

src/core/triggers.systemd.in

@@ -19,34 +19,46 @@
 
 # The contents of this are an example to be copied into systemd.spec.
 
-# This will run after any package is initially installed or
-# upgraded. We care about the case where a package is initially
-# installed, because other cases are covered by the scriptlets below,
-# so sometimes we will reload needlessly.
+%transfiletriggerin -P 900900 -p <lua> -- @systemunitdir@ /etc/systemd/system
+-- This script will run after any package is initially installed or
+-- upgraded. We care about the case where a package is initially
+-- installed, because other cases are covered by the *un scriptlets,
+-- so sometimes we will reload needlessly.
 
-%transfiletriggerin -- @systemunitdir@ /etc/systemd/system
-systemctl daemon-reload &>/dev/null || :
+pid = posix.fork()
+if pid == 0 then
+    assert(posix.exec("%{_bindir}/systemctl", "daemon-reload"))
+elseif pid > 0 then
+    posix.wait(pid)
+end
 
-# On removal, we need to run daemon-reload after any units have been
-# removed. %transfiletriggerpostun would be ideal, but it does not get
-# executed for some reason.
-# On upgrade, we need to run daemon-reload after any new unit files
-# have been installed, but before %postun scripts in packages get
-# executed. %transfiletriggerun gets the right list of files
-# but it is invoked too early (before changes happen).
-# %filetriggerpostun happens at the right time, but it fires for
-# every package.
-# To execute the reload at the right time, we create a state
-# file in %transfiletriggerun and execute the daemon-reload in
-# the first %filetriggerpostun.
+%transfiletriggerun -p <lua> -- @systemunitdir@ /etc/systemd/system
+-- On removal, we need to run daemon-reload after any units have been
+-- removed. %transfiletriggerpostun would be ideal, but it does not get
+-- executed for some reason.
+-- On upgrade, we need to run daemon-reload after any new unit files
+-- have been installed, but before %postun scripts in packages get
+-- executed. %transfiletriggerun gets the right list of files
+-- but it is invoked too early (before changes happen).
+-- %filetriggerpostun happens at the right time, but it fires for
+-- every package.
+-- To execute the reload at the right time, we create a state
+-- file in %transfiletriggerun and execute the daemon-reload in
+-- the first %filetriggerpostun.
 
-%transfiletriggerun -- @systemunitdir@ /etc/systemd/system
-mkdir -p %{_localstatedir}/lib/rpm-state/systemd
-touch %{_localstatedir}/lib/rpm-state/systemd/needs-reload
+posix.mkdir("%{_localstatedir}/lib")
+posix.mkdir("%{_localstatedir}/lib/rpm-state")
+posix.mkdir("%{_localstatedir}/lib/rpm-state/systemd")
+io.open("%{_localstatedir}/lib/rpm-state/systemd/needs-reload", "w")
 
-%filetriggerpostun -- @systemunitdir@ /etc/systemd/system
-if [ -e %{_localstatedir}/lib/rpm-state/systemd/needs-reload ]; then
-    rm %{_localstatedir}/lib/rpm-state/systemd/needs-reload || :
-    rmdir %{_localstatedir}/lib/rpm-state/systemd || :
-    systemctl daemon-reload || :
-fi
+%filetriggerpostun -P 1000100 -p <lua> -- @systemunitdir@ /etc/systemd/system
+if posix.access("%{_localstatedir}/lib/rpm-state/systemd/needs-reload") then
+    posix.unlink("%{_localstatedir}/lib/rpm-state/systemd/needs-reload")
+    posix.rmdir("%{_localstatedir}/lib/rpm-state/systemd")
+    pid = posix.fork()
+    if pid == 0 then
+        assert(posix.exec("%{_bindir}/systemctl", "daemon-reload"))
+    elseif pid > 0 then
+        posix.wait(pid)
+    end
+end