systemd.bbclass: make easier handle service enabling

This generates the postinst/prerm/postrm routines for the package
specified in SYSTEMD_PACKAGES avoding code duplication and
centralizing the handling of it for easy maintainence work.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>

meta-oe/classes/systemd.bbclass

@@ -0,0 +1,78 @@
+SYSTEMDPN ?= "${PN}"
+
+DEPENDS_append = " systemd-systemctl-native"
+RDEPENDS_${SYSTEMDPN}_append = " systemd"
+
+systemd_postinst() {
+OPTS=""
+
+if [ -n "$D" ]; then
+    OPTS="--root=$D"
+fi
+
+systemctl $OPTS enable ${SYSTEMD_SERVICE}
+
+if [ -z "$D" ]; then
+    systemctl start ${SYSTEMD_SERVICE}
+fi
+}
+
+systemd_prerm() {
+if [ -z "$D" ]; then
+    systemctl stop ${SYSTEMD_SERVICE}
+fi
+}
+
+systemd_postrm() {
+systemctl disable ${SYSTEMD_SERVICE}
+}
+
+def systemd_after_parse(d):
+    if bb.data.getVar('SYSTEMD_PACKAGES', d) == None:
+        if bb.data.getVar('SYSTEMD_SERVICE', d) == None:
+            raise bb.build.FuncFailed, "%s inherits systemd but doesn't set SYSTEMD_SERVICE" % bb.data.getVar('FILE', d)
+
+python __anonymous() {
+    systemd_after_parse(d)
+}
+
+python populate_packages_prepend () {
+	def systemd_package(pkg):
+		bb.debug(1, 'adding systemd calls to postinst/postrm for %s' % pkg)
+		localdata = bb.data.createCopy(d)
+		overrides = bb.data.getVar("OVERRIDES", localdata, 1)
+		bb.data.setVar("OVERRIDES", "%s:%s" % (pkg, overrides), localdata)
+		bb.data.update_data(localdata)
+
+		"""
+		systemd postinst is appended here because pkg_postinst may require to
+		execute on the target. Not doing so may cause systemd postinst invoked
+		twice to cause unwanted warnings.
+		""" 
+		postinst = bb.data.getVar('pkg_postinst', localdata, 1)
+		if not postinst:
+			postinst = '#!/bin/sh\n'
+		postinst += bb.data.getVar('systemd_postinst', localdata, 1)
+		bb.data.setVar('pkg_postinst_%s' % pkg, postinst, d)
+
+		prerm = bb.data.getVar('pkg_prerm', localdata, 1)
+		if not prerm:
+			prerm = '#!/bin/sh\n'
+		prerm += bb.data.getVar('systemd_prerm', localdata, 1)
+		bb.data.setVar('pkg_prerm_%s' % pkg, prerm, d)
+
+	        postrm = bb.data.getVar('pkg_postrm', localdata, 1)
+	        if not postrm:
+	                postrm = '#!/bin/sh\n'
+                postrm += bb.data.getVar('systemd_postrm', localdata, 1)
+		bb.data.setVar('pkg_postrm_%s' % pkg, postrm, d)
+
+	pkgs = bb.data.getVar('SYSTEMD_PACKAGES', d, 1)
+	if pkgs == None:
+		pkgs = bb.data.getVar('SYSTEMDPN', d, 1)
+		packages = (bb.data.getVar('PACKAGES', d, 1) or "").split()
+		if not pkgs in packages and packages != []:
+			pkgs = packages[0]
+	for pkg in pkgs.split():
+		systemd_package(pkg)
+}