Custom script to update submodules

- If the submodule doesn't eixst yet, then submodule update is called
- If the submodule points at the right commit then nothing happens.
- If the submodule is pointed at any other commit, this script will attempt to rebase.
  - If the rebase fails (for any reason!) then the local HEAD is used rather than just switching to whatever upstream uses.

All automatic updating is disabled by default.
Set submodule.update=true in private.properties to enable.

Change-Id: I9f370a33001bbfea5079687a41cc9cbfa07eea33
Reviewed-on: http://gerrit.dmdirc.com/326
Reviewed-by: Gregory Holmes <greboid@dmdirc.com>
Tested-by: Gregory Holmes <greboid@dmdirc.com>

build.xml

@@ -12,6 +12,51 @@
     <import file="build-tests.xml"/>
     <import file="build-versioning.xml"/>
 
+    <target name="-submodules" depends="-submodules-bash, -submodules-default"/>
+
+    <target name="-check-use">
+        <!-- Use script iff:
+               - bash is available
+               - submodule.update is set to true
+        -->
+        <condition property="use.bash.submodule">
+            <and>
+                <equals arg1="${submodule.update}" arg2="true" />
+                <equals arg1="${has.bash}" arg2="true" />
+            </and>
+        </condition>
+        
+        <!-- Use git's built in commands iff:
+             - submodule.update is set to true
+             - bash is not available
+        -->
+        <condition property="use.default.submodule">
+            <and>
+                <equals arg1="${submodule.update}" arg2="true" />
+                <equals arg1="${has.bash}" arg2="false" />
+            </and>
+        </condition>
+    </target>
+
+
+    <target name="-submodules-bash" depends="-check-use" if="use.bash.submodule">
+        <exec executable="/bin/bash">
+            <arg value="updateSubModules.sh"/>
+        </exec>
+    </target>
+
+    <target name="-submodules-default" depends="-check-use" if="use.default.submodule">
+        <exec executable="git">
+            <arg value="submodule"/>
+            <arg value="init"/>
+        </exec>
+        <exec executable="git">
+            <arg value="submodule"/>
+            <arg value="update"/>
+        </exec>
+    </target>
+
+    <target name="-pre-init" depends="-submodules"/>
     <target name="-post-compile" depends="-write-version, build-plugins, -addpluginlibs"/>
     <target name="-post-test-run" depends="-do-test-reports"/>
     <target name="-post-jar" depends="-addjarlibs"/>

updateSubModules.sh

@@ -0,0 +1,44 @@
+#!/bin/bash
+GIT=`which git`
+
+# Init any new submodules
+${GIT} submodule init
+
+DIR=${PWD}
+
+# Check every submodule.
+${GIT} submodule status | while read -r LINE; do
+	MISSING=`echo ${LINE} | grep ^-`
+	CHANGED=`echo ${LINE} | grep ^+`
+	MODULE=`echo ${LINE} | awk '{print $2}'`
+	
+	# If the module hasn't been checked out yet, then checkout.
+	if [ "${MISSING}" != "" ]; then
+		${GIT} submodule update ${MODULE}
+		if [ ${?} -ne 0 ]; then
+			echo "Error: Unable to update submodule ${MODULE}, aborting."
+			exit 1;
+		fi;
+	# Else, rebase current changes onto the new upstream version.
+	#   - If nothing has changed, this will just be a fast forward like normal
+	#   - If there are uncommited changes, this will fail and leave the submodule
+	#     as it is at the moment.
+	#   - If there are commited revisions on top of the submodule, then they will
+	#     be rebased onto the revision used upstream,
+	elif [ "${CHANGED}" != "" ]; then
+		# Get the revision used upstream
+		OLDREV=`git diff ${MODULE} | grep -- "-Subproject" | awk '{print $3}'`
+		if [ "${OLDREV}" != "" ]; then
+			cd ${MODULE}
+			${GIT} fetch origin 
+			${GIT} rebase ${OLDREV}
+			if [ ${?} -ne 0 ]; then
+				echo "Error: Rebase failed on ${MODULE}, continuing with current HEAD."
+				${GIT} rebase --abort
+			fi;
+		fi;
+	fi;
+	
+	# Go back to main project directory.
+	cd ${DIR}
+done;