Create a git manifest from source-repositories

As git repositories are copied into the image make a note of their
details and add them to a manifest on the build system.

This allows the code used in building an image to be found after
the image build is completed without needing to open the image up
for inspection.

Change-Id: I7dbe9e163ad38a418cf2869a81e720de2c27dfb1

elements/source-repositories/extra-data.d/98-source-repositories

@@ -88,7 +88,12 @@ function get_repos_for_element(){
                 pushd $REPO_DEST
                 sudo git fetch $CACHE_PATH $REPOREF
                 sudo git reset --hard FETCH_HEAD
+                # Get the reference in use
+                git_ref=$(git rev-parse FETCH_HEAD)
                 popd
+
+                # Write the reference being used into the source-repositories manifest
+                echo "$REPONAME git $REPOPATH $REPOLOCATION $git_ref" >> $GIT_MANIFEST
                 ;;
             tar)
                 # The top level directory of the tarball mightn't have a fixed name i.e.
@@ -168,8 +173,19 @@ if [ -e "$OLD_CACHE_BASE" ] ; then
     fi
 fi
 mkdir -p $CACHE_BASE
+# Use the IMAGE_NAME from the calling script, and make it unique with the temporary path
+GIT_MANIFEST_NAME=dib-git-manifest-$(basename ${IMAGE_NAME})
+GIT_MANIFEST_CACHE_NAME=${GIT_MANIFEST_NAME}_$(dirname ${TMP_MOUNT_PATH##*.})
+GIT_MANIFEST=$CACHE_BASE/${GIT_MANIFEST_CACHE_NAME}
+rm -f $GIT_MANIFEST
 
 # Get source repositories for the target
 for _SOURCEREPO in $(find $TMP_HOOKS_PATH -maxdepth 1 -name "source-repository-*" -not -name '*~'); do
     get_repos_for_element $_SOURCEREPO
 done
+
+# Copy the manifest into the image if it exists (there may be no git repositories used)
+if [ -e "$GIT_MANIFEST" ] ; then
+    sudo cp $GIT_MANIFEST $TMP_MOUNT_PATH/etc/$GIT_MANIFEST_NAME
+    sudo mv $GIT_MANIFEST $(dirname ${IMAGE_NAME})/$GIT_MANIFEST_NAME
+fi