overlay: added sopport for -n to overlay_apply to disable overwriting

lib/overlay/overlay-functions.in

@@ -2,7 +2,7 @@
 # This copyright note is auto-generated by ./scripts/Create-CopyPatch.
 #
 # Filename: lib/overlay/overlay-functions.in
-# Copyright (C) 2007 - 2008 The OpenSDE Project
+# Copyright (C) 2007 - 2009 The OpenSDE Project
 #
 # More information can be found in the files COPYING and README.
 #
@@ -14,8 +14,7 @@
 
 # returns the type of overlay based on the extension of the overlay file
 #
-overlay_get_type()
-{
+overlay_get_type() {
 	local ext="${1##*.}"
 
 	case "$ext" in
@@ -28,8 +27,7 @@ overlay_get_type()
 
 # returns the name of a target file based on the name overlay file
 #
-overlay_get_filename()
-{
+overlay_get_filename() {
 	local filename="${1##*/}"; filename="${filename%.*}"
 
 	# rock_substitute will add a leading / for most translations
@@ -38,10 +36,18 @@ overlay_get_filename()
 
 # apply an overlay dir
 overlay_apply() {
-	local overlaydir="$1" rootfs="${2:-$root}"
-	local file= source= target= ext=
+	local overlaydir= rootfs=
+	local file= source= target= fulltarget= ext=
 	local type= mode= ref= targetdir=
 	local patchopt="-p1 --no-backup-if-mismatch -N"
+	local overwrite=yes
+
+	if [ "x$1" = "x-n" ]; then
+		overwrite=
+		shift
+	fi
+
+	overlaydir="$1" rootfs="${2:-$root}"
 
 	for file in "$overlaydir"/*; do
 		# only consider known overlay types
@@ -50,7 +56,16 @@ overlay_apply() {
 
 		# full filename of the target file, and it's directory
 		target=$( overlay_get_filename "$file" )
-		targetdir="$rootfs/$target"; targetdir="${targetdir%/*}"
+		fulltarget="$rootfs/$target" targetdir="${fulltarget%/*}"
+
+		if [ -L "$rootfs/$target" -o -e "$rootfs/$target" ]; then
+			if [ "$overwrite" = yes ]; then
+				[ "$type" = patch ] || rm -f "$fulltarget"
+			else
+				echo_status "skipping $target ($type)"
+				continue
+			fi
+		fi
 
 		# final adjustments based on the type
 		case "$type" in
@@ -63,7 +78,6 @@ overlay_apply() {
 			exec|txt)
 				echo_status "injecting $target ($type)"
 				mkdir -p "$targetdir"
-				[ ! -L "$rootfs/$target" ] || rm -f "$rootfs/$target"
 				cat "$file" | rock_substitute > "$rootfs/$target"
 				chmod $mode "$rootfs/$target"
 				;;
@@ -79,4 +93,3 @@ overlay_apply() {
 		esac
 	done
 }
-