setup-disk: write mbr to correct devices when use raid

and strip trailing / from mounted partition

setup-disk.in

@@ -3,6 +3,7 @@
 PREFIX=
 . "$PREFIX/lib/libalpine.sh"
 
+MBR=${MBR:-"/usr/share/syslinux/mbr.bin"}
 
 in_list() {
 	local i="$1"
@@ -55,7 +56,9 @@ install_mounted_root() {
 		# get a list of slaves
 		rootdisk=
 		for i in /sys/block/$md/slaves/*; do
-			rootdisk="$rootdisk /dev/${i##*/}"
+			j=${i##*/}
+			i=${j%[0-9]*}
+			rootdisk="$rootdisk /dev/${i}"
 		done
 	fi
 	chroot "$mnt" /sbin/mkinitfs -F "$features" $kernel
@@ -74,7 +77,10 @@ install_mounted_root() {
 
 	# fix mbr for all disk devices
 	for i in $rootdisk; do
-		dd if=/usr/share/syslinux/mbr.bin of=$i
+		local errmsg
+		echo "Writing MBR to $i"
+		errmsg=$(dd if="$MBR" of=$i 2>&1) \
+			|| echo "$errmsg"
 	done
 	echo ""
 	echo "Installation is done. Please reboot."
@@ -108,7 +114,7 @@ useall() {
 
 if [ -d "$1" ]; then
 	# install to given mounted root
-	install_mounted_root "$1"
+	install_mounted_root "${1%/}"
 	exit $?
 fi