lbu: remount LBU_MEDIA as read-write if it was read-only

ref #477

lbu.in

 #!/bin/sh
 
 # lbu - utility to create local backups.
-# Copyright (c) 2006 Natanael Copa
+# Copyright (c) 2006-2010 Natanael Copa <ncopa@alpinelinux.org>
 # May be distributed under GPL2
 
 VERSION=@VERSION@
@@ -54,6 +54,9 @@ Common options:
 
 cleanup() {
 	local i
+	for i in $REMOUNT_RO_LIST; do
+		mount -o remount,ro $i
+	done
 	for i in $UMOUNT_LIST; do
 		umount $i
 	done
@@ -64,9 +67,30 @@ exit_clean() {
 	exit 1
 }
 
+# check if given dir is not a mounted mountpoint
+is_unmounted() {
+	awk "\$2 == \"$1\" {exit 1}" /proc/mounts
+}
+
 mount_once() {
-	if awk "\$2 == \"$1\" {exit 1}" /proc/mounts; then
-		mount $1 && UMOUNT_LIST="$1 $UMOUNT_LIST"
+	if is_unmounted "$1"; then
+		mount $1 && UMOUNT_LIST="$1 $UMOUNT_LIST" || return 1
+	fi
+}
+
+# check if given dir is read-only
+is_ro() {
+	local tmpfile=$(mktemp -p "$1")
+	[ -z "$tmpfile" ] && return 0
+	rm -f "$tmpfile"
+	return 1
+}
+
+mount_once_rw() {
+	mount_once "$1" || return 1
+	if is_ro "$1"; then
+		REMOUNT_RO_LIST="$1 $REMOUNT_RO_LIST"
+		mount -o remount,rw "$1"
 	fi
 }
 
@@ -385,7 +409,7 @@ cmd_commit() {
 	# mount media unles its already mounted
 	mnt=/media/$media
 	[ -d "$mnt" ] || usage
-	mount_once "$mnt" || die "failed to mount $mnt"
+	mount_once_rw "$mnt" || die "failed to mount $mnt"
 
 	# find the outfile
 	outfile="$mnt/$(hostname).apkovl.tar.gz"
@@ -538,7 +562,7 @@ cmd_revert() {
 	if [ -n "$ENCRYPTION" ]; then
 		current="$current.$ENCRYPTION"
 	fi
-	mount_once "$mnt" || die "failed to mount $mnt"
+	mount_once_rw "$mnt" || die "failed to mount $mnt"
 	[ -f "$revertto" ] || die "file not found: $revertto"
 	backup_apkovl "$current"
 	vecho "Reverting to $1"