lib/archroot.sh: Add is_btrfs helper

archbuild.in

@@ -52,7 +52,7 @@ if ${clean_first} || [[ ! -d "${chroots}/${repo}-${arch}" ]]; then
 
 		lock 9 "$copy.lock" "Locking chroot copy '$copy'"
 
-		if [[ "$(stat -f -c %T "${copy}")" == btrfs ]]; then
+		if is_btrfs "${copy}"; then
 			{ type -P btrfs && btrfs subvolume delete "${copy}"; } &>/dev/null
 		fi
 		rm -rf --one-file-system "${copy}"

lib/archroot.sh

@@ -12,3 +12,11 @@ check_root() {
 		exec su root -c "$(printf ' %q' "${orig_argv[@]}")"
 	fi
 }
+
+##
+#  usage : is_btrfs( $path )
+# return : whether $path is on a btrfs
+##
+is_btrfs() {
+	[[ -e "$1" && "$(stat -f -c %T "$1")" == btrfs ]]
+}

makechrootpkg.in

@@ -96,7 +96,7 @@ create_chroot() {
 		slock 8 "$chrootdir/root.lock" "Locking clean chroot"
 
 		stat_busy "Creating clean working copy [$copy]"
-		if [[ "$chroottype" == btrfs ]] && ! mountpoint -q "$copydir"; then
+		if is_btrfs "$chrootdir" && ! mountpoint -q "$copydir"; then
 			if [[ -d $copydir ]]; then
 				btrfs subvolume delete "$copydir" >/dev/null ||
 					die "Unable to delete subvolume %s" "$copydir"
@@ -119,7 +119,7 @@ create_chroot() {
 
 clean_temporary() {
 	stat_busy "Removing temporary copy [$copy]"
-	if [[ "$chroottype" == btrfs ]] && ! mountpoint -q "$copydir"; then
+	if is_btrfs "$chrootdir" && ! mountpoint -q "$copydir"; then
 		btrfs subvolume delete "$copydir" >/dev/null ||
 			die "Unable to delete subvolume %s" "$copydir"
 	else
@@ -285,9 +285,6 @@ chrootdir=$(readlink -e "$passeddir")
 [[ ! -d $chrootdir ]] && die "No chroot dir defined, or invalid path '%s'" "$passeddir"
 [[ ! -d $chrootdir/root ]] && die "Missing chroot dir root directory. Try using: mkarchroot %s/root base-devel" "$chrootdir"
 
-# Detect chrootdir filesystem type
-chroottype=$(stat -f -c %T "$chrootdir")
-
 if [[ ${copy:0:1} = / ]]; then
 	copydir=$copy
 else

mkarchroot.in

@@ -57,7 +57,7 @@ mkdir -p "$working_dir"
 
 lock 9 "${working_dir}.lock" "Locking chroot"
 
-if [[ $(stat -f -c %T "$working_dir") == btrfs ]]; then
+if is_btrfs "$working_dir"; then
 	rmdir "$working_dir"
 	if ! btrfs subvolume create "$working_dir"; then
 		die "Couldn't create subvolume for '%s'" "$working_dir"