init

mount-chroot.sh

@@ -0,0 +1,77 @@
+#!/usr/bin/env bash
+
+err() { echo "$1" >&2; }
+
+usage() {
+cat <<- EOF
+	Usage: "${0##*/}" [options] <chroot>
+	Options:
+		-s	chroot base dir
+		-n	mount name
+		-u	unmount chroot
+EOF
+}
+
+chroot.mount() {
+	for i in "$target_dir" "$chroot_base"; do
+		[[ "$i" ]] || {
+			usage
+			return 1
+		}
+	done
+
+	[[ -d "$chroot_base" ]] || {
+		err "Chroot base ($chroot_base) does not exist."
+		return 1
+	}
+
+	mount_name="${mount_name:-chroot}"
+
+	for i in "$target_dir" "${target_dir}.work"; do
+		[[ -d "$i" ]] || {
+			mkdir -p "$i" || {
+				return 3
+			}
+		}
+	done
+
+	mount -t overlayfs -o lowerdir="$chroot_base",upperdir="$target_dir",workdir="${target_dir}.work" "$mount_name" "$target_dir"
+	mount -t proc "${mount_name}_proc" "${target_dir}/proc"
+	mount --rbind /dev "${target_dir}/dev"
+	mount --rbind /sys "${target_dir}/sys"
+}
+
+chroot.umount() {
+	umount --recursive "$target_dir"
+}
+
+main() {
+	while [[ "$1" ]]; do
+		case "$1" in
+			-s) chroot_base="$2"; shift;;
+			-n) mount_name="$2"; shift;;
+			-u) action='umount';;
+
+			--) shift; break;;
+			-*)
+				err "Unknown key: $1"
+				usage
+				return 1
+			;;
+			*) break;;
+		esac
+		shift
+	done
+
+	target_dir="$1"
+	action="${action:-mount}"
+	mount_name="${mount_name:-chroot}"
+
+	case "$action" in
+		mount) chroot.mount;;
+		umount) chroot.umount;;
+	esac
+}
+
+main "$@"
+