#!/bin/sh
# オーバーレイイメージファイルの生成
# Usage: bin/overlay-gen dist/overlay.img
# Required: fallocate losetup mkfs.ext4 gzip
cd -- "$(dirname -- "$0")/.."
set -eux
size=512m
image="$1"
fallocate -l "${size}" "${image}"
mkfs.ext4 "${image}"
dev="$(losetup -f)"
finally="losetup -d '${dev}'"
trap 'sh -c "${finally}"' EXIT
losetup "${dev}" "${image}"
tmp="$(mktemp -d)"
finally="rmdir '${tmp}'; ${finally}"
mount "${dev}" "${tmp}"
finally="umount '${tmp}'; ${finally}"
mkdir -p "${tmp}/work/usr"
mkdir -p "${tmp}/upper/usr"