#!/bin/sh
# デバイスイメージファイルの生成
# Usage: bin/img-gen
# Required: gzip awk fallocate parted xargs losetup mkfs.fat tar
cd -- "$(dirname -- "$0")/.."
set -eux
size="$(gzip -l megabit-armhf.tar.gz | awk 'END{printf"%.f",$2*1.02}')"
fallocate -l "${size}" megabit-armhf.img
xargs -l parted -s megabit-armhf.img <<EOF
mklabel msdos
mkpart primary fat32 0 100%
set 1 boot on
EOF
dev="$(losetup -f)"
finally="losetup -d '${dev}'"
trap 'sh -c "${finally}"' EXIT
losetup -P "${dev}" megabit-armhf.img
part="${dev}p1"
mkfs.fat "${part}"
tmp="$(mktemp -d)"
finally="rmdir '${tmp}'; ${finally}"
mount "${part}" "${tmp}"
finally="umount '${tmp}'; ${finally}"
tar xf megabit-armhf.tar.gz -C "${tmp}"
finally="${finally}; gzip -f megabit-armhf.img"