#!/bin/bash
# vi: ts=4 noexpandtab

TEMP_D=""

error() { echo "$@" 1>&2; }
debug() {
	[ "${DEBUG}" -ge "${1}" ] || return 0;
	shift;
	error "$@"
}
fail() { [ $# -eq 0 ] || error "$@"; exit 1; }
Usage() {
	cat <<EOF
Usage: ${0##*/} initramfs_dir root_dir
   create an initramfs from initramfs_dir, copying files from root_dir

   Example:
    ${0##*/} initramfs/ rootfs/ > my.initramfs.img
EOF
}
bad_Usage() { Usage 1>&2; fail "$@"; }
cleanup() {
	[ -z "${TEMP_D}" -o ! -d "${TEMP_D}" ] || rm -Rf "${TEMP_D}"
}

short_opts="hv"
long_opts="help,verbose"
getopt_out=$(getopt --name "${0##*/}" \
	--options "${short_opts}" --long "${long_opts}" -- "$@") &&
	eval set -- "${getopt_out}" ||
	bad_Usage

while [ $# -ne 0 ]; do
	cur=${1}; next=${2};
	case "$cur" in
		-h|--help) Usage; exit 0;;
		-v|--verbose) DEBUG=$((${DEBUG}+1));;
		--) shift; break;;
	esac
	shift;
done

[ $# -eq 2 ] || bad_Usage "must give initramfs_dir and root_dir"
initramfs_d=${1}
root_d=${2}

[ -d "$initramfs_d" ] || fail "$initramfs_d is not a dir"
[ -d "$root_d" ] || fail "$root_d is not a dir"

TEMP_D=$(mktemp -d "${TMPDIR:-/tmp}/.${0##*/}.XXXXXX") ||
	fail "failed to make tempd"
trap cleanup EXIT

work_d="${TEMP_D}/workd"
src_d="$initramfs_d/src"
needs="$initramfs_d/needs"

[ -f "$needs" ] || fail "$needs is not a file"
[ -d "$src_d" ] || fail "$src_d is not a dir"

mkdir -p "${work_d}/"{bin,sbin,usr/bin,usr/sbin}

while read need; do
	need=${need%%#*}; need=${need% };
	[ -n "$need" ] || continue
	[ "${need#*..}" = "${need}" ] || fail "paths cannot have ..: $need"
	if [ -e "$root_d/$need" ]; then
		mkdir -p "$work_d/${need%/*}" &&
		cp -a "$root_d/$need" "$work_d/$need" ||
		fail "failed to copy $need to working dir"
	else
		fail "$need not found in $root_d"
	fi
done < $needs

loaders=$(cd "$root_d" &&
	echo lib/ld-uClibc.so.0 lib/ld-uClibc-*.so \
		lib/ld64-uClibc.so.0 lib/ld64-uClibc-*.so)

for f in $loaders; do
	[ -f "$root_d/$f" ] || continue
	mkdir -p "${work_d}/${f%/*}" &&
	cp -a "$root_d/$f" "$work_d/$f" ||
		fail "failed to copy $f"
done

rsync -a "$src_d/" "$work_d" ||
	fail "failed to sync $src_d to working dir"

( cd "${work_d}" && find . | cpio --quiet --dereference -o -H newc | gzip -9 )

exit 0