openwrt/package/block-extroot/files/55_determine_extroot_sysupgrade

#!/bin/sh
# Copyright (C) 2010 Daniel Dickinson
# This is free software, licensed under the GNU General Public License v2.
# See /LICENSE for more information.


check_set_md5sum() {
	local er_md5sum_file
	er_md5sum_file="${ER_OVERLAY_PREFIX}/.extroot.md5sum"
	local er_disabled
	if [ "${ER_OVERLAY_ROM}" = "/rom" ]; then
		er_disabled=/tmp/whole_root-disabled
	else
		er_disabled=/tmp${ER_OVERLAY_ROM}-disabled
	fi

	local er_extroot_md5sum
	if [ -f $md5sum_file ]; then
		er_extroot_md5sum="$(cat $er_md5sum_file)"
	fi

	local er_overlay_file="${ER_OVERLAY_ROM}/etc/extroot.md5sum"

	local er_extroot_overlay_md5sum
	if [ -f "$er_overlay_file" ]; then
		er_extroot_overlay_md5sum="$(cat $er_overlay_file)"
	fi

	if [ -z "$er_extroot_overlay_md5sum" ]; then
		cat $er_md5sum_file >$er_overlay_file
	elif [ "$er_extroot_overlay_md5sum" != "$er_extroot_md5sum" ]; then
		pi_extroot_mount_success="false"
		mkdir -p $er_disabled
		mount --move ${ER_OVERLAY_ROM} $er_disabled
	fi
}

set_jffs_md5sum() {
	# We do this anytime block-extroot exists, even on the first boot with
	# no extroot defined.

	local er_md5sum_file
	er_md5sum_file="${ER_OVERLAY_PREFIX}/.extroot.md5sum"

	local er_extroot_md5sum
	if [ -f $er_md5sum_file ]; then
		er_extroot_md5sum="$(cat $er_md5sum_file)"
	fi
	if [ -z "$er_extroot_md5sum" ]; then
		dd if=/dev/urandom count=32 bs=1k 2>/dev/null | md5sum | cut -f1 -d\  >$er_md5sum_file
	fi
}

determine_extroot_sysupgrade() {
	check_skip || set_jffs_md5sum

	check_skip || [ "$pi_extroot_mount_success" != "true" ] || {
		check_set_md5sum
	}
}

boot_hook_add preinit_mount_root determine_extroot_sysupgrade