1#!/bin/sh
2#
3# SPDX-License-Identifier: GPL-2.0-only
4#
5
6. /etc/default/rcS
7
8[ "$ROOTFS_READ_ONLY" = "no" ] && exit 0
9
10is_on_read_only_partition () {
11	DIRECTORY=$1
12	dir=`readlink -f $DIRECTORY`
13	while true; do
14		if [ ! -d "$dir" ]; then
15			echo "ERROR: $dir is not a directory"
16			exit 1
17		else
18			for flag in `awk -v dir=$dir '{ if ($2 == dir) { print "FOUND"; split($4,FLAGS,",") } }; \
19				END { for (f in FLAGS) print FLAGS[f] }' < /proc/mounts`; do
20				[ "$flag" = "FOUND" ] && partition="read-write"
21				[ "$flag" = "ro" ] && { partition="read-only"; break; }
22			done
23			if [ "$dir" = "/" -o -n "$partition" ]; then
24				break
25			else
26				dir=`dirname $dir`
27			fi
28		fi
29	done
30	[ "$partition" = "read-only" ] && echo "yes" || echo "no"
31}
32
33if [ "$1" = "start" ] ; then
34	if [ `is_on_read_only_partition /var/lib` = "yes" ]; then
35		grep -q "tmpfs /var/volatile" /proc/mounts || mount /var/volatile
36		mkdir -p /var/volatile/lib
37		mkdir -p /var/volatile/.lib-work
38		# Try to mount using overlay, which is much faster than copying
39		# files. If that fails, fallback to the slower copy
40		if ! mount -t overlay overlay SED_VARLIBMOUNTARGS -olowerdir=/var/lib,upperdir=/var/volatile/lib,workdir=/var/volatile/.lib-work /var/lib > /dev/null 2>&1; then
41			cp -a /var/lib/* /var/volatile/lib
42			mount SED_VARLIBMOUNTARGS --bind /var/volatile/lib /var/lib
43		fi
44	fi
45fi
46
47