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