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#!/bin/sh
# Copyright 2022 Tim Hildering
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
MSG_MODIFIED="original line modified by overlayroot"
MSG_DEACTIVATED="line deactivated by overlayroot"
OVLROOT_FS_ROONLY="msdos,fat,vfat,iso9660,udf,ntfs-3g,ntfs3"
OVLROOT_FS_RAMONLY="tmpfs,devpts,devtmpfs,tracefs,debugfs,\
configfs,securityfs,proc,sysfs,swap,ramfs"
OVLROOT_CFGFILE="/etc/overlayroot.conf"
OVLROOT_FSTAB="/tmp/overlayroot.fstab"
OVLROOT_MAINDIR="/.overlay"
OVLROOT_LOWERDIR_NAME="ro"
OVLROOT_UPPERDIR_NAME="rw"
OVLROOT_WORKDIR_NAME="work"
FSTAB_SYSTEM="/etc/fstab"
ROOTMNT="/new_root"
add_comments() {
while [ ${#} -gt 0 ]
do
echo "# ${1}"; shift 1
done
}
list_contains() {
local list="${1}" item="${2}"
for _item in ${list}
do
[ "${_item}" = "${item}" ] && return 0
done
return 1
}
fsopts_add_ro() {
local fsopts=${1}, fsopts_ro="ro"
local opt=""
for opt in ${fsopts//,/ }
do
case "${opt}" in
none | rw)
;;
ro)
fsopts_ro="${fsopts}"
break
;;
*)
fsopts_ro="${fsopts_ro},${opt}"
;;
esac
done
printf "%s" "${fsopts_ro}"
}
run_latehook() {
local line="" options="" noswap="" mnts_overlay="" mnts_rdonly=""
local ovlroot_lowerdir="" ovlroot_upperdir="" ovlroot_workdir=""
local fsopts_root="ro"
[ ${#overlayroot} -eq 0 ] && return
for opt in ${overlayroot//:/ }
do
case "${opt}" in
tmpfs=*)
mnts_overlay="${opt#tmpfs=}"
;;
ro=*)
mnts_rdonly="${opt#ro=}"
;;
opts=*)
options="${opt#options=}"
for opt in ${options//,/ }
do
case "${opt}" in
noswap)
noswap="y"
;;
esac
done
;;
esac
done
[ -f "${OVLROOT_CFGFILE}" ] && . "${OVLROOT_CFGFILE}"
ovlroot_lowerdir="${OVLROOT_MAINDIR}/${OVLROOT_LOWERDIR_NAME}"
ovlroot_upperdir="${OVLROOT_MAINDIR}/${OVLROOT_UPPERDIR_NAME}"
ovlroot_workdir="${OVLROOT_MAINDIR}/${OVLROOT_WORKDIR_NAME}"
mkdir -p "${OVLROOT_MAINDIR}"
mount -t "tmpfs" "overlayroot-tmpfs" "${OVLROOT_MAINDIR}"
mkdir -p "${ovlroot_lowerdir}"
mkdir -p "${ovlroot_upperdir}/root"
mkdir -p "${ovlroot_workdir}/root"
mount -o "move" "${ROOTMNT}" "${ovlroot_lowerdir}"
mount -t "overlay" -o "lowerdir=${ovlroot_lowerdir},\
upperdir=${ovlroot_upperdir}/root,workdir=${ovlroot_workdir}/root" \
"overlayroot" "${ROOTMNT}"
mkdir -p "${ROOTMNT}/${OVLROOT_MAINDIR}"
mount -o "move" "${OVLROOT_MAINDIR}" "${ROOTMNT}/${OVLROOT_MAINDIR}"
while IFS= read -r line
do
local fs="" fsdir="" fstype="" fsopts="" fsdump="" fspass=""
local error="" fsclass="" fsopts_ro=""
local _line="${line%%#*}"
[ ${#_line} -eq 0 ] && { echo "${line}"; continue; }
read -r fs fsdir fstype fsopts fsdump fspass error <<-EOF
${_line}
EOF
if [ ${#fs} -gt 0 ]
then
if [ ${#fsopts} -eq 0 ] || [ ${#error} -ne 0 ]
then
add_comments "${MSG_DEACTIVATED}" "${line}"
continue
fi
else
echo; continue
fi
fsopts_ro="$(fsopts_add_ro "${fsopts}")"
if [ "${fstype}" = "swap" ]
then
if [ "${noswap}" = "y" ]
then
add_comments "${MSG_DEACTIVATED}" "${line}"
continue
fi
fsclass="ram_only"
else
if list_contains "${OVLROOT_FS_ROONLY//,/ }" "${fstype}"
then
fsclass="ro_only"
elif list_contains "${OVLROOT_FS_RAMONLY//,/ }" "${fstype}"
then
fsclass="ram_only"
else
fsclass="overlay"
fi
fi
if [ "${fsdir}" = "/" ]
then
[ "${fsclass}" != "overlay" ] && return
fsopts_root="${fsopts_ro}"
add_comments "${MSG_DEACTIVATED}" "${line}"
continue
fi
if [ "${fsclass}" != "ram_only" ]
then
if [ "${mnts_overlay}" = "all" ] || \
list_contains "${mnts_overlay//,/ }" "${fsdir}"
then
if [ "${fsclass}" != "ro_only" ]
then
add_comments "${MSG_MODIFIED}" "${line}"
fstype="overlayroot.${fstype}"
fsopts="${fsopts_ro}"
fi
elif [ "${mnts_rdonly}" = "all" ] ||
list_contains "${mnts_rdonly//,/ }" "${fsdir}"
then
add_comments "${MSG_MODIFIED}" "${line}"
fsopts="${fsopts_ro}"
fspass=0
fi
fi
printf "%s\t%s\t%s\t%s\t%s\t%s\n" "${fs}" "${fsdir}" \
"${fstype}" "${fsopts}" "${fsdump}" "${fspass}"
done <"${ROOTMNT}/${FSTAB_SYSTEM}" >"${OVLROOT_FSTAB}"
mount -o "remount,${fsopts_root}" "${ROOTMNT}/${ovlroot_lowerdir}"
mv "${OVLROOT_FSTAB}" "${ROOTMNT}/${FSTAB_SYSTEM}"
}
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