93 lines
2.5 KiB
Bash
Executable file
93 lines
2.5 KiB
Bash
Executable file
#!/bin/sh
|
|
#
|
|
# overlayroot-chroot - chroot wrapper script for overlayroot
|
|
# Copyright (C) 2012 Dustin Kirkland <kirkland@ubuntu.com>
|
|
#
|
|
# Authors: Dustin Kirkland <kirkland@ubuntu.com>
|
|
#
|
|
# 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, version 3 of the License.
|
|
#
|
|
# 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/>.
|
|
|
|
set -e
|
|
set -f # disable path expansion
|
|
REMOUNTS=""
|
|
|
|
error() {
|
|
printf "ERROR: $@\n" 1>&2
|
|
}
|
|
fail() { [ $# -eq 0 ] || error "$@"; exit 1; }
|
|
|
|
info() {
|
|
printf "INFO: $@\n" 1>&2
|
|
}
|
|
|
|
get_lowerdir() {
|
|
local overlay=""
|
|
overlay=$(awk \
|
|
'$1 == "overlayroot" && $2 == "/" { print $0 }' /proc/mounts)
|
|
if [ -n "${overlay}" ]; then
|
|
lowerdir=${overlay##*lowerdir=}
|
|
lowerdir=${lowerdir%%,*}
|
|
if mountpoint "${lowerdir}" >/dev/null; then
|
|
_RET="${lowerdir}"
|
|
else
|
|
fail "Unable to find the overlayroot lowerdir"
|
|
fi
|
|
else
|
|
fail "Unable to find an overlayroot filesystem"
|
|
fi
|
|
}
|
|
|
|
clean_exit() {
|
|
local mounts="$1" rc=0 d="" lowerdir="" mp=""
|
|
for d in ${mounts}; do
|
|
if mountpoint ${d} >/dev/null; then
|
|
umount ${d} || rc=1
|
|
fi
|
|
done
|
|
for mp in $REMOUNTS; do
|
|
mount -o remount,ro "${mp}" ||
|
|
error "Note that [${mp}] is still mounted read/write"
|
|
done
|
|
[ "$2" = "return" ] && return ${rc} || exit ${rc}
|
|
}
|
|
|
|
# Try to find the overlayroot filesystem
|
|
get_lowerdir
|
|
lowerdir=${_RET}
|
|
|
|
recurse_mps=$(awk '$1 ~ /^\/dev\// && $2 ~ starts { print $2 }' \
|
|
starts="^$lowerdir/" /proc/mounts)
|
|
|
|
mounts=
|
|
for d in proc run sys; do
|
|
if ! mountpoint "${lowerdir}/${d}" >/dev/null; then
|
|
mount -o bind "/${d}" "${lowerdir}/${d}" || fail "Unable to bind /${d}"
|
|
mounts="$mounts $lowerdir/$d"
|
|
trap "clean_exit \"${mounts}\" || true" EXIT HUP INT QUIT TERM
|
|
fi
|
|
done
|
|
|
|
# Remount with read/write
|
|
for mp in "$lowerdir" $recurse_mps; do
|
|
mount -o remount,rw "${mp}" &&
|
|
REMOUNTS="$mp $REMOUNTS" ||
|
|
fail "Unable to remount [$mp] writable"
|
|
done
|
|
info "Chrooting into [${lowerdir}]"
|
|
chroot ${lowerdir} "$@"
|
|
|
|
# Clean up mounts on exit
|
|
clean_exit "${mounts}" "return"
|
|
trap "" EXIT HUP INT QUIT TERM
|
|
|
|
# vi: ts=4 noexpandtab
|