#!/bin/sh

# root_env="/real-root"
# init="/init"
# 
# mkdir -pv "$root_env"
# if mount -v -t aufs aufs "$root_env" -o br:/=rw ; then
# 
# 	# having a world writeable top directory in an aufs branch
# 	# may be a security issue
# 	chmod 0700 "$root_env"
# 
# 	mount --move /proc "$root_env"/proc
# 	mount --move /sys "$root_env"/sys
# 	# remove left-over lines from /etc/mtab
# 	# umount /proc /sys 2>/dev/null
# 
# 	cd "$root_env"
# 	# /etc/mtab and "$root_env"/etc/mtab are the same file
# 	sed -i -e "s,/*$root_env/*,/,g" etc/mtab
# 
# 	exec chroot . sh -c "exec $init" <dev/console >dev/console 2>&1
# fi

mkdir -p /mnt/{media,image,overlay}

# Find the drive with the disc containing 2nd stage images, in case there is
# more than one drive installed.
foundcdrom=0
aufsopt="br:/real-root=rw"
for cdromdev in /dev/cdroms/* ; do
	[ -e $cdromdev ] || continue

	if mount $cdromdev /mnt/media -o ro ; then
		if [ ! -f /mnt/media/*/2nd_stage-livecd.img ] ; then
			umount /mnt/media
			continue
		fi
		if [ -f /mnt/media/*/2nd_stage-overlay.img ] ; then
			mount /mnt/media/*/2nd_stage-overlay.img /mnt/overlay -o loop
			aufsopt="$aufsopt:/mnt/overlay=ro"
		fi
		mount /mnt/media/*/2nd_stage-livecd.img /mnt/image -o loop
		aufsopt="$aufsopt:/mnt/image=ro"

		foundcdrom=1
		break
	fi
done

if [ $foundcdrom = 1 ] ; then
	mount -t tmpfs tmpfs /real-root
	
	# Files from branches listed first in the mount option hide files with the same
	# name in later branches. The first branch listed must be writeable or the whole
	# directory that aufs is mounted on becomes read-only.
	mount -t aufs aufs /real-root -o $aufsopt
	
	mkdir -p /real-root/mnt/{media,image,overlay}
	
	for x in media image overlay ; do
		mount --move /mnt/$x /real-root/mnt/$x
	done
fi