#!/bin/sh

PATH=/bin

/bin/busybox --install
busybox sleep 1
busybox mount -t proc proc /proc
busybox mount -t sysfs sysfs /sys
busybox mount -t devtmpfs none /dev

root_sfs=""
root=""
overlay_dev=""
singleuser=0

for param in `cat /proc/cmdline`; do
	case $param in
	root=*)
		root="${param##root=}"
		;;
	root_sfs=*)
		root_sfs="${param##root_sfs=}"
		;;
	overlay_dev=*)
		overlay_dev="${param##overlay_dev=}"
		;;
	single*)
		singleuser=1
		;;
	esac
done

if [ -z "${root}" ]; then
	echo "No root drive specified!"
	exec /bin/busybox sh
fi

if [ -z "${root_sfs}" ]; then
	echo "No squashfs image specified!"
	exec /bin/busybox sh
fi

while [ ! -e ${root} ]; do
	echo "Waiting for root"
	busybox sleep 1
done

# file system setup
overlay_mount() {
	local lower=/newroot/${1}
	local upper=/newroot/${2}
	local work=/newroot/${2}_work
	local target=/newroot/${3}

	mount -t overlay overlay -olowerdir=${lower},upperdir=${upper},workdir=${work} ${target}
}

bind_mount() {
	mount --bind /newroot/${1} /newroot/${2}
}

setup_vfs() {
	local root=${1}

	mount -t proc proc $root/proc
	mount -t sysfs sysfs $root/sys
	mount -t devtmpfs none $root/dev

	# setup /dev
	[ -e $root/dev/fd ] || ln -snf /proc/self/fd $root/dev/fd
	[ -e $root/dev/stdin ] || ln -snf /proc/self/fd/0 $root/dev/stdin
	[ -e $root/dev/stdout ] || ln -snf /proc/self/fd/1 $root/dev/stdout
	[ -e $root/dev/stderr ] || ln -snf /proc/self/fd/2 $root/dev/stderr
	[ -e $root/proc/kcore ] && ln -snf /proc/kcore $root/dev/core

	for x in \
		"mqueue dev/mqueue 1777 ,nodev mqueue" \
		"devpts dev/pts 0755 ,gid=5,mode=0620 devpts" \
		"tmpfs dev/shm 1777 ,nodev,mode=1777 shm" \
	; do
		set -- $x
		grep -Eq "[[:space:]]+$1$" /proc/filesystems || continue

		if [ ! -d "$root/$2" ]; then
			mkdir -m $3 -p "$root/$2" >/dev/null 2>&1 || \
				echo "Could not create $root/$2!"
		fi

		if [ -d "$root/$2" ]; then
			mount -t $1 -o noexec,nosuid$4 $5 "$root/$2"
		fi
	done

	# set up additional mounts in /proc and /sys
	for x in \
		"sys/kernel/security securityfs nodev,noexec,nosuid" \
		"sys/kernel/config configfs nodev,noexec,nosuid" \
		"sys/fs/fuse/connections fusectl nodev,noexec,nosuid" \
		"sys/firmware/efi/efivars efivarfs ro" \
		"proc/sys/fs/binfmt_misc binfmt_misc nodev,noexec,nosuid" \
	; do
		set -- $x

		if [ -d "$root/$1" ]; then
			if grep -qs $2 "$root/proc/filesystems"; then
				echo "Mounting $2 filesystem"
				mount -n -t $2 -o $3 $2 "$root/$1"
			fi
		fi
	done

	unset -v x
}

mount ${root} /images

if [ ! -e /images/${root_sfs} ]; then
	echo "${root_sfs} not found!"
	exec /bin/busybox sh
	exit 1
fi

mount -t squashfs /images/${root_sfs} /newroot
setup_vfs "/newroot"
mount -t tmpfs none /newroot/tmp
mount -t tmpfs none /newroot/var
mount -t tmpfs none /newroot/run

chmod 755 /newroot/var
mkdir -p /newroot/run/log/journal
mkdir -p /newroot/var/log/fsck
mkdir -p /newroot/var/log/nginx
mkdir -p /newroot/var/log/mpd
mkdir -p /newroot/var/spool/
mkdir -p /newroot/var/lib/
mkdir -p /newroot/var/tmp
ln -s /run /newroot/var/run
ln -s /run/lock /newroot/var/lock

if [ ! -z "$overlay_dev" ]; then
	while [ ! -e ${overlay_dev} ]; do
		echo "Waiting for overlay device"
		busybox sleep 1
	done

	mount ${overlay_dev} /newroot/cfg/overlay

	overlay_mount "cfg/preserve/etc" "cfg/overlay/etc" "etc"
	overlay_mount "cfg/preserve/var_lib" "cfg/overlay/var_lib" "var/lib"
	overlay_mount "cfg/preserve/root" "cfg/overlay/root" "root"
else
	bind_mount "cfg/preserve/etc" "etc"
	bind_mount "cfg/preserve/var_lib" "var/lib"
	bind_mount "cfg/preserve/root" "root"
fi

# cleanup mounts
umount -l /images
umount -l /dev
umount /sys
umount /proc

if [ "$singleuser" == "1" ]; then
	unset -v singleuser overlay_dev root root_sfs
	exec /bin/busybox switch_root /newroot /bin/bash
fi

unset -v singleuser overlay_dev root root_sfs
exec /bin/busybox switch_root /newroot /bin/init