#!/bin/sh

mount -t proc none /proc
mount -t sysfs none /sys

/bin/busybox --install -s

# create mtab so that fsck won't complain
/bin/ln -sf /proc/mounts /etc/mtab

# wait for slow sdcards
/bin/sleep 5

# populate /dev
/sbin/mdev -s

ROOTDEV=""
ROOTFSTYPE="ext4"
ROOTFSOPTS="noatime"
RWFS=""
RWFSTYPE=""
RWFSOPTS="noatime"
AUFS=false
AUFSCK=false

for x in $(/bin/cat /proc/cmdline); do
    case $x in
    root=*)
        ROOTDEV=${x#root=}
        ;;
    rootfstype=*)
        ROOTFSTYPE=${x#rootfstype=}
        ;;
    rootfsopts=*)
        ROOTFSOPTS=${x#rootfsopts=}
        ;;
    rwfs=*)
        RWFS=${x#rwfs=}
        ;;
    rwfstype=*)
        RWFSTYPE=${x#rwfstype=}
        ;;
    rwfsopts=*)
        RWFSOPTS=${x#rwfsopts=}
        ;;
    aufsck)
        AUFSCK=true
        ;;
    esac
done

# check root device
if [ ! -b "${ROOTDEV}" ]; then
    echo "Root partition ${ROOTDEV} missing"
    exec /bin/sh
    exit 0
fi

# fsck root partition
echo "Checking root partition ${ROOTDEV}"
/sbin/e2fsck.static -y ${ROOTDEV}

# mount root
echo -n "Mounting root partition ${ROOTDEV} "
mount -t ${ROOTFSTYPE} -o ro,${ROOTFSOPTS} ${ROOTDEV} /rootfs
if [ $? -ne 0 ]; then
    echo "failed"
    exec /bin/sh
    exit 0
else
    echo "OK"
fi

# check for rw partition
if [ "${RWFS}" = "tmpfs" ]; then
    RWFS="aufs-tmpfs"
    RWFSTYPE="tmpfs"
    RWFSOPTS="rw"
else
    if [ ! -b "${RWFS}" ]; then
        echo "RW partition ${RWFS} missing"
   RWFS=""
    fi
fi

if ${AUFSCK} && [ -b "${RWFS}" ]; then
    # fsck rw partition
    echo "Checking RW partition ${ROOTDEV}"
    /sbin/e2fsck.static -y ${RWFS}
fi

if [ -n "${RWFS}" ]; then
    # mount rw partition
    echo -n "Mounting RW partition ${RWFS} "
    mount -o ${RWFSOPTS} -t ${RWFSTYPE} ${RWFS} /rw
    if [ $? -ne 0 ]; then
        echo "failed"
        AUFS=false
    else
        echo "OK"
        AUFS=true
    fi
else
    AUFS=false
fi

if ${AUFS}; then
    # mount aufs partition
    echo -n "Mounting AUFS "
    mount -t aufs -o dirs=/rw:/rootfs=ro aufs /aufs
    if [ $? -ne 0 ]; then
        echo "failed"
        AUFS=false
    else
        echo "OK"
    fi
fi

if ${AUFS}; then
    # mount aufs  as root partition
    # test for mount points on aufs file system
    [  -d /aufs/ro ] || /bin/mkdir /aufs/ro
    [  -d /aufs/rw ] || /bin/mkdir /aufs/rw

    # move RO and RW inside aufs
    mount --move /rw /aufs/rw
    mount --move /rootfs /aufs/ro
    # cleanup
    umount /proc
    umount /sys

    # Boot the real thing
    exec switch_root /aufs /sbin/init
else
    # revert to normal rootfs
    # remount root rw
    mount -o remount,rw ${ROOTDEV}
    # cleanup
    umount /proc
    umount /sys

    # Boot the real thing
    exec switch_root /rootfs /sbin/init
fi

echo "Failed to switch_root, dropping to a shell"
exec /bin/sh