initscript

#!/bin/sh

# layerpie: overlayfs for rpi

# initramfs script prologue
PREREQ=""
prereqs()
{
    echo "${PREREQ}"
}

case "$1" in
prereqs)
    prereqs
    exit 0
    ;;
esac

. /scripts/functions


# constants
BASEDIR=/mnt/lpie
TMPFS=$BASEDIR/rw
UPPER=$TMPFS/upper
WORK=$TMPFS/work
LOWER=$BASEDIR/ro


# utility functions
chk_fail()
{
    if [ $1 -ne 0 ] ; then
        panic "lpie: $2"
        exit 0
    fi
}


# check kernel cmdline if lpie is enabled
ENABLED=0
for CMD_PARAM in $(cat /proc/cmdline); do
    case ${CMD_PARAM} in
        lpie)
            ENABLED=1
            ;;
    esac
done
if [ $ENABLED -eq 0 ]; then
    exit 0
fi

# load driver
modprobe overlay
chk_fail $? "failed to load overlay driver"

# mount ramdisk and create directories
mkdir -p $TMPFS
mount -t tmpfs tmpfs $TMPFS
chk_fail $? "failed to mount tmpfs at $TMPFS"
mkdir -p $UPPER
mkdir -p $WORK

# mount rootfs
mkdir -p $LOWER
mount -o move $rootmnt $LOWER
chk_fail $? "failed to move rootfs from $rootmnt to $LOWER"

# initiate overlay mount
mount -t overlay -o lowerdir=$LOWER,upperdir=$UPPER,workdir=$WORK overlay $rootmnt
chk_fail $? "failed to mount overlayfs at $rootmnt"

# relocate mountpoints to rootmnt
mkdir -p ${rootmnt}${LOWER}
mount -o move $LOWER ${rootmnt}${LOWER}
chk_fail $? "failed to relocate $LOWER ro $rootmnt"
mkdir -p ${rootmnt}${TMPFS}
mount -o move $TMPFS ${rootmnt}${TMPFS}
chk_fail $? "failed to relocate $TMPFS to $rootmnt"

# adjust fstab
echo "# lpie fstab" > $rootmnt/etc/fstab
echo "/dev/mmcblk0p1    /boot   vfat    ro  0   2" >> $rootmnt/etc/fstab
echo "# raspian fstab (without / and /boot)" >> $rootmnt/etc/fstab
GREP=$rootmnt/bin/grep
cat ${rootmnt}${LOWER}/etc/fstab | $GREP -v " / " | $GREP -v " /boot " >> $rootmnt/etc/fstab

log_success_msg "lpie: file systems ready"
exit 0