overlay

#!/bin/sh

PREREQ=""

prereqs()
{
  echo "${PREREQ}"
}

case ${1} in
  prereqs)
    prereqs
    exit 0
    ;;
esac

. /scripts/functions
. /root/etc/overlay || true

overmount(){
  mkdir -p ${1}/lower ${1}/upper ${1}/work
  umount ${ROOT}
  mount ${ROOT} ${1}/lower || panic
  mount -t overlay overlay -o noatime,lowerdir=${1}/lower,upperdir=${1}/upper,workdir=${1}/work /root || panic
}

if [[ "x$OVERLAY_MODE" == "x" ]]; then
  echo -n "Enter overlay mode [none|ram|toram|*] (ram): "
  read OVERLAY_MODE </dev/console>/dev/console
fi

OVERLAY_MODE=${OVERLAY_MODE:-ram}
echo "OVERLAY_MODE='$OVERLAY_MODE'"

case ${OVERLAY_MODE} in
  none)
    echo "No overlay. Mounting /root as usual..."
    ;;
  toram)
    echo "No overlay. Copying /root to RAM..."
    mkdir /run/toram
    mount -t tmpfs tmpfs /run/toram
    cp -r -p /root/. /run/toram/
    echo "Mounting..."
    umount /root
    mount /run/toram /root
    ;;
  ram)
    echo "Mounting /root in memory..."
    mkdir /run/overlay
    mount -t tmpfs tmpfs /run/overlay
    overmount "/run/overlay"
    echo "Mounted, booting..."
    ;;
  *)
    panic
    ;;
esac