Make preallocation configurable

SYSTEM="$TMP/sys.img"

SYSTEM_SIZE="4954537983"

if [ "$ALLOCATE" != "Y" ]; then

  truncate -s "${SYSTEM_SIZE}" "${SYSTEM}"; 

else

  # Check free diskspace

  SPACE=$(df --output=avail -B 1 "$TMP" | tail -n 1)

  if (( SYSTEM_SIZE > SPACE )); then

  echo "ERROR: Not enough free space to create virtual system disk." && exit 87

    echo "ERROR: Not enough free space to create a 4 GB system disk." && exit 87

  fi

  if ! fallocate -l "${SYSTEM_SIZE}" "${SYSTEM}"; then

    rm -f "${SYSTEM}"

  echo "ERROR: Could not allocate file for virtual system disk." && exit 88

    echo "ERROR: Could not allocate a file for the system disk." && exit 88

  fi

fi

PART="$TMP/partition.fdisk"