#!/bin/sh
# this script depends on /sbin/blkid from the util-linux package

# usage: blkid <device> <fs_type> [<offset>]
# <device> may be any device that should be checked.
# if no <fs_type> is given, the check fails if no valid filesystem is found.
# if <fs_type> is given, the check fails when no filesystem type <fs_type>
# is found on the device. if <fs_type> is 'none', the check fails if any
# know filesystem is found.

if test ! -x "/sbin/blkid"; then
  echo " - WARNING: blkid from util-linux is not available, impossible to run checks."
  exit 1
fi

dev="$1"
fs="$2"
offset="${3-}"

blkid="$(/sbin/blkid -o value -s TYPE -p ${offset:+-O "$offset"} -- "$dev")"

# blkid output is empty if $dev has an unknown filesystem
if [ -z "$blkid" ] && [ -z "$fs" ]; then
  echo " - The device $dev does not contain a known filesystem${offset:+" at offset $offset"}."
  exit 1
elif [ -n "$blkid" ] && [ "$fs" = "none" ]; then
  echo " - The device $dev contains a filesystem type $blkid${offset:+" at offset $offset"}."
  exit 1
elif [ -n "$fs" ] && [ "$blkid" != "$fs" ]; then
  echo " - The device $dev does not contain a filesystem type $fs${offset:+" at offset $offset"}."
  exit 1
fi