#!/usr/bin/env bash

FILE=BattleBlockTheater
MD5_PRE=436e91811d8a38de1918991969347b3d
MD5_POST=71eb6519233b21d85c858b39f2b4871f
OFFSET=0x24f2b9
PAYLOAD='\x90\x90'

function getMD5()
{
   echo $(md5sum "${1}" | cut -d ' ' -f 1)
}

if [[ ${MD5_PRE} != $(getMD5 ${FILE}) ]]
then
   echo Input has wrong checksum. Already patched?
   exit 11
fi

echo -ne ${PAYLOAD} | dd if=/dev/stdin of="${FILE}" bs=1 conv=notrunc seek=$((${OFFSET})) status=none

if [[ $? != 0 ]]
then
   echo Patching binary failed.
   exit 77
fi

if [[ ${MD5_POST} != $(getMD5 ${FILE}) ]]
then
   echo Output has wrong checksum. Expect trouble!
   exit 22
fi

echo Yay... everything went well.