patch-shairport.sh

#!/bin/bash

set -e

BIN_NAME=shairport-sync
BIN_SRC=/usr/bin
BINARY="${BIN_SRC}/${BIN_NAME}"
PATCH_DIR=/tmp/shairport-patch
PATCH_BIN="${PATCH_DIR}/${BIN_NAME}"
PATCH_NAME="${PATCH_DIR}/string"

if [ ! -f "${BINARY}" ]
then
	echo binary not found
	exit 1
fi

OFFSET=$(strings -t d /usr/bin/shairport-sync | grep -F 'AirPort4,107' | awk '{ print $1 }')

if [ -z "${OFFSET}" ]
then
	echo substring not found
	exit 1
fi

mkdir -p "${PATCH_DIR}"
echo -n ShairportSyn > "${PATCH_NAME}"
cp -p "${BINARY}" "${PATCH_BIN}"
dd if="${PATCH_NAME}" of="${PATCH_BIN}" obs=1 seek="$[${OFFSET} + 3]" conv=notrunc
mv "${BINARY}" "${BINARY}.bak"
mv "${PATCH_BIN}" "${BINARY}"
rm -rf "${PATCH_DIR}"