#!/bin/sh

if [ -z "$2" ]; then
	echo "Usage: $0 <old fpm> <new fpm>"
	exit 1
fi

_set_fpm()
{
    if echo $1 | grep -q '^/'; then
        echo $1
    else
        echo $(pwd)/$1
    fi
}

_work_dir()
{
	cd $1
	tar -xf $2 boot
	xz -d < boot/initrd | cpio -t 2> /dev/null | sort -u | sed -r 's|^(lib/modules/)[0-9.]+-fw[0-9]+([a-z]+[0-9]+)?/?|\1|' > contents
}

FPM1=`_set_fpm "$1"`
FPM2=`_set_fpm "$2"`

if [ ! -f "$FPM1" -o ! -f "$FPM2" ]; then
	echo "One of the fpms does not exist."
	exit 1
fi

DIR1="$(mktemp -u)"
DIR2="$(mktemp -u)"

mkdir -p "$DIR1" "$DIR2"

_work_dir "$DIR1" "$FPM1"

_work_dir "$DIR2" "$FPM2"

diff -ur "$DIR1/contents" "$DIR2/contents"

rm -rf "$DIR1" "$DIR2"