#! /usr/bin/perl -w

use strict;

unless (2 == @ARGV) {
    print "usage: $0 pkg_1.0-1.diff.gz pkg_1.0-1+interix.1.diff.gz\n"
	. "       creates file  pkg_1.0-1_1.0-1+interix.1.interdiff.gz\n";
}


my $diffold = $ARGV[0];
my $diffnew = $ARGV[1];

my ($dop, $dov) = ($diffold =~ /^([^_]+)_([^_]+)\.diff\.gz$/)
    or die "diff1 has wrong file name";

my ($dnp, $dnv) = ($diffnew =~ /^([^_]+)_([^_]+)\.diff\.gz$/)
    or die "diff2 has wrong file name";

$dop eq $dnp
    or die "different package names: $dop $dnp";

my $interdiff = "${dop}_${dov}_${dnv}.interdiff.gz";

system "interdiff -z $diffold $diffnew | gzip > $interdiff";