#! /usr/bin/perl -w

#############################################################################

# Copyright (c) 2007 Novell, Inc.

# All Rights Reserved.

#

# This program is free software; you can redistribute it and/or

# modify it under the terms of version 2 of the GNU General Public License as

# published by the Free Software Foundation.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.   See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, contact Novell, Inc.

#

# To contact Novell about this file by physical or electronic mail,

# you may find current contact information at www.novell.com

#############################################################################

if (@ARGV < 2) {

    print STDERR "Usage: $0 <config1> <config2> [<config3>]\n";

    print STDERR "Diff kernel config files config1 and config2, or " .

		 "apply those differences to config3\n";

    exit 1;

}

open CONFIG1, $ARGV[0]

    or die $ARGV[0] . ": $!\n";

while (<CONFIG1>) {

    next unless /^(CONFIG_\w+)/a || /^# (CONFIG_\w+) is not set/a;

    $config1{$1} = $_;

}

open CONFIG2, $ARGV[1]

    or die $ARGV[1] . ": $!\n";

while (<CONFIG2>) {

    next unless /^(CONFIG_\w+)/a || /^# (CONFIG_\w+) is not set/a;

    $config2{$1} = $_;

}

while (($key, $value) = each %config2) {

    if (!exists $config1{$key} || $config1{$key} ne $value) {

	$diff{$key} = $value;

    }

}

if (@ARGV >= 3) {

    open OLD, $ARGV[2]

	or die $ARGV[2] . ": $!\n";

    while (<OLD>) {

	if (/^(CONFIG_\w+)/a || /^# (CONFIG_\w+) is not set/a) {

	    if (exists $diff{$1}) {

		print $diff{$1};

		$diff_used{$1} = 1;

		next;

   	    }

	}

	print;

    }

}

foreach my $key (sort(keys(%diff))) {

    next if exists $diff_used{$key};

    print $diff{$key};

}