#!/usr/bin/perl -w
#
# Fixes cvs diffs so that the Index: and "---" and "+++" are in sync,
# including diffs containing added or removed files, so that they patch
# correctly with patch(1).
#
# usage: fixcvsdiff [-p] [-b] [files to fix]
#
# -p prints the cvs commands that will be needed when applying
# the patch.
#
# -b keeps a .bak backup file
#
# Based on code by Amir Karger <karger@post.harvard.edu>
#
# Modified by John Levon <moz@compsoc.man.ac.uk> and
# Ville Skyttä <ville.skytta@iki.fi>.
#
# Contributed under the terms of the GNU GPL v2 or later:
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or (at
# your option) any later version.

use Getopt::Std;
our ($opt_b,$opt_p);
$add = 0;

getopts('pb');

if (defined($opt_b)) {
	$^I = '.bak';
} else {
	$^I = '';
}

while (<>) {
	# get the diff fragment filename
	if (/^Index: (.*)/) {
		$Filename = $1;
	}

	if (!defined($Filename)) {
		print;
		next;
	}

	# tack the filename on the end of lines like this:
	# diff [options] -r?.? -r?.?
	s/^diff(.*) -r(\S*)$/diff$1 -r$2 $Filename/;

	# Allow spaces in file names; the filename ends at the first TAB.
	if (/^(---|\+\+\+) ([^\t]+)\t/) {
		my ($pre, $currfile) = ($1, $2);

		if ($currfile =~ m|^/dev/null|) {
			my $action;
			if ($pre eq '---') {
				$action = 'add';
				$add = 1;
			} else {
				$action = 'remove';
	    		}
			if (defined($opt_p)) {
	    			print STDOUT "cvs $action $Filename\n";
			}
		}

		if ($add == 1 && $pre eq '+++' && $currfile =~ m|[^/]*|) {
			$add = 0;
		}

		# Replace all "(---|+++) foo" lines with the correct filename.
		if ($currfile ne $Filename) {
			# Don't use $pre here, just for safety with '+' ...
			s/^(---|\+\+\+) [^\t]+/$1 $Filename/;
		}
	}
	print;
}