1#!/usr/local/bin/perl
2#
3# Example implementation for the Git filter protocol version 2
4# See Documentation/gitattributes.txt, section "Filter Protocol"
5#
6# Please note, this pass-thru filter is a minimal skeleton. No proper
7# error handling was implemented.
8#
9
10use strict;
11use warnings;
12
13my $MAX_PACKET_CONTENT_SIZE = 65516;
14
15sub packet_bin_read {
16	my $buffer;
17	my $bytes_read = read STDIN, $buffer, 4;
18	if ( $bytes_read == 0 ) {
19
20		# EOF - Git stopped talking to us!
21		exit();
22	}
23	elsif ( $bytes_read != 4 ) {
24		die "invalid packet: '$buffer'";
25	}
26	my $pkt_size = hex($buffer);
27	if ( $pkt_size == 0 ) {
28		return ( 1, "" );
29	}
30	elsif ( $pkt_size > 4 ) {
31		my $content_size = $pkt_size - 4;
32		$bytes_read = read STDIN, $buffer, $content_size;
33		if ( $bytes_read != $content_size ) {
34			die "invalid packet ($content_size bytes expected; $bytes_read bytes read)";
35		}
36		return ( 0, $buffer );
37	}
38	else {
39		die "invalid packet size: $pkt_size";
40	}
41}
42
43sub packet_txt_read {
44	my ( $res, $buf ) = packet_bin_read();
45	unless ( $buf =~ s/\n$// ) {
46		die "A non-binary line MUST be terminated by an LF.";
47	}
48	return ( $res, $buf );
49}
50
51sub packet_bin_write {
52	my $buf = shift;
53	print STDOUT sprintf( "%04x", length($buf) + 4 );
54	print STDOUT $buf;
55	STDOUT->flush();
56}
57
58sub packet_txt_write {
59	packet_bin_write( $_[0] . "\n" );
60}
61
62sub packet_flush {
63	print STDOUT sprintf( "%04x", 0 );
64	STDOUT->flush();
65}
66
67( packet_txt_read() eq ( 0, "git-filter-client" ) ) || die "bad initialize";
68( packet_txt_read() eq ( 0, "version=2" ) )         || die "bad version";
69( packet_bin_read() eq ( 1, "" ) )                  || die "bad version end";
70
71packet_txt_write("git-filter-server");
72packet_txt_write("version=2");
73packet_flush();
74
75( packet_txt_read() eq ( 0, "capability=clean" ) )  || die "bad capability";
76( packet_txt_read() eq ( 0, "capability=smudge" ) ) || die "bad capability";
77( packet_bin_read() eq ( 1, "" ) )                  || die "bad capability end";
78
79packet_txt_write("capability=clean");
80packet_txt_write("capability=smudge");
81packet_flush();
82
83while (1) {
84	my ($command)  = packet_txt_read() =~ /^command=(.+)$/;
85	my ($pathname) = packet_txt_read() =~ /^pathname=(.+)$/;
86
87	if ( $pathname eq "" ) {
88		die "bad pathname '$pathname'";
89	}
90
91	packet_bin_read();
92
93	my $input = "";
94	{
95		binmode(STDIN);
96		my $buffer;
97		my $done = 0;
98		while ( !$done ) {
99			( $done, $buffer ) = packet_bin_read();
100			$input .= $buffer;
101		}
102	}
103
104	my $output;
105	if ( $command eq "clean" ) {
106		### Perform clean here ###
107		$output = $input;
108	}
109	elsif ( $command eq "smudge" ) {
110		### Perform smudge here ###
111		$output = $input;
112	}
113	else {
114		die "bad command '$command'";
115	}
116
117	packet_txt_write("status=success");
118	packet_flush();
119	while ( length($output) > 0 ) {
120		my $packet = substr( $output, 0, $MAX_PACKET_CONTENT_SIZE );
121		packet_bin_write($packet);
122		if ( length($output) > $MAX_PACKET_CONTENT_SIZE ) {
123			$output = substr( $output, $MAX_PACKET_CONTENT_SIZE );
124		}
125		else {
126			$output = "";
127		}
128	}
129	packet_flush();    # flush content!
130	packet_flush();    # empty list, keep "status=success" unchanged!
131
132}
133