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#
# Example implementation for the Git filter protocol version 2
# See Documentation/gitattributes.txt, section "Filter Protocol"
#
# The script takes the list of supported protocol capabilities as
# arguments ("clean", "smudge", etc).
#
# This implementation supports special test cases:
# (1) If data with the pathname "clean-write-fail.r" is processed with
# a "clean" operation then the write operation will die.
# (2) If data with the pathname "smudge-write-fail.r" is processed with
# a "smudge" operation then the write operation will die.
# (3) If data with the pathname "error.r" is processed with any
# operation then the filter signals that it cannot or does not want
# to process the file.
# (4) If data with the pathname "abort.r" is processed with any
# operation then the filter signals that it cannot or does not want
# to process the file and any file after that is processed with the
# same command.
#
use strict;
use warnings;
use IO::File;
my $MAX_PACKET_CONTENT_SIZE = 65516;
my @capabilities = @ARGV;
open my $debug, ">>", "rot13-filter.log" or die "cannot open log file: $!";
sub rot13 {
my $str = shift;
$str =~ y/A-Za-z/N-ZA-Mn-za-m/;
return $str;
}
sub packet_bin_read {
my $buffer;
my $bytes_read = read STDIN, $buffer, 4;
if ( $bytes_read == 0 ) {
# EOF - Git stopped talking to us!
print $debug "STOP\n";
exit();
}
elsif ( $bytes_read != 4 ) {
die "invalid packet: '$buffer'";
}
my $pkt_size = hex($buffer);
if ( $pkt_size == 0 ) {
return ( 1, "" );
}
elsif ( $pkt_size > 4 ) {
my $content_size = $pkt_size - 4;
$bytes_read = read STDIN, $buffer, $content_size;
if ( $bytes_read != $content_size ) {
die "invalid packet ($content_size bytes expected; $bytes_read bytes read)";
}
return ( 0, $buffer );
}
else {
die "invalid packet size: $pkt_size";
}
}
sub packet_txt_read {
my ( $res, $buf ) = packet_bin_read();
unless ( $buf =~ s/\n$// ) {
die "A non-binary line MUST be terminated by an LF.";
}
return ( $res, $buf );
}
sub packet_bin_write {
my $buf = shift;
print STDOUT sprintf( "%04x", length($buf) + 4 );
print STDOUT $buf;
STDOUT->flush();
}
sub packet_txt_write {
packet_bin_write( $_[0] . "\n" );
}
sub packet_flush {
print STDOUT sprintf( "%04x", 0 );
STDOUT->flush();
}
print $debug "START\n";
$debug->flush();
( packet_txt_read() eq ( 0, "git-filter-client" ) ) || die "bad initialize";
( packet_txt_read() eq ( 0, "version=2" ) ) || die "bad version";
( packet_bin_read() eq ( 1, "" ) ) || die "bad version end";
packet_txt_write("git-filter-server");
packet_txt_write("version=2");
packet_flush();
( packet_txt_read() eq ( 0, "capability=clean" ) ) || die "bad capability";
( packet_txt_read() eq ( 0, "capability=smudge" ) ) || die "bad capability";
( packet_bin_read() eq ( 1, "" ) ) || die "bad capability end";
foreach (@capabilities) {
packet_txt_write( "capability=" . $_ );
}
packet_flush();
print $debug "init handshake complete\n";
$debug->flush();
while (1) {
my ($command) = packet_txt_read() =~ /^command=([^=]+)$/;
print $debug "IN: $command";
$debug->flush();
my ($pathname) = packet_txt_read() =~ /^pathname=([^=]+)$/;
print $debug " $pathname";
$debug->flush();
# Flush
packet_bin_read();
my $input = "";
{
binmode(STDIN);
my $buffer;
my $done = 0;
while ( !$done ) {
( $done, $buffer ) = packet_bin_read();
$input .= $buffer;
}
print $debug " " . length($input) . " [OK] -- ";
$debug->flush();
}
my $output;
if ( $pathname eq "error.r" or $pathname eq "abort.r" ) {
$output = "";
}
elsif ( $command eq "clean" and grep( /^clean$/, @capabilities ) ) {
$output = rot13($input);
}
elsif ( $command eq "smudge" and grep( /^smudge$/, @capabilities ) ) {
$output = rot13($input);
}
else {
die "bad command '$command'";
}
print $debug "OUT: " . length($output) . " ";
$debug->flush();
if ( $pathname eq "error.r" ) {
print $debug "[ERROR]\n";
$debug->flush();
packet_txt_write("status=error");
packet_flush();
}
elsif ( $pathname eq "abort.r" ) {
print $debug "[ABORT]\n";
$debug->flush();
packet_txt_write("status=abort");
packet_flush();
}
else {
packet_txt_write("status=success");
packet_flush();
if ( $pathname eq "${command}-write-fail.r" ) {
print $debug "[WRITE FAIL]\n";
$debug->flush();
die "${command} write error";
}
while ( length($output) > 0 ) {
my $packet = substr( $output, 0, $MAX_PACKET_CONTENT_SIZE );
packet_bin_write($packet);
# dots represent the number of packets
print $debug ".";
if ( length($output) > $MAX_PACKET_CONTENT_SIZE ) {
$output = substr( $output, $MAX_PACKET_CONTENT_SIZE );
}
else {
$output = "";
}
}
packet_flush();
print $debug " [OK]\n";
$debug->flush();
packet_flush();
}
}
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