contrib/long-running-filter/example.pl

   1 #!/usr/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
  10 use strict;
  11 use warnings;
  12
  13 my $MAX_PACKET_CONTENT_SIZE = 65516;
  14
  15 sub 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
  43 sub 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
  51 sub packet_bin_write {
  52         my $buf = shift;
  53         print STDOUT sprintf( "%04x", length($buf) + 4 );
  54         print STDOUT $buf;
  55         STDOUT->flush();
  56 }
  57
  58 sub packet_txt_write {
  59         packet_bin_write( $_[0] . "\n" );
  60 }
  61
  62 sub packet_flush {
  63         print STDOUT sprintf( "%04x", 0 );
  64         STDOUT->flush();
  65 }
  66
  67 ( packet_txt_read() eq ( 0, "git-filter-client" ) ) || die "bad initialize";
  68 ( packet_txt_read() eq ( 0, "version=2" ) )         || die "bad version";
  69 ( packet_bin_read() eq ( 1, "" ) )                  || die "bad version end";
  70
  71 packet_txt_write("git-filter-server");
  72 packet_txt_write("version=2");
  73 packet_flush();
  74
  75 ( packet_txt_read() eq ( 0, "capability=clean" ) )  || die "bad capability";
  76 ( packet_txt_read() eq ( 0, "capability=smudge" ) ) || die "bad capability";
  77 ( packet_bin_read() eq ( 1, "" ) )                  || die "bad capability end";
  78
  79 packet_txt_write("capability=clean");
  80 packet_txt_write("capability=smudge");
  81 packet_flush();
  82
  83 while (1) {
  84         my ($command)  = packet_txt_read() =~ /^command=([^=]+)$/;
  85         my ($pathname) = packet_txt_read() =~ /^pathname=([^=]+)$/;
  86
  87         packet_bin_read();
  88
  89         my $input = "";
  90         {
  91                 binmode(STDIN);
  92                 my $buffer;
  93                 my $done = 0;
  94                 while ( !$done ) {
  95                         ( $done, $buffer ) = packet_bin_read();
  96                         $input .= $buffer;
  97                 }
  98         }
  99
 100         my $output;
 101         if ( $command eq "clean" ) {
 102                 ### Perform clean here ###
 103                 $output = $input;
 104         }
 105         elsif ( $command eq "smudge" ) {
 106                 ### Perform smudge here ###
 107                 $output = $input;
 108         }
 109         else {
 110                 die "bad command '$command'";
 111         }
 112
 113         packet_txt_write("status=success");
 114         packet_flush();
 115         while ( length($output) > 0 ) {
 116                 my $packet = substr( $output, 0, $MAX_PACKET_CONTENT_SIZE );
 117                 packet_bin_write($packet);
 118                 if ( length($output) > $MAX_PACKET_CONTENT_SIZE ) {
 119                         $output = substr( $output, $MAX_PACKET_CONTENT_SIZE );
 120                 }
 121                 else {
 122                         $output = "";
 123                 }
 124         }
 125         packet_flush();    # flush content!
 126         packet_flush();    # empty list, keep "status=success" unchanged!
 127
 128 }