diff options
| -rw-r--r-- | Documentation/gitattributes.txt | 4 | ||||
| -rwxr-xr-x | contrib/long-running-filter/example.pl | 128 |
2 files changed, 131 insertions, 1 deletions
diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt index 3f4d1edb1f..976243a63e 100644 --- a/Documentation/gitattributes.txt +++ b/Documentation/gitattributes.txt @@ -516,7 +516,9 @@ the command pipe on exit. The filter is expected to detect EOF and exit gracefully on its own. Git will wait until the filter process has stopped. -If you develop your own long running filter +A long running filter demo implementation can be found in +`contrib/long-running-filter/example.pl` located in the Git +core repository. If you develop your own long running filter process then the `GIT_TRACE_PACKET` environment variables can be very helpful for debugging (see linkgit:git[1]). diff --git a/contrib/long-running-filter/example.pl b/contrib/long-running-filter/example.pl new file mode 100755 index 0000000000..39457055a5 --- /dev/null +++ b/contrib/long-running-filter/example.pl @@ -0,0 +1,128 @@ +#!/usr/bin/perl +# +# Example implementation for the Git filter protocol version 2 +# See Documentation/gitattributes.txt, section "Filter Protocol" +# +# Please note, this pass-thru filter is a minimal skeleton. No proper +# error handling was implemented. +# + +use strict; +use warnings; + +my $MAX_PACKET_CONTENT_SIZE = 65516; + +sub packet_bin_read { + my $buffer; + my $bytes_read = read STDIN, $buffer, 4; + if ( $bytes_read == 0 ) { + + # EOF - Git stopped talking to us! + 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( $_[0] . "\n" ); +} + +sub packet_flush { + print STDOUT sprintf( "%04x", 0 ); + STDOUT->flush(); +} + +( packet_txt_read() eq ( 0, "git-filter-client" ) ) || die "bad initialize"; +( packet_txt_read() eq ( 0, "version=2" ) ) || die "bad version"; +( packet_bin_read() eq ( 1, "" ) ) || die "bad version end"; + +packet_txt_write("git-filter-server"); +packet_txt_write("version=2"); +packet_flush(); + +( packet_txt_read() eq ( 0, "capability=clean" ) ) || die "bad capability"; +( packet_txt_read() eq ( 0, "capability=smudge" ) ) || die "bad capability"; +( packet_bin_read() eq ( 1, "" ) ) || die "bad capability end"; + +packet_txt_write("capability=clean"); +packet_txt_write("capability=smudge"); +packet_flush(); + +while (1) { + my ($command) = packet_txt_read() =~ /^command=([^=]+)$/; + my ($pathname) = packet_txt_read() =~ /^pathname=([^=]+)$/; + + packet_bin_read(); + + my $input = ""; + { + binmode(STDIN); + my $buffer; + my $done = 0; + while ( !$done ) { + ( $done, $buffer ) = packet_bin_read(); + $input .= $buffer; + } + } + + my $output; + if ( $command eq "clean" ) { + ### Perform clean here ### + $output = $input; + } + elsif ( $command eq "smudge" ) { + ### Perform smudge here ### + $output = $input; + } + else { + die "bad command '$command'"; + } + + packet_txt_write("status=success"); + packet_flush(); + while ( length($output) > 0 ) { + my $packet = substr( $output, 0, $MAX_PACKET_CONTENT_SIZE ); + packet_bin_write($packet); + if ( length($output) > $MAX_PACKET_CONTENT_SIZE ) { + $output = substr( $output, $MAX_PACKET_CONTENT_SIZE ); + } + else { + $output = ""; + } + } + packet_flush(); # flush content! + packet_flush(); # empty list, keep "status=success" unchanged! + +} |