From: Lars Schneider
Add a simple pass-thru filter as example implementation for the Git
filter protocol version 2. See Documentation/gitattributes.txt, section
"Filter Protocol" for more info.
Signed-off-by: Lars Schneider
---
Documentation/gitattributes.txt| 4 +-
contrib/long-running-filter/example.pl | 127 +
2 files changed, 130 insertions(+), 1 deletion(-)
create mode 100755 contrib/long-running-filter/example.pl
diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt
index 5868f00..a182ef2 100644
--- a/Documentation/gitattributes.txt
+++ b/Documentation/gitattributes.txt
@@ -514,7 +514,9 @@ the next "key=value" list containing a command. Git will
close
the command pipe on exit. The filter is expected to detect EOF
and exit gracefully on its own.
-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 000..f4102d2
--- /dev/null
+++ b/contrib/long-running-filter/example.pl
@@ -0,0 +1,127 @@
+#!/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( $_[0] . "\n" );
+}
+
+sub packet_flush {
+ print STDOUT sprintf( "%04x", 0 );
+ STDOUT->flush();
+}
+
+( packet_txt_read() eq ( 0, "git-filter-client" ) ) || die "bad initialize";
+( packet_txt_read() eq ( 0, "version=2" ) ) || die "bad version";
+( packet_bin_read() eq ( 1, "" ) ) || die "bad version end";
+
+packet_txt_write("git-filter-server");
+packet_txt_write("version=2");
+
+( packet_txt_read() eq ( 0, "clean=true" ) ) || die "bad capability";
+( packet_txt_read() eq ( 0, "smudge=true" ) ) || die "bad capability";
+( packet_bin_read() eq ( 1, "" ) )|| die "bad capability end";
+
+packet_txt_write("clean=true");
+packet_txt_write("smudge=true");
+packet_flush();
+
+while (1) {
+ my ($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 );
+ }
+
