Initial pass at a git daemon for userv.

diff --git a/git-daemon/git-daemon.pl b/git-daemon/git-daemon.pl
new file mode 100644 (file)
index 0000000..f18f6b9
--- /dev/null
+++ b/git-daemon/git-daemon.pl
@@ -0,0 +1,62 @@
+#!/usr/bin/perl
+#
+# A very simple userv git-daemon wrapper.
+#
+# This reads the first packet-line of the protocol, checks the syntax
+# of the user, pathname, and hostname, then uses userv to invoke the
+# real git daemon as the target user with safe arguments.
+#
+# This was written by Tony Finch <dot@dotat.at>
+# You may do anything with it, at your own risk.
+# http://creativecommons.org/publicdomain/zero/1.0/
+
+use strict;
+use warnings;
+
+use POSIX;
+
+my $USER = qr{[0-9a-z]+};
+my $PATH = qr{[-+,._/0-9A-Za-z]+};
+my $HOST = qr{[-.0-9A-Za-z]+};
+
+sub xread {
+    my $length = shift;
+    my $buffer = "";
+    my $count = 0;
+    while ($length > length $buffer) {
+       my $data;
+       my $ret = sysread STDIN, $data, $len
+         while not defined $ret and ($! == EINTR or $! == EAGAIN);
+       die "read" unless defined $ret;
+       die "short read: expected $length bytes, got $count\n" if $ret == 0;
+       $buffer .= $data;
+       $count += $ret;
+    }
+    return $buffer;
+}
+
+my $len_hex = xread 4;
+die "bad packet length" unless $len_hex =~ m{^[0-9a-zA-Z]{4}$};
+my $len = hex $len;
+
+my $line = xread $len;
+$line =~ m{^git-upload-pack ~($USER)/($PATH[.]git)\0host=($HOST)\0$};
+my ($user,$path,$host) = ($1,$2,$3);
+
+# child's output will go directly to inetd
+open CHILD, '-|', 'userv', $user,
+  qw(git daemon --inetd --strict-paths
+     --user-path=public-git --forbid-override=receive-pack)
+  or die "open pipe to userv: $!\n";
+
+# proxy command line to child
+syswrite CHILD, $len_hex.$line
+  or die "write to userv: $!\n";
+
+# relay stdin to child
+open STDOUT, ">&CHILD"
+  or die "dup: $!\n";
+exec 'cat'
+  or die "exec: $!\n";
+
+die