From: Michael Witten <mfwitten@mit.edu>
Date: Wed, 05 Dec 2007 11:07:29 GMT
Subject: Re: [PATCH] git-cvsserver runs hooks/post-update
Message-ID: <7245A47D-143F-4DC7-8414-D8C99C0ED9C3@mit.edu>
In-Reply-To: <7v63zdtnjz.fsf@gitster.siamese.dyndns.org>


On 5 Dec 2007, at 5:59:12 AM, Junio C Hamano wrote:

> +	### Then hooks/post-update
> +	$hook = $ENV{GIT_DIR}.'hooks/post-update';
> +	if (-x $hook) {
> +		system($hook, "refs/heads/$state->{module}");
> +	}
> +

Firstly, I apologize for not getting this small patch done myself;
it's very hectic this time of year.

Secondly, I'd like to recall my unanswered question:

> Also, I explicitly decided to pipe input into post-receive
> by hand rather than relying on a system() call that someone
> might exploit maliciously:

	### Emulate git-receive-pack by running hooks/post-receive
	my $hook = $ENV{GIT_DIR}.'hooks/post-receive';
	if( -x $hook ) {
		open(my $pipe, "| $hook") || die "can't fork $!";

		local $SIG{PIPE} = sub { die 'pipe broke' };

		print $pipe "$parenthash $commithash refs/heads/$state->{module}\n";

		close $pipe || die "bad pipe: $! $?";
	}

> Unfortunately, it turns out that open() with a pipe essentially
> invokes system(); the solution is to fork a child process and
> then to turn the child into the process with which communication
> is desired via a call to exec().
>
> Because the rest of git-cvsserver.perl uses explicit system()
> calls, I have been wondering if I am being overly cautious.

Am I being overly cautious?