From: Jeff King <peff@peff.net>
Date: Wed, 23 Apr 2014 19:16:28 GMT
Subject: Re: [PATCH v2] git tag --contains : avoid stack overflow
Message-ID: <20140423191628.GA20596@sigill.intra.peff.net>
In-Reply-To: <xmqqeh0nzwq9.fsf@gitster.dls.corp.google.com>

On Wed, Apr 23, 2014 at 12:12:14PM -0700, Junio C Hamano wrote:

> > +ulimit_stack="ulimit -s 64"
> > +test_lazy_prereq ULIMIT 'bash -c "'"$ulimit_stack"'"'
> 
> With this implementaion, ULIMIT implies bash, and we use bash that
> appears on user's PATH that may not be the one the user chose to run
> git with.  Can't we fix both of them by using $SHELL_PATH?

I don't think so. The point is that we _must_ use bash here, not any
POSIX shell. So my $SHELL_PATH is /bin/sh, which is dash, and would not
run the test.

We want to run "some bash" if we can. We may pick a bash on the user's
PATH that is not what they put into $SHELL_PATH, but that should be
relatively rare. And the consequence is that either that bash works fine
and we run the test, or it does not, and we skip the test.

> How about doing it along this line instead?
> 
> 	run_with_limited_stack () {
> 		"$SHELL_PATH" -c "ulimit -s 64 && $*"
> 	}
> 
> 	test_lazy_prereq ULIMIT "run_with_limited_stack true"

That's a much more direct test. I like it (aside from the $SHELL_PATH
thing as described above).

-Peff