Re: [PATCH 2/3] run-command: Be more informative about what failed

From: Jeff King <peff@peff.net>
Date: Jan 31, 2013, 22:35 UTC
Message-ID: <20130131223559.GC21729@sigill.intra.peff.net>
In-Reply-To: <7vfw1hiami.fsf@alter.siamese.dyndns.org>

On Thu, Jan 31, 2013 at 08:24:21AM -0800, Junio C Hamano wrote:

Show 20 quoted lines

> Stephen Boyd <sboyd@codeaurora.org> writes:
> 
> > While debugging an error with verify_signed_buffer() the error
> > messages from run-command weren't very useful:
> >
> >  error: cannot create pipe for gpg: Too many open files
> >  error: could not run gpg.
> >
> > because they didn't indicate *which* pipe couldn't be created.
> 
> For the message emitted here with your update (or without for that
> matter) to be useful, it has to hold that there is a single leaker,
> that leaker fails in this codepath, and that there is nobody else
> involved.  Otherwise, you may be able to tell that one caller could
> not create its stdin, but the reason it couldn't may be because
> somebody else consumed all the available file descriptors.
> 
> I am not opposed to this change per-se, but I am not sure that
> saying "stdin" etc. makes the message more useful for the purpose of
> debugging.

Yeah, I had the same feeling. All that failed is pipe(), which does not have anything to do with what we are going to use the pipe for. So it gives some context, perhaps, but does not necessarily tell us anything useful.

But it is not much code, and sometimes it is surprising what information can be helpful when debugging, so like you, I am not opposed, just doubtful.

-Peff