Re: [PATCH 2/2] am: plug FILE * leak in split_mail_conv()

From: Jeff King <peff@peff.net>
Date: May 12, 2016, 08:03 UTC
Message-ID: <20160512080331.GA18874@sigill.intra.peff.net>
In-Reply-To: <20160512075939.GA31343@dcvr.yhbt.net>

On Thu, May 12, 2016 at 07:59:39AM +0000, Eric Wong wrote:

Show 10 quoted lines

> I think both patches in this series would benefit from capturing
> errno before cleanup.  `fclose` can call `free`, and `free` could
> do any manner of things such as calling `madvise` with a flag
> not implemented in the running kernel, or failing an optional
> trylock without being fatal.
> 
> There's lots of non-standard malloc implementations out there :)
> 
> So I'm not sure if there's ever a guarantee that a non-error
> function call preserves `errno`.

Good point. This came up not too long ago in:

  http://article.gmane.org/gmane.comp.version-control.git/286460

I believe POSIX does say that non-error calls should preserve errno, but all the world is not POSIX. And a future POSIX will mandate that `free` should not touch errno, but it's not the future yet (and also, all the world's not POSIX).

-Peff