Re: [PATCH] tempfile: avoid "ferror | fclose" trick

From: Jeff King <peff@peff.net>
Date: Feb 17, 2017, 20:54 UTC
Message-ID: <20170217205442.wnldfsxbj3dnnqvj@sigill.intra.peff.net>
In-Reply-To: <64eedabd-c0de-a7e0-8d98-ad23a9625b45@alum.mit.edu>

On Fri, Feb 17, 2017 at 11:42:25AM +0100, Michael Haggerty wrote:

Show 13 quoted lines

> On 02/17/2017 09:07 AM, Jeff King wrote:
> > [...]
> > That's similar to what I wrote earlier, but if we don't mind overwriting
> > errno unconditionally, I think just:
> > 
> >   errno = EIO; /* covers ferror(), overwritten by failing fclose() */
> >   err |= ferror(fp);
> >   err |= fclose(fp);
> > 
> > does the same thing.
> 
> True; I'd forgotten the convention that non-failing functions are
> allowed to change errno. Your solution is obviously simpler and faster.

I guess we are simultaneously assuming that it is OK to munge errno on success in our function, but that fclose() will not do so. Which seems a bit hypocritical. Maybe the "if" dance is better.

-Peff