Re: [PATCH 3/7] read_in_full: reset errno before reading

From: Jeff King <peff@peff.net>
Date: Sep 26, 2017, 00:25 UTC
Message-ID: <20170926002510.xmusj6fkvb25fm5w@sigill.intra.peff.net>
In-Reply-To: <20170926002020.GQ27425@aiede.mtv.corp.google.com>

On Mon, Sep 25, 2017 at 05:20:20PM -0700, Jonathan Nieder wrote:

Show 15 quoted lines

> > What do you think of ENODATA? The glibc text for it is pretty
> > appropriate. If it's not available everywhere, we'd have to fallback to
> > something else (EIO? 0?). I don't know how esoteric it is. The likely
> > candidate to be lacking it is Windows.
> 
> ENODATA with a fallback to ESPIPE sounds fine to me.
> 
> read() would never produce ESPIPE because it doesn't seek.
> 
> So that would be:
> 
> /* errno value to use for early EOF */
> #ifndef ENODATA
> #define ENODATA ESPIPE
> #endif

Thanks, I'll re-roll with that (and thank you Stefan for mentioning ENODATA again; I came across it early in my search but discounted it as not quite right semantically. I should have been looking at the strerror() text, which is what really matters).

What do you think of patch 7 in light of this? If the short-read case gives us a sane errno, should we even bother trying to consistently handle its error separately?

-Peff