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

From: Junio C Hamano <gitster@pobox.com>
Date: Sep 27, 2017, 04:27 UTC
Message-ID: <xmqqa81g7ol9.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20170927040721.6av4o7cjrrkzizzo@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 16 quoted lines

> You actually don't need errno for that. You can write:
>
>   ret = read_in_full(..., size);
>   if (ret < 0)
> 	die_errno("oops");
>   else if (ret != size)
> 	die("short read");
>
> So I think using errno as a sentinel value to tell between the two cases
> doesn't have much value.
> ...
> One of the reasons I dislike the helper I showed earlier is that it
> involves assembling a lego sentence. But the alternative is requiring
> the caller to write both sentences from scratch (and writing a good
> sentence for the short read really is long: you expected X bytes but got
> Y).

All sensible considerations. I probably should have read the entire discussion twice before starting to type X-<. Sorry about the noise.

> Sometimes a custom "short read" message can be better, if it's "could
> not read enough bytes for packfile header" or similar. You don't need to
> know the exact number then.

That's true, too.  I dunno, either.