Re: [PATCH] strbuf: clear errno before calling getdelim(3)

From: Yaroslav Halchenko <yoh@onerussian.com>
Date: Aug 10, 2017, 21:35 UTC
Message-ID: <20170810213555.fejnalargwwlws6k@hopa.kiewit.dartmouth.edu>
In-Reply-To: <20170810210246.p4vp2ibahgsii7fc@sigill.intra.peff.net>

On Thu, 10 Aug 2017, Jeff King wrote:

> On Thu, Aug 10, 2017 at 10:56:40PM +0200, René Scharfe wrote:

> > getdelim(3) returns -1 at the end of the file and if it encounters an
> > error, but sets errno only in the latter case.  Set errno to zero before
> > calling it to avoid misdiagnosing an out-of-memory condition due to a
> > left-over value from some other function call.

> Looks good to me.

> > Do we need to save and restore the original value of errno?  I doubt it,
> > but didn't think deeply about it, yet.

> I'd say no. Anybody depending on strbuf_getwholeline() is clearly
> already wrong in the error case. And in general I think we assume that
> syscalls can clear errno on success if they choose to (this isn't a
> syscall, but obviously it is calling some).

Shouldn't ideally errno being reset to 0 upon check of the syscall successful run right after that syscall? (I also see some spots within git code where it sets errno to ENOMEM)

-- 
Yaroslav O. Halchenko
Center for Open Neuroscience     http://centerforopenneuroscience.org
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