Re: [PATCH 2/2] A loose object is not corrupt if it cannot be read due to EMFILE

> On Thu, Nov 18, 2010 at 6:29 PM, Jonathan Nieder <jrnieder@gmail.com> wrote:
> > Erik Faye-Lund wrote:
> >
> >> I was wondering about the same thing, I don't think this approach is
> >> very easy to follow. But either way I think we should make sure
> >> opendir/closedir/readdir doesn't mess with errno.
> >
> > Other platforms and are allowed to (and do) clobber errno in many
> > non-error situations, so the main effect would be to work around/hide
> > some git bugs.
> 
> I don't think that's the case; K&R (section B1.7) says "In addition,
> the integer expression errno (declared in <errno.h>) may contain an
> error number that contains information about the most recent error.".
> A non-error condition would not be information about the most recent
> error. I interpret the use of the word "may" to mean "some functions
> does not update errno, so errno could also have information about
> older errors" not as "some functions can clear errno", but other might
> disagree with me.
> 
> POSIX (which defines opendir) says "No function in this volume of IEEE
> Std 1003.1-2001 shall set errno to 0", so I think it's clear cut in
> this case. (see
> http://www.opengroup.org/onlinepubs/009695399/functions/errno.html for
> the full text)
> 
> We also seem to depend quite heavily on errno being preserved on
> non-errors some places around in the code.