Re: More consistency for some file-related error message

On Wed, Jul 18, 2018 at 11:24:05PM -0400, Tom Lane wrote:
> read() is required by spec to set errno when returning a negative result.
> I think the previous coding paid attention to errno regardless of the sign
> of the result, which would justify pre-zeroing it ... but the new coding
> definitely doesn't.

Yes, my point is a bit different though..  Do you think that we need to
bother about the case where errno is not 0 before calling read(), in the
case where it returns a positive result?  This would mean that errno
would still have a previous errno set, still it returned a number of
bytes read.  For the code paths discussed here that visibly does not
matter so you are right, we could remove them, still patterns get easily
copy-pasted around...
--
Michael