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Re: _ATFILE_SOURCE Obsoletion
On Wed, Oct 18, 2017 at 1:33 PM, Carlos O'Donell <carlos@redhat.com> wrote:
> On 10/18/2017 07:34 AM, Michael Kerrisk (man-pages) wrote:
>> Also, broadening the meaning of _ATFILE_SOURCE to imply
>> _POSIX_C_SOURCE==200809L sems a little risky to me, in terms of
>> possibly creating developer pain.
>
> That risk is balanced against the *removal* of _ATFILE_SOURCE,
> which would mean fixing a lot of now broken packages that don't
> build. Those packages would have to evaluate what needs to change,
> find that they need to use _POSIX_C_SOURCE, at that point they
> would have made a change which is equivalent to the deprecation
> practice of defining the macro the superset feature but with a
> warning.
A little extra caution is required when promoting anything to mean
_POSIX_C_SOURCE=200809L because some older functions were *removed* at
that conformance level. I could see programs using _ATFILE_SOURCE to
get openat, but still wanting to be able to use gettimeofday, for
instance.
I'd also like to know whether any of the other Unixes still in wide
use (especially the BSDs and OSX) support _ATFILE_SOURCE and with what
semantics. I know that several of these have not yet bothered with a
full POSIX.1-2008 implementation.
zw