Add timeradd() and timersub() to <sys/time.h>. [PSARC/2008/368 FastTrack timeout 06/16/2008]

[Dan McDonald]

On Mon, Jun 09, 2008 at 09:43:14AM -0700, Garrett D'Amore wrote:
> Mostly looks good.  A few quick questions:
>
>     lint will complain about a constant conditional for timeradd() and
>     timersub().  Use of the /* LINTED */ comment before timeradd() or
>     timersub() is recommended.
>
> Can't this be rectified in the header by use of #ifdef lint and some special 
> lint-only version of the macros?  I particularly dislike the cases where 
> system headers (or system-supplied macros) make lint harder to use.

#ifdef lint seems to be the most expedient solution to the problem.

> Are macros the best way to add these?  As opposed to inline functions or 
> somesuch?  (In particular, do we know if the other systems -- Linux and 
> FreeBSD -- all implement these as macros?)

*BSD still has 'em as macros.  Not sure about Linux -- feel free to look,
though.

> The various caveats with macros tend to make me want to shy away from their
> use in system headers, particularly where the intended consumers are the
> larger audience of general programmers.  But if that's the way they are
> implemented everywhere else, then I suppose it won't hurt too badly to have
> them implemented as such as here.

I know for sure they're in BSD as macros.

> Are there any #define's to conditionally enable or disable these being
> added to the namespace?  (I'm thinking along the lines of dialect options
> that the C compiler exports, e.g. __STDC__, _POSIX_C_SOURCE, and
> __EXTENSIONS__.)

That's why I went to Don Cragun first.

Three of the five documented were ALREADY IN sys/time.h.  The two new ones
(timeradd/timersub) are in the same blocked areas as the first three.

> The other question (and this is just general, not architectural in nature)
> is, given that these functions seem to be widely useful and popular, are
> you aware of any movement in any of the standards bodies (POSIX) to
> standardize on these?

Ask Don -- that's his department.

Dan