struct timex and Linux adjtimex()

[Cy Schubert]

In message <25989.1607033614 at critter.freebsd.dk>, "Poul-Henning Kamp" 
writes:
> --------
> Cy Schubert writes:
>
> > I will go back 
> > with my initial proposal of a timespec add/subtract syscall takes a 
> > timespec as input increments or decrements the clock by the timespec and 
> > returns a timespec with the time.
>
> I would be tempted by the clock_settime(2) "clock_id" argument.
>
> The functionality required has a LOT more commonality with
> clock_settime(2) than with ntp_adjtime(2), and absconding with a
> couple of the top bits of clock_id for "CLOCK_ADD_ADJUSTMENT" and
> "CLOCK_SUB_ADJUSTMENT" would be be a pretty clean solution.

Correct. My initial proposal was:

+.Fn clock_updtime "clockid_t clock_id" "const struct timespec *itp"
"struct timespec *otp"

Briefly it does this:

+int
+kern_clock_updtime(struct thread *td, clockid_t clock_id,
+         const struct timespec *its, struct timespec *ots)
+{
+ struct timespec ats;
+ int error;
+
+ if ((error = kern_clock_gettime(td, clock_id, &ats)) != 0)
+         return (error);
+
+ timespecadd(its, &ats, &ats);
+
+ if ((error = kern_clock_settime(td, clock_id, &ats)) != 0)
+         return (error);
+
+ return(kern_clock_gettime(td, clock_id, ots));
+}

I can prepare a review if you want. I haven't touched the man page nor any 
tests yet.

It's affected by kib@'s https://reviews.freebsd.org/D27471, as conflicts 
will result. I'll wait until that's committed before continuing work on it, 
assuming this is the direction we want to go.


-- 
Cheers,
Cy Schubert <Cy.Schubert at cschubert.com>
FreeBSD UNIX:  <cy at FreeBSD.org>   Web:  https://FreeBSD.org
NTP:           <cy at nwtime.org>    Web:  https://nwtime.org

	The need of the many outweighs the greed of the few.