On Thu, Jun 17, 2021 at 08:41:39PM -0500, Scott Cheloha wrote:
> On Fri, Jun 11, 2021 at 12:17:02PM -0500, Scott Cheloha wrote:
> > Hi,
> >
> > setitimer(2) has a one hundred million second upper bound for timers.
> > Any timer interval larger than this is considered invalid and we set
> > EINVAL.
> >
> > There is no longer any reason to use this particular limit. Kclock
> > timeouts support the full range of a timespec, so we can trivially
> > increase the upper bound without any practical risk of overflow.
> >
> > This patch increases the upper bound to UINT_MAX seconds.
> >
> > Why UINT_MAX? UINT_MAX is the largest possible input to alarm(3). We
> > could then simplify the alarm(3) manpage and the libc alarm.c code in
> > a subsequent patch. POSIX says alarm(3) "is always successful". Our
> > implementation can fail. It would be nicer/simpler if ours were free
> > of failure modes.
> >
> > ok?
>
> 1 week bump.
>
> Updated patch: make the maximum value ("max") static and const.
OK claudio@
I wonder if we need a max at all? I guess there is an upper limit to not
overflow the time_t when calculating the absolute timeout but that is
probably close to LLONG_MAX / 2.
I think a simplified version of alarm(3) that never fails would be nice.
> Index: kern_time.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_time.c,v
> retrieving revision 1.153
> diff -u -p -r1.153 kern_time.c
> --- kern_time.c 11 Jun 2021 16:36:34 -0000 1.153
> +++ kern_time.c 18 Jun 2021 01:40:42 -0000
> @@ -709,15 +709,16 @@ out:
> int
> itimerfix(struct itimerval *itv)
> {
> + static const struct timeval max = { .tv_sec = UINT_MAX, .tv_usec = 0 };
> struct timeval min_interval = { .tv_sec = 0, .tv_usec = tick };
>
> if (itv->it_value.tv_sec < 0 || !timerisvalid(&itv->it_value))
> return EINVAL;
> - if (itv->it_value.tv_sec > 100000000)
> + if (timercmp(&itv->it_value, &max, >))
> return EINVAL;
> if (itv->it_interval.tv_sec < 0 || !timerisvalid(&itv->it_interval))
> return EINVAL;
> - if (itv->it_interval.tv_sec > 100000000)
> + if (timercmp(&itv->it_interval, &max, >))
> return EINVAL;
>
> if (!timerisset(&itv->it_value))
>
--
:wq Claudio
