On Wed, May 31, 2017 at 02:07:19PM +0200, Mike Belopuhov wrote:
> On Wed, May 31, 2017 at 08:37 +0200, Jan Schreiber wrote:
> > Hi,
> >
> > I recently stumbled upon software that relies on EV_RECEIPT and
> > EV_DISPATCH to be available as flags. It also showed up as dependency
> > for a Rust crate.
> > FreeBSD has it since 8.1 and OSX since 10.5.
> > Patch is below.
> >
> > mike@ looked throug, thanks a lot!
> >
>
> That was me (mikeb@).
Then you should commit it. OK bluhm@
>
> > Jan
> >
> > Index: sys/kern/kern_event.c
> > ===================================================================
> > RCS file: /cvs/src/sys/kern/kern_event.c,v
> > retrieving revision 1.78
> > diff -u -p -u -r1.78 kern_event.c
> > --- sys/kern/kern_event.c 11 Feb 2017 19:51:06 -0000 1.78
> > +++ sys/kern/kern_event.c 30 May 2017 22:38:49 -0000
> > @@ -512,7 +512,7 @@ sys_kevent(struct proc *p, void *v, regi
> > kevp = &kq->kq_kev[i];
> > kevp->flags &= ~EV_SYSFLAGS;
> > error = kqueue_register(kq, kevp, p);
> > - if (error) {
> > + if (error || (kevp->flags & EV_RECEIPT)) {
> > if (SCARG(uap, nevents) != 0) {
> > kevp->flags = EV_ERROR;
> > kevp->data = error;
> > @@ -788,9 +788,13 @@ start:
> > kn->kn_fop->f_detach(kn);
> > knote_drop(kn, p, p->p_fd);
> > s = splhigh();
> > - } else if (kn->kn_flags & EV_CLEAR) {
> > - kn->kn_data = 0;
> > - kn->kn_fflags = 0;
> > + } else if (kn->kn_flags & (EV_CLEAR | EV_DISPATCH)) {
> > + if (kn->kn_flags & EV_CLEAR) {
> > + kn->kn_data = 0;
> > + kn->kn_fflags = 0;
> > + }
> > + if (kn->kn_flags & EV_DISPATCH)
> > + kn->kn_status |= KN_DISABLED;
> > kn->kn_status &= ~(KN_QUEUED | KN_ACTIVE);
> > kq->kq_count--;
> > } else {
> > Index: sys/sys/event.h
> > ===================================================================
> > RCS file: /cvs/src/sys/sys/event.h,v
> > retrieving revision 1.23
> > diff -u -p -u -r1.23 event.h
> > --- sys/sys/event.h 24 Sep 2016 18:39:17 -0000 1.23
> > +++ sys/sys/event.h 30 May 2017 22:31:04 -0000
> > @@ -68,6 +68,8 @@ struct kevent {
> > /* flags */
> > #define EV_ONESHOT 0x0010 /* only report one occurrence */
> > #define EV_CLEAR 0x0020 /* clear event state after reporting */
> > +#define EV_RECEIPT 0x0040 /* force EV_ERROR on success, data=0 */
> > +#define EV_DISPATCH 0x0080 /* disable event after
> > reporting */
> >
> > #define EV_SYSFLAGS 0xF000 /* reserved by system */
> > #define EV_FLAG1 0x2000 /* filter-specific flag */
> > Index: lib/libc/sys/kqueue.2
> > ===================================================================
> > RCS file: /cvs/src/lib/libc/sys/kqueue.2,v
> > retrieving revision 1.33
> > diff -u -p -u -r1.33 kqueue.2
> > --- lib/libc/sys/kqueue.2 13 Aug 2016 17:05:02 -0000 1.33
> > +++ lib/libc/sys/kqueue.2 30 May 2017 22:30:29 -0000
> > @@ -184,10 +184,25 @@ Disable the event so
> > .Fn kevent
> > will not return it.
> > The filter itself is not disabled.
> > +.It Dv EV_DISPATCH
> > +Disable the event source immediately after delivery of an event.
> > +See
> > +.Dv EV_DISABLE
> > +above.
> > .It Dv EV_DELETE
> > Removes the event from the kqueue.
> > Events which are attached to file descriptors are automatically deleted
> > on the last close of the descriptor.
> > +.It Dv EV_RECEIPT
> > +Causes
> > +.Fn kevent
> > +to return with
> > +.Dv EV_ERROR
> > +set without draining any pending events after updating events in the
> > kqueue.
> > +When a filter is successfully added the
> > +.Va data
> > +field will be zero.
> > +This flag is useful for making bulk changes to a kqueue.
> > .It Dv EV_ONESHOT
> > Causes the event to return only the first occurrence of the filter
> > being triggered.
> >
>
> We've tweaked the description for EV_RECEIPT a bit because FreeBSD
> version didn't make a whole lot sense.
