From: mikeb <mikeb@openbsd.org>
Date: Wed, 31 May 2017 14:52:05 +0000 (+0000)
Subject: Add support for EV_RECEIPT and EV_DISPATCH flags
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=83c05d2a2887a46641fa7558826384e3bc121877;p=openbsd

Add support for EV_RECEIPT and EV_DISPATCH flags

From FreeBSD via Jan Schreiber <jes at posteo ! de>, thanks!
OK tedu, bluhm
---

diff --git a/lib/libc/sys/kqueue.2 b/lib/libc/sys/kqueue.2
index 35ca23d7dec..613a8f89259 100644
--- a/lib/libc/sys/kqueue.2
+++ b/lib/libc/sys/kqueue.2
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: kqueue.2,v 1.33 2016/08/13 17:05:02 tedu Exp $
+.\"	$OpenBSD: kqueue.2,v 1.34 2017/05/31 14:52:05 mikeb Exp $
 .\"
 .\" Copyright (c) 2000 Jonathan Lemon
 .\" All rights reserved.
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD: src/lib/libc/sys/kqueue.2,v 1.18 2001/02/14 08:48:35 guido Exp $
 .\"
-.Dd $Mdocdate: August 13 2016 $
+.Dd $Mdocdate: May 31 2017 $
 .Dt KQUEUE 2
 .Os
 .Sh NAME
@@ -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.
diff --git a/sys/kern/kern_event.c b/sys/kern/kern_event.c
index 561b9b256ea..e9a66f6fc4b 100644
--- a/sys/kern/kern_event.c
+++ b/sys/kern/kern_event.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_event.c,v 1.78 2017/02/11 19:51:06 guenther Exp $	*/
+/*	$OpenBSD: kern_event.c,v 1.79 2017/05/31 14:52:05 mikeb Exp $	*/
 
 /*-
  * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
@@ -512,7 +512,7 @@ sys_kevent(struct proc *p, void *v, register_t *retval)
 			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 {
diff --git a/sys/sys/event.h b/sys/sys/event.h
index 13b370b4c40..c359092be51 100644
--- a/sys/sys/event.h
+++ b/sys/sys/event.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: event.h,v 1.24 2017/05/31 07:12:28 tedu Exp $	*/
+/*	$OpenBSD: event.h,v 1.25 2017/05/31 14:52:05 mikeb Exp $	*/
 
 /*-
  * Copyright (c) 1999,2000,2001 Jonathan Lemon <jlemon@FreeBSD.org>
@@ -69,6 +69,8 @@ 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 */