Make EVFILT_EXCEPT handling separate from the read filter.

This is a change of behavior and events wont be generated if there
is something to read on the fd.  Only EV_EOF or NOTE_OOB will now
be reported.

While here a new filter for FIFOs supporting EV_EOF and __EV_HUP.

ok visa@

3 files changed, 189 insertions, 24 deletions

diff --git a/sys/kern/tty_pty.c b/sys/kern/tty_pty.c
index 660a2e86a9b..42eb39e2eb9 100644
--- a/sys/kern/tty_pty.c
+++ b/sys/kern/tty_pty.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tty_pty.c,v 1.108 2021/02/08 09:18:30 claudio Exp $	*/
+/*	$OpenBSD: tty_pty.c,v 1.109 2021/10/22 15:11:32 mpi Exp $	*/
 /*	$NetBSD: tty_pty.c,v 1.33.4.1 1996/06/02 09:08:11 mrg Exp $	*/
 
 /*
@@ -107,6 +107,7 @@ void	filt_ptcrdetach(struct knote *);
 int	filt_ptcread(struct knote *, long);
 void	filt_ptcwdetach(struct knote *);
 int	filt_ptcwrite(struct knote *, long);
+int	filt_ptcexcept(struct knote *, long);
 
 static struct pt_softc **ptyarralloc(int);
 static int check_pty(int);
@@ -670,16 +671,6 @@ filt_ptcread(struct knote *kn, long hint)
 	tp = pti->pt_tty;
 	kn->kn_data = 0;
 
-	if (kn->kn_sfflags & NOTE_OOB) {
-		/* If in packet or user control mode, check for data. */
-		if (((pti->pt_flags & PF_PKT) && pti->pt_send) ||
-		    ((pti->pt_flags & PF_UCNTL) && pti->pt_ucntl)) {
-			kn->kn_fflags |= NOTE_OOB;
-			kn->kn_data = 1;
-			return (1);
-		}
-		return (0);
-	}
 	if (ISSET(tp->t_state, TS_ISOPEN)) {
 		if (!ISSET(tp->t_state, TS_TTSTOP))
 			kn->kn_data = tp->t_outq.c_cc;
@@ -731,6 +722,34 @@ filt_ptcwrite(struct knote *kn, long hint)
 	return (kn->kn_data > 0);
 }
 
+int
+filt_ptcexcept(struct knote *kn, long hint)
+{
+	struct pt_softc *pti = (struct pt_softc *)kn->kn_hook;
+	struct tty *tp;
+
+	tp = pti->pt_tty;
+
+	if (kn->kn_sfflags & NOTE_OOB) {
+		/* If in packet or user control mode, check for data. */
+		if (((pti->pt_flags & PF_PKT) && pti->pt_send) ||
+		    ((pti->pt_flags & PF_UCNTL) && pti->pt_ucntl)) {
+			kn->kn_fflags |= NOTE_OOB;
+			kn->kn_data = 1;
+			return (1);
+		}
+		return (0);
+	}
+	if (!ISSET(tp->t_state, TS_CARR_ON)) {
+		kn->kn_flags |= EV_EOF;
+		if (kn->kn_flags & __EV_POLL)
+			kn->kn_flags |= __EV_HUP;
+		return (1);
+	}
+
+	return (0);
+}
+
 const struct filterops ptcread_filtops = {
 	.f_flags	= FILTEROP_ISFD,
 	.f_attach	= NULL,
@@ -749,7 +768,7 @@ const struct filterops ptcexcept_filtops = {
 	.f_flags	= FILTEROP_ISFD,
 	.f_attach	= NULL,
 	.f_detach	= filt_ptcrdetach,
-	.f_event	= filt_ptcread,
+	.f_event	= filt_ptcexcept,
 };
 
 int
diff --git a/sys/kern/uipc_socket.c b/sys/kern/uipc_socket.c
index 7b855ad3b77..afab85de1ee 100644
--- a/sys/kern/uipc_socket.c
+++ b/sys/kern/uipc_socket.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uipc_socket.c,v 1.265 2021/10/14 23:05:10 mvs Exp $	*/
+/*	$OpenBSD: uipc_socket.c,v 1.266 2021/10/22 15:11:32 mpi Exp $	*/
 /*	$NetBSD: uipc_socket.c,v 1.21 1996/02/04 02:17:52 christos Exp $	*/
 
 /*
@@ -78,6 +78,10 @@ int	filt_sowrite(struct knote *kn, long hint);
 int	filt_sowritemodify(struct kevent *kev, struct knote *kn);
 int	filt_sowriteprocess(struct knote *kn, struct kevent *kev);
 int	filt_sowrite_common(struct knote *kn, struct socket *so);
+int	filt_soexcept(struct knote *kn, long hint);
+int	filt_soexceptmodify(struct kevent *kev, struct knote *kn);
+int	filt_soexceptprocess(struct knote *kn, struct kevent *kev);
+int	filt_soexcept_common(struct knote *kn, struct socket *so);
 int	filt_solisten(struct knote *kn, long hint);
 int	filt_solistenmodify(struct kevent *kev, struct knote *kn);
 int	filt_solistenprocess(struct knote *kn, struct kevent *kev);
@@ -114,9 +118,9 @@ const struct filterops soexcept_filtops = {
 	.f_flags	= FILTEROP_ISFD,
 	.f_attach	= NULL,
 	.f_detach	= filt_sordetach,
-	.f_event	= filt_soread,
-	.f_modify	= filt_soreadmodify,
-	.f_process	= filt_soreadprocess,
+	.f_event	= filt_soexcept,
+	.f_modify	= filt_soexceptmodify,
+	.f_process	= filt_soexceptprocess,
 };
 
 #ifndef SOMINCONN
@@ -2089,13 +2093,7 @@ filt_soread_common(struct knote *kn, struct socket *so)
 		rv = 0;
 	} else
 #endif /* SOCKET_SPLICE */
-	if (kn->kn_sfflags & NOTE_OOB) {
-		if (so->so_oobmark || (so->so_state & SS_RCVATMARK)) {
-			kn->kn_fflags |= NOTE_OOB;
-			kn->kn_data -= so->so_oobmark;
-			rv = 1;
-		}
-	} else if (so->so_state & SS_CANTRCVMORE) {
+	if (so->so_state & SS_CANTRCVMORE) {
 		kn->kn_flags |= EV_EOF;
 		if (kn->kn_flags & __EV_POLL) {
 			if (so->so_state & SS_ISDISCONNECTED)
@@ -2235,6 +2233,77 @@ filt_sowriteprocess(struct knote *kn, struct kevent *kev)
 }
 
 int
+filt_soexcept_common(struct knote *kn, struct socket *so)
+{
+	int rv = 0;
+
+	soassertlocked(so);
+
+#ifdef SOCKET_SPLICE
+	if (isspliced(so)) {
+		rv = 0;
+	} else
+#endif /* SOCKET_SPLICE */
+	if (kn->kn_sfflags & NOTE_OOB) {
+		if (so->so_oobmark || (so->so_state & SS_RCVATMARK)) {
+			kn->kn_fflags |= NOTE_OOB;
+			kn->kn_data -= so->so_oobmark;
+			rv = 1;
+		}
+	} else if (so->so_state & SS_CANTRCVMORE) {
+		kn->kn_flags |= EV_EOF;
+		if (kn->kn_flags & __EV_POLL) {
+			if (so->so_state & SS_ISDISCONNECTED)
+				kn->kn_flags |= __EV_HUP;
+		}
+		kn->kn_fflags = so->so_error;
+		rv = 1;
+	}
+
+	return rv;
+}
+
+int
+filt_soexcept(struct knote *kn, long hint)
+{
+	struct socket *so = kn->kn_fp->f_data;
+
+	return (filt_soexcept_common(kn, so));
+}
+
+int
+filt_soexceptmodify(struct kevent *kev, struct knote *kn)
+{
+	struct socket *so = kn->kn_fp->f_data;
+	int rv, s;
+
+	s = solock(so);
+	knote_modify(kev, kn);
+	rv = filt_soexcept_common(kn, so);
+	sounlock(so, s);
+
+	return (rv);
+}
+
+int
+filt_soexceptprocess(struct knote *kn, struct kevent *kev)
+{
+	struct socket *so = kn->kn_fp->f_data;
+	int rv, s;
+
+	s = solock(so);
+	if (kev != NULL && (kn->kn_flags & EV_ONESHOT))
+		rv = 1;
+	else
+		rv = filt_soexcept_common(kn, so);
+	if (rv != 0)
+		knote_submit(kn, kev);
+	sounlock(so, s);
+
+	return (rv);
+}
+
+int
 filt_solisten_common(struct knote *kn, struct socket *so)
 {
 	soassertlocked(so);
diff --git a/sys/miscfs/fifofs/fifo_vnops.c b/sys/miscfs/fifofs/fifo_vnops.c
index 072187f1e80..6aa0c3284e2 100644
--- a/sys/miscfs/fifofs/fifo_vnops.c
+++ b/sys/miscfs/fifofs/fifo_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: fifo_vnops.c,v 1.82 2021/10/15 06:30:06 semarie Exp $	*/
+/*	$OpenBSD: fifo_vnops.c,v 1.83 2021/10/22 15:11:32 mpi Exp $	*/
 /*	$NetBSD: fifo_vnops.c,v 1.18 1996/03/16 23:52:42 christos Exp $	*/
 
 /*
@@ -112,6 +112,10 @@ int	filt_fifowrite(struct knote *kn, long hint);
 int	filt_fifowritemodify(struct kevent *kev, struct knote *kn);
 int	filt_fifowriteprocess(struct knote *kn, struct kevent *kev);
 int	filt_fifowrite_common(struct knote *kn, struct socket *so);
+int	filt_fifoexcept(struct knote *kn, long hint);
+int	filt_fifoexceptmodify(struct kevent *kev, struct knote *kn);
+int	filt_fifoexceptprocess(struct knote *kn, struct kevent *kev);
+int	filt_fifoexcept_common(struct knote *kn, struct socket *so);
 
 const struct filterops fiforead_filtops = {
 	.f_flags	= FILTEROP_ISFD,
@@ -131,6 +135,15 @@ const struct filterops fifowrite_filtops = {
 	.f_process	= filt_fifowriteprocess,
 };
 
+const struct filterops fifoexcept_filtops = {
+	.f_flags	= FILTEROP_ISFD,
+	.f_attach	= NULL,
+	.f_detach	= filt_fifordetach,
+	.f_event	= filt_fifoexcept,
+	.f_modify	= filt_fifoexceptmodify,
+	.f_process	= filt_fifoexceptprocess,
+};
+
 /*
  * Open called to set up a new instance of a fifo or
  * to find an active instance of a fifo.
@@ -522,6 +535,11 @@ fifo_kqfilter(void *v)
 		so = fip->fi_writesock;
 		sb = &so->so_snd;
 		break;
+	case EVFILT_EXCEPT:
+		ap->a_kn->kn_fop = &fifoexcept_filtops;
+		so = fip->fi_readsock;
+		sb = &so->so_rcv;
+		break;
 	default:
 		return (EINVAL);
 	}
@@ -670,3 +688,62 @@ filt_fifowriteprocess(struct knote *kn, struct kevent *kev)
 
 	return (rv);
 }
+
+int
+filt_fifoexcept_common(struct knote *kn, struct socket *so)
+{
+	int rv = 0;
+
+	soassertlocked(so);
+
+	if (so->so_state & SS_CANTRCVMORE) {
+		kn->kn_flags |= EV_EOF;
+		if (kn->kn_flags & __EV_POLL) {
+			if (so->so_state & SS_ISDISCONNECTED)
+				kn->kn_flags |= __EV_HUP;
+		}
+		rv = 1;
+	}
+
+	return (rv);
+}
+
+int
+filt_fifoexcept(struct knote *kn, long hint)
+{
+	struct socket *so = kn->kn_hook;
+
+	return (filt_fifoexcept_common(kn, so));
+}
+
+int
+filt_fifoexceptmodify(struct kevent *kev, struct knote *kn)
+{
+	struct socket *so = kn->kn_hook;
+	int rv, s;
+
+	s = solock(so);
+	knote_modify(kev, kn);
+	rv = filt_fifoexcept_common(kn, so);
+	sounlock(so, s);
+
+	return (rv);
+}
+
+int
+filt_fifoexceptprocess(struct knote *kn, struct kevent *kev)
+{
+	struct socket *so = kn->kn_hook;
+	int rv, s;
+
+	s = solock(so);
+	if (kev != NULL && (kn->kn_flags & EV_ONESHOT))
+		rv = 1;
+	else
+		rv = filt_fifoexcept_common(kn, so);
+	if (rv != 0)
+		knote_submit(kn, kev);
+	sounlock(so, s);
+
+	return (rv);
+}