Now that we have a_fflag in struct vop_poll_args we can handle

things like POLLOUT on a read-only fd more sensibly.  Previously,
any poll events could be used regardless of the actual file flags
of the descriptor.  The new fifo_poll() is effectively a pared down
soo_poll() with slightly different semantics to batter match FIFOs.
OK and feedback from guenther@

diff --git a/sys/miscfs/fifofs/fifo_vnops.c b/sys/miscfs/fifofs/fifo_vnops.c
index c8977ee..41a6f8a 100644 (file)
--- a/sys/miscfs/fifofs/fifo_vnops.c
+++ b/sys/miscfs/fifofs/fifo_vnops.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: fifo_vnops.c,v 1.45 2015/02/12 14:31:02 millert Exp $ */
+/*     $OpenBSD: fifo_vnops.c,v 1.46 2015/05/05 20:14:10 millert Exp $ */
 /*     $NetBSD: fifo_vnops.c,v 1.18 1996/03/16 23:52:42 christos Exp $ */
 
 /*
@@ -38,6 +38,7 @@
 #include <sys/namei.h>
 #include <sys/vnode.h>
 #include <sys/lock.h>
+#include <sys/protosw.h>
 #include <sys/socket.h>
 #include <sys/socketvar.h>
 #include <sys/stat.h>
@@ -289,21 +290,41 @@ int
 fifo_poll(void *v)
 {
        struct vop_poll_args *ap = v;
-       struct file filetmp;
-       const int events = ap->a_events;
+       struct socket *rso = ap->a_vp->v_fifoinfo->fi_readsock;
+       struct socket *wso = ap->a_vp->v_fifoinfo->fi_writesock;
+       int events = 0;
        int revents = 0;
 
-       if (events & (POLLIN | POLLPRI | POLLRDNORM | POLLRDBAND)) {
-               filetmp.f_data = ap->a_vp->v_fifoinfo->fi_readsock;
-               if (filetmp.f_data)
-                       revents |= soo_poll(&filetmp, events, ap->a_p);
+       /*
+        * Just return if there are no supported events specified,
+        * FIFOs don't support out-of-band or high priority data.
+        */
+       if (ap->a_fflag & FREAD)
+               events |= ap->a_events & (POLLIN | POLLRDNORM);
+       if (ap->a_fflag & FWRITE)
+               events |= ap->a_events & (POLLOUT | POLLWRNORM);
+       if (events == 0)
+               return (0);
+
+       if (events & (POLLIN | POLLRDNORM)) {
+               if (soreadable(rso))
+                       revents |= events & (POLLIN | POLLRDNORM);
        }
-       /* POLLHUP and POLLOUT/POLLWRNORM/POLLWRBAND are mutually exclusive */
-       if (!(revents & POLLHUP)) {
-               if (events & (POLLOUT | POLLWRNORM | POLLWRBAND)) {
-                       filetmp.f_data = ap->a_vp->v_fifoinfo->fi_writesock;
-                       if (filetmp.f_data)
-                               revents |= soo_poll(&filetmp, events, ap->a_p);
+       /* NOTE: POLLHUP and POLLOUT/POLLWRNORM are mutually exclusive */
+       if (rso->so_state & SS_ISDISCONNECTED) {
+               revents |= POLLHUP;
+       } else if (events & (POLLOUT | POLLWRNORM)) {
+               if (sowriteable(wso))
+                       revents |= events & (POLLOUT | POLLWRNORM);
+       }
+       if (revents == 0) {
+               if (events & (POLLIN | POLLRDNORM)) {
+                       selrecord(ap->a_p, &rso->so_rcv.sb_sel);
+                       rso->so_rcv.sb_flagsintr |= SB_SEL;
+               }
+               if (events & (POLLOUT | POLLWRNORM)) {
+                       selrecord(ap->a_p, &wso->so_snd.sb_sel);
+                       wso->so_snd.sb_flagsintr |= SB_SEL;
                }
        }
        return (revents);