Replace select backends with poll backends. selscan() and pollscan()

now call the poll backend.  With this change we implement greater
poll(2) functionality instead of emulating it via the select backend.
Adapted from NetBSD and including some changes from FreeBSD.
Tested by many, deraadt@ OK

1 files changed, 31 insertions, 40 deletions

diff --git a/sys/kern/sys_generic.c b/sys/kern/sys_generic.c
index 3a668bac241..713de532eaa 100644
--- a/sys/kern/sys_generic.c
+++ b/sys/kern/sys_generic.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sys_generic.c,v 1.45 2003/09/01 18:06:03 henning Exp $	*/
+/*	$OpenBSD: sys_generic.c,v 1.46 2003/09/23 16:51:12 millert Exp $	*/
 /*	$NetBSD: sys_generic.c,v 1.24 1996/03/29 00:25:32 cgd Exp $	*/
 
 /*
@@ -767,7 +767,7 @@ selscan(p, ibits, obits, nfd, retval)
 	register fd_mask bits;
 	struct file *fp;
 	int ni, n = 0;
-	static int flag[3] = { FREAD, FWRITE, 0 };
+	static const int flag[3] = { POLLIN, POLLOUT, POLLPRI };
 
 	/*
 	 * if nfd > FD_SETSIZE then the fd_set's contain nfd bits (rounded
@@ -788,7 +788,7 @@ selscan(p, ibits, obits, nfd, retval)
 				if ((fp = fd_getfile(fdp, fd)) == NULL)
 					return (EBADF);
 				FREF(fp);
-				if ((*fp->f_ops->fo_select)(fp, flag[msk], p)) {
+				if ((*fp->f_ops->fo_poll)(fp, flag[msk], p)) {
 					FD_SET(fd, pobits);
 					n++;
 				}
@@ -802,13 +802,13 @@ selscan(p, ibits, obits, nfd, retval)
 
 /*ARGSUSED*/
 int
-seltrue(dev, flag, p)
+seltrue(dev, events, p)
 	dev_t dev;
-	int flag;
+	int events;
 	struct proc *p;
 {
 
-	return (1);
+	return (events & (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM));
 }
 
 /*
@@ -871,39 +871,25 @@ pollscan(p, pl, nfd, retval)
 	int nfd;
 	register_t *retval;
 {
-	register struct filedesc *fdp = p->p_fd;
-	register int msk, i;
+	struct filedesc *fdp = p->p_fd;
 	struct file *fp;
-	int x, n = 0;
-	static int flag[3] = { FREAD, FWRITE, 0 };
-	static int pflag[3] = { POLLIN|POLLRDNORM, POLLOUT, POLLERR };
+	int i, n = 0;
 
-	/* 
-	 * XXX: We need to implement the rest of the flags.
-	 */
-	for (i = 0; i < nfd; i++) {
+	for (i = 0; i < nfd; i++, pl++) {
 		/* Check the file descriptor. */
-		if (pl[i].fd < 0) {
-			pl[i].revents = 0;
+		if (pl->fd < 0) {
+			pl->revents = 0;
 			continue;
 		}
-		if ((fp = fd_getfile(fdp, pl[i].fd)) == NULL) {
-			pl[i].revents = POLLNVAL;
+		if ((fp = fd_getfile(fdp, pl->fd)) == NULL) {
+			pl->revents = POLLNVAL;
 			n++;
 			continue;
 		}
 		FREF(fp);
-		for (x = msk = 0; msk < 3; msk++) {
-			if (pl[i].events & pflag[msk]) {
-				if ((*fp->f_ops->fo_select)(fp, flag[msk], p)) {
-					pl[i].revents |= pflag[msk] &
-					    pl[i].events;
-					x++;
-				}
-			}
-		}
+		pl->revents = (*fp->f_ops->fo_poll)(fp, pl->events, p);
 		FRELE(fp);
-		if (x)
+		if (pl->revents != 0)
 			n++;
 	}
 	*retval = n;
@@ -921,7 +907,7 @@ sys_poll(struct proc *p, void *v, register_t *retval)
 	struct pollfd pfds[4], *pl = pfds;
 	int msec = SCARG(uap, timeout);
 	struct timeval atv;
-	int timo, ncoll, i, s, error, error2;
+	int timo, ncoll, i, s, error;
 	extern int nselcoll, selwait;
 	u_int nfds;
 
@@ -946,7 +932,7 @@ sys_poll(struct proc *p, void *v, register_t *retval)
 	for (i = 0; i < nfds; i++)
 		pl[i].revents = 0;
 
-	if (msec != -1) {
+	if (msec != INFTIM) {
 		atv.tv_sec = msec / 1000;
 		atv.tv_usec = (msec - (atv.tv_sec * 1000)) * 1000;
 
@@ -966,7 +952,7 @@ retry:
 	pollscan(p, pl, nfds, retval);
 	if (*retval)
 		goto done;
-	if (msec != -1) {
+	if (msec != INFTIM) {
 		/*
 		 * We have to recalculate the timeout on every retry.
 		 */
@@ -987,16 +973,21 @@ retry:
 
 done:
 	p->p_flag &= ~P_SELECT;
-	/* poll is not restarted after signals... */
-	if (error == ERESTART)
+	/*
+	 * NOTE: poll(2) is not restarted after a signal and EWOULDBLOCK is
+	 *       ignored (since the whole point is to see what would block).
+	 */
+	switch (error) {
+	case ERESTART:
 		error = EINTR;
-	if (error == EWOULDBLOCK)
-		error = 0;
-	if ((error2 = copyout(pl, SCARG(uap, fds), sz)) != 0)
-		error = error2;
+		break;
+	case EWOULDBLOCK:
+	case 0:
+		error = copyout(pl, SCARG(uap, fds), sz);
+		break;
+	}
 bad:
 	if (pl != pfds)
-		free((char *) pl, M_TEMP);
+		free(pl, M_TEMP);
 	return (error);
 }
-