Restore the ability to detach from a tty via SIOCSTTY and document

recent changes in a manpage.

Reviewed by:	cognet

3 files changed, 16 insertions, 13 deletions

diff --git a/share/man/man4/snp.4 b/share/man/man4/snp.4
index 809d30b..df70cb2 100644
--- a/share/man/man4/snp.4
+++ b/share/man/man4/snp.4
@@ -1,7 +1,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd February 24, 1995
+.Dd September 18, 2005
 .Dt SNP 4
 .Os
 .Sh NAME
@@ -30,17 +30,20 @@ To associate a given
 .Nm
 device with a tty to be observed, open the
 .Nm
-device and then use the
+device and a tty device, and then issue the
 .Dv SNPSTTY
-ioctl.
+ioctl on
+.Nm
+device.
 The argument passed to the
 .Xr ioctl 2
 is the address of a variable of type
-.Vt udev_t .
+.Vt int ,
+holding the file descriptor of a tty device.
 To detach the
 .Nm
 device from a tty use a pointer to a value of
-.Dv NODEV .
+\-1.
 .Pp
 The
 .Dv SNPGTTY
diff --git a/sys/dev/snp/snp.c b/sys/dev/snp/snp.c
index c18a4ce..4008bae 100644
--- a/sys/dev/snp/snp.c
+++ b/sys/dev/snp/snp.c
@@ -527,17 +527,18 @@ snpioctl(dev, cmd, data, flags, td)
 	switch (cmd) {
 	case SNPSTTY:
 		s = *(int *)data;
-		if (s < 0 || fget(td, s, &fp) != 0)
+		if (s < 0)
+			return (snp_down(snp));
+		if (fget(td, s, &fp) != 0)
 			return (EINVAL);
 		if (fp->f_type != DTYPE_VNODE ||
-		    fp->f_vnode->v_type != VCHR) {
+		    fp->f_vnode->v_type != VCHR ||
+		    fp->f_vnode->v_rdev == NULL) {
 			fdrop(fp, td);
 			return (EINVAL);
 		}
 		tdev = fp->f_vnode->v_rdev;
 		fdrop(fp, td);
-		if (tdev == NULL)
-			return (snp_down(snp));
 
 		tp = snpdevtotty(tdev);
 		if (!tp)
@@ -593,7 +594,6 @@ snpioctl(dev, cmd, data, flags, td)
 			*(int *)data = snp->snp_len;
 		else
 			if (snp->snp_flags & SNOOP_DOWN) {
-				printf("IT IS DOWN\n");
 				if (snp->snp_flags & SNOOP_OFLOW)
 					*(int *)data = SNP_OFLOW;
 				else
diff --git a/usr.sbin/watch/watch.c b/usr.sbin/watch/watch.c
index a062ae0..11a80af 100644
--- a/usr.sbin/watch/watch.c
+++ b/usr.sbin/watch/watch.c
@@ -218,10 +218,10 @@ setup_scr(void)
 static void
 detach_snp(void)
 {
-	dev_t		dev;
+	int		fd;
 
-	dev = NODEV;
-	ioctl(snp_io, SNPSTTY, &dev);
+	fd = -1;
+	ioctl(snp_io, SNPSTTY, &fd);
 }
 
 static void