From 1c0f77f024b01c2df41c395b7e5afd760d0a9062 Mon Sep 17 00:00:00 2001
From: peter <peter@FreeBSD.org>
Date: Tue, 11 Mar 1997 12:40:45 +0000
Subject: Merge from Lite2 (use new getvfsbyname() and mount(2) interface)

---
 sbin/mount_null/Makefile     |  1 +
 sbin/mount_null/mount_null.8 | 30 +++++++++++++++++++++---------
 sbin/mount_null/mount_null.c | 23 ++++++++++++-----------
 3 files changed, 34 insertions(+), 20 deletions(-)

(limited to 'sbin/mount_null')

diff --git a/sbin/mount_null/Makefile b/sbin/mount_null/Makefile
index 3f8b3ef..97f3c62 100644
--- a/sbin/mount_null/Makefile
+++ b/sbin/mount_null/Makefile
@@ -5,6 +5,7 @@ SRCS=	mount_null.c getmntopts.c
 MAN8=	mount_null.8
 
 MOUNT=	${.CURDIR}/../mount
+CFLAGS+= -D_NEW_VFSCONF
 CFLAGS+= -I${.CURDIR}/../../sys -I${MOUNT}
 .PATH:	${MOUNT}
 
diff --git a/sbin/mount_null/mount_null.8 b/sbin/mount_null/mount_null.8
index 1a47b27..38473fa 100644
--- a/sbin/mount_null/mount_null.8
+++ b/sbin/mount_null/mount_null.8
@@ -34,15 +34,16 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"     @(#)mount_null.8	8.4 (Berkeley) 4/19/94
-.\"	$Id$
+.\"     @(#)mount_null.8	8.6 (Berkeley) 5/1/95
+.\"	$Id: mount_null.8,v 1.7 1997/02/22 14:32:50 peter Exp $
 .\"
-.Dd April 19, 1994
+.Dd May 1, 1995
 .Dt MOUNT_NULL 8
 .Os BSD 4.4
 .Sh NAME
 .Nm mount_null
-.Nd demonstrate the use of a null file system layer
+.Nd mount a loopback filesystem sub-tree;
+demonstrate the use of a null file system layer
 .Sh SYNOPSIS
 .Nm mount_null
 .Op Fl o Ar options
@@ -54,11 +55,22 @@ The
 command creates a
 null layer, duplicating a sub-tree of the file system
 name space under another part of the global file system namespace.
-In this respect, it is
-similar to the loopback file system (see
-.Xr mount_lofs 8 ) .
-It differs from
-the loopback file system in two respects: it is implemented using
+This allows existing files and directories to be accessed
+using a different pathname.
+.Pp
+The primary differences between a virtual copy of the filesystem
+and a symbolic link are that
+.Xr getcwd 3
+functions correctly in the virtual copy, and that other filesystems
+may be mounted on the virtual copy without affecting the original.
+A different device number for the virtual copy is returned by
+.Xr stat 2 ,
+but in other respects it is indistinguishable from the original.
+.Pp
+The
+.Nm mount_null
+filesystem differs from a traditional
+loopback file system in two respects: it is implemented using
 a stackable layers techniques, and it's 
 .Do
 null-node
diff --git a/sbin/mount_null/mount_null.c b/sbin/mount_null/mount_null.c
index 2d654c6..9269a71 100644
--- a/sbin/mount_null/mount_null.c
+++ b/sbin/mount_null/mount_null.c
@@ -42,10 +42,10 @@ char copyright[] =
 
 #ifndef lint
 /*
-static char sccsid[] = "@(#)mount_null.c	8.5 (Berkeley) 3/27/94";
+static char sccsid[] = "@(#)mount_null.c	8.6 (Berkeley) 4/26/95";
 */
 static const char rcsid[] =
-	"$Id$";
+	"$Id: mount_null.c,v 1.7 1997/02/22 14:32:51 peter Exp $";
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -77,7 +77,8 @@ main(argc, argv)
 	struct null_args args;
 	int ch, mntflags;
 	char target[MAXPATHLEN];
-	struct vfsconf *vfc;
+	struct vfsconf vfc;
+	int error;
 
 	mntflags = 0;
 	while ((ch = getopt(argc, argv, "o:")) != EOF)
@@ -104,18 +105,18 @@ main(argc, argv)
 
 	args.target = target;
 
-	vfc = getvfsbyname("null");
-	if(!vfc && vfsisloadable("null")) {
+	error = getvfsbyname("null", &vfc);
+	if (error && vfsisloadable("null")) {
 		if(vfsload("null"))
 			err(EX_OSERR, "vfsload(null)");
-		endvfsent();	/* flush cache */
-		vfc = getvfsbyname("null");
+		endvfsent();
+		error = getvfsbyname("null", &vfc);
 	}
-	if (!vfc)
-		errx(EX_OSERR, "null filesystem is not available");
+	if (error)
+		errx(EX_OSERR, "null/loopback filesystem is not available");
 
-	if (mount(vfc->vfc_index, argv[1], mntflags, &args))
-		err(EX_OSERR, target);
+	if (mount(vfc.vfc_name, argv[1], mntflags, &args))
+		err(1, NULL);
 	exit(0);
 }
 
-- 
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