2 * Copyright (c) 1992, 1993, 1994
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36 * @(#) Copyright (c) 1992, 1993, 1994 The Regents of the University of California. All rights reserved.
37 * @(#)mount_null.c 8.6 (Berkeley) 4/26/95
38 * $FreeBSD: src/sbin/mount_null/mount_null.c,v 1.13 1999/10/09 11:54:11 phk Exp $
39 * $DragonFly: src/sbin/mount_null/mount_null.c,v 1.11 2008/09/18 16:08:31 dillon Exp $
42 #include <sys/param.h>
43 #include <sys/mount.h>
44 #include <vfs/nullfs/null.h>
55 struct mntopt mopts[] = {
61 static void usage(void) __dead2;
64 main(int argc, char **argv)
66 struct null_args args;
68 char source[MAXPATHLEN];
69 char target[MAXPATHLEN];
73 bzero(&args, sizeof(args));
75 while ((ch = getopt(argc, argv, "o:u")) != -1)
78 getmntopts(optarg, mopts, &mntflags, 0);
81 mntflags |= MNT_UPDATE;
91 * Resolve target and source with realpath(3). Only the mount point
92 * needs be specified in update mode, but mount(8) passes us two
93 * arguments, the second of which is the source directory.
95 if ((mntflags & MNT_UPDATE) && argc == 1) {
97 checkpath(argv[0], source);
98 } else if (argc == 2) {
100 checkpath(argv[0], target);
101 checkpath(argv[1], source);
106 * Mount points that did not use distinct paths (e.g. / on /mnt)
107 * used to be disallowed because mount linkages were stored in
108 * vnodes and would lead to endlessly recursive trees. DragonFly
109 * stores mount linkages in the namecache topology and does not
110 * have this problem, so paths no longer need to be distinct.
113 error = getvfsbyname("null", &vfc);
114 if (error && vfsisloadable("null")) {
116 err(EX_OSERR, "vfsload(null)");
118 error = getvfsbyname("null", &vfc);
121 errx(EX_OSERR, "null/loopback filesystem is not available");
123 if (mount(vfc.vfc_name, source, mntflags, &args))
132 "usage: mount_null [-o options] target_fs mount_point\n");
134 " mount_null -u [-o options] mount_point\n");