1 /* 2 * Copyright (c) 1992, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software donated to Berkeley by 6 * Jan-Simon Pendry. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 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 */ 40 41 #include <sys/param.h> 42 #include <sys/mount.h> 43 #include <vfs/nullfs/null.h> 44 45 #include <err.h> 46 #include <mntopts.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include <sysexits.h> 51 #include <unistd.h> 52 53 struct mntopt mopts[] = { 54 MOPT_STDOPTS, 55 MOPT_UPDATE, 56 MOPT_NULL 57 }; 58 59 static void usage(void) __dead2; 60 61 int 62 main(int argc, char **argv) 63 { 64 struct null_args args; 65 int ch, mntflags; 66 char source[MAXPATHLEN]; 67 char target[MAXPATHLEN]; 68 struct vfsconf vfc; 69 int error; 70 71 bzero(&args, sizeof(args)); 72 mntflags = 0; 73 while ((ch = getopt(argc, argv, "o:u")) != -1) 74 switch(ch) { 75 case 'o': 76 getmntopts(optarg, mopts, &mntflags, 0); 77 break; 78 case 'u': 79 mntflags |= MNT_UPDATE; 80 break; 81 case '?': 82 default: 83 usage(); 84 } 85 argc -= optind; 86 argv += optind; 87 88 /* 89 * Resolve target and source with realpath(3). Only the mount point 90 * needs be specified in update mode, but mount(8) passes us two 91 * arguments, the second of which is the source directory. 92 */ 93 if ((mntflags & MNT_UPDATE) && argc == 1) { 94 args.target = NULL; 95 checkpath(argv[0], source); 96 } else if (argc == 2) { 97 args.target = target; 98 checkpath(argv[0], target); 99 checkpath(argv[1], source); 100 } else 101 usage(); 102 103 /* 104 * Mount points that did not use distinct paths (e.g. / on /mnt) 105 * used to be disallowed because mount linkages were stored in 106 * vnodes and would lead to endlessly recursive trees. DragonFly 107 * stores mount linkages in the namecache topology and does not 108 * have this problem, so paths no longer need to be distinct. 109 */ 110 111 error = getvfsbyname("null", &vfc); 112 if (error && vfsisloadable("null")) { 113 if(vfsload("null")) 114 err(EX_OSERR, "vfsload(null)"); 115 endvfsent(); 116 error = getvfsbyname("null", &vfc); 117 } 118 if (error) 119 errx(EX_OSERR, "null/loopback filesystem is not available"); 120 121 if (mount(vfc.vfc_name, source, mntflags, &args)) 122 err(1, NULL); 123 exit(0); 124 } 125 126 static void 127 usage(void) 128 { 129 fprintf(stderr, 130 "usage: mount_null [-o options] target_fs mount_point\n"); 131 fprintf(stderr, 132 " mount_null -u [-o options] mount_point\n"); 133 exit(1); 134 } 135