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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#) Copyright (c) 1992, 1993, 1994 The Regents of the University of California. All rights reserved. 33 * @(#)mount_null.c 8.6 (Berkeley) 4/26/95 34 * $FreeBSD: src/sbin/mount_null/mount_null.c,v 1.13 1999/10/09 11:54:11 phk Exp $ 35 */ 36 37 #include <sys/param.h> 38 #include <sys/mount.h> 39 #include <vfs/nullfs/null.h> 40 41 #include <err.h> 42 #include <mntopts.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <sysexits.h> 47 #include <unistd.h> 48 49 struct mntopt mopts[] = { 50 MOPT_STDOPTS, 51 MOPT_UPDATE, 52 MOPT_NULL 53 }; 54 55 static void usage(void) __dead2; 56 57 int 58 main(int argc, char **argv) 59 { 60 struct null_args args; 61 int ch, mntflags; 62 char source[MAXPATHLEN]; 63 char target[MAXPATHLEN]; 64 struct vfsconf vfc; 65 int error; 66 67 bzero(&args, sizeof(args)); 68 mntflags = 0; 69 while ((ch = getopt(argc, argv, "o:u")) != -1) 70 switch(ch) { 71 case 'o': 72 getmntopts(optarg, mopts, &mntflags, 0); 73 break; 74 case 'u': 75 mntflags |= MNT_UPDATE; 76 break; 77 case '?': 78 default: 79 usage(); 80 } 81 argc -= optind; 82 argv += optind; 83 84 /* 85 * Resolve target and source with realpath(3). Only the mount point 86 * needs be specified in update mode, but mount(8) passes us two 87 * arguments, the second of which is the source directory. 88 */ 89 if ((mntflags & MNT_UPDATE) && argc == 1) { 90 args.target = NULL; 91 checkpath(argv[0], source); 92 } else if (argc == 2) { 93 args.target = target; 94 checkpath(argv[0], target); 95 checkpath(argv[1], source); 96 } else 97 usage(); 98 99 /* 100 * Mount points that did not use distinct paths (e.g. / on /mnt) 101 * used to be disallowed because mount linkages were stored in 102 * vnodes and would lead to endlessly recursive trees. DragonFly 103 * stores mount linkages in the namecache topology and does not 104 * have this problem, so paths no longer need to be distinct. 105 */ 106 107 error = getvfsbyname("null", &vfc); 108 if (error && vfsisloadable("null")) { 109 if(vfsload("null")) 110 err(EX_OSERR, "vfsload(null)"); 111 endvfsent(); 112 error = getvfsbyname("null", &vfc); 113 } 114 if (error) 115 errx(EX_OSERR, "null/loopback filesystem is not available"); 116 117 if (mount(vfc.vfc_name, source, mntflags, &args)) 118 err(1, NULL); 119 exit(0); 120 } 121 122 static void 123 usage(void) 124 { 125 fprintf(stderr, 126 "usage: mount_null [-o options] target_fs mount_point\n"); 127 fprintf(stderr, 128 " mount_null -u [-o options] mount_point\n"); 129 exit(1); 130 } 131