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 * $DragonFly: src/sbin/mount_null/mount_null.c,v 1.11 2008/09/18 16:08:31 dillon Exp $ 40 */ 41 42 #include <sys/param.h> 43 #include <sys/mount.h> 44 #include <vfs/nullfs/null.h> 45 46 #include <err.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include <sysexits.h> 51 #include <unistd.h> 52 53 #include "mntopts.h" 54 55 struct mntopt mopts[] = { 56 MOPT_STDOPTS, 57 MOPT_UPDATE, 58 MOPT_NULL 59 }; 60 61 static void usage(void) __dead2; 62 63 int 64 main(int argc, char **argv) 65 { 66 struct null_args args; 67 int ch, mntflags; 68 char source[MAXPATHLEN]; 69 char target[MAXPATHLEN]; 70 struct vfsconf vfc; 71 int error; 72 73 bzero(&args, sizeof(args)); 74 mntflags = 0; 75 while ((ch = getopt(argc, argv, "o:u")) != -1) 76 switch(ch) { 77 case 'o': 78 getmntopts(optarg, mopts, &mntflags, 0); 79 break; 80 case 'u': 81 mntflags |= MNT_UPDATE; 82 break; 83 case '?': 84 default: 85 usage(); 86 } 87 argc -= optind; 88 argv += optind; 89 90 /* 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. 94 */ 95 if ((mntflags & MNT_UPDATE) && argc == 1) { 96 args.target = NULL; 97 checkpath(argv[0], source); 98 } else if (argc == 2) { 99 args.target = target; 100 checkpath(argv[0], target); 101 checkpath(argv[1], source); 102 } else 103 usage(); 104 105 /* 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. 111 */ 112 113 error = getvfsbyname("null", &vfc); 114 if (error && vfsisloadable("null")) { 115 if(vfsload("null")) 116 err(EX_OSERR, "vfsload(null)"); 117 endvfsent(); 118 error = getvfsbyname("null", &vfc); 119 } 120 if (error) 121 errx(EX_OSERR, "null/loopback filesystem is not available"); 122 123 if (mount(vfc.vfc_name, source, mntflags, &args)) 124 err(1, NULL); 125 exit(0); 126 } 127 128 static void 129 usage(void) 130 { 131 fprintf(stderr, 132 "usage: mount_null [-o options] target_fs mount_point\n"); 133 fprintf(stderr, 134 " mount_null -u [-o options] mount_point\n"); 135 exit(1); 136 } 137