1 /* $NetBSD: compat_util.c,v 1.4 1996/03/14 19:31:45 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1994 Christos Zoulas 5 * Copyright (c) 1995 Frank van der Linden 6 * All rights reserved. 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. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 * 30 */ 31 32 #include <sys/param.h> 33 #include <sys/systm.h> 34 #include <sys/namei.h> 35 #include <sys/proc.h> 36 #include <sys/file.h> 37 #include <sys/stat.h> 38 #include <sys/filedesc.h> 39 #include <sys/ioctl.h> 40 #include <sys/kernel.h> 41 #include <sys/malloc.h> 42 #include <sys/vnode.h> 43 44 #include <compat/common/compat_util.h> 45 46 /* 47 * Search an alternate path before passing pathname arguments on 48 * to system calls. Useful for keeping a separate 'emulation tree'. 49 * 50 * If cflag is set, we check if an attempt can be made to create 51 * the named file, i.e. we check if the directory it should 52 * be in exists. 53 */ 54 int 55 emul_find(p, sgp, prefix, path, pbuf, cflag) 56 struct proc *p; 57 caddr_t *sgp; /* Pointer to stackgap memory */ 58 const char *prefix; 59 char *path; 60 char **pbuf; 61 int cflag; 62 { 63 struct nameidata nd; 64 struct nameidata ndroot; 65 struct vattr vat; 66 struct vattr vatroot; 67 int error; 68 char *ptr, *buf, *cp; 69 const char *pr; 70 size_t sz, len; 71 72 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 73 *pbuf = path; 74 75 for (ptr = buf, pr = prefix; (*ptr = *pr) != '\0'; ptr++, pr++) 76 continue; 77 78 sz = MAXPATHLEN - (ptr - buf); 79 80 /* 81 * If sgp is not given then the path is already in kernel space 82 */ 83 if (sgp == NULL) 84 error = copystr(path, ptr, sz, &len); 85 else 86 error = copyinstr(path, ptr, sz, &len); 87 88 if (error) 89 goto bad; 90 91 if (*ptr != '/') { 92 error = EINVAL; 93 goto bad; 94 } 95 96 /* 97 * We know that there is a / somewhere in this pathname. 98 * Search backwards for it, to find the file's parent dir 99 * to see if it exists in the alternate tree. If it does, 100 * and we want to create a file (cflag is set). We don't 101 * need to worry about the root comparison in this case. 102 */ 103 104 if (cflag) { 105 for (cp = &ptr[len] - 1; *cp != '/'; cp--) 106 ; 107 *cp = '\0'; 108 109 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p); 110 111 if ((error = namei(&nd)) != 0) 112 goto bad; 113 114 *cp = '/'; 115 } 116 else { 117 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p); 118 119 if ((error = namei(&nd)) != 0) 120 goto bad; 121 122 /* 123 * We now compare the vnode of the emulation root to the one 124 * vnode asked. If they resolve to be the same, then we 125 * ignore the match so that the real root gets used. 126 * This avoids the problem of traversing "../.." to find the 127 * root directory and never finding it, because "/" resolves 128 * to the emulation root directory. This is expensive :-( 129 */ 130 /* XXX: prototype should have const here for NDINIT */ 131 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, 132 (char *) prefix, p); 133 134 if ((error = namei(&ndroot)) != 0) 135 goto bad2; 136 137 if ((error = VOP_GETATTR(nd.ni_vp, &vat, p->p_ucred, p)) != 0) 138 goto bad3; 139 140 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p)) 141 != 0) 142 goto bad3; 143 144 if (vat.va_fsid == vatroot.va_fsid && 145 vat.va_fileid == vatroot.va_fileid) { 146 error = ENOENT; 147 goto bad3; 148 } 149 } 150 if (sgp == NULL) 151 *pbuf = buf; 152 else { 153 sz = &ptr[len] - buf; 154 *pbuf = stackgap_alloc(sgp, sz + 1); 155 error = copyout(buf, *pbuf, sz); 156 free(buf, M_TEMP); 157 } 158 159 vrele(nd.ni_vp); 160 if (!cflag) 161 vrele(ndroot.ni_vp); 162 return error; 163 164 bad3: 165 vrele(ndroot.ni_vp); 166 bad2: 167 vrele(nd.ni_vp); 168 bad: 169 free(buf, M_TEMP); 170 return error; 171 } 172