1 /* 2 * Copyright (c) 1994 Christos Zoulas 3 * Copyright (c) 1995 Frank van der Linden 4 * Copyright (c) 1995 Scott Bartram 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 * 29 * from: svr4_util.c,v 1.5 1995/01/22 23:44:50 christos Exp 30 * $Id: linux_util.c,v 1.5 1997/02/22 09:38:29 peter Exp $ 31 */ 32 33 #include <sys/param.h> 34 #include <sys/systm.h> 35 #include <sys/namei.h> 36 #include <sys/proc.h> 37 #include <sys/file.h> 38 #include <sys/stat.h> 39 #include <sys/filedesc.h> 40 #include <sys/kernel.h> 41 #include <sys/malloc.h> 42 #include <sys/vnode.h> 43 44 #include <i386/linux/linux_util.h> 45 46 const char linux_emul_path[] = "/compat/linux"; 47 48 /* 49 * Search an alternate path before passing pathname arguments on 50 * to system calls. Useful for keeping a seperate 'emulation tree'. 51 * 52 * If cflag is set, we check if an attempt can be made to create 53 * the named file, i.e. we check if the directory it should 54 * be in exists. 55 */ 56 int 57 linux_emul_find(p, sgp, prefix, path, pbuf, cflag) 58 struct proc *p; 59 caddr_t *sgp; /* Pointer to stackgap memory */ 60 const char *prefix; 61 char *path; 62 char **pbuf; 63 int cflag; 64 { 65 struct nameidata nd; 66 struct nameidata ndroot; 67 struct vattr vat; 68 struct vattr vatroot; 69 int error; 70 char *ptr, *buf, *cp; 71 size_t sz, len; 72 73 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 74 *pbuf = path; 75 76 for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++) 77 continue; 78 79 sz = MAXPATHLEN - (ptr - buf); 80 81 /* 82 * If sgp is not given then the path is already in kernel space 83 */ 84 if (sgp == NULL) 85 error = copystr(path, ptr, sz, &len); 86 else 87 error = copyinstr(path, ptr, sz, &len); 88 89 if (error) { 90 free(buf, M_TEMP); 91 return error; 92 } 93 94 if (*ptr != '/') { 95 free(buf, M_TEMP); 96 return EINVAL; 97 } 98 99 /* 100 * We know that there is a / somewhere in this pathname. 101 * Search backwards for it, to find the file's parent dir 102 * to see if it exists in the alternate tree. If it does, 103 * and we want to create a file (cflag is set). We don't 104 * need to worry about the root comparison in this case. 105 */ 106 107 if (cflag) { 108 for (cp = &ptr[len] - 1; *cp != '/'; cp--); 109 *cp = '\0'; 110 111 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p); 112 113 if ((error = namei(&nd)) != 0) { 114 free(buf, M_TEMP); 115 return error; 116 } 117 118 *cp = '/'; 119 } 120 else { 121 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p); 122 123 if ((error = namei(&nd)) != 0) { 124 free(buf, M_TEMP); 125 return error; 126 } 127 128 /* 129 * We now compare the vnode of the linux_root to the one 130 * vnode asked. If they resolve to be the same, then we 131 * ignore the match so that the real root gets used. 132 * This avoids the problem of traversing "../.." to find the 133 * root directory and never finding it, because "/" resolves 134 * to the emulation root directory. This is expensive :-( 135 */ 136 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, linux_emul_path, 137 p); 138 139 if ((error = namei(&ndroot)) != 0) { 140 /* Cannot happen! */ 141 free(buf, M_TEMP); 142 vrele(nd.ni_vp); 143 return error; 144 } 145 146 if ((error = VOP_GETATTR(nd.ni_vp, &vat, p->p_ucred, p)) != 0) { 147 goto bad; 148 } 149 150 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p)) 151 != 0) { 152 goto bad; 153 } 154 155 if (vat.va_fsid == vatroot.va_fsid && 156 vat.va_fileid == vatroot.va_fileid) { 157 error = ENOENT; 158 goto bad; 159 } 160 161 } 162 if (sgp == NULL) 163 *pbuf = buf; 164 else { 165 sz = &ptr[len] - buf; 166 *pbuf = stackgap_alloc(sgp, sz + 1); 167 error = copyout(buf, *pbuf, sz); 168 free(buf, M_TEMP); 169 } 170 171 vrele(nd.ni_vp); 172 if (!cflag) 173 vrele(ndroot.ni_vp); 174 return error; 175 176 bad: 177 vrele(ndroot.ni_vp); 178 vrele(nd.ni_vp); 179 free(buf, M_TEMP); 180 return error; 181 } 182