1 /* $NetBSD: compat_util.c,v 1.6 1996/10/25 23:14:00 cgd 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/exec.h> 40 #include <sys/ioctl.h> 41 #include <sys/kernel.h> 42 #include <sys/malloc.h> 43 #include <sys/vnode.h> 44 45 #include <vm/vm_param.h> 46 47 #include <compat/common/compat_util.h> 48 49 /* 50 * Search an alternate path before passing pathname arguments on 51 * to system calls. Useful for keeping a separate 'emulation tree'. 52 * 53 * If cflag is set, we check if an attempt can be made to create 54 * the named file, i.e. we check if the directory it should 55 * be in exists. 56 */ 57 int 58 emul_find(p, sgp, prefix, path, pbuf, cflag) 59 struct proc *p; 60 caddr_t *sgp; /* Pointer to stackgap memory */ 61 const char *prefix; 62 char *path; 63 char **pbuf; 64 int cflag; 65 { 66 struct nameidata nd; 67 struct nameidata ndroot; 68 struct vattr vat; 69 struct vattr vatroot; 70 int error; 71 char *ptr, *buf, *cp; 72 const char *pr; 73 size_t sz, len; 74 75 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 76 *pbuf = path; 77 78 for (ptr = buf, pr = prefix; (*ptr = *pr) != '\0'; ptr++, pr++) 79 continue; 80 81 sz = MAXPATHLEN - (ptr - buf); 82 83 /* 84 * If sgp is not given then the path is already in kernel space 85 */ 86 if (sgp == NULL) 87 error = copystr(path, ptr, sz, &len); 88 else 89 error = copyinstr(path, ptr, sz, &len); 90 91 if (error) 92 goto bad; 93 94 if (*ptr != '/') { 95 error = EINVAL; 96 goto bad; 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 ; 110 *cp = '\0'; 111 112 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p); 113 114 if ((error = namei(&nd)) != 0) 115 goto bad; 116 117 *cp = '/'; 118 } 119 else { 120 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p); 121 122 if ((error = namei(&nd)) != 0) 123 goto bad; 124 125 /* 126 * We now compare the vnode of the emulation root to the one 127 * vnode asked. If they resolve to be the same, then we 128 * ignore the match so that the real root gets used. 129 * This avoids the problem of traversing "../.." to find the 130 * root directory and never finding it, because "/" resolves 131 * to the emulation root directory. This is expensive :-( 132 */ 133 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, prefix, p); 134 135 if ((error = namei(&ndroot)) != 0) 136 goto bad2; 137 138 if ((error = VOP_GETATTR(nd.ni_vp, &vat, p->p_ucred, p)) != 0) 139 goto bad3; 140 141 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p)) 142 != 0) 143 goto bad3; 144 145 if (vat.va_fsid == vatroot.va_fsid && 146 vat.va_fileid == vatroot.va_fileid) { 147 error = ENOENT; 148 goto bad3; 149 } 150 } 151 if (sgp == NULL) 152 *pbuf = buf; 153 else { 154 sz = &ptr[len] - buf; 155 *pbuf = stackgap_alloc(sgp, sz + 1); 156 error = copyout(buf, *pbuf, sz); 157 free(buf, M_TEMP); 158 } 159 160 vrele(nd.ni_vp); 161 if (!cflag) 162 vrele(ndroot.ni_vp); 163 return error; 164 165 bad3: 166 vrele(ndroot.ni_vp); 167 bad2: 168 vrele(nd.ni_vp); 169 bad: 170 free(buf, M_TEMP); 171 return error; 172 } 173 174 caddr_t 175 stackgap_init(e) 176 struct emul *e; 177 { 178 179 #define szsigcode ((caddr_t)(e->e_esigcode - e->e_sigcode)) 180 return STACKGAPBASE; 181 #undef szsigcode 182 } 183 184 185 void * 186 stackgap_alloc(sgp, sz) 187 caddr_t *sgp; 188 size_t sz; 189 { 190 void *p = (void *) *sgp; 191 192 *sgp += ALIGN(sz); 193 return p; 194 } 195