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 * $FreeBSD: src/sys/i386/linux/linux_util.c,v 1.3.2.1 1999/09/05 08:14:20 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/ioctl.h>
41 #include <sys/kernel.h>
42 #include <sys/malloc.h>
43 #include <sys/vnode.h>
44
45 #include <i386/linux/linux_util.h>
46
47 const char linux_emul_path[] = "/compat/linux";
48
49 /*
50 * Search an alternate path before passing pathname arguments on
51 * to system calls. Useful for keeping a seperate '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 linux_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 size_t sz, len;
73
74 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
75 *pbuf = path;
76
77 for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
78 continue;
79
80 sz = MAXPATHLEN - (ptr - buf);
81
82 /*
83 * If sgp is not given then the path is already in kernel space
84 */
85 if (sgp == NULL)
86 error = copystr(path, ptr, sz, &len);
87 else
88 error = copyinstr(path, ptr, sz, &len);
89
90 if (error) {
91 free(buf, M_TEMP);
92 return error;
93 }
94
95 if (*ptr != '/') {
96 free(buf, M_TEMP);
97 return EINVAL;
98 }
99
100 /*
101 * We know that there is a / somewhere in this pathname.
102 * Search backwards for it, to find the file's parent dir
103 * to see if it exists in the alternate tree. If it does,
104 * and we want to create a file (cflag is set). We don't
105 * need to worry about the root comparison in this case.
106 */
107
108 if (cflag) {
109 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
110 *cp = '\0';
111
112 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
113
114 if ((error = namei(&nd)) != 0) {
115 free(buf, M_TEMP);
116 return error;
117 }
118
119 *cp = '/';
120 }
121 else {
122 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
123
124 if ((error = namei(&nd)) != 0) {
125 free(buf, M_TEMP);
126 return error;
127 }
128
129 /*
130 * We now compare the vnode of the linux_root to the one
131 * vnode asked. If they resolve to be the same, then we
132 * ignore the match so that the real root gets used.
133 * This avoids the problem of traversing "../.." to find the
134 * root directory and never finding it, because "/" resolves
135 * to the emulation root directory. This is expensive :-(
136 */
137 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, linux_emul_path,
138 p);
139
140 if ((error = namei(&ndroot)) != 0) {
141 /* Cannot happen! */
142 free(buf, M_TEMP);
143 vrele(nd.ni_vp);
144 return error;
145 }
146
147 if ((error = VOP_GETATTR(nd.ni_vp, &vat, p->p_ucred, p)) != 0) {
148 goto bad;
149 }
150
151 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p))
152 != 0) {
153 goto bad;
154 }
155
156 if (vat.va_fsid == vatroot.va_fsid &&
157 vat.va_fileid == vatroot.va_fileid) {
158 error = ENOENT;
159 goto bad;
160 }
161
162 }
163 if (sgp == NULL)
164 *pbuf = buf;
165 else {
166 sz = &ptr[len] - buf;
167 *pbuf = stackgap_alloc(sgp, sz + 1);
168 error = copyout(buf, *pbuf, sz);
169 free(buf, M_TEMP);
170 }
171
172 vrele(nd.ni_vp);
173 if (!cflag)
174 vrele(ndroot.ni_vp);
175 return error;
176
177 bad:
178 vrele(ndroot.ni_vp);
179 vrele(nd.ni_vp);
180 free(buf, M_TEMP);
181 return error;
182 }
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