Initial import from FreeBSD RELENG_4:
[dragonfly.git] / sys / emulation / linux / linux_util.c
CommitLineData
984263bc
MD
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/compat/linux/linux_util.c,v 1.12.2.2 2001/11/05 19:08:23 marcel 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/malloc.h>
38#include <sys/vnode.h>
39
40#include <compat/linux/linux_util.h>
41
42const char linux_emul_path[] = "/compat/linux";
43
44/*
45 * Search an alternate path before passing pathname arguments on
46 * to system calls. Useful for keeping a separate 'emulation tree'.
47 *
48 * If cflag is set, we check if an attempt can be made to create
49 * the named file, i.e. we check if the directory it should
50 * be in exists.
51 */
52int
53linux_emul_find(p, sgp, prefix, path, pbuf, cflag)
54 struct proc *p;
55 caddr_t *sgp; /* Pointer to stackgap memory */
56 const char *prefix;
57 char *path;
58 char **pbuf;
59 int cflag;
60{
61 struct nameidata nd;
62 struct nameidata ndroot;
63 struct vattr vat;
64 struct vattr vatroot;
65 int error;
66 char *ptr, *buf, *cp;
67 size_t sz, len;
68
69 buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
70 *pbuf = path;
71
72 for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
73 continue;
74
75 sz = MAXPATHLEN - (ptr - buf);
76
77 /*
78 * If sgp is not given then the path is already in kernel space
79 */
80 if (sgp == NULL)
81 error = copystr(path, ptr, sz, &len);
82 else
83 error = copyinstr(path, ptr, sz, &len);
84
85 if (error) {
86 free(buf, M_TEMP);
87 return error;
88 }
89
90 if (*ptr != '/') {
91 free(buf, M_TEMP);
92 return EINVAL;
93 }
94
95 /*
96 * We know that there is a / somewhere in this pathname.
97 * Search backwards for it, to find the file's parent dir
98 * to see if it exists in the alternate tree. If it does,
99 * and we want to create a file (cflag is set). We don't
100 * need to worry about the root comparison in this case.
101 */
102
103 if (cflag) {
104 for (cp = &ptr[len] - 1; *cp != '/'; cp--);
105 *cp = '\0';
106
107 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
108
109 if ((error = namei(&nd)) != 0) {
110 free(buf, M_TEMP);
111 return error;
112 }
113
114 *cp = '/';
115 }
116 else {
117 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
118
119 if ((error = namei(&nd)) != 0) {
120 free(buf, M_TEMP);
121 return error;
122 }
123
124 /*
125 * We now compare the vnode of the linux_root to the one
126 * vnode asked. If they resolve to be the same, then we
127 * ignore the match so that the real root gets used.
128 * This avoids the problem of traversing "../.." to find the
129 * root directory and never finding it, because "/" resolves
130 * to the emulation root directory. This is expensive :-(
131 */
132 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, linux_emul_path,
133 p);
134
135 if ((error = namei(&ndroot)) != 0) {
136 /* Cannot happen! */
137 free(buf, M_TEMP);
138 NDFREE(&nd, NDF_ONLY_PNBUF);
139 vrele(nd.ni_vp);
140 return error;
141 }
142
143 if ((error = VOP_GETATTR(nd.ni_vp, &vat, p->p_ucred, p)) != 0) {
144 goto bad;
145 }
146
147 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p))
148 != 0) {
149 goto bad;
150 }
151
152 if (vat.va_fsid == vatroot.va_fsid &&
153 vat.va_fileid == vatroot.va_fileid) {
154 error = ENOENT;
155 goto bad;
156 }
157
158 }
159 if (sgp == NULL)
160 *pbuf = buf;
161 else {
162 sz = &ptr[len] - buf;
163 *pbuf = stackgap_alloc(sgp, sz + 1);
164 if (*pbuf != NULL)
165 error = copyout(buf, *pbuf, sz);
166 else
167 error = ENAMETOOLONG;
168 free(buf, M_TEMP);
169 }
170
171 NDFREE(&nd, NDF_ONLY_PNBUF);
172 vrele(nd.ni_vp);
173 if (!cflag) {
174 NDFREE(&ndroot, NDF_ONLY_PNBUF);
175 vrele(ndroot.ni_vp);
176 }
177 return error;
178
179bad:
180 NDFREE(&ndroot, NDF_ONLY_PNBUF);
181 vrele(ndroot.ni_vp);
182 NDFREE(&nd, NDF_ONLY_PNBUF);
183 vrele(nd.ni_vp);
184 free(buf, M_TEMP);
185 return error;
186}