proc->thread stage 4: rework the VFS and DEVICE subsystems to take thread
[dragonfly.git] / sys / emulation / linux / linux_util.c
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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 $
dadab5e9 31 * $DragonFly: src/sys/emulation/linux/linux_util.c,v 1.4 2003/06/25 03:55:44 dillon Exp $
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32 */
33
34#include <sys/param.h>
35#include <sys/systm.h>
984263bc 36#include <sys/proc.h>
dadab5e9 37#include <sys/namei.h>
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38#include <sys/malloc.h>
39#include <sys/vnode.h>
40
41#include <compat/linux/linux_util.h>
42
43const char linux_emul_path[] = "/compat/linux";
44
45/*
46 * Search an alternate path before passing pathname arguments on
47 * to system calls. Useful for keeping a separate 'emulation tree'.
48 *
49 * If cflag is set, we check if an attempt can be made to create
50 * the named file, i.e. we check if the directory it should
51 * be in exists.
52 */
53int
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54linux_emul_find(td, sgp, prefix, path, pbuf, cflag)
55 struct thread *td;
56 caddr_t *sgp; /* Pointer to stackgap memory */
57 const char *prefix;
58 char *path;
984263bc 59 char **pbuf;
dadab5e9 60 int cflag;
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61{
62 struct nameidata nd;
63 struct nameidata ndroot;
64 struct vattr vat;
65 struct vattr vatroot;
66 int error;
67 char *ptr, *buf, *cp;
68 size_t sz, len;
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69 struct ucred *cred;
70
71 KKASSERT(td->td_proc);
72 cred = td->td_proc->p_ucred;
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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
dadab5e9 112 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
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113
114 if ((error = namei(&nd)) != 0) {
115 free(buf, M_TEMP);
116 return error;
117 }
118
119 *cp = '/';
120 }
121 else {
dadab5e9 122 NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
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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 */
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137 NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE,
138 linux_emul_path, td);
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139
140 if ((error = namei(&ndroot)) != 0) {
141 /* Cannot happen! */
142 free(buf, M_TEMP);
143 NDFREE(&nd, NDF_ONLY_PNBUF);
144 vrele(nd.ni_vp);
145 return error;
146 }
147
dadab5e9 148 if ((error = VOP_GETATTR(nd.ni_vp, &vat, cred, td)) != 0) {
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149 goto bad;
150 }
151
dadab5e9 152 if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, cred, td))
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153 != 0) {
154 goto bad;
155 }
156
157 if (vat.va_fsid == vatroot.va_fsid &&
158 vat.va_fileid == vatroot.va_fileid) {
159 error = ENOENT;
160 goto bad;
161 }
162
163 }
164 if (sgp == NULL)
165 *pbuf = buf;
166 else {
167 sz = &ptr[len] - buf;
168 *pbuf = stackgap_alloc(sgp, sz + 1);
169 if (*pbuf != NULL)
170 error = copyout(buf, *pbuf, sz);
171 else
172 error = ENAMETOOLONG;
173 free(buf, M_TEMP);
174 }
175
176 NDFREE(&nd, NDF_ONLY_PNBUF);
177 vrele(nd.ni_vp);
178 if (!cflag) {
179 NDFREE(&ndroot, NDF_ONLY_PNBUF);
180 vrele(ndroot.ni_vp);
181 }
182 return error;
183
184bad:
185 NDFREE(&ndroot, NDF_ONLY_PNBUF);
186 vrele(ndroot.ni_vp);
187 NDFREE(&nd, NDF_ONLY_PNBUF);
188 vrele(nd.ni_vp);
189 free(buf, M_TEMP);
190 return error;
191}