ibcs2_util.c revision 24203 
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 */
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/kernel.h>
40#include <sys/malloc.h>
41#include <sys/vnode.h>
42
43#include <i386/ibcs2/ibcs2_util.h>
44
45const char      ibcs2_emul_path[] = "/compat/ibcs2";
46
47/*
48 * Search an alternate path before passing pathname arguments on
49 * to system calls. Useful for keeping a seperate 'emulation tree'.
50 *
51 * If cflag is set, we check if an attempt can be made to create
52 * the named file, i.e. we check if the directory it should
53 * be in exists.
54 */
55int
56ibcs2_emul_find(p, sgp, prefix, path, pbuf, cflag)
57	struct proc	 *p;
58	caddr_t		 *sgp;		/* Pointer to stackgap memory */
59	const char	 *prefix;
60	char		 *path;
61	char		**pbuf;
62	int		  cflag;
63{
64	struct nameidata	 nd;
65	struct nameidata	 ndroot;
66	struct vattr		 vat;
67	struct vattr		 vatroot;
68	int			 error;
69	char			*ptr, *buf, *cp;
70	size_t			 sz, len;
71
72	buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
73	*pbuf = path;
74
75	for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
76		continue;
77
78	sz = MAXPATHLEN - (ptr - buf);
79
80	/*
81	 * If sgp is not given then the path is already in kernel space
82	 */
83	if (sgp == NULL)
84		error = copystr(path, ptr, sz, &len);
85	else
86		error = copyinstr(path, ptr, sz, &len);
87
88	if (error) {
89		free(buf, M_TEMP);
90		return error;
91	}
92
93	if (*ptr != '/') {
94		free(buf, M_TEMP);
95		return EINVAL;
96	}
97
98	/*
99	 * We know that there is a / somewhere in this pathname.
100	 * Search backwards for it, to find the file's parent dir
101	 * to see if it exists in the alternate tree. If it does,
102	 * and we want to create a file (cflag is set). We don't
103	 * need to worry about the root comparison in this case.
104	 */
105
106	if (cflag) {
107		for (cp = &ptr[len] - 1; *cp != '/'; cp--);
108		*cp = '\0';
109
110		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
111
112		if ((error = namei(&nd)) != 0) {
113			free(buf, M_TEMP);
114			return error;
115		}
116
117		*cp = '/';
118	}
119	else {
120		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
121
122		if ((error = namei(&nd)) != 0) {
123			free(buf, M_TEMP);
124			return error;
125		}
126
127		/*
128		 * We now compare the vnode of the ibcs2_root to the one
129		 * vnode asked. If they resolve to be the same, then we
130		 * ignore the match so that the real root gets used.
131		 * This avoids the problem of traversing "../.." to find the
132		 * root directory and never finding it, because "/" resolves
133		 * to the emulation root directory. This is expensive :-(
134		 */
135		NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, ibcs2_emul_path,
136		       p);
137
138		if ((error = namei(&ndroot)) != 0) {
139			/* Cannot happen! */
140			free(buf, M_TEMP);
141			vrele(nd.ni_vp);
142			return error;
143		}
144
145		if ((error = VOP_GETATTR(nd.ni_vp, &vat, p->p_ucred, p)) != 0) {
146			goto done;
147		}
148
149		if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p))
150		    != 0) {
151			goto done;
152		}
153
154		if (vat.va_fsid == vatroot.va_fsid &&
155		    vat.va_fileid == vatroot.va_fileid) {
156			error = ENOENT;
157			goto done;
158		}
159
160	}
161	if (sgp == NULL)
162		*pbuf = buf;
163	else {
164		sz = &ptr[len] - buf;
165		*pbuf = stackgap_alloc(sgp, sz + 1);
166		error = copyout(buf, *pbuf, sz);
167		free(buf, M_TEMP);
168	}
169
170
171done:
172	vrele(nd.ni_vp);
173	if (!cflag)
174		vrele(ndroot.ni_vp);
175	return error;
176}
177