ibcs2_util.c revision 115684 
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/cdefs.h>
33__FBSDID("$FreeBSD: head/sys/i386/ibcs2/ibcs2_util.c 115684 2003-06-02 06:48:51Z obrien $");
34
35#include <sys/param.h>
36#include <sys/systm.h>
37#include <sys/namei.h>
38#include <sys/malloc.h>
39#include <sys/vnode.h>
40
41#include <i386/ibcs2/ibcs2_util.h>
42
43
44const char      ibcs2_emul_path[] = "/compat/ibcs2";
45
46/*
47 * Search an alternate path before passing pathname arguments on
48 * to system calls. Useful for keeping a separate 'emulation tree'.
49 *
50 * If cflag is set, we check if an attempt can be made to create
51 * the named file, i.e. we check if the directory it should
52 * be in exists.
53 */
54int
55ibcs2_emul_find(td, sgp, prefix, path, pbuf, cflag)
56	struct thread	 *td;
57	caddr_t		 *sgp;		/* Pointer to stackgap memory */
58	const char	 *prefix;
59	char		 *path;
60	char		**pbuf;
61	int		  cflag;
62{
63	struct nameidata	 nd;
64	struct nameidata	 ndroot;
65	struct vattr		 vat;
66	struct vattr		 vatroot;
67	int			 error;
68	char			*ptr, *buf, *cp;
69	size_t			 sz, len;
70
71	buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
72	*pbuf = path;
73
74	for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
75		continue;
76
77	sz = MAXPATHLEN - (ptr - buf);
78
79	/*
80	 * If sgp is not given then the path is already in kernel space
81	 */
82	if (sgp == NULL)
83		error = copystr(path, ptr, sz, &len);
84	else
85		error = copyinstr(path, ptr, sz, &len);
86
87	if (error) {
88		free(buf, M_TEMP);
89		return error;
90	}
91
92	if (*ptr != '/') {
93		free(buf, M_TEMP);
94		return EINVAL;
95	}
96
97	/*
98	 * We know that there is a / somewhere in this pathname.
99	 * Search backwards for it, to find the file's parent dir
100	 * to see if it exists in the alternate tree. If it does,
101	 * and we want to create a file (cflag is set). We don't
102	 * need to worry about the root comparison in this case.
103	 */
104
105	if (cflag) {
106		for (cp = &ptr[len] - 1; *cp != '/'; cp--);
107		*cp = '\0';
108
109		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
110
111		if ((error = namei(&nd)) != 0) {
112			free(buf, M_TEMP);
113			return error;
114		}
115
116		*cp = '/';
117	}
118	else {
119		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
120
121		if ((error = namei(&nd)) != 0) {
122			free(buf, M_TEMP);
123			return error;
124		}
125
126		/*
127		 * We now compare the vnode of the ibcs2_root to the one
128		 * vnode asked. If they resolve to be the same, then we
129		 * ignore the match so that the real root gets used.
130		 * This avoids the problem of traversing "../.." to find the
131		 * root directory and never finding it, because "/" resolves
132		 * to the emulation root directory. This is expensive :-(
133		 */
134		NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, ibcs2_emul_path,
135		       td);
136
137		if ((error = namei(&ndroot)) != 0) {
138			/* Cannot happen! */
139			free(buf, M_TEMP);
140			NDFREE(&nd, NDF_ONLY_PNBUF);
141			vrele(nd.ni_vp);
142			return error;
143		}
144
145		if ((error = VOP_GETATTR(nd.ni_vp, &vat, td->td_ucred, td)) != 0) {
146			goto done;
147		}
148
149		if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, td->td_ucred, td))
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	NDFREE(&nd, NDF_ONLY_PNBUF);
173	vrele(nd.ni_vp);
174	if (!cflag) {
175		NDFREE(&ndroot, NDF_ONLY_PNBUF);
176		vrele(ndroot.ni_vp);
177	}
178	return error;
179}
180