ibcs2_util.c revision 11397 
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/ioctl.h>
40#include <sys/kernel.h>
41#include <sys/malloc.h>
42#include <sys/vnode.h>
43
44#include <i386/ibcs2/ibcs2_util.h>
45
46const char      ibcs2_emul_path[] = "/emul/ibcs2";
47
48/*
49 * Search an alternate path before passing pathname arguments on
50 * to system calls. Useful for keeping a seperate 'emulation tree'.
51 *
52 * If cflag is set, we check if an attempt can be made to create
53 * the named file, i.e. we check if the directory it should
54 * be in exists.
55 */
56int
57ibcs2_emul_find(p, sgp, prefix, path, pbuf, cflag)
58	struct proc	 *p;
59	caddr_t		 *sgp;		/* Pointer to stackgap memory */
60	const char	 *prefix;
61	char		 *path;
62	char		**pbuf;
63	int		  cflag;
64{
65	struct nameidata	 nd;
66	struct nameidata	 ndroot;
67	struct vattr		 vat;
68	struct vattr		 vatroot;
69	int			 error;
70	char			*ptr, *buf, *cp;
71	size_t			 sz, len;
72
73	buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
74	*pbuf = path;
75
76	for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
77		continue;
78
79	sz = MAXPATHLEN - (ptr - buf);
80
81	/*
82	 * If sgp is not given then the path is already in kernel space
83	 */
84	if (sgp == NULL)
85		error = copystr(path, ptr, sz, &len);
86	else
87		error = copyinstr(path, ptr, sz, &len);
88
89	if (error) {
90		free(buf, M_TEMP);
91		return error;
92	}
93
94	if (*ptr != '/') {
95		free(buf, M_TEMP);
96		return EINVAL;
97	}
98
99	/*
100	 * We know that there is a / somewhere in this pathname.
101	 * Search backwards for it, to find the file's parent dir
102	 * to see if it exists in the alternate tree. If it does,
103	 * and we want to create a file (cflag is set). We don't
104	 * need to worry about the root comparison in this case.
105	 */
106
107	if (cflag) {
108		for (cp = &ptr[len] - 1; *cp != '/'; cp--);
109		*cp = '\0';
110
111		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
112
113		if ((error = namei(&nd)) != 0) {
114			free(buf, M_TEMP);
115			return error;
116		}
117
118		*cp = '/';
119	}
120	else {
121		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, p);
122
123		if ((error = namei(&nd)) != 0) {
124			free(buf, M_TEMP);
125			return error;
126		}
127
128		/*
129		 * We now compare the vnode of the ibcs2_root to the one
130		 * vnode asked. If they resolve to be the same, then we
131		 * ignore the match so that the real root gets used.
132		 * This avoids the problem of traversing "../.." to find the
133		 * root directory and never finding it, because "/" resolves
134		 * to the emulation root directory. This is expensive :-(
135		 */
136		/* XXX: prototype should have const here for NDINIT */
137		NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE,
138		       (char *) ibcs2_emul_path, 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 done;
149		}
150
151		if ((error = VOP_GETATTR(ndroot.ni_vp, &vatroot, p->p_ucred, p))
152		    != 0) {
153			goto done;
154		}
155
156		if (vat.va_fsid == vatroot.va_fsid &&
157		    vat.va_fileid == vatroot.va_fileid) {
158			error = ENOENT;
159			goto done;
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
173done:
174	vrele(nd.ni_vp);
175	if (!cflag)
176		vrele(ndroot.ni_vp);
177	return error;
178}
179