linux_util.c revision 130959 
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/compat/linux/linux_util.c 130959 2004-06-23 06:35:43Z bde $");
34
35#include <sys/param.h>
36#include <sys/lock.h>
37#include <sys/malloc.h>
38#include <sys/mutex.h>
39#include <sys/namei.h>
40#include <sys/proc.h>
41#include <sys/systm.h>
42#include <sys/vnode.h>
43
44#include <machine/stdarg.h>
45
46#include <compat/linux/linux_util.h>
47
48const char      linux_emul_path[] = "/compat/linux";
49
50/*
51 * Search an alternate path before passing pathname arguments on
52 * to system calls. Useful for keeping a separate 'emulation tree'.
53 *
54 * If cflag is set, we check if an attempt can be made to create
55 * the named file, i.e. we check if the directory it should
56 * be in exists.
57 */
58int
59linux_emul_find(td, sgp, path, pbuf, cflag)
60	struct thread	 *td;
61	caddr_t		 *sgp;		/* Pointer to stackgap memory */
62	char		 *path;
63	char		**pbuf;
64	int		  cflag;
65{
66	char *newpath;
67	size_t sz;
68	int error;
69
70	error = linux_emul_convpath(td, path, (sgp == NULL) ? UIO_SYSSPACE :
71	    UIO_USERSPACE, &newpath, cflag);
72	if (newpath == NULL)
73		return (error);
74
75	if (sgp == NULL) {
76		*pbuf = newpath;
77		return (error);
78	}
79
80	sz = strlen(newpath);
81	*pbuf = stackgap_alloc(sgp, sz + 1);
82	if (*pbuf != NULL)
83		error = copyout(newpath, *pbuf, sz + 1);
84	else
85		error = ENAMETOOLONG;
86	free(newpath, M_TEMP);
87
88	return (error);
89}
90
91int
92linux_emul_convpath(td, path, pathseg, pbuf, cflag)
93	struct thread	 *td;
94	char		 *path;
95	enum uio_seg	  pathseg;
96	char		**pbuf;
97	int		  cflag;
98{
99	struct nameidata	 nd;
100	struct nameidata	 ndroot;
101	int			 error;
102	const char		*prefix;
103	char			*ptr, *buf, *cp;
104	size_t			 len, sz;
105
106	GIANT_REQUIRED;
107
108	buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
109	*pbuf = buf;
110
111	prefix = linux_emul_path;
112	for (ptr = buf; (*ptr = *prefix) != '\0'; ptr++, prefix++)
113		continue;
114	sz = MAXPATHLEN - (ptr - buf);
115
116	if (pathseg == UIO_SYSSPACE)
117		error = copystr(path, ptr, sz, &len);
118	else
119		error = copyinstr(path, ptr, sz, &len);
120
121	if (error) {
122		*pbuf = NULL;
123		free(buf, M_TEMP);
124		return error;
125	}
126
127	if (*ptr != '/') {
128		error = EINVAL;
129		goto keeporig;
130	}
131
132	/*
133	 * We know that there is a / somewhere in this pathname.
134	 * Search backwards for it, to find the file's parent dir
135	 * to see if it exists in the alternate tree. If it does,
136	 * and we want to create a file (cflag is set). We don't
137	 * need to worry about the root comparison in this case.
138	 */
139
140	if (cflag) {
141		for (cp = &ptr[len] - 1; *cp != '/'; cp--);
142		*cp = '\0';
143
144		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
145		error = namei(&nd);
146		*cp = '/';
147		if (error != 0)
148			goto keeporig;
149	}
150	else {
151		NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, buf, td);
152
153		if ((error = namei(&nd)) != 0)
154			goto keeporig;
155
156		/*
157		 * We now compare the vnode of the linux_root to the one
158		 * vnode asked. If they resolve to be the same, then we
159		 * ignore the match so that the real root gets used.
160		 * This avoids the problem of traversing "../.." to find the
161		 * root directory and never finding it, because "/" resolves
162		 * to the emulation root directory. This is expensive :-(
163		 */
164		NDINIT(&ndroot, LOOKUP, FOLLOW, UIO_SYSSPACE, linux_emul_path,
165		       td);
166
167		if ((error = namei(&ndroot)) != 0) {
168			/* Cannot happen! */
169			NDFREE(&nd, NDF_ONLY_PNBUF);
170			vrele(nd.ni_vp);
171			goto keeporig;
172		}
173
174		if (nd.ni_vp == ndroot.ni_vp) {
175			error = ENOENT;
176			goto bad;
177		}
178
179	}
180
181	NDFREE(&nd, NDF_ONLY_PNBUF);
182	vrele(nd.ni_vp);
183	if (!cflag) {
184		NDFREE(&ndroot, NDF_ONLY_PNBUF);
185		vrele(ndroot.ni_vp);
186	}
187	return error;
188
189bad:
190	NDFREE(&ndroot, NDF_ONLY_PNBUF);
191	vrele(ndroot.ni_vp);
192	NDFREE(&nd, NDF_ONLY_PNBUF);
193	vrele(nd.ni_vp);
194keeporig:
195	/* Keep the original path; copy it back to the start of the buffer. */
196	bcopy(ptr, buf, len);
197	return error;
198}
199
200void
201linux_msg(const struct thread *td, const char *fmt, ...)
202{
203	va_list ap;
204	struct proc *p;
205
206	p = td->td_proc;
207	printf("linux: pid %d (%s): ", (int)p->p_pid, p->p_comm);
208	va_start(ap, fmt);
209	vprintf(fmt, ap);
210	va_end(ap);
211	printf("\n");
212}
213