1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 * Copyright 2021 OmniOS Community Edition (OmniOSce) Association.
26 */
27
28 #include <sys/copyops.h>
29 #include <sys/errno.h>
30 #include <sys/kmem.h>
31 #include <sys/param.h>
32 #include <sys/pathname.h>
33 #include <sys/sysmacros.h>
34 #include <sys/systm.h>
35 #include <sys/types.h>
36 #include <sys/vnode.h>
37
38 int
getcwd(char * buf,size_t buflen)39 getcwd(char *buf, size_t buflen)
40 {
41 int err;
42 char *kbuf;
43 size_t kbuflen;
44
45 /*
46 * If the buffer cannot accommodate one character and nul terminator,
47 * it is too small.
48 */
49 if (buflen < 2)
50 return (set_errno(ERANGE));
51
52 /*
53 * The user should be able to specify any size buffer, but we don't want
54 * to arbitrarily allocate huge kernel buffers just because the user
55 * requests it. So we'll start with MAXPATHLEN (which should hold any
56 * normal path), and only increase it if we fail with
57 * ERANGE / ENAMETOOLONG.
58 *
59 * To protect against unbounded memory usage, cap to kmem_max_cached.
60 * This is far bigger than the length of any practical path on the
61 * system, and avoids allocating memory from the kmem_oversized arena.
62 */
63 kbuflen = MIN(buflen, MAXPATHLEN);
64
65 while (kbuflen <= kmem_max_cached) {
66 kbuf = kmem_alloc(kbuflen, KM_SLEEP);
67
68 if (((err = dogetcwd(kbuf, kbuflen)) == 0) &&
69 (copyout(kbuf, buf, strlen(kbuf) + 1) != 0)) {
70 err = EFAULT;
71 }
72
73 kmem_free(kbuf, kbuflen);
74
75 /*
76 * dogetcwd() inconsistently returns ERANGE or ENAMETOOLONG
77 * depending on whether it calls dirtopath() and then whether
78 * the subsequent operations run out of space whilst
79 * evaluating a cached vnode path or otherwise.
80 */
81 if (err == ENAMETOOLONG || err == ERANGE) {
82 /* For some reason, getcwd() uses ERANGE. */
83 err = ERANGE;
84 /*
85 * If the user's buffer really was too small, give up.
86 */
87 if (kbuflen == buflen)
88 break;
89 kbuflen = MIN(kbuflen * 2, buflen);
90 } else {
91 break;
92 }
93 }
94
95 return ((err != 0) ? set_errno(err) : 0);
96 }
97