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1/* $OpenBSD: dl_dirname.c,v 1.4 2022/01/08 06:49:41 guenther Exp $ */
2
3/*
4 * Copyright (c) 1997, 2004 Todd C. Miller <millert@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19#include <sys/types.h>
20#include <limits.h>
21
22#include "util.h"
23
24/*
25 * This file was copied from libc/stdlib/realpath.c and modified for ld.so's
26 * syscall method which returns -errno.
27 */
28
29char *
30_dl_dirname(const char *path)
31{
32 static char dname[PATH_MAX];
33 size_t len;
34 const char *endp;
35
36 /* Empty or NULL string gets treated as "." */
37 if (path == NULL || *path == '\0') {
38 dname[0] = '.';
39 dname[1] = '\0';
40 return (dname);
41 }
42
43 /* Strip any trailing slashes */
44 endp = path + strlen(path) - 1;
45 while (endp > path && *endp == '/')
46 endp--;
47
48 /* Find the start of the dir */
49 while (endp > path && *endp != '/')
50 endp--;
51
52 /* Either the dir is "/" or there are no slashes */
53 if (endp == path) {
54 dname[0] = *endp == '/' ? '/' : '.';
55 dname[1] = '\0';
56 return (dname);
57 } else {
58 /* Move forward past the separating slashes */
59 do {
60 endp--;
61 } while (endp > path && *endp == '/');
62 }
63
64 len = endp - path + 1;
65 if (len >= sizeof(dname)) {
66 return (NULL);
67 }
68 _dl_bcopy(path, dname, len);
69 dname[len] = '\0';
70 return (dname);
71}