1 /* $OpenBSD: dirname.c,v 1.17 2020/10/20 19:30:14 naddy 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 <errno.h>
20 #include <libgen.h>
21 #include <limits.h>
22 #include <string.h>
23
24 /* A slightly modified copy of this file exists in libexec/ld.so */
25
26 char *
dirname(char * path)27 dirname(char *path)
28 {
29 static char dname[PATH_MAX];
30 size_t len;
31 const char *endp;
32
33 /* Empty or NULL string gets treated as "." */
34 if (path == NULL || *path == '\0') {
35 dname[0] = '.';
36 dname[1] = '\0';
37 return (dname);
38 }
39
40 /* Strip any trailing slashes */
41 endp = path + strlen(path) - 1;
42 while (endp > path && *endp == '/')
43 endp--;
44
45 /* Find the start of the dir */
46 while (endp > path && *endp != '/')
47 endp--;
48
49 /* Either the dir is "/" or there are no slashes */
50 if (endp == path) {
51 dname[0] = *endp == '/' ? '/' : '.';
52 dname[1] = '\0';
53 return (dname);
54 } else {
55 /* Move forward past the separating slashes */
56 do {
57 endp--;
58 } while (endp > path && *endp == '/');
59 }
60
61 len = endp - path + 1;
62 if (len >= sizeof(dname)) {
63 errno = ENAMETOOLONG;
64 return (NULL);
65 }
66 memcpy(dname, path, len);
67 dname[len] = '\0';
68 return (dname);
69 }
70