xref: /openbsd-src/lib/libc/gen/dirname.c (revision db3296cf5c1dd9058ceecc3a29fe4aaa0bd26000)
1 /*	$OpenBSD: dirname.c,v 1.10 2003/06/17 21:56:23 millert Exp $	*/
2 
3 /*
4  * Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
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 #ifndef lint
20 static char rcsid[] = "$OpenBSD: dirname.c,v 1.10 2003/06/17 21:56:23 millert Exp $";
21 #endif /* not lint */
22 
23 #include <errno.h>
24 #include <libgen.h>
25 #include <string.h>
26 #include <sys/param.h>
27 
28 char *
29 dirname(const char *path)
30 {
31 	static char bname[MAXPATHLEN];
32 	register const char *endp;
33 
34 	/* Empty or NULL string gets treated as "." */
35 	if (path == NULL || *path == '\0') {
36 		(void)strlcpy(bname, ".", sizeof bname);
37 		return(bname);
38 	}
39 
40 	/* Strip 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 		(void)strlcpy(bname, *endp == '/' ? "/" : ".", sizeof bname);
52 		return(bname);
53 	} else {
54 		do {
55 			endp--;
56 		} while (endp > path && *endp == '/');
57 	}
58 
59 	if (endp - path + 2 > sizeof(bname)) {
60 		errno = ENAMETOOLONG;
61 		return(NULL);
62 	}
63 	strlcpy(bname, path, endp - path + 2);
64 	return(bname);
65 }
66