xref: /freebsd/lib/libc/gen/dirname.c (revision cdebaff820b2a4915a16cedfd511823d78aab171)
1 /*-
2  * Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23  * SUCH DAMAGE.
24  */
25 
26 #include <sys/cdefs.h>
27 __FBSDID("$FreeBSD$");
28 
29 #include <libgen.h>
30 #include <string.h>
31 
32 char *
33 (dirname)(char *path)
34 {
35 	char *end;
36 
37 	/*
38 	 * If path is a null pointer or points to an empty string,
39 	 * dirname() shall return a pointer to the string ".".
40 	 */
41 	if (path == NULL || *path == '\0')
42 		return (__DECONST(char *, "."));
43 
44 	/* Find end of last pathname component. */
45 	end = path + strlen(path);
46 	while (end > path + 1 && *(end - 1) == '/')
47 		--end;
48 
49 	/* Strip off the last pathname component. */
50 	while (end > path && *(end - 1) != '/')
51 		--end;
52 
53 	/*
54 	 * If path does not contain a '/', then dirname() shall return a
55 	 * pointer to the string ".".
56 	 */
57 	if (end == path) {
58 		path[0] = '.';
59 		path[1] = '\0';
60 		return (path);
61 	}
62 
63 	/*
64 	 * Remove trailing slashes from the resulting directory name. Ensure
65 	 * that at least one character remains.
66 	 */
67 	while (end > path + 1 && *(end - 1) == '/')
68 		--end;
69 
70 	/* Null terminate directory name and return it. */
71 	*end = '\0';
72 	return (path);
73 }
74