xref: /freebsd/sys/libkern/strsep.c (revision ef36b3f75658d201edb495068db5e1be49593de5)
1 /*-
2  * Copyright (c) 1990, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #if defined(LIBC_SCCS) && !defined(lint)
31 static char sccsid[] = "@(#)strsep.c	8.1 (Berkeley) 6/4/93";
32 #endif /* LIBC_SCCS and not lint */
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35 
36 #include <sys/param.h>
37 #include <sys/libkern.h>
38 
39 /*
40  * Get next token from string *stringp, where tokens are possibly-empty
41  * strings separated by characters from delim.
42  *
43  * Writes NULs into the string at *stringp to end tokens.
44  * delim need not remain constant from call to call.
45  * On return, *stringp points past the last NUL written (if there might
46  * be further tokens), or is NULL (if there are definitely no more tokens).
47  *
48  * If *stringp is NULL, strsep returns NULL.
49  */
50 char *
51 strsep(stringp, delim)
52 	char **stringp;
53 	const char *delim;
54 {
55 	char *s;
56 	const char *spanp;
57 	int c, sc;
58 	char *tok;
59 
60 	if ((s = *stringp) == NULL)
61 		return (NULL);
62 	for (tok = s;;) {
63 		c = *s++;
64 		spanp = delim;
65 		do {
66 			if ((sc = *spanp++) == c) {
67 				if (c == 0)
68 					s = NULL;
69 				else
70 					s[-1] = 0;
71 				*stringp = s;
72 				return (tok);
73 			}
74 		} while (sc != 0);
75 	}
76 	/* NOTREACHED */
77 }
78