xref: /openbsd-src/lib/libc/string/strsep.c (revision a4afd6dad3fba28f80e70208181c06c482259988)
1 /*-
2  * Copyright (c) 1990 The Regents of the University of California.
3  * 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. All advertising materials mentioning features or use of this software
14  *    must display the following acknowledgement:
15  *	This product includes software developed by the University of
16  *	California, Berkeley and its contributors.
17  * 4. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #if defined(LIBC_SCCS) && !defined(lint)
35 static char *rcsid = "$OpenBSD: strsep.c,v 1.2 1996/08/19 08:34:24 tholo Exp $";
36 #endif /* LIBC_SCCS and not lint */
37 
38 #include <string.h>
39 
40 /*
41  * Get next token from string *stringp, where tokens are nonempty
42  * strings separated by characters from delim.
43  *
44  * Writes NULs into the string at *stringp to end tokens.
45  * delim need not remain constant from call to call.
46  * On return, *stringp points past the last NUL written (if there might
47  * be further tokens), or is NULL (if there are definitely no more tokens).
48  *
49  * If *stringp is NULL, strtoken returns NULL.
50  */
51 char *
52 strsep(stringp, delim)
53 	register char **stringp;
54 	register const char *delim;
55 {
56 	register char *s;
57 	register const char *spanp;
58 	register int c, sc;
59 	char *tok;
60 
61 	if ((s = *stringp) == NULL)
62 		return (NULL);
63 	for (tok = s;;) {
64 		c = *s++;
65 		spanp = delim;
66 		do {
67 			if ((sc = *spanp++) == c) {
68 				if (c == 0)
69 					s = NULL;
70 				else
71 					s[-1] = 0;
72 				*stringp = s;
73 				return (tok);
74 			}
75 		} while (sc != 0);
76 	}
77 	/* NOTREACHED */
78 }
79