xref: /freebsd/lib/libc/amd64/string/strsep.c (revision f81cdf24ba5436367377f7c8e8f51f6df2a75ca7)
1 /*-
2  * Copyright (c) 2023 The FreeBSD Foundation
3  *
4  * This software was developed by Robert Clausecker <fuz@FreeBSD.org>
5  * under sponsorship from the FreeBSD Foundation.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ''AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE
27  */
28 
29 #include <sys/cdefs.h>
30 #include <string.h>
31 
32 size_t __strcspn(const char *, const char *);
33 
34 /*
35  * We have a fast strcspn() on amd64.  Use it over a direct
36  * implementation of strsep for better performance.
37  */
38 char *
39 strsep(char **stringp, const char *delim)
40 {
41 	size_t n;
42 	char *s;
43 
44 	s = *stringp;
45 	if (s == NULL)
46 		return (NULL);
47 
48 	n = __strcspn(s, delim);
49 	if (s[n] == '\0')
50 		*stringp = NULL;
51 	else {
52 		s[n] = '\0';
53 		*stringp = s + n + 1;
54 	}
55 
56 	return (s);
57 }
58