xref: /freebsd/lib/libc/string/strchrnul.c (revision edf8578117e8844e02c0121147f45e4609b30680)
1 /*-
2  * SPDX-License-Identifier: MIT
3  *
4  * Copyright (c) 2005-2014 Rich Felker, et al.
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining
7  * a copy of this software and associated documentation files (the
8  * "Software"), to deal in the Software without restriction, including
9  * without limitation the rights to use, copy, modify, merge, publish,
10  * distribute, sublicense, and/or sell copies of the Software, and to
11  * permit persons to whom the Software is furnished to do so, subject to
12  * the following conditions:
13  *
14  * The above copyright notice and this permission notice shall be
15  * included in all copies or substantial portions of the Software.
16  *
17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
20  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
21  * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
22  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
23  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
24  */
25 #include <sys/cdefs.h>
26 #include <limits.h>
27 #include <stdint.h>
28 #include <string.h>
29 
30 #define ALIGN (sizeof(size_t))
31 #define ONES ((size_t)-1 / UCHAR_MAX)
32 #define HIGHS (ONES * (UCHAR_MAX / 2 + 1))
33 #define HASZERO(x) (((x)-ONES) & ~(x)&HIGHS)
34 
35 char *__strchrnul(const char *, int);
36 
37 char *
38 __strchrnul(const char *s, int c)
39 {
40 	c = (unsigned char)c;
41 	if (!c)
42 		return (char *)s + strlen(s);
43 
44 #ifdef __GNUC__
45 	typedef size_t __attribute__((__may_alias__)) word;
46 	const word *w;
47 	for (; (uintptr_t)s % ALIGN; s++)
48 		if (!*s || *(unsigned char *)s == c)
49 			return (char *)s;
50 	size_t k = ONES * c;
51 	for (w = (void *)s; !HASZERO(*w) && !HASZERO(*w ^ k); w++)
52 		;
53 	s = (void *)w;
54 #endif
55 	for (; *s && *(unsigned char *)s != c; s++)
56 		;
57 	return (char *)s;
58 }
59 
60 __weak_reference(__strchrnul, strchrnul);
61