libc/string/strstr.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37

/******************************************************************************
 * Copyright (c) 2004, 2008 IBM Corporation
 * All rights reserved.
 * This program and the accompanying materials
 * are made available under the terms of the BSD License
 * which accompanies this distribution, and is available at
 * http://www.opensource.org/licenses/bsd-license.php
 *
 * Contributors:
 *     IBM Corporation - initial implementation
 *****************************************************************************/

#include <string.h>

char *
strstr(const char *hay, const char *needle)
{
	char *pos;
	size_t hlen, nlen;

	if (hay == NULL || needle == NULL)
		return NULL;
	
	hlen = strlen(hay);
	nlen = strlen(needle);
	if (nlen < 1)
		return (char *)hay;

	for (pos = (char *)hay; pos < hay + hlen; pos++) {
		if (strncmp(pos, needle, nlen) == 0) {
			return pos;
		}
	}

	return NULL;
}