strcasestr.c

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/*  $NetBSD: strcasestr.c,v 1.3 2005/11/29 03:12:00 christos Exp $  */
 
/*-
 * Copyright (c) 1990, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
 
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: strcasestr.c,v 1.3 2005/11/29 03:12:00 christos Exp $");
__RCSID("$NetBSD: strncasecmp.c,v 1.2 2007/06/04 18:19:27 christos Exp $");
#endif /* LIBC_SCCS and not lint */
 
#include "file.h"
 
#include <assert.h>
#include <ctype.h>
#include <string.h>
 
static int
_strncasecmp(const char *s1, const char *s2, size_t n)
{
    if (n != 0) {
        const unsigned char *us1 = (const unsigned char *)s1,
                *us2 = (const unsigned char *)s2;
 
        do {
            if (tolower(*us1) != tolower(*us2++))
                return tolower(*us1) - tolower(*--us2);
            if (*us1++ == '\0')
                break;
        } while (--n != 0);
    }
    return 0;
}
 
/*
 * Find the first occurrence of find in s, ignore case.
 */
char *
strcasestr(const char *s, const char *find)
{
    char c, sc;
    size_t len;
 
    if ((c = *find++) != 0) {
        c = tolower((unsigned char)c);
        len = strlen(find);
        do {
            do {
                if ((sc = *s++) == 0)
                    return (NULL);
            } while ((char)tolower((unsigned char)sc) != c);
        } while (_strncasecmp(s, find, len) != 0);
        s--;
    }
    return (char *)(intptr_t)(s);
}