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      1 /*	Id: compat_strcasestr.c,v 1.5 2020/06/15 01:37:15 schwarze Exp  */
      2 /*	NetBSD: strcasestr.c,v 1.3 2005/11/29 03:12:00 christos Exp 	*/
      3 
      4 /*-
      5  * Copyright (c) 1990, 1993
      6  *	The Regents of the University of California.  All rights reserved.
      7  *
      8  * This code is derived from software contributed to Berkeley by
      9  * Chris Torek.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  * 3. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 #include "config.h"
     36 
     37 #include <sys/types.h>
     38 #include <ctype.h>
     39 #include <string.h>
     40 
     41 #define	__UNCONST(a)	((void *)(unsigned long)(const void *)(a))
     42 
     43 /*
     44  * Find the first occurrence of find in s, ignore case.
     45  */
     46 char *
     47 strcasestr(const char *s, const char *find)
     48 {
     49 	char c, sc;
     50 	size_t len;
     51 
     52 	if ((c = *find++) != 0) {
     53 		c = tolower((unsigned char)c);
     54 		len = strlen(find);
     55 		do {
     56 			do {
     57 				if ((sc = *s++) == 0)
     58 					return (NULL);
     59 			} while ((char)tolower((unsigned char)sc) != c);
     60 		} while (strncasecmp(s, find, len) != 0);
     61 		s--;
     62 	}
     63 	return __UNCONST(s);
     64 }
     65