compat_strcasestr.c

   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 }