newlib/libc/string/wcsstr.c

   1 /*
   2 FUNCTION
   3         <<wcsstr>>---find a wide-character substring
   4
   5 SYNOPSIS
   6         #include <wchar.h>
   7         wchar_t *wcsstr(const wchar_t *__restrict <[big]>,
   8                         const wchar_t *__restrict <[little]>);
   9
  10 DESCRIPTION
  11         The <<wcsstr>> function locates the first occurrence in the
  12         wide-character string pointed to by <[big]> of the sequence of
  13         wide characters (excluding the terminating null wide character) in the
  14         wide-character string pointed to by <[little]>.
  15
  16 RETURNS
  17         On successful completion, <<wcsstr>> returns a pointer to the located
  18         wide-character string, or a null pointer if the wide-character string
  19         is not found.
  20
  21         If <[little]> points to a wide-character string with zero length,
  22         the function returns <[big]>.
  23
  24 PORTABILITY
  25 <<wcsstr>> is ISO/IEC 9899/AMD1:1995 (ISO C).
  26
  27 */
  28
  29 /*      $NetBSD: wcsstr.c,v 1.1 2000/12/23 23:14:37 itojun Exp $        */
  30
  31 /*-
  32  * Copyright (c)1999 Citrus Project,
  33  * All rights reserved.
  34  *
  35  * Redistribution and use in source and binary forms, with or without
  36  * modification, are permitted provided that the following conditions
  37  * are met:
  38  * 1. Redistributions of source code must retain the above copyright
  39  *    notice, this list of conditions and the following disclaimer.
  40  * 2. Redistributions in binary form must reproduce the above copyright
  41  *    notice, this list of conditions and the following disclaimer in the
  42  *    documentation and/or other materials provided with the distribution.
  43  *
  44  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  45  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  46  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  47  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  48  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  49  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  50  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  51  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  52  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  53  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  54  * SUCH DAMAGE.
  55  *
  56  *      citrus Id: wcsstr.c,v 1.2 2000/12/21 05:07:25 itojun Exp
  57  */
  58
  59 #include <_ansi.h>
  60 #include <stddef.h>
  61 #include <wchar.h>
  62
  63 wchar_t *
  64 wcsstr (const wchar_t *__restrict big,
  65         const wchar_t *__restrict little)
  66 {
  67   const wchar_t *p;
  68   const wchar_t *q;
  69   const wchar_t *r;
  70
  71   if (!*little)
  72     {
  73       /* LINTED interface specification */
  74       return (wchar_t *) big;
  75     }
  76   if (wcslen (big) < wcslen (little))
  77     return NULL;
  78
  79   p = big;
  80   q = little;
  81   while (*p)
  82     {
  83       q = little;
  84       r = p;
  85       while (*q)
  86         {
  87           if (*r != *q)
  88             break;
  89           q++;
  90           r++;
  91         }
  92       if (!*q)
  93         {
  94           /* LINTED interface specification */
  95           return (wchar_t *) p;
  96         }
  97       p++;
  98     }
  99   return NULL;
 100 }