/*
 * Copyright (C) 1991, 1992 Free Software Foundation, Inc.
 * This file is part of the GNU C Library.
 * 
 * The GNU C Library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * The GNU C Library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with the GNU C Library; see the file COPYING.LIB in the
 * root directory of this distribution.  If not, write to the, 1992
 * Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/types.h>
#include <linux/string.h>

char * strstr(const char * haystack,const char * needle)
{
  register const char *const needle_end = strchr(needle, '\0');
  register const char *const haystack_end = strchr(haystack, '\0');
  register const size_t needle_len = needle_end - needle;
  register const size_t needle_last = needle_len - 1;
  register const char *begin;

  if (needle_len == 0)
    return (char *) haystack_end;
  if ((size_t) (haystack_end - haystack) < needle_len)
    return NULL;

  for (begin = &haystack[needle_last]; begin < haystack_end; ++begin)
    {
      register const char *n = &needle[needle_last];
      register const char *h = begin;

      do
	if (*h != *n)
	  goto loop;		/* continue for loop */
      while (--n >= needle && --h >= haystack);

      return (char *) h;

    loop:;
    }

  return NULL;
}