/* Return the offset of one string within another.

   Copyright (C) 1994-2018 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 Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

/*

 * My personal strstr() implementation that beats most other algorithms.

 * Until someone tells me otherwise, I assume that this is the

 * fastest implementation of strstr() in C.

 * I deliberately chose not to comment it.  You should have at least

 * as much fun trying to understand it, as I had to write it :-).

 *

 * Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de	*/

/* Specification.  */

#include <string.h>

#include <ctype.h>

#include <stdbool.h>

#include <strings.h>

#define TOLOWER(Ch) tolower (Ch)

/* Two-Way algorithm.  */

#define RETURN_TYPE char *

#define AVAILABLE(h, h_l, j, n_l)			\

  (((j) + (n_l) <= (h_l)) \

   || ((h_l) += __strnlen ((void*)((h) + (h_l)), (n_l) + 512), \

       (j) + (n_l) <= (h_l)))

#define CHECK_EOL (1)

#define RET0_IF_0(a) if (!a) goto ret0

#define CANON_ELEMENT(c) TOLOWER (c)

#define CMP_FUNC(p1, p2, l)				\

  __strncasecmp ((const char *) (p1), (const char *) (p2), l)

#include "str-two-way.h"

#undef strcasestr

#undef __strcasestr

#ifndef STRCASESTR

#define STRCASESTR __strcasestr

#endif

/* Find the first occurrence of NEEDLE in HAYSTACK, using

   case-insensitive comparison.  This function gives unspecified

   results in multibyte locales.  */

char *

STRCASESTR (const char *haystack, const char *needle)

{

  size_t needle_len; /* Length of NEEDLE.  */

  size_t haystack_len; /* Known minimum length of HAYSTACK.  */

  /* Handle empty NEEDLE special case.  */

  if (needle[0] == '\0')

    return (char *) haystack;

  /* Ensure HAYSTACK length is at least as long as NEEDLE length.

     Since a match may occur early on in a huge HAYSTACK, use strnlen

     and read ahead a few cachelines for improved performance.  */

  needle_len = strlen (needle);

  haystack_len = __strnlen (haystack, needle_len + 256);

  if (haystack_len < needle_len)

    return NULL;

  /* Perform the search.  Abstract memory is considered to be an array

     of 'unsigned char' values, not an array of 'char' values.  See

     ISO C 99 section 6.2.6.1.  */

  if (needle_len < LONG_NEEDLE_THRESHOLD)

    return two_way_short_needle ((const unsigned char *) haystack,

				 haystack_len,

				 (const unsigned char *) needle,

				 needle_len);

  return two_way_long_needle ((const unsigned char *) haystack, haystack_len,

			      (const unsigned char *) needle,

			      needle_len);

}

#undef LONG_NEEDLE_THRESHOLD

#ifndef NO_ALIAS

weak_alias (__strcasestr, strcasestr)

#endif