/* 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/>.  */

/* This particular implementation was written by Eric Blake, 2008.  */

#ifndef _LIBC

# include <config.h>

#endif

/* Specification of strstr.  */

#include <string.h>

#include <stdbool.h>

#ifndef _LIBC

# define __builtin_expect(expr, val)   (expr)

#endif

#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 FASTSEARCH(S,C,N) (void*) strchr ((void*)(S), (C))

#include "str-two-way.h"

#undef strstr

#ifndef STRSTR

#define STRSTR strstr

#endif

/* Return the first occurrence of NEEDLE in HAYSTACK.  Return HAYSTACK

   if NEEDLE is empty, otherwise NULL if NEEDLE is not found in

   HAYSTACK.  */

char *

STRSTR (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;

  /* Skip until we find the first matching char from NEEDLE.  */

  haystack = strchr (haystack, needle[0]);

  if (haystack == NULL || needle[1] == '\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;

  /* Check whether we have a match.  This improves performance since we avoid

     the initialization overhead of the two-way algorithm.  */

  if (memcmp (haystack, needle, needle_len) == 0)

    return (char *) haystack;

  /* 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);

}

libc_hidden_builtin_def (strstr)

#undef LONG_NEEDLE_THRESHOLD