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/* 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) \
(!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l)) \
&& ((h_l) = (j) + (n_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_start, const char *needle_start)
{
const char *haystack = haystack_start;
const char *needle = needle_start;
size_t needle_len; /* Length of NEEDLE. */
size_t haystack_len; /* Known minimum length of HAYSTACK. */
bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */
/* Determine length of NEEDLE, and in the process, make sure
HAYSTACK is at least as long (no point processing all of a long
NEEDLE if HAYSTACK is too short). */
while (*haystack && *needle)
{
ok &= (TOLOWER ((unsigned char) *haystack)
== TOLOWER ((unsigned char) *needle));
haystack++;
needle++;
}
if (*needle)
return NULL;
if (ok)
return (char *) haystack_start;
needle_len = needle - needle_start;
haystack = haystack_start + 1;
haystack_len = needle_len - 1;
/* 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_start,
needle_len);
return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
(const unsigned char *) needle_start,
needle_len);
}
#undef LONG_NEEDLE_THRESHOLD
#ifndef NO_ALIAS
weak_alias (__strcasestr, strcasestr)
#endif
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