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/* c-strcasestr.c -- case insensitive substring search in C locale
Copyright (C) 2005-2023 Free Software Foundation, Inc.
Written by Bruno Haible <bruno@clisp.org>, 2005.
This file 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.
This file 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 this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include "c-strcasestr.h"
#include <string.h>
#include "c-ctype.h"
#include "c-strcase.h"
/* 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 CANON_ELEMENT c_tolower
#define CMP_FUNC(p1, p2, l) \
c_strncasecmp ((const char *) (p1), (const char *) (p2), l)
#include "str-two-way.h"
/* Find the first occurrence of NEEDLE in HAYSTACK, using case-insensitive
comparison from the C locale, regardless of the current locale. */
char *
c_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 &= (c_tolower ((unsigned char) *haystack++)
== c_tolower ((unsigned char) *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
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