mirror of
git://sourceware.org/git/glibc.git
synced 2024-12-21 04:31:04 +08:00
cf11e74b0d
It uses the same two-way algorithm used on strstr, strcasestr, and memmem. Different than strstr, neither the "shift table" optimization nor the self-adapting filtering check is used because it would result in a too-large shift table (and it also simplifies the implementation bit). Checked on x86_64-linux-gnu and aarch64-linux-gnu. Reviewed-by: DJ Delorie <dj@redhat.com>
53 lines
1.9 KiB
C
53 lines
1.9 KiB
C
/* Locate a substring in a wide-character string.
|
|
Copyright (C) 1995-2024 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
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <wchar.h>
|
|
#include <string.h>
|
|
|
|
#define AVAILABLE(h, h_l, j, n_l) \
|
|
(((j) + (n_l) <= (h_l)) \
|
|
|| ((h_l) += __wcsnlen ((void*)((h) + (h_l)), (n_l) + 128), \
|
|
(j) + (n_l) <= (h_l)))
|
|
#include "wcs-two-way.h"
|
|
|
|
#ifndef WCSSTR
|
|
# define WCSSTR wcsstr
|
|
#endif
|
|
|
|
wchar_t *
|
|
WCSSTR (const wchar_t *haystack, const wchar_t *needle)
|
|
{
|
|
/* 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. */
|
|
size_t ne_len = __wcslen (needle);
|
|
size_t hs_len = __wcsnlen (haystack, ne_len | 128);
|
|
if (hs_len < ne_len)
|
|
return NULL;
|
|
|
|
/* Check whether we have a match. This improves performance since we
|
|
avoid initialization overheads. */
|
|
if (__wmemcmp (haystack, needle, ne_len) == 0)
|
|
return (wchar_t *) haystack;
|
|
|
|
return two_way_short_needle (haystack, hs_len, needle, ne_len);
|
|
}
|
|
/* This alias is for backward compatibility with drafts of the ISO C
|
|
standard. Unfortunately the Unix(TM) standard requires this name. */
|
|
weak_alias (wcsstr, wcswcs)
|