79 lines
2.9 KiB
C
79 lines
2.9 KiB
C
|
/* Copyright (C) 1991-1994, 1996-1998, 2000, 2004, 2007-2020 Free Software
|
||
|
|
Foundation, Inc.
|
||
|
|
This file is part of the GNU C Library.
|
||
|
|
|
||
|
|
This program is free software; you can redistribute it and/or modify
|
||
|
|
it under the terms of the GNU General Public License as published by
|
||
|
|
the Free Software Foundation; either version 3, or (at your option)
|
||
|
|
any later version.
|
||
|
|
|
||
|
|
This program 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 General Public License for more details.
|
||
|
|
|
||
|
|
You should have received a copy of the GNU General Public License along
|
||
|
|
with this program; if not, see <https://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>
|
||
|
|
|
||
|
|
#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)))
|
||
|
|
#include "str-two-way.h"
|
||
|
|
|
||
|
|
/* 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_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 &= *haystack++ == *needle++;
|
||
|
|
if (*needle)
|
||
|
|
return NULL;
|
||
|
|
if (ok)
|
||
|
|
return (char *) haystack_start;
|
||
|
|
|
||
|
|
/* Reduce the size of haystack using strchr, since it has a smaller
|
||
|
|
linear coefficient than the Two-Way algorithm. */
|
||
|
|
needle_len = needle - needle_start;
|
||
|
|
haystack = strchr (haystack_start + 1, *needle_start);
|
||
|
|
if (!haystack || __builtin_expect (needle_len == 1, 0))
|
||
|
|
return (char *) haystack;
|
||
|
|
needle -= needle_len;
|
||
|
|
haystack_len = (haystack > haystack_start + needle_len ? 1
|
||
|
|
: needle_len + haystack_start - 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);
|
||
|
|
}
|
||
|
|
|
||
|
|
#undef LONG_NEEDLE_THRESHOLD
|