149 lines
4.8 KiB
C
149 lines
4.8 KiB
C
/*
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FUNCTION
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<<strcasestr>>---case-insensitive character string search
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INDEX
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strcasestr
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ANSI_SYNOPSIS
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#include <string.h>
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char *strcasestr(const char *<[s]>, const char *<[find]>);
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TRAD_SYNOPSIS
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#include <string.h>
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int strcasecmp(<[s]>, <[find]>)
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char *<[s]>;
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char *<[find]>;
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DESCRIPTION
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<<strcasestr>> searchs the string <[s]> for
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the first occurrence of the sequence <[find]>. <<strcasestr>>
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is identical to <<strstr>> except the search is
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case-insensitive.
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RETURNS
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A pointer to the first case-insensitive occurrence of the sequence
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<[find]> or <<NULL>> if no match was found.
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PORTABILITY
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<<strcasestr>> is in the Berkeley Software Distribution.
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<<strcasestr>> requires no supporting OS subroutines. It uses
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tolower() from elsewhere in this library.
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QUICKREF
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strcasestr
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*/
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/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* The quadratic code is derived from software contributed to Berkeley by
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* Chris Torek.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/* Linear algorithm Copyright (C) 2008 Eric Blake
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* Permission to use, copy, modify, and distribute the linear portion of
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* software is freely granted, provided that this notice is preserved.
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*/
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#include <sys/cdefs.h>
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#include <ctype.h>
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#include <string.h>
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#include <strings.h>
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#if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__)
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# define RETURN_TYPE char *
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# define AVAILABLE(h, h_l, j, n_l) \
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(!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l)) \
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&& ((h_l) = (j) + (n_l)))
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# define CANON_ELEMENT(c) tolower (c)
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# define CMP_FUNC strncasecmp
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# include "str-two-way.h"
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#endif
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/*
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* Find the first occurrence of find in s, ignore case.
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*/
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char *
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strcasestr(s, find)
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const char *s, *find;
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{
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#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
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/* Less code size, but quadratic performance in the worst case. */
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char c, sc;
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size_t len;
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if ((c = *find++) != 0) {
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c = tolower((unsigned char)c);
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len = strlen(find);
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do {
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do {
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if ((sc = *s++) == 0)
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return (NULL);
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} while ((char)tolower((unsigned char)sc) != c);
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} while (strncasecmp(s, find, len) != 0);
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s--;
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}
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return ((char *)s);
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#else /* compilation for speed */
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/* Larger code size, but guaranteed linear performance. */
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const char *haystack = s;
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const char *needle = find;
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size_t needle_len; /* Length of NEEDLE. */
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size_t haystack_len; /* Known minimum length of HAYSTACK. */
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int ok = 1; /* True if NEEDLE is prefix of HAYSTACK. */
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/* Determine length of NEEDLE, and in the process, make sure
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HAYSTACK is at least as long (no point processing all of a long
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NEEDLE if HAYSTACK is too short). */
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while (*haystack && *needle)
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ok &= (tolower ((unsigned char) *haystack++)
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== tolower ((unsigned char) *needle++));
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if (*needle)
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return NULL;
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if (ok)
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return (char *) s;
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needle_len = needle - find;
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haystack = s + 1;
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haystack_len = needle_len - 1;
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/* Perform the search. */
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if (needle_len < LONG_NEEDLE_THRESHOLD)
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return two_way_short_needle ((const unsigned char *) haystack,
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haystack_len,
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(const unsigned char *) find, needle_len);
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return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
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(const unsigned char *) find, needle_len);
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#endif /* compilation for speed */
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}
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