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1/* Case-insensitive searching in a string.
2 Copyright (C) 2005-2013 Free Software Foundation, Inc.
3 Written by Bruno Haible <bruno@clisp.org>, 2005.
4
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3, or (at your option)
8 any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, see <http://www.gnu.org/licenses/>. */
17
18#include <config.h>
19
20/* Specification. */
21#include <string.h>
22
23#include <ctype.h>
24#include <stdbool.h>
25#include <strings.h>
26
27#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
28
29/* Two-Way algorithm. */
30#define RETURN_TYPE char *
31#define AVAILABLE(h, h_l, j, n_l) \
32 (!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l)) \
33 && ((h_l) = (j) + (n_l)))
34#define CANON_ELEMENT(c) TOLOWER (c)
35#define CMP_FUNC(p1, p2, l) \
36 strncasecmp ((const char *) (p1), (const char *) (p2), l)
37#include "str-two-way.h"
38
39/* Find the first occurrence of NEEDLE in HAYSTACK, using
40 case-insensitive comparison. This function gives unspecified
41 results in multibyte locales. */
42char *
43strcasestr (const char *haystack_start, const char *needle_start)
44{
45 const char *haystack = haystack_start;
46 const char *needle = needle_start;
47 size_t needle_len; /* Length of NEEDLE. */
48 size_t haystack_len; /* Known minimum length of HAYSTACK. */
49 bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */
50
51 /* Determine length of NEEDLE, and in the process, make sure
52 HAYSTACK is at least as long (no point processing all of a long
53 NEEDLE if HAYSTACK is too short). */
54 while (*haystack && *needle)
55 {
56 ok &= (TOLOWER ((unsigned char) *haystack)
57 == TOLOWER ((unsigned char) *needle));
58 haystack++;
59 needle++;
60 }
61 if (*needle)
62 return NULL;
63 if (ok)
64 return (char *) haystack_start;
65 needle_len = needle - needle_start;
66 haystack = haystack_start + 1;
67 haystack_len = needle_len - 1;
68
69 /* Perform the search. Abstract memory is considered to be an array
70 of 'unsigned char' values, not an array of 'char' values. See
71 ISO C 99 section 6.2.6.1. */
72 if (needle_len < LONG_NEEDLE_THRESHOLD)
73 return two_way_short_needle ((const unsigned char *) haystack,
74 haystack_len,
75 (const unsigned char *) needle_start,
76 needle_len);
77 return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
78 (const unsigned char *) needle_start,
79 needle_len);
80}
81
82#undef LONG_NEEDLE_THRESHOLD