1/* Case-insensitive searching in a string.
2   Copyright (C) 2005-2014 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
83