1/* Case-insensitive searching in a string.
2   Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software Foundation,
3   Inc.
4   Written by Bruno Haible <bruno@clisp.org>, 2005.
5
6   This program is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 3, or (at your option)
9   any later version.
10
11   This program is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with this program; if not, write to the Free Software Foundation,
18   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
19
20#include <config.h>
21
22/* Specification.  */
23#include <string.h>
24
25#include <ctype.h>
26#include <stdbool.h>
27#include <strings.h>
28
29#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
30
31/* Two-Way algorithm.  */
32#define RETURN_TYPE char *
33#define AVAILABLE(h, h_l, j, n_l)			\
34  (!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l))	\
35   && ((h_l) = (j) + (n_l)))
36#define CANON_ELEMENT(c) TOLOWER (c)
37#define CMP_FUNC(p1, p2, l)				\
38  strncasecmp ((const char *) (p1), (const char *) (p2), l)
39#include "str-two-way.h"
40
41/* Find the first occurrence of NEEDLE in HAYSTACK, using
42   case-insensitive comparison.  This function gives unspecified
43   results in multibyte locales.  */
44char *
45strcasestr (const char *haystack_start, const char *needle_start)
46{
47  const char *haystack = haystack_start;
48  const char *needle = needle_start;
49  size_t needle_len; /* Length of NEEDLE.  */
50  size_t haystack_len; /* Known minimum length of HAYSTACK.  */
51  bool ok = true; /* True if NEEDLE is prefix of HAYSTACK.  */
52
53  /* Determine length of NEEDLE, and in the process, make sure
54     HAYSTACK is at least as long (no point processing all of a long
55     NEEDLE if HAYSTACK is too short).  */
56  while (*haystack && *needle)
57    {
58      ok &= (TOLOWER ((unsigned char) *haystack)
59	     == TOLOWER ((unsigned char) *needle));
60      haystack++;
61      needle++;
62    }
63  if (*needle)
64    return NULL;
65  if (ok)
66    return (char *) haystack_start;
67  needle_len = needle - needle_start;
68  haystack = haystack_start + 1;
69  haystack_len = needle_len - 1;
70
71  /* Perform the search.  Abstract memory is considered to be an array
72     of 'unsigned char' values, not an array of 'char' values.  See
73     ISO C 99 section 6.2.6.1.  */
74  if (needle_len < LONG_NEEDLE_THRESHOLD)
75    return two_way_short_needle ((const unsigned char *) haystack,
76				 haystack_len,
77				 (const unsigned char *) needle_start,
78				 needle_len);
79  return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
80			      (const unsigned char *) needle_start,
81			      needle_len);
82}
83
84#undef LONG_NEEDLE_THRESHOLD
85