1 /*
2 FUNCTION
3 <<strcasestr>>---case-insensitive character string search
4
5 INDEX
6 strcasestr
7
8 SYNOPSIS
9 #include <string.h>
10 char *strcasestr(const char *<[s]>, const char *<[find]>);
11
12 DESCRIPTION
13 <<strcasestr>> searchs the string <[s]> for
14 the first occurrence of the sequence <[find]>. <<strcasestr>>
15 is identical to <<strstr>> except the search is
16 case-insensitive.
17
18 RETURNS
19
20 A pointer to the first case-insensitive occurrence of the sequence
21 <[find]> or <<NULL>> if no match was found.
22
23 PORTABILITY
24 <<strcasestr>> is in the Berkeley Software Distribution.
25
26 <<strcasestr>> requires no supporting OS subroutines. It uses
27 tolower() from elsewhere in this library.
28
29 QUICKREF
30 strcasestr
31 */
32
33 /*-
34 * Copyright (c) 1990, 1993
35 * The Regents of the University of California. All rights reserved.
36 *
37 * The quadratic code is derived from software contributed to Berkeley by
38 * Chris Torek.
39 *
40 * Redistribution and use in source and binary forms, with or without
41 * modification, are permitted provided that the following conditions
42 * are met:
43 * 1. Redistributions of source code must retain the above copyright
44 * notice, this list of conditions and the following disclaimer.
45 * 2. Redistributions in binary form must reproduce the above copyright
46 * notice, this list of conditions and the following disclaimer in the
47 * documentation and/or other materials provided with the distribution.
48 * 4. Neither the name of the University nor the names of its contributors
49 * may be used to endorse or promote products derived from this software
50 * without specific prior written permission.
51 *
52 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
53 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
56 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
57 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
58 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
59 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
60 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
61 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
62 * SUCH DAMAGE.
63 */
64 /* Linear algorithm Copyright (C) 2008 Eric Blake
65 * Permission to use, copy, modify, and distribute the linear portion of
66 * software is freely granted, provided that this notice is preserved.
67 */
68
69 #include <sys/cdefs.h>
70
71 #include <ctype.h>
72 #include <string.h>
73 #include <strings.h>
74
75 #if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__)
76 # define RETURN_TYPE char *
77 # define AVAILABLE(h, h_l, j, n_l) \
78 (!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l)) \
79 && ((h_l) = (j) + (n_l)))
80 # define CANON_ELEMENT(c) tolower (c)
81 #if __GNUC_PREREQ (4, 2)
82 /* strncasecmp uses signed char, CMP_FUNC is expected to use unsigned char. */
83 #pragma GCC diagnostic ignored "-Wpointer-sign"
84 #endif
85 # define CMP_FUNC strncasecmp
86 # include "str-two-way.h"
87 #endif
88
89 /*
90 * Find the first occurrence of find in s, ignore case.
91 */
92 char *
strcasestr(const char * s,const char * find)93 strcasestr (const char *s,
94 const char *find)
95 {
96 #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
97
98 /* Less code size, but quadratic performance in the worst case. */
99 char c, sc;
100 size_t len;
101
102 if ((c = *find++) != 0) {
103 c = tolower((unsigned char)c);
104 len = strlen(find);
105 do {
106 do {
107 if ((sc = *s++) == 0)
108 return (NULL);
109 } while ((char)tolower((unsigned char)sc) != c);
110 } while (strncasecmp(s, find, len) != 0);
111 s--;
112 }
113 return ((char *)s);
114
115 #else /* compilation for speed */
116
117 /* Larger code size, but guaranteed linear performance. */
118 const char *haystack = s;
119 const char *needle = find;
120 size_t needle_len; /* Length of NEEDLE. */
121 size_t haystack_len; /* Known minimum length of HAYSTACK. */
122 int ok = 1; /* True if NEEDLE is prefix of HAYSTACK. */
123
124 /* Determine length of NEEDLE, and in the process, make sure
125 HAYSTACK is at least as long (no point processing all of a long
126 NEEDLE if HAYSTACK is too short). */
127 while (*haystack && *needle)
128 ok &= (tolower ((unsigned char) *haystack++)
129 == tolower ((unsigned char) *needle++));
130 if (*needle)
131 return NULL;
132 if (ok)
133 return (char *) s;
134 needle_len = needle - find;
135 haystack = s + 1;
136 haystack_len = needle_len - 1;
137
138 /* Perform the search. */
139 if (needle_len < LONG_NEEDLE_THRESHOLD)
140 return two_way_short_needle ((const unsigned char *) haystack,
141 haystack_len,
142 (const unsigned char *) find, needle_len);
143 return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
144 (const unsigned char *) find, needle_len);
145 #endif /* compilation for speed */
146 }
147
