source: trunk/essentials/sys-apps/findutils/gnulib/lib/strstr.c

Last change on this file was 3170, checked in by bird, 18 years ago

findutils 4.3.2
File size: 3.3 KB
Line 
1/* Searching in a string.
2 Copyright (C) 2005-2006 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 2, 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, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
18
19#include <config.h>
20
21/* Specification. */
22#include "strstr.h"
23
24#include <stddef.h> /* for NULL */
25
26#if HAVE_MBRTOWC
27# include "mbuiter.h"
28#endif
29
30/* Find the first occurrence of NEEDLE in HAYSTACK. */
31char *
32strstr (const char *haystack, const char *needle)
33{
34 /* Be careful not to look at the entire extent of haystack or needle
35 until needed. This is useful because of these two cases:
36 - haystack may be very long, and a match of needle found early,
37 - needle may be very long, and not even a short initial segment of
38 needle may be found in haystack. */
39#if HAVE_MBRTOWC
40 if (MB_CUR_MAX > 1)
41 {
42 mbui_iterator_t iter_needle;
43
44 mbui_init (iter_needle, needle);
45 if (mbui_avail (iter_needle))
46 {
47 mbui_iterator_t iter_haystack;
48
49 mbui_init (iter_haystack, haystack);
50 for (;; mbui_advance (iter_haystack))
51 {
52 if (!mbui_avail (iter_haystack))
53 /* No match. */
54 return NULL;
55
56 if (mb_equal (mbui_cur (iter_haystack), mbui_cur (iter_needle)))
57 /* The first character matches. */
58 {
59 mbui_iterator_t rhaystack;
60 mbui_iterator_t rneedle;
61
62 memcpy (&rhaystack, &iter_haystack, sizeof (mbui_iterator_t));
63 mbui_advance (rhaystack);
64
65 mbui_init (rneedle, needle);
66 if (!mbui_avail (rneedle))
67 abort ();
68 mbui_advance (rneedle);
69
70 for (;; mbui_advance (rhaystack), mbui_advance (rneedle))
71 {
72 if (!mbui_avail (rneedle))
73 /* Found a match. */
74 return (char *) mbui_cur_ptr (iter_haystack);
75 if (!mbui_avail (rhaystack))
76 /* No match. */
77 return NULL;
78 if (!mb_equal (mbui_cur (rhaystack), mbui_cur (rneedle)))
79 /* Nothing in this round. */
80 break;
81 }
82 }
83 }
84 }
85 else
86 return (char *) haystack;
87 }
88 else
89#endif
90 {
91 if (*needle != '\0')
92 {
93 /* Speed up the following searches of needle by caching its first
94 character. */
95 char b = *needle++;
96
97 for (;; haystack++)
98 {
99 if (*haystack == '\0')
100 /* No match. */
101 return NULL;
102 if (*haystack == b)
103 /* The first character matches. */
104 {
105 const char *rhaystack = haystack + 1;
106 const char *rneedle = needle;
107
108 for (;; rhaystack++, rneedle++)
109 {
110 if (*rneedle == '\0')
111 /* Found a match. */
112 return (char *) haystack;
113 if (*rhaystack == '\0')
114 /* No match. */
115 return NULL;
116 if (*rhaystack != *rneedle)
117 /* Nothing in this round. */
118 break;
119 }
120 }
121 }
122 }
123 else
124 return (char *) haystack;
125 }
126}
Note: See TracBrowser for help on using the repository browser.