1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright (c) 1989, 2010, Oracle and/or its affiliates. All rights reserved.
24 */
25
26 /* Copyright (c) 1988 AT&T */
27 /* All Rights Reserved */
28
29 #include "lint.h"
30 #include <string.h>
31 #include <stddef.h>
32 #include <sys/types.h>
33
34 /*
35 * strstr() locates the first occurrence in the string as1 of
36 * the sequence of characters (excluding the terminating null
37 * character) in the string as2. strstr() returns a pointer
38 * to the located string, or a null pointer if the string is
39 * not found. If as2 is empty, the function returns as1.
40 */
41
42 char *
strstr(const char * as1,const char * as2)43 strstr(const char *as1, const char *as2)
44 {
45 const char *s1, *s2;
46 const char *tptr;
47 char c;
48
49 s1 = as1;
50 s2 = as2;
51
52 if (s2 == NULL || *s2 == '\0')
53 return ((char *)s1);
54
55 c = *s2;
56 while (*s1 != '\0') {
57 if (c == *s1++) {
58 tptr = s1;
59 while ((c = *++s2) == *s1++ && c != '\0')
60 continue;
61 if (c == '\0')
62 return ((char *)tptr - 1);
63 s1 = tptr;
64 s2 = as2;
65 c = *s2;
66 }
67 }
68
69 return (NULL);
70 }
71
72 /*
73 * strnstr() locates the first occurrence in the string as1 of
74 * the sequence of characters (excluding the terminating null
75 * character) in the string as2, where not more than n characters
76 * from the string as1 are searched. strnstr() returns a pointer
77 * to the located string, or a null pointer if the string is
78 * not found. If as2 is empty, the function returns as1.
79 */
80
81 char *
strnstr(const char * as1,const char * as2,size_t n)82 strnstr(const char *as1, const char *as2, size_t n)
83 {
84 const char *s1, *s2;
85 const char *tptr;
86 size_t k;
87 char c;
88
89 s1 = as1;
90 s2 = as2;
91
92 if (s2 == NULL || *s2 == '\0')
93 return ((char *)s1);
94
95 c = *s2;
96 while (*s1 != '\0' && n--) {
97 if (c == *s1++) {
98 k = n;
99 tptr = s1;
100 while ((c = *++s2) == *s1++ && c != '\0' && k--)
101 continue;
102 if (c == '\0')
103 return ((char *)tptr - 1);
104 s1 = tptr;
105 s2 = as2;
106 c = *s2;
107 }
108 }
109
110 return (NULL);
111 }
112