1 /*	$OpenBSD: getenv.c,v 1.10 2010/08/23 22:31:50 millert Exp $ */
2 /*
3  * Copyright (c) 1987, 1993
4  *	The Regents of the University of California.  All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of the University nor the names of its contributors
15  *    may be used to endorse or promote products derived from this software
16  *    without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  */
30 
31 #include <stdlib.h>
32 #include <string.h>
33 
34 char *__findenv(const char *name, int len, int *offset);
35 
36 /*
37  * __findenv --
38  *	Returns pointer to value associated with name, if any, else NULL.
39  *	Starts searching within the environmental array at offset.
40  *	Sets offset to be the offset of the name/value combination in the
41  *	environmental array, for use by putenv(3), setenv(3) and unsetenv(3).
42  *	Explicitly removes '=' in argument name.
43  *
44  *	This routine *should* be a static; don't use it.
45  */
46 char *
__findenv(const char * name,int len,int * offset)47 __findenv(const char *name, int len, int *offset)
48 {
49 	extern char **environ;
50 	int i;
51 	const char *np;
52 	char **p, *cp;
53 
54 	if (name == NULL || environ == NULL)
55 		return (NULL);
56 	for (p = environ + *offset; (cp = *p) != NULL; ++p) {
57 		for (np = name, i = len; i && *cp; i--)
58 			if (*cp++ != *np++)
59 				break;
60 		if (i == 0 && *cp++ == '=') {
61 			*offset = p - environ;
62 			return (cp);
63 		}
64 	}
65 	return (NULL);
66 }
67 
68 /*
69  * getenv --
70  *	Returns ptr to value associated with name, if any, else NULL.
71  */
72 char *
getenv(const char * name)73 getenv(const char *name)
74 {
75 	int offset = 0;
76 	const char *np;
77 
78 	for (np = name; *np && *np != '='; ++np)
79 		;
80 	return (__findenv(name, (int)(np - name), &offset));
81 }
82