getenv.c revision 1574 
1/*
2 * Copyright (c) 1987, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 *    must display the following acknowledgement:
15 *	This product includes software developed by the University of
16 *	California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#if defined(LIBC_SCCS) && !defined(lint)
35static char sccsid[] = "@(#)getenv.c	8.1 (Berkeley) 6/4/93";
36#endif /* LIBC_SCCS and not lint */
37
38#include <stdlib.h>
39#include <stddef.h>
40#include <string.h>
41
42char *__findenv __P((const char *, int *));
43
44/*
45 * getenv --
46 *	Returns ptr to value associated with name, if any, else NULL.
47 */
48char *
49getenv(name)
50	const char *name;
51{
52	int offset;
53
54	return (__findenv(name, &offset));
55}
56
57/*
58 * __findenv --
59 *	Returns pointer to value associated with name, if any, else NULL.
60 *	Sets offset to be the offset of the name/value combination in the
61 *	environmental array, for use by setenv(3) and unsetenv(3).
62 *	Explicitly removes '=' in argument name.
63 *
64 *	This routine *should* be a static; don't use it.
65 */
66char *
67__findenv(name, offset)
68	register const char *name;
69	int *offset;
70{
71	extern char **environ;
72	register int len;
73	register const char *np;
74	register char **p, *c;
75
76	if (name == NULL || environ == NULL)
77		return (NULL);
78	for (np = name; *np && *np != '='; ++np)
79		continue;
80	len = np - name;
81	for (p = environ; (c = *p) != NULL; ++p)
82		if (strncmp(c, name, len) == 0 && c[len] == '=') {
83			*offset = p - environ;
84			return (c + len + 1);
85		}
86	return (NULL);
87}
88