getenv.c revision 169109 
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 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#if defined(LIBC_SCCS) && !defined(lint)
31static char sccsid[] = "@(#)getenv.c	8.1 (Berkeley) 6/4/93";
32#endif /* LIBC_SCCS and not lint */
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD: head/lib/libc/stdlib/getenv.c 169109 2007-04-30 02:25:02Z ache $");
35
36#include <stdlib.h>
37#include <stddef.h>
38#include <string.h>
39
40inline char *__findenv(const char *, int *);
41
42/*
43 * __findenv --
44 *	Returns pointer to value associated with name, if any, else NULL.
45 *	Sets offset to be the offset of the name/value combination in the
46 *	environmental array, for use by setenv(3) and unsetenv(3).
47 *
48 *	This routine *should* be a static; don't use it.
49 */
50inline char *
51__findenv(name, offset)
52	const char *name;
53	int *offset;
54{
55	extern char **environ;
56	int len, i;
57	const char *np;
58	char **p, *cp;
59
60	if (environ == NULL)
61		return (NULL);
62	len = strlen(name);
63	for (p = environ; (cp = *p) != NULL; ++p) {
64		for (np = name, i = len; i && *cp; i--)
65			if (*cp++ != *np++)
66				break;
67		if (i == 0 && *cp++ == '=') {
68			*offset = p - environ;
69			return (cp);
70		}
71	}
72	return (NULL);
73}
74
75/*
76 * getenv --
77 *	Returns ptr to value associated with name, if any, else NULL.
78 */
79char *
80getenv(name)
81	const char *name;
82{
83	int offset;
84
85	if (name == NULL || !*name || strchr(name, '=') != NULL)
86		return (NULL);
87
88	return (__findenv(name, &offset));
89}
90