1/*	$NetBSD: setenv.c,v 1.42 2010/11/03 15:01:07 christos Exp $	*/
2
3/*
4 * Copyright (c) 1987, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#if defined(LIBC_SCCS) && !defined(lint)
34#if 0
35static char sccsid[] = "@(#)setenv.c	8.1 (Berkeley) 6/4/93";
36#else
37__RCSID("$NetBSD: setenv.c,v 1.42 2010/11/03 15:01:07 christos Exp $");
38#endif
39#endif /* LIBC_SCCS and not lint */
40
41#include "namespace.h"
42
43#include <assert.h>
44#include <errno.h>
45#include <stdlib.h>
46#include <string.h>
47
48#include "env.h"
49#include "reentrant.h"
50#include "local.h"
51
52#ifdef __weak_alias
53__weak_alias(setenv,_setenv)
54#endif
55
56/*
57 * setenv --
58 *	Set the value of the environmental variable "name" to be
59 *	"value".  If rewrite is set, replace any current value.
60 */
61int
62setenv(const char *name, const char *value, int rewrite)
63{
64	size_t l_name, l_value, length;
65	ssize_t offset;
66	char *envvar;
67
68	_DIAGASSERT(name != NULL);
69	_DIAGASSERT(value != NULL);
70
71	l_name = __envvarnamelen(name, false);
72	if (l_name == 0 || value == NULL) {
73		errno = EINVAL;
74		return -1;
75	}
76
77	if (!__writelockenv())
78		return -1;
79
80	/* Find slot in the enviroment. */
81	offset = __getenvslot(name, l_name, true);
82	if (offset == -1)
83		goto bad;
84
85	l_value = strlen(value);
86	length = l_name + l_value + 2;
87
88	/* Handle overwriting a current environt variable. */
89	envvar = environ[offset];
90	if (envvar != NULL) {
91		if (!rewrite)
92			goto good;
93		/*
94		 * Check whether the buffer was allocated via setenv(3) and
95		 * whether there is enough space. If so simply overwrite the
96		 * existing value.
97		 */
98		if (__canoverwriteenvvar(envvar, length)) {
99			envvar += l_name + 1;
100			goto copy;
101		}
102	}
103
104	/* Allocate memory for name + `=' + value + NUL. */
105	if ((envvar = __allocenvvar(length)) == NULL)
106		goto bad;
107
108	if (environ[offset] != NULL)
109		__freeenvvar(environ[offset]);
110
111	environ[offset] = envvar;
112
113	(void)memcpy(envvar, name, l_name);
114
115	envvar += l_name;
116	*envvar++ = '=';
117
118copy:
119	(void)memcpy(envvar, value, l_value + 1);
120
121good:
122	(void)__unlockenv();
123	return 0;
124
125bad:
126	(void)__unlockenv();
127	return -1;
128}
129