1/*	$OpenBSD: setenv.c,v 1.9 2005/08/08 08:05:37 espie Exp $ */
2/*
3 * Copyright (c) 1987 Regents of the University of California.
4 * 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
34char *__findenv(const char *name, int *offset);
35
36extern char **environ;
37
38/*
39 * setenv --
40 *	Set the value of the environmental variable "name" to be
41 *	"value".  If rewrite is set, replace any current value.
42 */
43int
44setenv(const char *name, const char *value, int rewrite)
45{
46	static char **lastenv;			/* last value of environ */
47	char *C;
48	int l_value, offset;
49
50	if (*value == '=')			/* no `=' in value */
51		++value;
52	l_value = strlen(value);
53	if ((C = __findenv(name, &offset))) {	/* find if already exists */
54		if (!rewrite)
55			return (0);
56		if ((int)strlen(C) >= l_value) {	/* old larger; copy over */
57			while ((*C++ = *value++))
58				;
59			return (0);
60		}
61	} else {					/* create new slot */
62		size_t cnt;
63		char **P;
64
65		for (P = environ; *P != NULL; P++)
66			;
67		cnt = P - environ;
68        P = (char **)realloc(lastenv, sizeof(char *) * (cnt + 2));
69		if (!P)
70			return (-1);
71		if (lastenv != environ)
72			memcpy(P, environ, cnt * sizeof(char *));
73		lastenv = environ = P;
74		offset = cnt;
75		environ[cnt + 1] = NULL;
76	}
77	for (C = (char *)name; *C && *C != '='; ++C)
78		;				/* no `=' in name */
79	if (!(environ[offset] =			/* name + `=' + value */
80	    malloc((size_t)((int)(C - name) + l_value + 2))))
81		return (-1);
82	for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
83		;
84	for (*C++ = '='; (*C++ = *value++); )
85		;
86	return (0);
87}
88
89/*
90 * unsetenv(name) --
91 *	Delete environmental variable "name".
92 */
93int
94unsetenv(const char *name)
95{
96	char **P;
97	int offset;
98
99	while (__findenv(name, &offset))	/* if set multiple times */
100		for (P = &environ[offset];; ++P)
101			if (!(*P = *(P + 1)))
102				break;
103
104        return 0;
105}
106