setenv.c revision 113908 
1/*
2 * Copyright (c) 1987 Regents of the University of California.
3 * 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#include "includes.h"
35#ifndef HAVE_SETENV
36
37#if defined(LIBC_SCCS) && !defined(lint)
38static char *rcsid = "$OpenBSD: setenv.c,v 1.5 2002/12/10 22:44:13 mickey Exp $";
39#endif /* LIBC_SCCS and not lint */
40
41#include <stdlib.h>
42#include <string.h>
43
44char *__findenv(const char *name, int *offset);
45
46/*
47 * __findenv --
48 *	Returns pointer to value associated with name, if any, else NULL.
49 *	Sets offset to be the offset of the name/value combination in the
50 *	environmental array, for use by setenv(3) and unsetenv(3).
51 *	Explicitly removes '=' in argument name.
52 *
53 *	This routine *should* be a static; don't use it.
54 */
55char *
56__findenv(name, offset)
57	register const char *name;
58	int *offset;
59{
60	extern char **environ;
61	register int len, i;
62	register const char *np;
63	register char **p, *cp;
64
65	if (name == NULL || environ == NULL)
66		return (NULL);
67	for (np = name; *np && *np != '='; ++np)
68		;
69	len = np - name;
70	for (p = environ; (cp = *p) != NULL; ++p) {
71		for (np = name, i = len; i && *cp; i--)
72			if (*cp++ != *np++)
73				break;
74		if (i == 0 && *cp++ == '=') {
75			*offset = p - environ;
76			return (cp);
77		}
78	}
79	return (NULL);
80}
81
82/*
83 * setenv --
84 *	Set the value of the environmental variable "name" to be
85 *	"value".  If rewrite is set, replace any current value.
86 */
87int
88setenv(name, value, rewrite)
89	register const char *name;
90	register const char *value;
91	int rewrite;
92{
93	extern char **environ;
94	static int alloced;			/* if allocated space before */
95	register char *C;
96	int l_value, offset;
97
98	if (*value == '=')			/* no `=' in value */
99		++value;
100	l_value = strlen(value);
101	if ((C = __findenv(name, &offset))) {	/* find if already exists */
102		if (!rewrite)
103			return (0);
104		if (strlen(C) >= l_value) {	/* old larger; copy over */
105			while ((*C++ = *value++))
106				;
107			return (0);
108		}
109	} else {					/* create new slot */
110		register int	cnt;
111		register char	**P;
112
113		for (P = environ, cnt = 0; *P; ++P, ++cnt);
114		if (alloced) {			/* just increase size */
115			P = (char **)realloc((void *)environ,
116			    (size_t)(sizeof(char *) * (cnt + 2)));
117			if (!P)
118				return (-1);
119			environ = P;
120		}
121		else {				/* get new space */
122			alloced = 1;		/* copy old entries into it */
123			P = (char **)malloc((size_t)(sizeof(char *) *
124			    (cnt + 2)));
125			if (!P)
126				return (-1);
127			memmove(P, environ, cnt * sizeof(char *));
128			environ = P;
129		}
130		environ[cnt + 1] = NULL;
131		offset = cnt;
132	}
133	for (C = (char *)name; *C && *C != '='; ++C);	/* no `=' in name */
134	if (!(environ[offset] =			/* name + `=' + value */
135	    malloc((size_t)((int)(C - name) + l_value + 2))))
136		return (-1);
137	for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
138		;
139	for (*C++ = '='; (*C++ = *value++); )
140		;
141	return (0);
142}
143
144/*
145 * unsetenv(name) --
146 *	Delete environmental variable "name".
147 */
148void
149unsetenv(name)
150	const char	*name;
151{
152	extern char **environ;
153	register char **P;
154	int offset;
155	char *__findenv();
156
157	while (__findenv(name, &offset))		/* if set multiple times */
158		for (P = &environ[offset];; ++P)
159			if (!(*P = *(P + 1)))
160				break;
161}
162
163#endif /* HAVE_SETENV */
164