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 "config.h"
35 #ifndef HAVE_SETENV
36 
37 #if defined(LIBC_SCCS) && !defined(lint)
38 static char *rcsid = "$OpenBSD: setenv.c,v 1.4 2001/07/09 06:57:45 deraadt Exp $";
39 #endif /* LIBC_SCCS and not lint */
40 
41 #include <stdlib.h>
42 #include <string.h>
43 
44 /*
45  * __findenv --
46  *	Returns pointer to value associated with name, if any, else NULL.
47  *	Sets offset to be the offset of the name/value combination in the
48  *	environmental array, for use by setenv(3) and unsetenv(3).
49  *	Explicitly removes '=' in argument name.
50  *
51  *	This routine *should* be a static; don't use it.
52  */
53 char *
54 __findenv(name, offset)
55 	register const char *name;
56 	int *offset;
57 {
58 	extern char **environ;
59 	register int len, i;
60 	register const char *np;
61 	register char **p, *cp;
62 
63 	if (name == NULL || environ == NULL)
64 		return (NULL);
65 	for (np = name; *np && *np != '='; ++np)
66 		;
67 	len = np - name;
68 	for (p = environ; (cp = *p) != NULL; ++p) {
69 		for (np = name, i = len; i && *cp; i--)
70 			if (*cp++ != *np++)
71 				break;
72 		if (i == 0 && *cp++ == '=') {
73 			*offset = p - environ;
74 			return (cp);
75 		}
76 	}
77 	return (NULL);
78 }
79 
80 /*
81  * setenv --
82  *	Set the value of the environmental variable "name" to be
83  *	"value".  If rewrite is set, replace any current value.
84  */
85 int
86 setenv(name, value, rewrite)
87 	register const char *name;
88 	register const char *value;
89 	int rewrite;
90 {
91 	extern char **environ;
92 	static int alloced;			/* if allocated space before */
93 	register char *C;
94 	int l_value, offset;
95 	char *__findenv();
96 
97 	if (*value == '=')			/* no `=' in value */
98 		++value;
99 	l_value = strlen(value);
100 	if ((C = __findenv(name, &offset))) {	/* find if already exists */
101 		if (!rewrite)
102 			return (0);
103 		if (strlen(C) >= l_value) {	/* old larger; copy over */
104 			while ((*C++ = *value++))
105 				;
106 			return (0);
107 		}
108 	} else {					/* create new slot */
109 		register int	cnt;
110 		register char	**P;
111 
112 		for (P = environ, cnt = 0; *P; ++P, ++cnt);
113 		if (alloced) {			/* just increase size */
114 			P = (char **)realloc((void *)environ,
115 			    (size_t)(sizeof(char *) * (cnt + 2)));
116 			if (!P)
117 				return (-1);
118 			environ = P;
119 		}
120 		else {				/* get new space */
121 			alloced = 1;		/* copy old entries into it */
122 			P = (char **)malloc((size_t)(sizeof(char *) *
123 			    (cnt + 2)));
124 			if (!P)
125 				return (-1);
126 			memmove(P, environ, cnt * sizeof(char *));
127 			environ = P;
128 		}
129 		environ[cnt + 1] = NULL;
130 		offset = cnt;
131 	}
132 	for (C = (char *)name; *C && *C != '='; ++C);	/* no `=' in name */
133 	if (!(environ[offset] =			/* name + `=' + value */
134 	    malloc((size_t)((int)(C - name) + l_value + 2))))
135 		return (-1);
136 	for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
137 		;
138 	for (*C++ = '='; (*C++ = *value++); )
139 		;
140 	return (0);
141 }
142 
143 /*
144  * unsetenv(name) --
145  *	Delete environmental variable "name".
146  */
147 void
148 unsetenv(name)
149 	const char	*name;
150 {
151 	extern char **environ;
152 	register char **P;
153 	int offset;
154 	char *__findenv();
155 
156 	while (__findenv(name, &offset))		/* if set multiple times */
157 		for (P = &environ[offset];; ++P)
158 			if (!(*P = *(P + 1)))
159 				break;
160 }
161 
162 #endif /* HAVE_SETENV */
163