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)
38 static 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 
44 char *__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  */
55 char *
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  */
87 int
88 setenv(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  */
148 void
149 unsetenv(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