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. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #include "includes.h"
31 #ifndef HAVE_SETENV
32 
33 #if defined(LIBC_SCCS) && !defined(lint)
34 static char *rcsid = "$OpenBSD: setenv.c,v 1.6 2003/06/02 20:18:38 millert Exp $";
35 #endif /* LIBC_SCCS and not lint */
36 
37 #include <stdlib.h>
38 #include <string.h>
39 
40 char *__findenv(const char *name, int *offset);
41 
42 /*
43  * __findenv --
44  *	Returns pointer to value associated with name, if any, else NULL.
45  *	Sets offset to be the offset of the name/value combination in the
46  *	environmental array, for use by setenv(3) and unsetenv(3).
47  *	Explicitly removes '=' in argument name.
48  *
49  *	This routine *should* be a static; don't use it.
50  */
51 char *
52 __findenv(name, offset)
53 	register const char *name;
54 	int *offset;
55 {
56 	extern char **environ;
57 	register int len, i;
58 	register const char *np;
59 	register char **p, *cp;
60 
61 	if (name == NULL || environ == NULL)
62 		return (NULL);
63 	for (np = name; *np && *np != '='; ++np)
64 		;
65 	len = np - name;
66 	for (p = environ; (cp = *p) != NULL; ++p) {
67 		for (np = name, i = len; i && *cp; i--)
68 			if (*cp++ != *np++)
69 				break;
70 		if (i == 0 && *cp++ == '=') {
71 			*offset = p - environ;
72 			return (cp);
73 		}
74 	}
75 	return (NULL);
76 }
77 
78 /*
79  * setenv --
80  *	Set the value of the environmental variable "name" to be
81  *	"value".  If rewrite is set, replace any current value.
82  */
83 int
84 setenv(name, value, rewrite)
85 	register const char *name;
86 	register const char *value;
87 	int rewrite;
88 {
89 	extern char **environ;
90 	static int alloced;			/* if allocated space before */
91 	register char *C;
92 	int l_value, offset;
93 
94 	if (*value == '=')			/* no `=' in value */
95 		++value;
96 	l_value = strlen(value);
97 	if ((C = __findenv(name, &offset))) {	/* find if already exists */
98 		if (!rewrite)
99 			return (0);
100 		if (strlen(C) >= l_value) {	/* old larger; copy over */
101 			while ((*C++ = *value++))
102 				;
103 			return (0);
104 		}
105 	} else {					/* create new slot */
106 		register int	cnt;
107 		register char	**P;
108 
109 		for (P = environ, cnt = 0; *P; ++P, ++cnt);
110 		if (alloced) {			/* just increase size */
111 			P = (char **)realloc((void *)environ,
112 			    (size_t)(sizeof(char *) * (cnt + 2)));
113 			if (!P)
114 				return (-1);
115 			environ = P;
116 		}
117 		else {				/* get new space */
118 			alloced = 1;		/* copy old entries into it */
119 			P = (char **)malloc((size_t)(sizeof(char *) *
120 			    (cnt + 2)));
121 			if (!P)
122 				return (-1);
123 			memmove(P, environ, cnt * sizeof(char *));
124 			environ = P;
125 		}
126 		environ[cnt + 1] = NULL;
127 		offset = cnt;
128 	}
129 	for (C = (char *)name; *C && *C != '='; ++C);	/* no `=' in name */
130 	if (!(environ[offset] =			/* name + `=' + value */
131 	    malloc((size_t)((int)(C - name) + l_value + 2))))
132 		return (-1);
133 	for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
134 		;
135 	for (*C++ = '='; (*C++ = *value++); )
136 		;
137 	return (0);
138 }
139 
140 /*
141  * unsetenv(name) --
142  *	Delete environmental variable "name".
143  */
144 void
145 unsetenv(name)
146 	const char	*name;
147 {
148 	extern char **environ;
149 	register char **P;
150 	int offset;
151 	char *__findenv();
152 
153 	while (__findenv(name, &offset))		/* if set multiple times */
154 		for (P = &environ[offset];; ++P)
155 			if (!(*P = *(P + 1)))
156 				break;
157 }
158 
159 #endif /* HAVE_SETENV */
160