1 /* OPENBSD ORIGINAL: lib/libc/stdlib/setenv.c */
2 
3 /*
4  * Copyright (c) 1987 Regents of the University of California.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include "includes.h"
33 #if !defined(HAVE_SETENV) || !defined(HAVE_UNSETENV)
34 
35 #if defined(LIBC_SCCS) && !defined(lint)
36 static char *rcsid = "$OpenBSD: setenv.c,v 1.6 2003/06/02 20:18:38 millert Exp $";
37 #endif /* LIBC_SCCS and not lint */
38 
39 #include <stdlib.h>
40 #include <string.h>
41 
42 /* OpenSSH Portable: __findenv is from getenv.c rev 1.8, made static */
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 static char *
52 __findenv(const char *name, int *offset)
53 {
54 	extern char **environ;
55 	int len, i;
56 	const char *np;
57 	char **p, *cp;
58 
59 	if (name == NULL || environ == NULL)
60 		return (NULL);
61 	for (np = name; *np && *np != '='; ++np)
62 		;
63 	len = np - name;
64 	for (p = environ; (cp = *p) != NULL; ++p) {
65 		for (np = name, i = len; i && *cp; i--)
66 			if (*cp++ != *np++)
67 				break;
68 		if (i == 0 && *cp++ == '=') {
69 			*offset = p - environ;
70 			return (cp);
71 		}
72 	}
73 	return (NULL);
74 }
75 
76 #ifndef HAVE_SETENV
77 /*
78  * setenv --
79  *	Set the value of the environmental variable "name" to be
80  *	"value".  If rewrite is set, replace any current value.
81  */
82 int
83 setenv(name, value, rewrite)
84 	register const char *name;
85 	register const char *value;
86 	int rewrite;
87 {
88 	extern char **environ;
89 	static int alloced;			/* if allocated space before */
90 	register char *C;
91 	int l_value, offset;
92 
93 	if (*value == '=')			/* no `=' in value */
94 		++value;
95 	l_value = strlen(value);
96 	if ((C = __findenv(name, &offset))) {	/* find if already exists */
97 		if (!rewrite)
98 			return (0);
99 		if (strlen(C) >= l_value) {	/* old larger; copy over */
100 			while ((*C++ = *value++))
101 				;
102 			return (0);
103 		}
104 	} else {					/* create new slot */
105 		register int	cnt;
106 		register char	**P;
107 
108 		for (P = environ, cnt = 0; *P; ++P, ++cnt);
109 		if (alloced) {			/* just increase size */
110 			P = (char **)realloc((void *)environ,
111 			    (size_t)(sizeof(char *) * (cnt + 2)));
112 			if (!P)
113 				return (-1);
114 			environ = P;
115 		}
116 		else {				/* get new space */
117 			alloced = 1;		/* copy old entries into it */
118 			P = (char **)malloc((size_t)(sizeof(char *) *
119 			    (cnt + 2)));
120 			if (!P)
121 				return (-1);
122 			memmove(P, environ, cnt * sizeof(char *));
123 			environ = P;
124 		}
125 		environ[cnt + 1] = NULL;
126 		offset = cnt;
127 	}
128 	for (C = (char *)name; *C && *C != '='; ++C);	/* no `=' in name */
129 	if (!(environ[offset] =			/* name + `=' + value */
130 	    malloc((size_t)((int)(C - name) + l_value + 2))))
131 		return (-1);
132 	for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
133 		;
134 	for (*C++ = '='; (*C++ = *value++); )
135 		;
136 	return (0);
137 }
138 #endif /* HAVE_SETENV */
139 
140 #ifndef HAVE_UNSETENV
141 /*
142  * unsetenv(name) --
143  *	Delete environmental variable "name".
144  */
145 void
146 unsetenv(name)
147 	const char	*name;
148 {
149 	extern char **environ;
150 	register char **P;
151 	int offset;
152 	char *__findenv();
153 
154 	while (__findenv(name, &offset))		/* if set multiple times */
155 		for (P = &environ[offset];; ++P)
156 			if (!(*P = *(P + 1)))
157 				break;
158 }
159 #endif /* HAVE_UNSETENV */
160 
161 #endif /* !defined(HAVE_SETENV) || !defined(HAVE_UNSETENV) */
162