1 /*	$OpenBSD: setenv.c,v 1.9 2005/08/08 08:05:37 espie Exp $ */
2 /*
3  * Copyright (c) 1987 Regents of the University of California.
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  * 3. Neither the name of the University nor the names of its contributors
15  *    may be used to endorse or promote products derived from this software
16  *    without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  */
30 
31 /* OPENBSD ORIGINAL: lib/libc/stdlib/setenv.c */
32 
33 #include "includes.h"
34 #if !defined(HAVE_SETENV) || !defined(HAVE_UNSETENV)
35 
36 #include <stdlib.h>
37 #include <string.h>
38 
39 extern char **environ;
40 
41 /* OpenSSH Portable: __findenv is from getenv.c rev 1.8, made static */
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 static char *
50 __findenv(const char *name, size_t *offset)
51 {
52 	extern char **environ;
53 	int len, i;
54 	const char *np;
55 	char **p, *cp;
56 
57 	if (name == NULL || environ == NULL)
58 		return (NULL);
59 	for (np = name; *np && *np != '='; ++np)
60 		;
61 	len = np - name;
62 	for (p = environ; (cp = *p) != NULL; ++p) {
63 		for (np = name, i = len; i && *cp; i--)
64 			if (*cp++ != *np++)
65 				break;
66 		if (i == 0 && *cp++ == '=') {
67 			*offset = p - environ;
68 			return (cp);
69 		}
70 	}
71 	return (NULL);
72 }
73 
74 #ifndef HAVE_SETENV
75 /*
76  * setenv --
77  *	Set the value of the environmental variable "name" to be
78  *	"value".  If rewrite is set, replace any current value.
79  */
80 int
81 setenv(const char *name, const char *value, int rewrite)
82 {
83 	static char **lastenv;			/* last value of environ */
84 	char *C;
85 	size_t l_value, offset;
86 
87 	if (*value == '=')			/* no `=' in value */
88 		++value;
89 	l_value = strlen(value);
90 	if ((C = __findenv(name, &offset))) {	/* find if already exists */
91 		if (!rewrite)
92 			return (0);
93 		if (strlen(C) >= l_value) {	/* old larger; copy over */
94 			while ((*C++ = *value++))
95 				;
96 			return (0);
97 		}
98 	} else {					/* create new slot */
99 		size_t cnt;
100 		char **P;
101 
102 		for (P = environ; *P != NULL; P++)
103 			;
104 		cnt = P - environ;
105 		P = (char **)realloc(lastenv, sizeof(char *) * (cnt + 2));
106 		if (!P)
107 			return (-1);
108 		if (lastenv != environ)
109 			memcpy(P, environ, cnt * sizeof(char *));
110 		lastenv = environ = P;
111 		offset = cnt;
112 		environ[cnt + 1] = NULL;
113 	}
114 	for (C = (char *)name; *C && *C != '='; ++C)
115 		;				/* no `=' in name */
116 	if (!(environ[offset] =			/* name + `=' + value */
117 	    malloc((size_t)((int)(C - name) + l_value + 2))))
118 		return (-1);
119 	for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
120 		;
121 	for (*C++ = '='; (*C++ = *value++); )
122 		;
123 	return (0);
124 }
125 #endif /* HAVE_SETENV */
126 
127 #ifndef HAVE_UNSETENV
128 /*
129  * unsetenv(name) --
130  *	Delete environmental variable "name".
131  */
132 void
133 unsetenv(const char *name)
134 {
135 	char **P;
136 	size_t offset;
137 
138 	while (__findenv(name, &offset))	/* if set multiple times */
139 		for (P = &environ[offset];; ++P)
140 			if (!(*P = *(P + 1)))
141 				break;
142 }
143 #endif /* HAVE_UNSETENV */
144 
145 #endif /* !defined(HAVE_SETENV) || !defined(HAVE_UNSETENV) */
146