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 #include <stdlib.h>
32 #include <string.h>
33
34 char *__findenv(const char *name, int *offset);
35
36 extern char **environ;
37
38 /*
39 * setenv --
40 * Set the value of the environmental variable "name" to be
41 * "value". If rewrite is set, replace any current value.
42 */
43 int
setenv(const char * name,const char * value,int rewrite)44 setenv(const char *name, const char *value, int rewrite)
45 {
46 static char **lastenv; /* last value of environ */
47 char *C;
48 int l_value, offset;
49
50 if (*value == '=') /* no `=' in value */
51 ++value;
52 l_value = strlen(value);
53 if ((C = __findenv(name, &offset))) { /* find if already exists */
54 if (!rewrite)
55 return (0);
56 if ((int)strlen(C) >= l_value) { /* old larger; copy over */
57 while ((*C++ = *value++))
58 ;
59 return (0);
60 }
61 } else { /* create new slot */
62 size_t cnt;
63 char **P;
64
65 for (P = environ; *P != NULL; P++)
66 ;
67 cnt = P - environ;
68 P = (char **)realloc(lastenv, sizeof(char *) * (cnt + 2));
69 if (!P)
70 return (-1);
71 if (lastenv != environ)
72 memcpy(P, environ, cnt * sizeof(char *));
73 lastenv = environ = P;
74 offset = cnt;
75 environ[cnt + 1] = NULL;
76 }
77 for (C = (char *)name; *C && *C != '='; ++C)
78 ; /* no `=' in name */
79 if (!(environ[offset] = /* name + `=' + value */
80 malloc((size_t)((int)(C - name) + l_value + 2))))
81 return (-1);
82 for (C = environ[offset]; (*C = *name++) && *C != '='; ++C)
83 ;
84 for (*C++ = '='; (*C++ = *value++); )
85 ;
86 return (0);
87 }
88
89 /*
90 * unsetenv(name) --
91 * Delete environmental variable "name".
92 */
93 int
unsetenv(const char * name)94 unsetenv(const char *name)
95 {
96 char **P;
97 int offset;
98
99 while (__findenv(name, &offset)) /* if set multiple times */
100 for (P = &environ[offset];; ++P)
101 if (!(*P = *(P + 1)))
102 break;
103
104 return 0;
105 }
106