1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 1987 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /* Copyright (c) 1984 AT&T */
28 /* All Rights Reserved */
29
30 #pragma ident "%Z%%M% %I% %E% SMI"
31
32 /* LINTLIBRARY */
33 /* putenv - change environment variables
34 *
35 * input - char *change = a pointer to a string of the form
36 * "name=value"
37 *
38 * output - 0, if successful
39 * 1, otherwise
40 */
41
42 #include <stdio.h>
43 #include <stdlib.h>
44
45 extern char **environ; /* pointer to enviroment */
46 static int reall; /* flag to reallocate space, if putenv is called
47 more than once */
48 static int find(char *);
49 static int match(char *, char *);
50
51 int
putenv(char * change)52 putenv(char *change)
53 {
54 char **newenv; /* points to new environment */
55 int which; /* index of variable to replace */
56
57 if ((which = find(change)) < 0) {
58 /* if a new variable */
59 /* which is negative of table size, so invert and
60 count new element */
61 which = (-which) + 1;
62 if (reall) {
63 /* we have expanded environ before */
64 newenv = (char **)realloc(environ,
65 which*sizeof(char *));
66 if (newenv == NULL) return (-1);
67 /* now that we have space, change environ */
68 environ = newenv;
69 } else {
70 /* environ points to the original space */
71 reall++;
72 newenv = (char **)malloc(which*sizeof(char *));
73 if (newenv == NULL) return (-1);
74 (void)memcpy((char *)newenv, (char *)environ,
75 (int)(which*sizeof(char *)));
76 environ = newenv;
77 }
78 environ[which-2] = change;
79 environ[which-1] = NULL;
80 } else {
81 /* we are replacing an old variable */
82 environ[which] = change;
83 }
84 return (0);
85 }
86
87 /* find - find where s2 is in environ
88 *
89 * input - str = string of form name=value
90 *
91 * output - index of name in environ that matches "name"
92 * -size of table, if none exists
93 */
94 static int
find(char * str)95 find(char *str)
96 {
97 int ct = 0; /* index into environ */
98
99 while(environ[ct] != NULL) {
100 if (match(environ[ct], str) != 0)
101 return (ct);
102 ct++;
103 }
104 return (-(++ct));
105 }
106 /*
107 * s1 is either name, or name=value
108 * s2 is name=value
109 * if names match, return value of 1,
110 * else return 0
111 */
112
113 static int
match(char * s1,char * s2)114 match(char *s1, char *s2)
115 {
116 while(*s1 == *s2++) {
117 if (*s1 == '=')
118 return (1);
119 s1++;
120 }
121 return (0);
122 }
123