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
45extern char **environ;		/* pointer to enviroment */
46static int	reall;		/* flag to reallocate space, if putenv is called
47				   more than once */
48static int	find(char *);
49static int	match(char *, char *);
50
51int
52putenv(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*/
94static int
95find(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
113static int
114match(char *s1, char *s2)
115{
116	while(*s1 == *s2++)  {
117		if (*s1 == '=')
118			return (1);
119		s1++;
120	}
121	return (0);
122}
123