putenv.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 1987 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1984 AT&T */
/* All Rights Reserved */
#pragma ident "%Z%%M% %I% %E% SMI" /* from S5R2 1.2 */
/* LINTLIBRARY */
/* putenv - change environment variables
input - char *change = a pointer to a string of the form
"name=value"
output - 0, if successful
1, otherwise
*/
#define NULL 0
extern char **environ; /* pointer to enviroment */
static reall; /* flag to reallocate space, if putenv is called
more than once */
int
putenv(change)
char *change;
{
char **newenv; /* points to new environment */
register int which; /* index of variable to replace */
char *realloc(), *malloc(); /* memory alloc routines */
if ((which = find(change)) < 0) {
/* if a new variable */
/* which is negative of table size, so invert and
count new element */
which = (-which) + 1;
if (reall) {
/* we have expanded environ before */
newenv = (char **)realloc(environ,
which*sizeof(char *));
if (newenv == NULL) return -1;
/* now that we have space, change environ */
environ = newenv;
} else {
/* environ points to the original space */
reall++;
newenv = (char **)malloc(which*sizeof(char *));
if (newenv == NULL) return -1;
(void)memcpy((char *)newenv, (char *)environ,
(int)(which*sizeof(char *)));
environ = newenv;
}
environ[which-2] = change;
environ[which-1] = NULL;
} else {
/* we are replacing an old variable */
environ[which] = change;
}
return 0;
}
/* find - find where s2 is in environ
*
* input - str = string of form name=value
*
* output - index of name in environ that matches "name"
* -size of table, if none exists
*/
static
find(str)
register char *str;
{
register int ct = 0; /* index into environ */
while(environ[ct] != NULL) {
if (match(environ[ct], str) != 0)
return ct;
ct++;
}
return -(++ct);
}
/*
* s1 is either name, or name=value
* s2 is name=value
* if names match, return value of 1,
* else return 0
*/
static
match(s1, s2)
register char *s1, *s2;
{
while(*s1 == *s2++) {
if (*s1 == '=')
return 1;
s1++;
}
return 0;
}