coreutils/lib/putenv.c
1992-11-01 05:44:29 +00:00

102 lines
2.5 KiB
C

/* Copyright (C) 1991 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <sys/types.h>
#include <errno.h>
#ifdef STDC_HEADERS
#include <stdlib.h>
#else
extern int errno;
#endif
#if defined(STDC_HEADERS) || defined(USG)
#include <string.h>
#define index strchr
#define bcopy(s, d, n) memcpy((d), (s), (n))
#else /* not (STDC_HEADERS or USG) */
#include <strings.h>
#endif /* STDC_HEADERS or USG */
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifndef NULL
#define NULL 0
#endif
#if !__STDC__
#define const
#endif
extern char **environ;
/* Put STRING, which is of the form "NAME=VALUE", in the environment. */
int
putenv (string)
const char *string;
{
char *name_end = index (string, '=');
register size_t size;
register char **ep;
if (name_end == NULL)
{
/* Remove the variable from the environment. */
size = strlen (string);
for (ep = environ; *ep != NULL; ++ep)
if (!strncmp (*ep, string, size) && (*ep)[size] == '=')
{
while (ep[1] != NULL)
{
ep[0] = ep[1];
++ep;
}
*ep = NULL;
return 0;
}
}
size = 0;
for (ep = environ; *ep != NULL; ++ep)
if (!strncmp (*ep, string, name_end - string) &&
(*ep)[name_end - string] == '=')
break;
else
++size;
if (*ep == NULL)
{
static char **last_environ = NULL;
char **new_environ = (char **) malloc ((size + 2) * sizeof (char *));
if (new_environ == NULL)
return -1;
(void) bcopy ((char *) environ, (char *) new_environ, size * sizeof (char *));
new_environ[size] = (char *) string;
new_environ[size + 1] = NULL;
if (last_environ != NULL)
free ((char *) last_environ);
last_environ = new_environ;
environ = new_environ;
}
else
*ep = (char *) string;
return 0;
}