minix/lib/nbsd_libc/stdlib/unsetenv.c

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/* $NetBSD: unsetenv.c,v 1.10 2010/11/14 18:11:43 tron Exp $ */
/*
* Copyright (c) 1987, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "from: @(#)setenv.c 8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: unsetenv.c,v 1.10 2010/11/14 18:11:43 tron Exp $");
#endif
#endif /* LIBC_SCCS and not lint */
#include "namespace.h"
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <bitstring.h>
#include "env.h"
#include "reentrant.h"
#include "local.h"
/*
* unsetenv(name) --
* Delete environmental variable "name".
*/
int
unsetenv(const char *name)
{
size_t l_name;
ssize_t r_offset, w_offset;
_DIAGASSERT(name != NULL);
l_name = __envvarnamelen(name, false);
if (l_name == 0) {
errno = EINVAL;
return -1;
}
if (!__writelockenv())
return -1;
/* Search for the given name in the environment. */
r_offset = __getenvslot(name, l_name, false);
if (r_offset == -1) {
/* Not found. */
(void)__unlockenv();
return 0;
}
__freeenvvar(environ[r_offset]);
/*
* Remove all matches from the environment and free the associated
* memory if possible.
*/
w_offset = r_offset;
while (environ[++r_offset] != NULL) {
if (strncmp(environ[r_offset], name, l_name) != 0 ||
environ[r_offset][l_name] != '=') {
/* Not a match, keep this entry. */
environ[w_offset++] = environ[r_offset];
} else {
/* We found another match. */
__freeenvvar(environ[r_offset]);
}
}
/* Clear out remaining stale entries in the environment vector. */
do {
environ[w_offset++] = NULL;
} while (w_offset < r_offset);
(void)__unlockenv();
return 0;
}