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unsetenv.c revision 1.9 
      1 /*	$NetBSD: unsetenv.c,v 1.9 2010/09/30 12:41:33 tron Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1987, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "from: @(#)setenv.c	8.1 (Berkeley) 6/4/93";
     36 #else
     37 __RCSID("$NetBSD: unsetenv.c,v 1.9 2010/09/30 12:41:33 tron Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include "namespace.h"
     42 
     43 #include <assert.h>
     44 #include <errno.h>
     45 #include <stdlib.h>
     46 #include <string.h>
     47 #include <bitstring.h>
     48 #include "reentrant.h"
     49 #include "local.h"
     50 
     51 /*
     52  * unsetenv(name) --
     53  *	Delete environmental variable "name".
     54  */
     55 int
     56 unsetenv(const char *name)
     57 {
     58 	int offset;
     59 
     60 	_DIAGASSERT(name != NULL);
     61 
     62 	if (name == NULL || *name == '\0' || strchr(name, '=') != NULL) {
     63 		errno = EINVAL;
     64 		return -1;
     65 	}
     66 
     67 	if (rwlock_wrlock(&__environ_lock) != 0)
     68 		return -1;
     69 
     70 	if (__allocenv(-1) == -1) {
     71 		rwlock_unlock(&__environ_lock);
     72 		return -1;
     73 	}
     74 
     75 	while (__findenv(name, &offset) != NULL) { /* if set multiple times */
     76 		if (environ[offset] == __environ_malloced[offset])
     77 			free(__environ_malloced[offset]);
     78 
     79 		while (environ[offset] != NULL) {
     80 			environ[offset] = environ[offset + 1];
     81 			__environ_malloced[offset] =
     82 			    __environ_malloced[offset + 1];
     83 			offset++;
     84 		}
     85 		__environ_malloced[offset] = NULL;
     86 	}
     87 	rwlock_unlock(&__environ_lock);
     88 
     89 	return 0;
     90 }
     91