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unsetenv.c revision 1.3 
      1 /*	$NetBSD: unsetenv.c,v 1.3 2005/09/13 01:44:10 christos 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 1.3 2005/09/13 01:44:10 christos 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 "local.h"
     48 #include "reentrant.h"
     49 
     50 #ifdef _REENTRANT
     51 extern rwlock_t __environ_lock;
     52 #endif
     53 
     54 extern char **environ;
     55 
     56 /*
     57  * unsetenv(name) --
     58  *	Delete environmental variable "name".
     59  */
     60 int
     61 unsetenv(name)
     62 	const char *name;
     63 {
     64 	char **p;
     65 	int offset;
     66 
     67 	_DIAGASSERT(name != NULL);
     68 
     69 	if (name == NULL || *name == '\0' || strchr(name, '=') != NULL) {
     70 		errno = EINVAL;
     71 		return -1;
     72 	}
     73 
     74 	rwlock_wrlock(&__environ_lock);
     75 	while (__findenv(name, &offset))	/* if set multiple times */
     76 		for (p = &environ[offset];; ++p)
     77 			if (!(*p = *(p + 1)))
     78 				break;
     79 	rwlock_unlock(&__environ_lock);
     80 
     81 	return 0;
     82 }
     83