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      1 /*	$NetBSD: setenv.c,v 1.45 2021/08/12 20:53:18 andvar 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[] = "@(#)setenv.c	8.1 (Berkeley) 6/4/93";
     36 #else
     37 __RCSID("$NetBSD: setenv.c,v 1.45 2021/08/12 20:53:18 andvar 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 
     48 #include "env.h"
     49 #include "local.h"
     50 
     51 #ifdef __weak_alias
     52 __weak_alias(setenv,_setenv)
     53 #endif
     54 
     55 /*
     56  * setenv --
     57  *	Set the value of the environmental variable "name" to be
     58  *	"value".  If rewrite is set, replace any current value.
     59  */
     60 int
     61 setenv(const char *name, const char *value, int rewrite)
     62 {
     63 	size_t l_name, l_value, length;
     64 	ssize_t offset;
     65 	char *envvar;
     66 
     67 	_DIAGASSERT(name != NULL);
     68 	_DIAGASSERT(value != NULL);
     69 
     70 	l_name = __envvarnamelen(name, false);
     71 	if (l_name == 0 || value == NULL) {
     72 		errno = EINVAL;
     73 		return -1;
     74 	}
     75 
     76 	if (!__writelockenv())
     77 		return -1;
     78 
     79 	/* Find slot in the environment. */
     80 	offset = __getenvslot(name, l_name, true);
     81 	if (offset == -1)
     82 		goto bad;
     83 
     84 	l_value = strlen(value);
     85 	length = l_name + l_value + 2;
     86 
     87 	/* Handle overwriting a current environt variable. */
     88 	envvar = environ[offset];
     89 	if (envvar != NULL) {
     90 		if (!rewrite)
     91 			goto good;
     92 		/*
     93 		 * Check whether the buffer was allocated via setenv(3) and
     94 		 * whether there is enough space. If so simply overwrite the
     95 		 * existing value.
     96 		 */
     97 		if (__canoverwriteenvvar(envvar, length)) {
     98 			envvar += l_name + 1;
     99 			goto copy;
    100 		}
    101 	}
    102 
    103 	/* Allocate memory for name + `=' + value + NUL. */
    104 	if ((envvar = __allocenvvar(length)) == NULL)
    105 		goto bad;
    106 
    107 	if (environ[offset] != NULL)
    108 		__freeenvvar(environ[offset]);
    109 
    110 	environ[offset] = envvar;
    111 
    112 	(void)memcpy(envvar, name, l_name);
    113 
    114 	envvar += l_name;
    115 	*envvar++ = '=';
    116 
    117 copy:
    118 	(void)memcpy(envvar, value, l_value + 1);
    119 
    120 good:
    121 	(void)__unlockenv();
    122 	return 0;
    123 
    124 bad:
    125 	(void)__unlockenv();
    126 	return -1;
    127 }
    128