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setenv.c revision 1.25 
      1 /*	$NetBSD: setenv.c,v 1.25 2005/02/17 04:16:09 enami 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 1.25 2005/02/17 04:16:09 enami 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 __weak_alias
     51 __weak_alias(setenv,_setenv)
     52 #endif
     53 
     54 #ifdef _REENTRANT
     55 extern rwlock_t __environ_lock;
     56 #endif
     57 
     58 extern char **environ;
     59 
     60 /*
     61  * setenv --
     62  *	Set the value of the environmental variable "name" to be
     63  *	"value".  If rewrite is set, replace any current value.
     64  */
     65 int
     66 setenv(name, value, rewrite)
     67 	const char *name;
     68 	const char *value;
     69 	int rewrite;
     70 {
     71 	static char **saveenv;	/* copy of previously allocated space */
     72 	char *c, **newenv;
     73 	const char *cc;
     74 	size_t l_value;
     75 	int offset;
     76 
     77 	_DIAGASSERT(name != NULL);
     78 	_DIAGASSERT(value != NULL);
     79 
     80 	if (*value == '=')			/* no `=' in value */
     81 		++value;
     82 	l_value = strlen(value);
     83 	rwlock_wrlock(&__environ_lock);
     84 	/* find if already exists */
     85 	if ((c = __findenv(name, &offset)) != NULL) {
     86 		if (!rewrite)
     87 			goto good;
     88 		if (strlen(c) >= l_value) {	/* old larger; copy over */
     89 			(void)memcpy(c, value, l_value + 1);
     90 			goto good;
     91 		}
     92 	} else {					/* create new slot */
     93 		size_t cnt, siz;
     94 
     95 		for (cnt = 0; *environ[cnt]; ++cnt)
     96 			continue;
     97 		siz = (size_t)(sizeof(char *) * (cnt + 2));
     98 		if (saveenv == environ) {		/* just increase size */
     99 			if ((newenv = realloc(saveenv, siz)) == NULL)
    100 				goto bad;
    101 			saveenv = newenv;
    102 		} else {				/* get new space */
    103 			free(saveenv);
    104 			if ((saveenv = malloc(siz)) == NULL)
    105 				goto bad;
    106 			(void)memcpy(saveenv, environ, cnt * sizeof(char *));
    107 		}
    108 		environ = saveenv;
    109 		environ[cnt + 1] = NULL;
    110 		offset = cnt;
    111 	}
    112 	for (cc = name; *cc && *cc != '='; ++cc)	/* no `=' in name */
    113 		continue;
    114 	if (!(environ[offset] =			/* name + `=' + value */
    115 	    malloc((size_t)((int)(cc - name) + l_value + 2))))
    116 		goto bad;
    117 	c = environ[offset];
    118 	(void)memcpy(c, name, cc - name);
    119 	c += cc - name;
    120 	*c++ = '=';
    121 	(void)memcpy(c, value, l_value + 1);
    122 good:
    123 	rwlock_unlock(&__environ_lock);
    124 	return 0;
    125 bad:
    126 	rwlock_unlock(&__environ_lock);
    127 	return -1;
    128 }
    129