/*      $NetBSD: setenv.c,v 1.45 2021/08/12 20:53:18 andvar 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[] = "@(#)setenv.c    8.1 (Berkeley) 6/4/93";
#else
__RCSID("$NetBSD: setenv.c,v 1.45 2021/08/12 20:53:18 andvar Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"

#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include "env.h"
#include "local.h"

#ifdef __weak_alias
__weak_alias(setenv,_setenv)
#endif

/*
* setenv --
*      Set the value of the environmental variable "name" to be
*      "value".  If rewrite is set, replace any current value.
*/
int
setenv(const char *name, const char *value, int rewrite)
{
       size_t l_name, l_value, length;
       ssize_t offset;
       char *envvar;

       _DIAGASSERT(name != NULL);
       _DIAGASSERT(value != NULL);

       l_name = __envvarnamelen(name, false);
       if (l_name == 0 || value == NULL) {
               errno = EINVAL;
               return -1;
       }

       if (!__writelockenv())
               return -1;

       /* Find slot in the environment. */
       offset = __getenvslot(name, l_name, true);
       if (offset == -1)
               goto bad;

       l_value = strlen(value);
       length = l_name + l_value + 2;

       /* Handle overwriting a current environt variable. */
       envvar = environ[offset];
       if (envvar != NULL) {
               if (!rewrite)
                       goto good;
               /*
                * Check whether the buffer was allocated via setenv(3) and
                * whether there is enough space. If so simply overwrite the
                * existing value.
                */
               if (__canoverwriteenvvar(envvar, length)) {
                       envvar += l_name + 1;
                       goto copy;
               }
       }

       /* Allocate memory for name + `=' + value + NUL. */
       if ((envvar = __allocenvvar(length)) == NULL)
               goto bad;

       if (environ[offset] != NULL)
               __freeenvvar(environ[offset]);

       environ[offset] = envvar;

       (void)memcpy(envvar, name, l_name);

       envvar += l_name;
       *envvar++ = '=';

copy:
       (void)memcpy(envvar, value, l_value + 1);

good:
       (void)__unlockenv();
       return 0;

bad:
       (void)__unlockenv();
       return -1;
}