//-----------------------------------------------------------------------------
// Copyright © 2006 - Philip Howard - All rights reserved
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//-----------------------------------------------------------------------------
// package	libh/ctools
// homepage	http://libh.slashusr.org/
//-----------------------------------------------------------------------------
// author	Philip Howard
// email	libh at ipal dot org
// homepage	http://phil.ipal.org/
//-----------------------------------------------------------------------------
// This file is best viewed using a fixed spaced font such as Courier
// and in a display at least 120 columns wide.
//-----------------------------------------------------------------------------

#include "ctools_lib.h"

#include <stdarg.h>
#include <stdlib.h>

__PROTO_BEGIN__
//-----------------------------------------------------------------------------
// function	env_str
//
// purpose	Select the first defined environment variable from a given list
//		that is defined and non-empty, and return a pointer to the
//		environment value string.
//
// arguments	1..N (const char *) list of variable names, ending in NULL
//
// returns	(const char *) pointer to value string or NULL if not found
//-----------------------------------------------------------------------------
const char *
env_str (
    const char *	arg_name
    ,
    ...
    )
__PROTO_END__
{
    va_list		varargs		;
    const char *	value		;
    const char *	name		;

    name = arg_name;
    va_start( varargs, arg_name );
    while ( ( ! ( value = getenv( name ) ) || ! * value ) && ( name = va_arg( varargs, const char * ) ) );
    va_end( varargs );
    return value;
}