environment.hpp

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/** \file environment.hpp
 * \author Jared R. Males
 * \brief Utilities for working with the environment
 * \ingroup utils_files
 */
 
//***********************************************************************//
// Copyright 2015-2020 Jared R. Males (jaredmales@gmail.com)
//
// This file is part of mxlib.
//
// mxlib 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 3 of the License, or
// (at your option) any later version.
//
// mxlib 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 mxlib.  If not, see <http://www.gnu.org/licenses/>.
//***********************************************************************//
 
#ifndef environment_hpp
#define environment_hpp
 
#include <locale>
#include <string>
#include <string.h>
 
namespace mx
{
namespace sys
{
 
/// Return the value of an environment variable
/** Call the standard getenv function, but handles the null pointer as an empty string.
 *
 * \returns the value of the environment varialbe, or empty string if it doesn't exist
 *
 * \tparam maxsz is the maximum allowable size of the environment variable.  Prevents buffer overflow.
 *
 * \ingroup system
 */
template<size_t maxsz=4096>
std::string getEnv( const std::string &estr /**< [in] is the name of the environment variable to query */ )
{
    char *e = getenv( estr.c_str() );
 
    if( e )
    {
        size_t sz = strnlen(e, maxsz);
        if(sz < maxsz)
        {
            return std::string( e );
        }
        else
        {
            return "";
        }
    }
    else
    {
        return "";
    }
}
 
} // namespace sys
} // namespace mx
 
#endif // environment_hpp