Env.h

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/*---------------------------------------------------------------------\
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|                          / /__ | | | | | |                           |
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\---------------------------------------------------------------------*/
#ifndef ZYPP_BASE_ENV_H
#define ZYPP_BASE_ENV_H

#include <cstdlib>
#include <string>
#include <memory>

namespace zypp
{
  namespace env
  {
    struct ScopedSet
    {
      ScopedSet( const ScopedSet & )             = delete;
      ScopedSet & operator=( const ScopedSet & ) = delete;

      ScopedSet( ScopedSet && )                  = default;
      ScopedSet & operator=( ScopedSet && )      = default;

    public:
      ScopedSet()
      {}

      ScopedSet( std::string var_r, const char * val_r )
      : _var { std::move(var_r) }
      {
        if ( !_var.empty() )
        {
          if ( const char * orig = ::getenv( _var.c_str() ) )
            _val.reset( new std::string( orig ) );
          setval( val_r );
        }
      }

      ~ScopedSet()
      {
        if ( !_var.empty() )
          setval( _val ? _val->c_str() : nullptr );
      }

    private:
      void setval( const char * val_r )
      {
        if ( val_r )
          ::setenv( _var.c_str(), val_r, 1 );
        else
          ::unsetenv( _var.c_str() );
      }

    private:
      std::string _var;
      std::unique_ptr<std::string> _val;
    };

  } // namespace env
} // namespace zypp
#endif // ZYPP_BASE_ENV_H