#include <QDir>
#include <windows.h>
#include <QString>

quint64 getDiskFreeSpace (const QString& path)
{

    QString sCurDir = QDir::current().absolutePath();
       QDir::setCurrent( path );

       double fTotal;
       double fFree;

       ULARGE_INTEGER free,total;
       bool bRes = ::GetDiskFreeSpaceExA( 0 , &free , &total , NULL );
       if ( !bRes ) return false;

       QDir::setCurrent( sCurDir );

       fFree = static_cast<double>( static_cast<__int64>(free.QuadPart) );
       return fFree;
}