function SizeOfFile64(const FileName: string): Int64;
var
  FH: THandle;  // file handle
begin
  FH := SysUtils.FileOpen(
    FileName, SysUtils.fmOpenRead or SysUtils.fmShareDenyNone
  );
  try
    SysUtils.Int64Rec(Result).Lo := Windows.GetFileSize(
      FH, @SysUtils.Int64Rec(Result).Hi
    );
    if (SysUtils.Int64Rec(Result).Lo = $FFFFFFFF) and
      (Windows.GetLastError <> Windows.NO_ERROR) then
      Result := -1;
  finally
    SysUtils.FileClose(FH);
  end;
end;
//delphi/2226