Get file size

function GetFileSize(const filename: string): Int64;
var
  f: TWin32FindData;
  h: THandle;
begin
  result := -1;
  try
    if not FileExists(filename) then
      exit;
    h := FindFirstFile(PChar(filename), f);
    if h = INVALID_HANDLE_VALUE then
      RaiseLastWin32Error;
    try
      Result := f.nFileSizeHigh shl 32 + f.nFileSizeLow;
    finally
      windows.FindClose(h);
    end;
  except
  end;
end;