/// <summary>
/// Set internal file desriptor information before calling Select.
/// </summary>
/// <returns>
/// A <see cref="CURLMcode"/>, hopefully <c>CURLMcode.CURLM_OK</c>
/// </returns>
/// <exception cref="System.NullReferenceException">
/// This is thrown if the native <c>Multi</c> handle wasn't
/// created successfully.
/// </exception>
public CURLMcode FDSet()
{
EnsureHandle();
return(External.curl_shim_multi_fdset(m_pMulti,
m_fdSets, ref m_maxFD));
}