title: What is the struct for the handle to the main program returned by dlopen(NULL, RTLD_NOW)?
body: <p>According to the <a href="http://man7.org/linux/man-pages/man3/dlopen.3.html" rel="nofollow">man page</a> for <code>dlopen</code>:</p>
  
  <blockquote>
    <p>If filename is NULL, then the returned handle is for the main
           program.</p>
  </blockquote>
  
  <p>So my question is what is the structure for this handle to the main program and in what header is it located? Thanks.</p>