title: Check if a symbol is available, to prevent dlopen lazy binding failure
body: <p>I load a <code>.so</code> library using <code>dlopen()</code>. The library calls <code>myfunc()</code>. The function is available in version <code>1.0</code> of the loader. So calling <code>myfunc()</code> works. In version <code>0.9</code> however, there is no <code>myfunc()</code>, and <code>libdl</code> shows error about lazy binding failure.</p>
  
  <p>Can I, within the <code>so.</code> library, check if <code>myfunc()</code> exists, and only then call the function? The function is not mandatory, not important, I can safely skip calling it if loader is in version <code>0.9</code> or lower.</p>