enience function that
     selects an appropriate SQLSTATE error identifier for a failure in a
     file-access-related system call.  It uses the saved
     <code class="literal">errno</code> to determine which error code to generate.
     Usually this should be used in combination with <code class="literal">%m</code> in the
     primary error message text.
    </p></li><li class="listitem"><p>
     <code class="function">errcode_for_socket_access()</code> is a convenience function that
     selects an appr