() and take appropriate action is an extension is absent.</p>

<p>If X509_get0_subject_key_id() returns <b>NULL</b> then the extension may be absent or malformed. Applications can determine the precise reason using X509_get_ext_d2i().</p>

<h1 id="RETURN-VALUES">RETURN VALUES</h1>

<p>X509_get_pathlen() returns the path length value, or -1 if the extension is not present.</p>

<p>X509_get_extension_flags(), X509_get_key_usage() and X509_get_extended_key_usage() return sets of flags corresponding to the cert