teger or 0 on success; otherwise it returns -1 on error.</p>

<p>UI_process() returns 0 on success or a negative value on error.</p>

<p>UI_ctrl() returns a mask on success or -1 on error.</p>

<p>UI_get_default_method(), UI_get_method(), UI_OpenSSL(), UI_null() and UI_set_method() return either a valid <b>UI_METHOD</b> structure or NULL respectively.</p>

<h1 id="HISTORY">HISTORY</h1>

<p>The UI_dup_user_data() function was added in OpenSSL 1.1.1.</p>

<h1 id="COPYRIGHT">COPYRIGHT</h1>

<p>Copyright 2001-2