static const AVClass *urlcontext_child_class_next(const AVClass *prev) { URLProtocol *p = NULL; /* find the protocol that corresponds to prev */ while (prev && (p = ffurl_protocol_next(p))) if (p->priv_data_class == prev) break; /* find next protocol with priv options */ while (p = ffurl_protocol_next(p)) if (p->priv_data_class) return p->priv_data_class; return NULL; }