OSSL_DECODER_CTX_set_construct(), OSSL_DECODER_CTX_set_construct_data() and OSSL_DECODER_CTX_set_cleanup() return 1 on success, or 0 on failure.</p>

<p>OSSL_DECODER_CTX_get_construct(), OSSL_DECODER_CTX_get_construct_data() and OSSL_DECODER_CTX_get_cleanup() return the current pointers to the constructor, the constructor data and the cleanup functions, respectively.</p>

<p>OSSL_DECODER_CTX_num_decoders() returns the current number of decoders. It returns 0 if <i>ctx</i> is NULL.</p>

<p>OSSL_DECODER_expor