BIO_number_written
unsigned long BIO_number_written(BIO *bio);
LCRYPTO_ALIAS(BIO_number_written);
LCRYPTO_USED(BIO_number_written);
BIO_printf(bio_err, "bytes written:%8ld\n", BIO_number_written(out));
BIO_number_written(SSL_get_wbio(s)));