TEST_SINGLE_WRITE_SIZE
if (!TEST_ptr(msg = OPENSSL_zalloc(TEST_SINGLE_WRITE_SIZE))
|| !TEST_ptr(recvbuf = OPENSSL_zalloc(TEST_SINGLE_WRITE_SIZE)))
sendlen > TEST_SINGLE_WRITE_SIZE ? TEST_SINGLE_WRITE_SIZE
recvlen > TEST_SINGLE_WRITE_SIZE ? TEST_SINGLE_WRITE_SIZE