write() with poll()

        pfd[0].fd = fd;
        pfd[0].events = POLLIN
        while (len > 0) {
           nready = poll(pfd, 1, 0);
           if (nready == -1)
               err(1, "poll");
           if ((pfd[0].revents & (POLLERR|POLLNVAL)))
                errx(1, "bad fd %d", pfd[0].fd);
           if ((pfd[0].revents & (pfd[0].events|POLLHUP))) {
                ssize_t ret;
                ret = write(ctx, buf, len);
                if (ret < 0) {
                    if(errno != EAGAIN && errno != EINTR)
                        err(1, "tls_write: %s", tls_error(ctx));
                } else {
                    buf += ret;
                    len -= ret;
                }
            }
        }