Is there a cleaner way to use the write() function reliably?

Question

I read the man pages, and my understanding is that if write() fails and sets the errno to EAGAIN or EINTR, I may

Answer 1

I would prefer to poll the descriptor in case of EAGAIN instead of just busy looping and burning up CPU for no good reason. This is kind of a "blocking wrapper" for a non-blocking write I use:

ssize_t written = 0;

while (written < to_write) {
    ssize_t result;
    if ((result = write(fd, buffer, to_write - written)) < 0) {
        if (errno == EAGAIN) {
            struct pollfd pfd = { .fd = fd, .events = POLLOUT };
            if (poll(&pfd, 1, -1) <= 0 && errno != EAGAIN) {
                break;
            }
            continue;
        }
        return written ? written : result;
    }
    written += result;
    buffer += result;
}
return written;

Note that I'm not actually checking the results of poll other than the return value; I figure the following write will fail if there is a permanent error on the descriptor.

You may wish to include EINTR as a retryable error as well by simply adding it to the conditions with EAGAIN, but I prefer it to actually interrupt I/O.