Listing 3. nonblockuio.c

writeiovall(int fd, struct iov *iov, int nvec) {

        int i, bytes;

        i = 0;
        while (i < nvec) {
                do
                {
                        rv = writev(fd, &vec[i], nvec - i);
                } while (rv == -1 &&
                                (errno == EINTR || errno == EAGAIN));

                if (rv == -1) {
                        if (errno != EINTR && errno != EAGAIN) {
                                perror("write");
                        }
                        return -1;
                }
                bytes += rv;
                /* recalculate vec to deal with partial writes */
                while (rv > 0) {
                        if (rv < vec[i].iov_len) {
                                vec[i].iov_base = (char *)
vec[i].iov_base + rv;
                                vec[i].iov_len -= rv;
                                rv = 0;
                        }
                        else {
                                rv -= vec[i].iov_len;
                                ++i;
                        }
                }
        }

        /* We should get here only after we write out everything */

        return 0;

}