vsock_ioctl_int
return vsock_ioctl_int(fd, SIOCOUTQ, 0);
bool vsock_ioctl_int(int fd, unsigned long op, int expected);
if (!vsock_ioctl_int(fd, SIOCINQ, MSG_BUF_IOCTL_LEN)) {
vsock_ioctl_int(fd, SIOCINQ, 0);
vsock_ioctl_int(fd, SIOCINQ, PAGE_SIZE + 1 + GOOD_COPY_LEN);