#define NBD_BUFFER_SIZE (1024*1024)
-size_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read);
+ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read);
int tcp_socket_outgoing(const char *address, uint16_t port);
int tcp_socket_incoming(const char *address, uint16_t port);
int tcp_socket_outgoing_spec(const char *address_and_port);