+int get_mtime(const char *file_name, struct timespec *mtime);
+
+void xpipe(int fds[2]);
+void xpipe_nonblocking(int fds[2]);
+
+char *describe_fd(int fd);
+
+/* Default value of dscp bits for connection between controller and manager.
+ * Value of IPTOS_PREC_INTERNETCONTROL = 0xc0 which is defined
+ * in <netinet/ip.h> is used. */
+#define DSCP_DEFAULT (IPTOS_PREC_INTERNETCONTROL >> 2)
+
+/* Maximum number of fds that we support sending or receiving at one time
+ * across a Unix domain socket. */
+#define SOUTIL_MAX_FDS 8
+
+/* Iovecs. */
+size_t iovec_len(const struct iovec *iovs, size_t n_iovs);
+bool iovec_is_empty(const struct iovec *iovs, size_t n_iovs);
+
+/* Functions particularly useful for Unix domain sockets. */
+void xsocketpair(int domain, int type, int protocol, int fds[2]);
+int send_iovec_and_fds(int sock,
+ const struct iovec *iovs, size_t n_iovs,
+ const int fds[], size_t n_fds);
+int send_iovec_and_fds_fully(int sock,
+ const struct iovec *iovs, size_t n_iovs,
+ const int fds[], size_t n_fds,
+ size_t skip_bytes, size_t *bytes_sent);
+int send_iovec_and_fds_fully_block(int sock,
+ const struct iovec *iovs, size_t n_iovs,
+ const int fds[], size_t n_fds);
+int recv_data_and_fds(int sock,
+ void *data, size_t size,
+ int fds[SOUTIL_MAX_FDS], size_t *n_fdsp);
+
+/* Helpers for calling ioctl() on an AF_INET socket. */
+struct ifreq;
+int af_inet_ioctl(unsigned long int command, const void *arg);
+int af_inet_ifreq_ioctl(const char *name, struct ifreq *,
+ unsigned long int cmd, const char *cmd_name);