-SR_PRIV int sr_source_remove(int fd);
-SR_PRIV int sr_source_remove_pollfd(GPollFD *pollfd);
-SR_PRIV int sr_source_remove_channel(GIOChannel *channel);
-SR_PRIV int sr_source_add(int fd, int events, int timeout,
- sr_receive_data_callback cb, void *cb_data);
-SR_PRIV int sr_source_add_pollfd(GPollFD *pollfd, int timeout,
- sr_receive_data_callback cb, void *cb_data);
-SR_PRIV int sr_source_add_channel(GIOChannel *channel, int events, int timeout,
- sr_receive_data_callback cb, void *cb_data);