+/**
+ * Get the operating system handle for a port.
+ *
+ * The type of the handle depends on the operating system. On Unix based
+ * systems, the handle is a file descriptor of type "int". On Windows, the
+ * handle is of type "HANDLE". The user should allocate a variable of the
+ * appropriate type and pass a pointer to this to receive the result.
+ *
+ * To obtain a valid handle, the port must first be opened by calling
+ * sp_open() using the same port structure.
+ *
+ * After the port is closed or the port structure freed, the handle may
+ * no longer be valid.
+ *
+ * @warning This feature is provided so that programs may make use of
+ * OS-specific functionality where desired. Obviously this comes
+ * at a cost in portability, however it also cannot be guaranteed
+ * that direct usage of the OS handle will not conflict with the
+ * library's own usage of the port. Be careful.
+ *
+ * @return SP_OK upon success, a negative error code otherwise.
+ */
+enum sp_return sp_get_port_handle(const struct sp_port *port, void *result);
+