+
+/**
+ * Afs command handlers run as a process which is not related to the afs
+ * process, i.e. they can not change the address space of afs directly.
+ * Therefore afs commands typically consist of two functions: The command
+ * handler and the corresponding callback function that runs in afs context.
+ *
+ * \sa send_callback_request().
+ */
+typedef void callback_function(int fd, const struct osl_object *);
+
+/**
+ * Callbacks send chunks to data back to the command handler. Pointers to
+ * this type of function are used by \ref send_callback_request and friends
+ * to deal with the data in the command handler process.
+ *
+ * \sa \ref send_callback_request().
+ */
+typedef int callback_result_handler(struct osl_object *result, void *private);
+int send_result(struct osl_object *result, void *fd_ptr);
+int pass_buffer_as_shm(char *buf, size_t size, void *fd_ptr);
+