+/**
+ * Codes used for communication between the server and the afs process.
+ *
+ * Before forking the afs child, para_server creates a bidirectional pipe
+ * through which both processes communicate. Usually para_server requests a new
+ * audio in order to start streaming or when the end of the current audio file
+ * has been reached. The afs process responds to such a request by sending
+ * back an eight byte buffer. The first four bytes is the uint32_t
+ * representation of the code, usually \p NEXT_AUDIO_FILE if an admissible
+ * audio file was found, successfully opened and verified. The other four bytes
+ * represent the shared memory id of the shared memory area that contains
+ * details about the audio file to be streamed next. The open file descriptor
+ * of that file is also passed from afs to para_server through the same pipe.
+ */
+enum afs_server_code {
+ /** An audio file was successfully opened. */
+ NEXT_AUDIO_FILE,
+ /** No admissible audio file was found. */
+ NO_ADMISSIBLE_FILES,
+};
+
+/** Flags passed to for_each_matching_row(). */
+enum pattern_match_flags {
+ /** Loop in reverse order. */
+ PM_REVERSE_LOOP = 1,
+ /** If no pattern is given, loop over all rows. */
+ PM_NO_PATTERN_MATCHES_EVERYTHING = 2,
+ /** If the data in match_column is the empty string, skip this row. */
+ PM_SKIP_EMPTY_NAME = 4,
+};
+
+/** Structure passed to for_each_matching_row(). */
+struct pattern_match_data {
+ /** Loop over all rows in this table. */
+ struct osl_table *table;
+ /** Determines the loop order. Must be an rbtree column. */
+ unsigned loop_col_num;
+ /** Data from this column is matched against the given patterns. */
+ unsigned match_col_num;
+ /** \see pattern_match_flags. */
+ unsigned pm_flags;
+ /** This value is passed verbatim to fnmatch(). */
+ int fnmatch_flags;
+ /** Null-terminated array of patterns. */
+ struct osl_object patterns;
+ /** Data pointer passed to the action function. */
+ void *data;
+ /** For each matching row, this function will be called. */
+ int (*action)(struct osl_table *table, struct osl_row *row, const char *name, void *data);
+};
+
+
+/**
+ * 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 sc_send_result(struct osl_object *result, void *private);
+int pass_buffer_as_shm(char *buf, size_t size, void *fd_ptr);
+
+__noreturn void afs_init(uint32_t cookie, int socket_fd);
+void afs_event(enum afs_events event, struct para_buffer *pb,
+ void *data);