+/**
+ * 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);
+int send_callback_request(callback_function *f, struct osl_object *query,
+ callback_result_handler *result_handler,
+ void *private_result_data);
+int send_option_arg_callback_request(struct osl_object *options,
+ int argc, char * const * const argv, callback_function *f,
+ callback_result_handler *result_handler,
+ void *private_result_data);
+int send_standard_callback_request(int argc, char * const * const argv,
+ callback_function *f, callback_result_handler *result_handler,
+ void *private_result_data);
+int string_compare(const struct osl_object *obj1, const struct osl_object *obj2);
+int for_each_matching_row(struct pattern_match_data *pmd);
+
+/* score */
+void score_init(struct afs_table *t);
+int admissible_file_loop(void *data, osl_rbtree_loop_func *func);
+int admissible_file_loop_reverse(void *data, osl_rbtree_loop_func *func);
+int score_get_best(struct osl_row **aft_row, long *score);
+int get_score_and_aft_row(struct osl_row *score_row, long *score, struct osl_row **aft_row);
+int score_add(const struct osl_row *row, long score);
+int score_update(const struct osl_row *aft_row, long new_score);
+int get_num_admissible_files(unsigned *num);
+int score_delete(const struct osl_row *aft_row);
+int clear_score_table(void);
+int row_belongs_to_score_table(const struct osl_row *aft_row, unsigned *rank);
+
+/* attribute */
+void attribute_init(struct afs_table *t);
+void get_attribute_bitmap(const uint64_t *atts, char *buf); /* needed by com_ls() */
+int get_attribute_bitnum_by_name(const char *att_name, unsigned char *bitnum);
+int get_attribute_text(uint64_t *atts, const char *delim, char **text);
+
+/* aft */
+void aft_init(struct afs_table *t);
+int aft_get_row_of_path(const char *path, struct osl_row **row);
+int open_and_update_audio_file(struct osl_row *aft_row, long score,
+ struct audio_file_data *afd);
+int load_afd(int shmid, struct audio_file_data *afd);
+int load_afsi(struct afs_info *afsi, struct osl_object *obj);
+void save_afsi(struct afs_info *afsi, struct osl_object *obj);
+int get_afsi_of_row(const struct osl_row *row, struct afs_info *afsi);
+int get_afhi_of_row(const struct osl_row *row, struct afh_info *afhi);
+int get_afsi_of_path(const char *path, struct afs_info *afsi);
+int get_audio_file_path_of_row(const struct osl_row *row, char **path);
+int get_afsi_object_of_row(const struct osl_row *row, struct osl_object *obj);
+int audio_file_loop(void *private_data, osl_rbtree_loop_func *func);
+void aft_check_callback(int fd, __a_unused const struct osl_object *query);
+
+/* playlist */
+int playlist_open(char *name);
+void playlist_close(void);
+void playlist_check_callback(int fd, __a_unused const struct osl_object *query);
+
+/** evaluates to 1 if x < y, to -1 if x > y and to 0 if x == y */
+#define NUM_COMPARE(x, y) ((int)((x) < (y)) - (int)((x) > (y)))
+
+
+/** Define exported functions and a table pointer for an osl blob table. */
+#define DECLARE_BLOB_SYMBOLS(table_name, cmd_prefix) \
+ void table_name ## _init(struct afs_table *t); \
+ int cmd_prefix ## _get_name_by_id(uint32_t id, char **name); \
+ int cmd_prefix ## _get_def_by_id(uint32_t id, struct osl_object *def); \
+ int cmd_prefix ## _get_def_by_name(char *name, struct osl_object *def); \
+ int cmd_prefix ## _get_name_and_def_by_row(const struct osl_row *row, \
+ char **name, struct osl_object *def); \
+ int table_name ##_event_handler(enum afs_events event, \
+ struct para_buffer *pb, void *data); \
+ extern struct osl_table *table_name ## _table;
+
+DECLARE_BLOB_SYMBOLS(lyrics, lyr);
+DECLARE_BLOB_SYMBOLS(images, img);
+DECLARE_BLOB_SYMBOLS(moods, mood);
+DECLARE_BLOB_SYMBOLS(playlists, pl);
+
+/** The columns of an abstract blob table. */
+enum blob_table_columns {
+ /** The identifier, a positive integer that never repeats. */
+ BLOBCOL_ID,
+ /** The unique name of the blob. */
+ BLOBCOL_NAME,
+ /** The actual blob contents. */
+ BLOBCOL_DEF,
+ /** A blob table has that many columns. */
+ NUM_BLOB_COLUMNS
+};