+ * Before forking the afs child, para_server creates a bidirectional pipe
+ * through which both processes communicate. Usually para_server requests a new
+ * audio file 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 \ref pattern_match_flags. */
+ unsigned pm_flags;
+ /** This value is passed verbatim to fnmatch(). */
+ int fnmatch_flags;
+ /** Obtained by deserializing the query buffer in the callback. */
+ struct lls_parse_result *lpr;
+ /** Do not try to match the first inputs of lpr */
+ unsigned input_skip;
+ /** Data pointer passed to the action function. */
+ void *data;
+ /** Gets increased by one for each match. */
+ unsigned num_matches;
+ /** For each matching row, this function will be called. */
+ int (*action)(struct osl_table *table, struct osl_row *row, const char *name, void *data);
+};
+
+/** Arguments passed to each afs callback. */
+struct afs_callback_arg {
+ /** The local socket connecting afs and the command handler. */
+ int fd;
+ /** Callback-specific data. */
+ struct osl_object query;
+ /** Will be written on band SBD_OUTPUT, fully buffered. */
+ struct para_buffer pbout;
+ /**
+ * Convenience pointer for the deserialized parse result.
+ *
+ * Most afs command handlers call \ref send_lls_callback_request() to
+ * serialize the parse result of the subcommand and pass it to the
+ * callback. In afs context a pointer to the deserialized parse result
+ * is stored here.
+ */
+ struct lls_parse_result *lpr;
+};
+