decoder: converted dc.error to a dc.state value

The player did not care about the exact error value, it only checked
whether an error has occured.  This could fit well into
decoder_control.state - introduce a new state "DECODE_STATE_ERROR".

src/decoder_control.c

@@ -27,7 +27,6 @@ void dc_init(void)
 	notify_init(&dc.notify);
 	dc.state = DECODE_STATE_STOP;
 	dc.command = DECODE_COMMAND_NONE;
-	dc.error = DECODE_ERROR_NOERROR;
 }
 
 void dc_deinit(void)
@@ -63,7 +62,6 @@ dc_start(struct notify *notify, struct song *song)
 	assert(song != NULL);
 
 	dc.next_song = song;
-	dc.error = DECODE_ERROR_NOERROR;
 	dc_command(notify, DECODE_COMMAND_START);
 }
 
@@ -73,7 +71,6 @@ dc_start_async(struct song *song)
 	assert(song != NULL);
 
 	dc.next_song = song;
-	dc.error = DECODE_ERROR_NOERROR;
 	dc_command_async(DECODE_COMMAND_START);
 }
 
@@ -81,7 +78,7 @@ void
 dc_stop(struct notify *notify)
 {
 	if (dc.command == DECODE_COMMAND_START ||
-	    dc.state != DECODE_STATE_STOP)
+	    (dc.state != DECODE_STATE_STOP && dc.state != DECODE_STATE_ERROR))
 		dc_command(notify, DECODE_COMMAND_STOP);
 }
 
@@ -90,7 +87,8 @@ dc_seek(struct notify *notify, double where)
 {
 	assert(where >= 0.0);
 
-	if (dc.state == DECODE_STATE_STOP || !dc.seekable)
+	if (dc.state == DECODE_STATE_STOP ||
+	    dc.state == DECODE_STATE_ERROR || !dc.seekable)
 		return false;
 
 	dc.seek_where = where;

src/decoder_control.h

@@ -25,19 +25,23 @@
 #include "audio_format.h"
 #include "notify.h"
 
+#include <assert.h>
+
 #define DECODE_TYPE_FILE	0
 #define DECODE_TYPE_URL		1
 
 enum decoder_state {
 	DECODE_STATE_STOP = 0,
 	DECODE_STATE_START,
-	DECODE_STATE_DECODE
+	DECODE_STATE_DECODE,
-};
 
-enum decoder_error {
+	/**
-	DECODE_ERROR_NOERROR = 0,
+	 * The last "START" command failed, because there was an I/O
-	DECODE_ERROR_UNKTYPE,
+	 * error or because no decoder was able to decode the file.
-	DECODE_ERROR_FILE,
+	 * This state will only come after START; once the state has
+	 * turned to DECODE, by definition no such error can occur.
+	 */
+	DECODE_STATE_ERROR,
 };
 
 struct decoder_control {
@@ -45,7 +49,6 @@ struct decoder_control {
 
 	volatile enum decoder_state state;
 	volatile enum decoder_command command;
-	volatile enum decoder_error error;
 	bool seek_error;
 	bool seekable;
 	volatile double seek_where;
@@ -69,7 +72,8 @@ void dc_deinit(void);
 
 static inline bool decoder_is_idle(void)
 {
-	return dc.state == DECODE_STATE_STOP &&
+	return (dc.state == DECODE_STATE_STOP ||
+		dc.state == DECODE_STATE_ERROR) &&
 		dc.command != DECODE_COMMAND_START;
 }
 
@@ -79,14 +83,28 @@ static inline bool decoder_is_starting(void)
 		dc.state == DECODE_STATE_START;
 }
 
+static inline bool decoder_has_failed(void)
+{
+	assert(dc.command == DECODE_COMMAND_NONE);
+
+	return dc.state == DECODE_STATE_ERROR;
+}
+
 static inline struct song *
 decoder_current_song(void)
 {
-	if (dc.state == DECODE_STATE_STOP ||
+	switch (dc.state) {
-	    dc.error != DECODE_ERROR_NOERROR)
+	case DECODE_STATE_STOP:
+	case DECODE_STATE_ERROR:
 		return NULL;
 
-	return dc.current_song;
+	case DECODE_STATE_START:
+	case DECODE_STATE_DECODE:
+		return dc.current_song;
+	}
+
+	assert(false);
+	return NULL;
 }
 
 void

src/decoder_thread.c

@@ -61,13 +61,13 @@ static void decoder_run(void)
 	else
 		uri = song_get_url(song, buffer);
 	if (uri == NULL) {
-		dc.error = DECODE_ERROR_FILE;
+		dc.state = DECODE_STATE_ERROR;
 		return;
 	}
 
 	dc.current_song = dc.next_song; /* NEED LOCK */
 	if (!input_stream_open(&input_stream, uri)) {
-		dc.error = DECODE_ERROR_FILE;
+		dc.state = DECODE_STATE_ERROR;
 		return;
 	}
 
@@ -84,19 +84,21 @@ static void decoder_run(void)
 	while (!input_stream.ready) {
 		if (dc.command != DECODE_COMMAND_NONE) {
 			input_stream_close(&input_stream);
+			dc.state = DECODE_STATE_STOP;
 			return;
 		}
 
 		ret = input_stream_buffer(&input_stream);
 		if (ret < 0) {
 			input_stream_close(&input_stream);
-			dc.error = DECODE_ERROR_FILE;
+			dc.state = DECODE_STATE_ERROR;
 			return;
 		}
 	}
 
 	if (dc.command == DECODE_COMMAND_STOP) {
 		input_stream_close(&input_stream);
+		dc.state = DECODE_STATE_STOP;
 		return;
 	}
 
@@ -161,27 +163,23 @@ static void decoder_run(void)
 
 	music_pipe_flush();
 
-	if (!ret) {
-		dc.error = plugin == NULL
-			? DECODE_ERROR_UNKTYPE
-			: DECODE_ERROR_FILE;
-	}
-
 	if (close_instream)
 		input_stream_close(&input_stream);
+
+	dc.state = ret ? DECODE_STATE_STOP : DECODE_STATE_ERROR;
 }
 
 static void * decoder_task(mpd_unused void *arg)
 {
 	while (1) {
-		assert(dc.state == DECODE_STATE_STOP);
+		assert(dc.state == DECODE_STATE_STOP ||
+		       dc.state == DECODE_STATE_ERROR);
 
 		switch (dc.command) {
 		case DECODE_COMMAND_START:
 		case DECODE_COMMAND_SEEK:
 			decoder_run();
 
-			dc.state = DECODE_STATE_STOP;
 			dc.command = DECODE_COMMAND_NONE;
 			notify_signal(&pc.notify);
 			break;

src/player_thread.c

@@ -93,7 +93,7 @@ static int player_wait_for_decoder(struct player *player)
 {
 	dc_command_wait(&pc.notify);
 
-	if (dc.error != DECODE_ERROR_NOERROR) {
+	if (decoder_has_failed()) {
 		assert(dc.next_song == NULL || dc.next_song->url != NULL);
 		pc.errored_song = dc.next_song;
 		pc.error = PLAYER_ERROR_FILE;
@@ -305,7 +305,7 @@ static void do_play(void)
 		}
 
 		if (player.decoder_starting) {
-			if (dc.error != DECODE_ERROR_NOERROR) {
+			if (decoder_has_failed()) {
 				/* the decoder failed */
 				assert(dc.next_song == NULL || dc.next_song->url != NULL);
 				pc.errored_song = dc.next_song;