state_file: don't rewind the stream while reading the state file

Parse the state file line by line, let each subsystem probe a line.
Only the playlist_state code gets the FILE pointer to read the
following lines.

src/output_state.c

@@ -49,35 +49,34 @@ saveAudioDevicesState(FILE *fp)
 	}
 }
 
-void
-readAudioDevicesState(FILE *fp)
+bool
+readAudioDevicesState(const char *line)
 {
-	char buffer[1024];
+	long value;
+	char *endptr;
+	const char *name;
+	struct audio_output *ao;
 
-	while (fgets(buffer, sizeof(buffer), fp)) {
-		char *c, *name;
-		struct audio_output *ao;
+	if (!g_str_has_prefix(line, AUDIO_DEVICE_STATE))
+		return false;
 
-		g_strchomp(buffer);
+	line += sizeof(AUDIO_DEVICE_STATE) - 1;
 
-		if (!g_str_has_prefix(buffer, AUDIO_DEVICE_STATE))
-			continue;
+	value = strtol(line, &endptr, 10);
+	if (*endptr != ':' || (value != 0 && value != 1))
+		return false;
 
-		c = strchr(buffer, ':');
-		if (!c || !(++c))
-			goto errline;
+	if (value != 0)
+		/* state is "enabled": no-op */
+		return true;
 
-		name = strchr(c, ':');
-		if (!name || !(++name))
-			goto errline;
-
-		ao = audio_output_find(name);
-		if (ao != NULL && atoi(c) == 0)
-			ao->enabled = false;
-
-		continue;
-errline:
-		/* nonfatal */
-		g_warning("invalid line in state_file: %s\n", buffer);
+	name = endptr + 1;
+	ao = audio_output_find(name);
+	if (ao == NULL) {
+		g_debug("Ignoring device state for '%s'", name);
+		return true;
 	}
+
+	ao->enabled = false;
+	return true;
 }

src/output_state.h

@@ -25,10 +25,11 @@
 #ifndef OUTPUT_STATE_H
 #define OUTPUT_STATE_H
 
+#include <stdbool.h>
 #include <stdio.h>
 
-void
-readAudioDevicesState(FILE *fp);
+bool
+readAudioDevicesState(const char *line);
 
 void
 saveAudioDevicesState(FILE *fp);

src/playlist_state.c

@@ -115,8 +115,8 @@ playlist_state_load(FILE *fp, struct playlist *playlist, char *buffer)
 	queue_increment_version(&playlist->queue);
 }
 
-void
-playlist_state_restore(FILE *fp, struct playlist *playlist)
+bool
+playlist_state_restore(const char *line, FILE *fp, struct playlist *playlist)
 {
 	int current = -1;
 	int seek_time = 0;
@@ -124,21 +124,20 @@ playlist_state_restore(FILE *fp, struct playlist *playlist)
 	char buffer[PLAYLIST_BUFFER_SIZE];
 	bool random_mode = false;
 
+	if (!g_str_has_prefix(line, PLAYLIST_STATE_FILE_STATE))
+		return false;
+
+	line += sizeof(PLAYLIST_STATE_FILE_STATE) - 1;
+
+	if (strcmp(line, PLAYLIST_STATE_FILE_STATE_PLAY) == 0)
+		state = PLAYER_STATE_PLAY;
+	else if (strcmp(line, PLAYLIST_STATE_FILE_STATE_PAUSE) == 0)
+		state = PLAYER_STATE_PAUSE;
+
 	while (fgets(buffer, sizeof(buffer), fp)) {
 		g_strchomp(buffer);
 
-		if (g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_STATE)) {
-			if (strcmp(&(buffer[strlen(PLAYLIST_STATE_FILE_STATE)]),
-				   PLAYLIST_STATE_FILE_STATE_PLAY) == 0) {
-				state = PLAYER_STATE_PLAY;
-			} else
-			    if (strcmp
-				(&(buffer[strlen(PLAYLIST_STATE_FILE_STATE)]),
-				 PLAYLIST_STATE_FILE_STATE_PAUSE)
-				== 0) {
-				state = PLAYER_STATE_PAUSE;
-			}
-		} else if (g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_TIME)) {
+		if (g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_TIME)) {
 			seek_time =
 			    atoi(&(buffer[strlen(PLAYLIST_STATE_FILE_TIME)]));
 		} else if (g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_REPEAT)) {
@@ -198,4 +197,6 @@ playlist_state_restore(FILE *fp, struct playlist *playlist)
 		if (state == PLAYER_STATE_PAUSE)
 			playerPause();
 	}
+
+	return true;
 }

src/playlist_state.h

@@ -25,6 +25,7 @@
 #ifndef PLAYLIST_STATE_H
 #define PLAYLIST_STATE_H
 
+#include <stdbool.h>
 #include <stdio.h>
 
 struct playlist;
@@ -32,7 +33,7 @@ struct playlist;
 void
 playlist_state_save(FILE *fp, const struct playlist *playlist);
 
-void
-playlist_state_restore(FILE *fp, struct playlist *playlist);
+bool
+playlist_state_restore(const char *line, FILE *fp, struct playlist *playlist);
 
 #endif

src/state_file.c

@@ -63,6 +63,8 @@ static void
 state_file_read(void)
 {
 	FILE *fp;
+	char line[1024];
+	bool success;
 
 	assert(state_file_path != NULL);
 
@@ -75,11 +77,15 @@ state_file_read(void)
 		return;
 	}
 
-	read_sw_volume_state(fp);
-	rewind(fp);
-	readAudioDevicesState(fp);
-	rewind(fp);
-	playlist_state_restore(fp, &g_playlist);
+	while (fgets(line, sizeof(line), fp) != NULL) {
+		g_strchomp(line);
+
+		success = read_sw_volume_state(line) ||
+			readAudioDevicesState(line) ||
+			playlist_state_restore(line, fp, &g_playlist);
+		if (!success)
+			g_warning("Unrecognized line in state file: %s", line);
+	}
 
 	while(fclose(fp) && errno == EINTR) /* nothing */;
 }

src/volume.c

@@ -100,24 +100,22 @@ bool volume_level_change(unsigned volume)
 	return hardware_volume_change(volume);
 }
 
-void read_sw_volume_state(FILE *fp)
+bool
+read_sw_volume_state(const char *line)
 {
-	char buf[sizeof(SW_VOLUME_STATE) + sizeof("100") - 1];
 	char *end = NULL;
 	long int sv;
 
-	while (fgets(buf, sizeof(buf), fp)) {
-		if (!g_str_has_prefix(buf, SW_VOLUME_STATE))
-			continue;
+	if (!g_str_has_prefix(line, SW_VOLUME_STATE))
+		return false;
 
-		g_strchomp(buf);
-		sv = strtol(buf + strlen(SW_VOLUME_STATE), &end, 10);
-		if (G_LIKELY(!*end) && sv >= 0 && sv <= 100)
-			software_volume_change(sv);
-		else
-			g_warning("Can't parse software volume: %s\n", buf);
-		return;
-	}
+	line += sizeof(SW_VOLUME_STATE) - 1;
+	sv = strtol(line, &end, 10);
+	if (*end == 0 && sv >= 0 && sv <= 100)
+		software_volume_change(sv);
+	else
+		g_warning("Can't parse software volume: %s\n", line);
+	return true;
 }
 
 void save_sw_volume_state(FILE *fp)

src/volume.h

@@ -31,7 +31,8 @@ int volume_level_get(void);
 
 bool volume_level_change(unsigned volume);
 
-void read_sw_volume_state(FILE *fp);
+bool
+read_sw_volume_state(const char *line);
 
 void save_sw_volume_state(FILE *fp);