4 files changed, 39 insertions, 9 deletions
diff --git a/src/output/plugins/AlsaOutputPlugin.cxx b/src/output/plugins/AlsaOutputPlugin.cxx
index a18cedc70..0ebf3ddbe 100644
--- a/src/output/plugins/AlsaOutputPlugin.cxx
+++ b/src/output/plugins/AlsaOutputPlugin.cxx
@@ -825,6 +825,7 @@ alsa_play(AudioOutput *ao, const void *chunk, size_t size,
 {
 	AlsaOutput *ad = (AlsaOutput *)ao;
 
+	assert(size > 0);
 	assert(size % ad->in_frame_size == 0);
 
 	if (ad->must_prepare) {
@@ -838,12 +839,22 @@ alsa_play(AudioOutput *ao, const void *chunk, size_t size,
 	}
 
 	const auto e = ad->pcm_export->Export({chunk, size});
+	if (e.size == 0)
+		/* the DoP (DSD over PCM) filter converts two frames
+		   at a time and ignores the last odd frame; if there
+		   was only one frame (e.g. the last frame in the
+		   file), the result is empty; to avoid an endless
+		   loop, bail out here, and pretend the one frame has
+		   been played */
+		return size;
+
 	chunk = e.data;
 	size = e.size;
 
 	assert(size % ad->out_frame_size == 0);
 
 	size /= ad->out_frame_size;
+	assert(size > 0);
 
 	while (true) {
 		snd_pcm_sframes_t ret = ad->writei(ad->pcm, chunk, size);
diff --git a/src/output/plugins/OssOutputPlugin.cxx b/src/output/plugins/OssOutputPlugin.cxx
index f2618491c..39d87fc35 100644
--- a/src/output/plugins/OssOutputPlugin.cxx
+++ b/src/output/plugins/OssOutputPlugin.cxx
@@ -724,6 +724,8 @@ oss_output_play(AudioOutput *ao, const void *chunk, size_t size,
 	OssOutput *od = (OssOutput *)ao;
 	ssize_t ret;
 
+	assert(size > 0);
+
 	/* reopen the device since it was closed by dropBufferedAudio */
 	if (od->fd < 0 && !oss_reopen(od, error))
 		return 0;
@@ -734,6 +736,8 @@ oss_output_play(AudioOutput *ao, const void *chunk, size_t size,
 	size = e.size;
 #endif
 
+	assert(size > 0);
+
 	while (true) {
 		ret = write(od->fd, chunk, size);
 		if (ret > 0) {
diff --git a/src/queue/Playlist.hxx b/src/queue/Playlist.hxx
index 581d2a73b..ea19d9bba 100644
--- a/src/queue/Playlist.hxx
+++ b/src/queue/Playlist.hxx
@@ -251,6 +251,10 @@ public:
 
 	void PlayPrevious(PlayerControl &pc);
 
+	PlaylistResult SeekSongOrder(PlayerControl &pc,
+				     unsigned song_order,
+				     SongTime seek_time);
+
 	PlaylistResult SeekSongPosition(PlayerControl &pc,
 					unsigned song_position,
 					SongTime seek_time);
diff --git a/src/queue/PlaylistControl.cxx b/src/queue/PlaylistControl.cxx
index df6b6ed0f..f7e80dc46 100644
--- a/src/queue/PlaylistControl.cxx
+++ b/src/queue/PlaylistControl.cxx
@@ -190,18 +190,12 @@ playlist::PlayPrevious(PlayerControl &pc)
 }
 
 PlaylistResult
-playlist::SeekSongPosition(PlayerControl &pc,
-			   unsigned song, SongTime seek_time)
+playlist::SeekSongOrder(PlayerControl &pc, unsigned i, SongTime seek_time)
 {
-	if (!queue.IsValidPosition(song))
-		return PlaylistResult::BAD_RANGE;
+	assert(queue.IsValidOrder(i));
 
 	const DetachedSong *queued_song = GetQueuedSong();
 
-	unsigned i = queue.random
-		? queue.PositionToOrder(song)
-		: song;
-
 	pc.ClearError();
 	stop_on_error = true;
 	error_count = 0;
@@ -229,6 +223,20 @@ playlist::SeekSongPosition(PlayerControl &pc,
 }
 
 PlaylistResult
+playlist::SeekSongPosition(PlayerControl &pc, unsigned song,
+			   SongTime seek_time)
+{
+	if (!queue.IsValidPosition(song))
+		return PlaylistResult::BAD_RANGE;
+
+	unsigned i = queue.random
+		? queue.PositionToOrder(song)
+		: song;
+
+	return SeekSongOrder(pc, i, seek_time);
+}
+
+PlaylistResult
 playlist::SeekSongId(PlayerControl &pc, unsigned id, SongTime seek_time)
 {
 	int song = queue.IdToPosition(id);
@@ -257,5 +265,8 @@ playlist::SeekCurrent(PlayerControl &pc,
 			seek_time = SignedSongTime::zero();
 	}
 
-	return SeekSongPosition(pc, current, SongTime(seek_time));
+	if (seek_time.IsNegative())
+		seek_time = SignedSongTime::zero();
+
+	return SeekSongOrder(pc, current, SongTime(seek_time));
 }