decoder/Control: wrap DetachedSong* in std::unique_ptr

src/decoder/DecoderControl.cxx

@@ -38,8 +38,6 @@ DecoderControl::DecoderControl(Mutex &_mutex, Cond &_client_cond,
 DecoderControl::~DecoderControl() noexcept
 {
 	ClearError();
-
-	delete song;
 }
 
 void
@@ -92,7 +90,7 @@ DecoderControl::IsCurrentSong(const DetachedSong &_song) const noexcept
 }
 
 void
-DecoderControl::Start(DetachedSong *_song,
+DecoderControl::Start(std::unique_ptr<DetachedSong> _song,
 		      SongTime _start_time, SongTime _end_time,
 		      MusicBuffer &_buffer, MusicPipe &_pipe) noexcept
 {
@@ -101,8 +99,7 @@ DecoderControl::Start(DetachedSong *_song,
 	assert(_song != nullptr);
 	assert(_pipe.IsEmpty());
 
-	delete song;
-	song = _song;
+	song = std::move(_song);
 	start_time = _start_time;
 	end_time = _end_time;
 	buffer = &_buffer;

src/decoder/DecoderControl.hxx

@@ -31,8 +31,8 @@
 #include "ReplayGainMode.hxx"
 
 #include <exception>
-
 #include <utility>
+#include <memory>
 
 #include <assert.h>
 #include <stdint.h>
@@ -130,11 +130,8 @@ struct DecoderControl {
 	 * The song currently being decoded.  This attribute is set by
 	 * the player thread, when it sends the #DecoderCommand::START
 	 * command.
-	 *
-	 * This is a duplicate, and must be freed when this attribute
-	 * is cleared.
 	 */
-	DetachedSong *song = nullptr;
+	std::unique_ptr<DetachedSong> song;
 
 	/**
 	 * The initial seek position, e.g. to the start of a sub-track
@@ -382,7 +379,8 @@ public:
 	 * @param pipe the pipe which receives the decoded chunks (owned by
 	 * the caller)
 	 */
-	void Start(DetachedSong *song, SongTime start_time, SongTime end_time,
+	void Start(std::unique_ptr<DetachedSong> song,
+		   SongTime start_time, SongTime end_time,
 		   MusicBuffer &buffer, MusicPipe &pipe) noexcept;
 
 	void Stop() noexcept;

src/player/Thread.cxx

@@ -360,7 +360,7 @@ Player::StartDecoder(MusicPipe &_pipe)
 
 	SongTime start_time = pc.next_song->GetStartTime() + pc.seek_time;
 
-	dc.Start(new DetachedSong(*pc.next_song),
+	dc.Start(std::make_unique<DetachedSong>(*pc.next_song),
 		 start_time, pc.next_song->GetEndTime(),
 		 buffer, _pipe);
 }