LibAudio: Factorize stream initialisation to base class `LoaderPlugin`

All actual plugins follow the same logic to initialize their stream,
this commit factorizes all of this to their base class: `LoaderPlugin`.

Meta/Lagom/Fuzzers/FuzzFlacLoader.cpp

@@ -11,7 +11,7 @@
 extern "C" int LLVMFuzzerTestOneInput(uint8_t const* data, size_t size)
 {
     auto flac_data = ByteBuffer::copy(data, size).release_value();
-    auto flac = make<Audio::FlacLoaderPlugin>(flac_data);
+    auto flac = make<Audio::FlacLoaderPlugin>(flac_data.bytes());
 
     if (flac->initialize().is_error())
         return 1;

Meta/Lagom/Fuzzers/FuzzMP3Loader.cpp

@@ -11,7 +11,7 @@
 extern "C" int LLVMFuzzerTestOneInput(uint8_t const* data, size_t size)
 {
     auto flac_data = ByteBuffer::copy(data, size).release_value();
-    auto mp3 = make<Audio::MP3LoaderPlugin>(flac_data);
+    auto mp3 = make<Audio::MP3LoaderPlugin>(flac_data.bytes());
 
     if (mp3->initialize().is_error())
         return 1;

Userland/Libraries/LibAudio/FlacLoader.cpp

@@ -26,21 +26,18 @@
 namespace Audio {
 
 FlacLoaderPlugin::FlacLoaderPlugin(StringView path)
-    : m_path(path)
+    : LoaderPlugin(path)
 {
 }
 
-FlacLoaderPlugin::FlacLoaderPlugin(Bytes& buffer)
-    : m_backing_memory(buffer)
+FlacLoaderPlugin::FlacLoaderPlugin(Bytes buffer)
+    : LoaderPlugin(buffer)
 {
 }
 
 MaybeLoaderError FlacLoaderPlugin::initialize()
 {
-    if (m_backing_memory.has_value())
-        m_stream = LOADER_TRY(Core::Stream::MemoryStream::construct(m_backing_memory.value()));
-    else
-        m_stream = LOADER_TRY(Core::Stream::File::open(m_path, Core::Stream::OpenMode::Read));
+    LOADER_TRY(LoaderPlugin::initialize());
 
     TRY(parse_header());
     TRY(reset());

Userland/Libraries/LibAudio/FlacLoader.h

@@ -48,7 +48,7 @@ ALWAYS_INLINE ErrorOr<i32> decode_unsigned_exp_golomb(u8 order, BigEndianInputBi
 class FlacLoaderPlugin : public LoaderPlugin {
 public:
     explicit FlacLoaderPlugin(StringView path);
-    explicit FlacLoaderPlugin(Bytes& buffer);
+    explicit FlacLoaderPlugin(Bytes buffer);
     ~FlacLoaderPlugin()
     {
     }
@@ -95,8 +95,6 @@ private:
     ALWAYS_INLINE ErrorOr<u32, LoaderError> convert_sample_rate_code(u8 sample_rate_code);
     ALWAYS_INLINE ErrorOr<PcmSampleFormat, LoaderError> convert_bit_depth_code(u8 bit_depth_code);
 
-    StringView m_path;
-
     // Data obtained directly from the FLAC metadata: many values have specific bit counts
     u32 m_sample_rate { 0 };         // 20 bit
     u8 m_num_channels { 0 };         // 3 bit
@@ -113,8 +111,6 @@ private:
 
     // keep track of the start of the data in the FLAC stream to seek back more easily
     u64 m_data_start_location { 0 };
-    OwnPtr<Core::Stream::SeekableStream> m_stream;
-    Optional<Bytes> m_backing_memory;
     Optional<FlacFrameHeader> m_current_frame;
     // Whatever the last get_more_samples() call couldn't return gets stored here.
     Vector<Sample, FLAC_BUFFER_SIZE> m_unread_data;

Userland/Libraries/LibAudio/Loader.cpp

@@ -11,6 +11,26 @@
 
 namespace Audio {
 
+LoaderPlugin::LoaderPlugin(StringView path)
+    : m_path(path)
+{
+}
+
+LoaderPlugin::LoaderPlugin(Bytes buffer)
+    : m_backing_memory(buffer)
+{
+}
+
+MaybeLoaderError LoaderPlugin::initialize()
+{
+    if (m_backing_memory.has_value())
+        m_stream = LOADER_TRY(Core::Stream::MemoryStream::construct(m_backing_memory.value()));
+    else
+        m_stream = LOADER_TRY(Core::Stream::File::open(m_path, Core::Stream::OpenMode::Read));
+
+    return {};
+}
+
 Loader::Loader(NonnullOwnPtr<LoaderPlugin> plugin)
     : m_plugin(move(plugin))
 {

Userland/Libraries/LibAudio/Loader.h

@@ -18,6 +18,7 @@
 #include <LibAudio/LoaderError.h>
 #include <LibAudio/Sample.h>
 #include <LibAudio/SampleFormats.h>
+#include <LibCore/Stream.h>
 
 namespace Audio {
 
@@ -28,6 +29,8 @@ using MaybeLoaderError = Result<void, LoaderError>;
 
 class LoaderPlugin {
 public:
+    explicit LoaderPlugin(StringView path);
+    explicit LoaderPlugin(Bytes buffer);
     virtual ~LoaderPlugin() = default;
 
     virtual MaybeLoaderError initialize() = 0;
@@ -53,6 +56,12 @@ public:
     // Human-readable name of the file format, of the form <full abbreviation> (.<ending>)
     virtual String format_name() = 0;
     virtual PcmSampleFormat pcm_format() = 0;
+
+protected:
+    StringView m_path;
+    OwnPtr<Core::Stream::SeekableStream> m_stream;
+    // The constructor might set this so that we can initialize the data stream later.
+    Optional<Bytes> m_backing_memory;
 };
 
 class Loader : public RefCounted<Loader> {

Userland/Libraries/LibAudio/MP3Loader.cpp

@@ -20,7 +20,7 @@ MP3LoaderPlugin::MP3LoaderPlugin(StringView path)
 }
 
 MP3LoaderPlugin::MP3LoaderPlugin(Bytes buffer)
-    : m_backing_memory(buffer)
+    : LoaderPlugin(buffer)
 {
 }
 

Userland/Libraries/LibAudio/MP3Loader.h

@@ -72,9 +72,6 @@ private:
 
     AK::Optional<MP3::MP3Frame> m_current_frame;
     u32 m_current_frame_read;
-    StringView m_path;
-    OwnPtr<Core::Stream::SeekableStream> m_stream;
-    Optional<Bytes const&> m_backing_memory;
     OwnPtr<Core::Stream::BigEndianInputBitStream> m_bitstream;
     DuplexMemoryStream m_bit_reservoir;
 };

Userland/Libraries/LibAudio/WavLoader.cpp

@@ -19,23 +19,20 @@ namespace Audio {
 static constexpr size_t const maximum_wav_size = 1 * GiB; // FIXME: is there a more appropriate size limit?
 
 WavLoaderPlugin::WavLoaderPlugin(StringView path)
-    : m_path(path)
+    : LoaderPlugin(path)
 {
 }
 
 MaybeLoaderError WavLoaderPlugin::initialize()
 {
-    if (m_backing_memory.has_value())
-        m_stream = LOADER_TRY(Core::Stream::MemoryStream::construct(m_backing_memory.value()));
-    else
-        m_stream = LOADER_TRY(Core::Stream::File::open(m_path, Core::Stream::OpenMode::Read));
+    LOADER_TRY(LoaderPlugin::initialize());
 
     TRY(parse_header());
     return {};
 }
 
-WavLoaderPlugin::WavLoaderPlugin(Bytes const& buffer)
-    : m_backing_memory(buffer)
+WavLoaderPlugin::WavLoaderPlugin(Bytes buffer)
+    : LoaderPlugin(buffer)
 {
 }
 

Userland/Libraries/LibAudio/WavLoader.h

@@ -30,7 +30,7 @@ static constexpr unsigned const WAVE_FORMAT_EXTENSIBLE = 0xFFFE; // Determined b
 class WavLoaderPlugin : public LoaderPlugin {
 public:
     explicit WavLoaderPlugin(StringView path);
-    explicit WavLoaderPlugin(Bytes const& buffer);
+    explicit WavLoaderPlugin(Bytes buffer);
 
     virtual MaybeLoaderError initialize() override;
 
@@ -56,11 +56,6 @@ private:
     template<typename SampleReader>
     MaybeLoaderError read_samples_from_stream(Core::Stream::Stream& stream, SampleReader read_sample, FixedArray<Sample>& samples) const;
 
-    StringView m_path;
-    OwnPtr<Core::Stream::SeekableStream> m_stream;
-    // The constructor might set this so that we can initialize the data stream later.
-    Optional<Bytes const&> m_backing_memory;
-
     u32 m_sample_rate { 0 };
     u16 m_num_channels { 0 };
     PcmSampleFormat m_sample_format;