LibAudio: Handle unknown-sized streams better

Especially FLAC had an issue here before, but the loader infrastructure
itself wouldn't handle end of stream properly if the "available samples"
information didn't match up.

Userland/Libraries/LibAudio/FlacLoader.cpp

@@ -22,6 +22,7 @@
 #include <LibAudio/FlacTypes.h>
 #include <LibAudio/GenericTypes.h>
 #include <LibAudio/LoaderError.h>
+#include <LibAudio/MultiChannel.h>
 #include <LibAudio/Resampler.h>
 #include <LibAudio/VorbisComment.h>
 #include <LibCore/File.h>
@@ -338,7 +339,7 @@ ErrorOr<Vector<FixedArray<Sample>>, LoaderError> FlacLoaderPlugin::load_chunks(s
 {
     ssize_t remaining_samples = static_cast<ssize_t>(m_total_samples - m_loaded_samples);
     // The first condition is relevant for unknown-size streams (total samples = 0 in the header)
-    if (m_stream->is_eof() || remaining_samples <= 0)
+    if (m_stream->is_eof() || (m_total_samples < NumericLimits<u64>::max() && remaining_samples <= 0))
         return Vector<FixedArray<Sample>> {};
 
     size_t samples_to_read = min(samples_to_read_from_input, remaining_samples);

Userland/Libraries/LibAudio/Loader.cpp

@@ -68,6 +68,9 @@ ErrorOr<NonnullOwnPtr<LoaderPlugin>, LoaderError> Loader::create_plugin(NonnullO
 
 LoaderSamples Loader::get_more_samples(size_t samples_to_read_from_input)
 {
+    if (m_plugin_at_end_of_stream)
+        return FixedArray<Sample> {};
+
     size_t remaining_samples = total_samples() - loaded_samples();
     size_t samples_to_read = min(remaining_samples, samples_to_read_from_input);
     auto samples = TRY(FixedArray<Sample>::create(samples_to_read));
@@ -88,8 +91,10 @@ LoaderSamples Loader::get_more_samples(size_t samples_to_read_from_input)
     while (sample_index < samples_to_read) {
         auto chunk_data = TRY(m_plugin->load_chunks(samples_to_read - sample_index));
         chunk_data.remove_all_matching([](auto& chunk) { return chunk.is_empty(); });
-        if (chunk_data.is_empty())
+        if (chunk_data.is_empty()) {
+            m_plugin_at_end_of_stream = true;
             break;
+        }
         for (auto& chunk : chunk_data) {
             if (sample_index < samples_to_read) {
                 auto count = min(samples_to_read - sample_index, chunk.size());

Userland/Libraries/LibAudio/Loader.h

@@ -91,10 +91,15 @@ public:
     // Will only read less samples if we're at the end of the stream.
     LoaderSamples get_more_samples(size_t samples_to_read_from_input = 128 * KiB);
 
-    MaybeLoaderError reset() const { return m_plugin->reset(); }
+    MaybeLoaderError reset() const
+    {
+        m_plugin_at_end_of_stream = false;
+        return m_plugin->reset();
+    }
     MaybeLoaderError seek(int const position) const
     {
         m_buffer.clear_with_capacity();
+        m_plugin_at_end_of_stream = false;
         return m_plugin->seek(position);
     }
 
@@ -114,6 +119,8 @@ private:
     explicit Loader(NonnullOwnPtr<LoaderPlugin>);
 
     mutable NonnullOwnPtr<LoaderPlugin> m_plugin;
+    // The plugin can signal an end of stream by returning no (or only empty) chunks.
+    mutable bool m_plugin_at_end_of_stream { false };
     mutable Vector<Sample, loader_buffer_size> m_buffer;
 };