Fixed Issue #52

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.0.13
+
+- Fixed issue [#52](https://github.com/instantiations/es_compression/issues/52) (special thanks to [Abitofevrything](https://github.com/abitofevrything) for a helpful issue report)
+
 ## 2.0.12
 
 - Removed deprecated `dart:cli.waitFor()` uses. [#50](https://github.com/instantiations/es_compression/issues/50)

lib/src/brotli/ffi/decompress_filter.dart

@@ -24,6 +24,9 @@ class BrotliDecompressFilter extends NativeCodecFilterBase {
   /// Native brotli state object.
   late final Pointer<BrotliDecoderState> _brotliState;
 
+  /// Special Case: Empty input
+  late bool _emptyInput = false;
+
   /// Construct an [BrotliDecompressFilter] with the supplied options.
   BrotliDecompressFilter(
       {bool ringBufferReallocation = true,
@@ -66,6 +69,7 @@ class BrotliDecompressFilter extends NativeCodecFilterBase {
     if (!outputBufferHolder.isLengthSet()) {
       outputBufferHolder.length = brotliDecoderOutputBufferLength;
     }
+    _emptyInput = end - start <= 0;
     return 0;
   }
 
@@ -94,7 +98,8 @@ class BrotliDecompressFilter extends NativeCodecFilterBase {
   /// state.
   @override
   int doFinalize(CodecBuffer<dynamic> outputBuffer) {
-    if (!_dispatcher.callBrotliDecoderIsFinished(_brotliState)) {
+    if (!_dispatcher.callBrotliDecoderIsFinished(_brotliState) &&
+        !_emptyInput) {
       throw const FormatException('Failure to finish decoding');
     }
     return 0;

lib/src/framework/filters.dart

@@ -139,6 +139,12 @@ abstract class CodecFilter<P, CB extends CodecBuffer<P>> {
       if (flush == true) _flush(builder);
       if (end == true) _finalize(builder);
     }
+
+    // Return null if no bytes were added to the builder
+    if (builder.isEmpty) {
+      return null;
+    }
+
     return builder.takeBytes();
   }
 

lib/src/lz4/ffi/decompress_filter.dart

@@ -65,8 +65,10 @@ class Lz4DecompressFilter extends NativeCodecFilterBase {
     final numBytes = inputBufferHolder.buffer.nextPutAll(bytes, start, end);
     if (numBytes > 0) _readFrameInfo(inputBufferHolder.buffer);
 
+    const defaultBlockSize = 65536;
+
     outputBufferHolder.length = max(
-        _frameInfo!.ref.blockSize,
+        _frameInfo?.ref.blockSize ?? defaultBlockSize,
         outputBufferHolder.isLengthSet()
             ? outputBufferHolder.length
             : max(lz4DecoderOutputBufferLength, inputBufferHolder.length));

pubspec.yaml

@@ -1,6 +1,6 @@
 name: es_compression
 description: Compression framework providing FFI implementations for Brotli, Lz4, Zstd (Zstandard) with ready-to-use prebuilt binaries for Win/Linux/Mac.
-version: 2.0.12
+version: 2.0.13
 homepage: https://www.instantiations.com
 issue_tracker: https://github.com/instantiations/es_compression/issues
 repository: https://github.com/instantiations/es_compression

test/brotli_test.dart

@@ -21,6 +21,13 @@ void main() {
     expect(() => brotli.decode(<int>[1, 2, 3]), throwsFormatException);
   });
 
+  test('Test Brotli Decode Empty Stream Produces No Chunks', () async {
+    final result =
+        await const Stream<List<int>>.empty().transform(brotli.decoder).isEmpty;
+    expect(result, isTrue,
+        reason: "Stream should be empty and emit no chunks.");
+  });
+
   test('Test Empty Brotli Encode/Decode', () {
     const data = '';
     final header = [107, 0, 3];

test/lz4_test.dart

@@ -32,6 +32,13 @@ void main() {
     expect(const ListEquality<int>().equals(dataBytes, decoded), true);
   });
 
+  test('Test Lz4 Decode Empty Stream Produces No Chunks', () async {
+    final result =
+        await const Stream<List<int>>.empty().transform(lz4.decoder).isEmpty;
+    expect(result, isTrue,
+        reason: "Stream should be empty and emit no chunks.");
+  });
+
   test('Test Simple Lz4 Encode/Decode', () {
     const data = 'MyDart';
     final expected = [

test/zstd_test.dart

@@ -31,6 +31,13 @@ void main() {
     expect(const ListEquality<int>().equals(dataBytes, decoded), true);
   });
 
+  test('Test Zstd Decode Empty Stream Produces No Chunks', () async {
+    final result =
+        await const Stream<List<int>>.empty().transform(zstd.decoder).isEmpty;
+    expect(result, isTrue,
+        reason: "Stream should be empty and emit no chunks.");
+  });
+
   test('Test Simple Zstd Encode/Decode', () {
     const data = 'MyDart';
     final expected = [