Fixed incorrect parsing of tag size field - fixes #1.

Added unit tests.

CHANGELOG.md

@@ -1,4 +1,11 @@
-## 0.1.0
+#Changes
+
+##Version 0.2.0
+
+### Bug fixes
+* Fixed incorrect parsing of tag size field (resolves [issue 1](https://github.com/tolo/id3tag/issues/1), reported by @VirtualAstronaut). 
+
+##Version 0.1.0
 
 * Support for parsing ID3 v2.3 and above
 * Basic structure in place, with some inspiration from [OutcastID3](https://github.com/CrunchyBagel/OutcastID3)

lib/src/extensions/byte_list_extension.dart

@@ -3,27 +3,35 @@ import '../exceptions.dart';
 
 extension ID3ByteList on List<int> {
 
-  int parseInt() {
+  int _parseInt({required bool syncSafe}) {
     int value;
     if (length == 4) {
-      value = this[0] << 24;
-      value += this[1] << 16;
-      value += this[2] << 8;
-      value += this[3];
+      if (syncSafe) {
+        value = (this[0] & 0x7f) << 21;
+        value += (this[1] & 0x7f) << 14;
+        value += (this[2] & 0x7f) << 7;
+        value += (this[3] & 0x7f);
+      } else {
+        value = this[0] << 24;
+        value += this[1] << 16;
+        value += this[2] << 8;
+        value += this[3];
+      }
     } else {
       throw ID3ParserException("Unable to parse int value from byte array of length $length");
     }
 
     return value;
   }
 
+  int parseInt(int id3MinorVersion) {
+    return _parseInt(syncSafe: id3MinorVersion >= 4);
+  }
+
   int parseID3FileHeaderSize() {
     int size;
     if (length == 4) {
-      size = (this[0] & 0x7f) << 21;
-      size += (this[1] & 0x7f) << 14;
-      size += (this[2] & 0x7f) << 7;
-      size += (this[3] & 0x7f);
+      size = _parseInt(syncSafe: true);
     } else if (length == 3) {
       size = this[0] << 16;
       size += this[1] << 8;

lib/src/extensions/iterable_extension.dart

@@ -5,4 +5,11 @@ extension IterableExtensions<E> on Iterable<E> {
 
   E? lastIfAny({minLength = 1}) => length >= minLength ? last : null;
 
+  E? firstWhereOrNull(bool Function(E element) test) {
+    try {
+      return firstWhere(test);
+    } catch(e) {
+      return null;
+    }
+  }
 }

lib/src/frame_body.dart

@@ -11,10 +11,11 @@ import 'exceptions.dart';
 
 class FrameBody {
   final List<int> buffer;
+  final int tagMinorVersion;
   int pos = 0;
   int lastEncoding = 0x00; // default to latin1
 
-  FrameBody(this.buffer);
+  FrameBody(this.buffer, this.tagMinorVersion);
 
   List<int> readUntilTerminator(List<int> terminator, {bool aligned = false, bool terminatorMandatory = true}) {
     if (remainingBytes == 0) {
@@ -131,7 +132,7 @@ class FrameBody {
   }
 
   int readInt() {
-    return readBytes(4).parseInt();
+    return readBytes(4).parseInt(tagMinorVersion);
   }
 
   List<int> readRemainingBytes() {

lib/src/id3_parser.dart

@@ -25,7 +25,9 @@ class ID3Parser implements ID3TagReader {
 
   @override bool get id3TagFound => id3FileHeader.id3TagSize > 0;
 
-  final _ID3FileHeader id3FileHeader;
+  int get id3CompleteTagSize => id3FileHeaderLength + _id3TagBytes.length;
+
+  final ID3FileHeader id3FileHeader;
 
   final List<int> _id3TagBytes;
   final int _initialOffset;
@@ -49,26 +51,26 @@ class ID3Parser implements ID3TagReader {
 
     try {
       final length = _reader.lengthSync();
-      final List<int> fileHeaderBytes = length > 10 ? _reader.readSync(id3FileHeaderLength) : [];
+      final List<int> fileHeaderBytes = length > id3FileHeaderLength ? _reader.readSync(id3FileHeaderLength) : [];
       // Assume ID3 tag is at beginning of file
-      final List<int>? id3FileTag = fileHeaderBytes.length == 10 ? fileHeaderBytes.sublist(0, 3) : null;
+      final List<int>? id3FileTag = fileHeaderBytes.length == id3FileHeaderLength ? fileHeaderBytes.sublist(0, 3) : null;
 
       if (id3FileTag != null && latin1.decode(id3FileTag) == 'ID3') {
         final headerBytes = fileHeaderBytes.toList();
-        final header = _ID3FileHeader.fromHeaderBytes(headerBytes);
+        final header = ID3FileHeader.fromHeaderBytes(headerBytes);
 
         final id3TagBytes = _reader.readSync(header.id3TagSize);
 
         int initialOffset = 0;
         if (header.hasExtendedHeader) {
-          final extendedHeaderSize = id3TagBytes.sublist(0, 4).parseInt();
+          final extendedHeaderSize = id3TagBytes.sublist(0, 4).parseInt(header.tagMinorVersion);
           initialOffset = extendedHeaderSize + 4; // Size doesn't include size itself
         }
 
         return ID3Parser._raw(frameParsers: frameParsers ?? ID3Parser._defaultParsers, id3FileHeader: header,
             id3TagBytes: id3TagBytes, initialOffset: initialOffset);
       } else {
-        return ID3Parser._raw(frameParsers: {}, id3FileHeader: _ID3FileHeader.empty(),
+        return ID3Parser._raw(frameParsers: {}, id3FileHeader: ID3FileHeader.empty(),
             id3TagBytes: [], initialOffset: 0);
       }
     } finally {
@@ -122,8 +124,10 @@ class ID3Parser implements ID3TagReader {
       return null;
     }
 
-    int frameContentSize = frameHeader.sublist(_frameNameLength, _frameNameLength + _frameSizeLength).parseInt();
-    final List<int> frameContent = buffer.sublist(offset + _frameHeaderLength, offset + _frameHeaderLength + frameContentSize);
+    int frameContentSize = frameHeader.sublist(_frameNameLength, _frameNameLength + _frameSizeLength)
+        .parseInt(id3FileHeader.tagMinorVersion);
+    final List<int> frameContent = buffer
+        .sublist(offset + _frameHeaderLength, offset + _frameHeaderLength + frameContentSize);
 
     return RawFrame(this, frameName, _frameHeaderLength + frameContentSize, frameContent);
   }
@@ -147,7 +151,7 @@ class ID3Parser implements ID3TagReader {
 }
 
 
-class _ID3FileHeader {
+class ID3FileHeader {
   final String id3TagVersion;
   /// The ID3 minor version, i.e. the X in 2.X.0
   final int tagMinorVersion;
@@ -163,10 +167,10 @@ class _ID3FileHeader {
   final bool hasExtendedHeader;
 
 
-  _ID3FileHeader.raw({required this.id3TagVersion, required this.tagMinorVersion, required this.id3TagSize,
+  ID3FileHeader.raw({required this.id3TagVersion, required this.tagMinorVersion, required this.id3TagSize,
     required this.hasExtendedHeader});
 
-  factory _ID3FileHeader.fromHeaderBytes(List<int> headerBytes) {
+  factory ID3FileHeader.fromHeaderBytes(List<int> headerBytes) {
     final int tagMinorVersion = headerBytes[3];
     final int tagMicroVersion = headerBytes[4];
     final int flag = headerBytes[5];
@@ -177,15 +181,15 @@ class _ID3FileHeader {
 
     final id3TagSize = headerBytes.sublist(6, 10).parseID3FileHeaderSize();
 
-    return _ID3FileHeader.raw(
+    return ID3FileHeader.raw(
       id3TagVersion: '2.$tagMinorVersion.$tagMicroVersion',
       tagMinorVersion: tagMinorVersion,
       id3TagSize: id3TagSize,
       hasExtendedHeader: hasExtendedHeader,
     );
   }
 
-  factory _ID3FileHeader.empty() {
-    return _ID3FileHeader.raw(id3TagVersion: '-', tagMinorVersion: 0, id3TagSize: 0, hasExtendedHeader: false);
+  factory ID3FileHeader.empty() {
+    return ID3FileHeader.raw(id3TagVersion: '-', tagMinorVersion: 0, id3TagSize: 0, hasExtendedHeader: false);
   }
 }

lib/src/id3_tag.dart

@@ -80,5 +80,3 @@ class ID3Tag {
     return framesWithTypeAndName<T>(name).firstIfAny();
   }
 }
-
-

lib/src/raw_frame.dart

@@ -14,7 +14,7 @@ class RawFrame {
   final FrameBody frameContent;
 
   RawFrame(this.id3Parser, this.frameName, this.frameSize, List<int> frameContentBytes) :
-        frameContent = FrameBody(frameContentBytes);
+        frameContent = FrameBody(frameContentBytes, id3Parser.id3FileHeader.tagMinorVersion);
 
 
   RawFrame? parseRawSubFrame(List<int> buffer, {int offset = 0}) {

pubspec.lock

@@ -7,14 +7,14 @@ packages:
       name: _fe_analyzer_shared
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "31.0.0"
+    version: "40.0.0"
   analyzer:
     dependency: transitive
     description:
       name: analyzer
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.8.0"
+    version: "4.1.0"
   args:
     dependency: transitive
     description:
@@ -43,13 +43,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.3.1"
-  cli_util:
-    dependency: transitive
-    description:
-      name: cli_util
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.3.5"
   collection:
     dependency: transitive
     description:
@@ -91,7 +84,7 @@ packages:
       name: flutter_lints
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "2.0.1"
   frontend_server_client:
     dependency: transitive
     description:
@@ -140,7 +133,7 @@ packages:
       name: lints
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.1"
+    version: "2.0.0"
   logging:
     dependency: transitive
     description:
@@ -287,21 +280,21 @@ packages:
       name: test
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.19.5"
+    version: "1.21.4"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.4.8"
+    version: "0.4.12"
   test_core:
     dependency: transitive
     description:
       name: test_core
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.4.9"
+    version: "0.4.16"
   typed_data:
     dependency: transitive
     description:
@@ -345,4 +338,4 @@ packages:
     source: hosted
     version: "3.1.0"
 sdks:
-  dart: ">=2.14.0 <3.0.0"
+  dart: ">=2.17.0-206.0.dev <3.0.0"

pubspec.yaml

@@ -7,5 +7,5 @@ environment:
   sdk: ">=2.13.0 <3.0.0"
 
 dev_dependencies:
-  flutter_lints: ^1.0.4
-  test: ^1.17.10
+  flutter_lints: ^2.0.1
+  test: ^1.21.4

test/id3frames_test.dart

@@ -1,7 +1,38 @@
-//import 'package:id3tag/id3tag.dart';
+import 'dart:io';
+import 'package:test/test.dart';
+
+import 'package:id3tag/src/id3_parser.dart';
+import 'package:id3tag/src/extensions/iterable_extension.dart';
+
 
 void main() {
-  // test('TODO', () {
-  //
-  // });
+  /*test('Truncate file to ID3 tag size', () {
+    final file = File('test/truncate.mp3');
+    final parser = ID3Parser(file);
+    final fileID3TagSize = parser.id3CompleteTagSize;
+
+    final RandomAccessFile raf = file.openSync(mode: FileMode.append);
+    raf.truncateSync(fileID3TagSize);
+    raf.flushSync();
+    raf.closeSync();
+  });*/
+
+  test('Tag should contain chapters', () {
+    final parser = ID3Parser(File('test/chap.mp3'));
+    final tag = parser.readTagSync();
+    // print('ID3 tag found: ${tag.tagFound} - version: ${tag.tagVersion}');
+    // print('Title: ${tag.title}');
+    // print('Duration: ${tag.duration}');
+    // print('Chapters: ${tag.chapters}');
+    // print('frameDictionaries: ${tag.frameDictionaries}');
+    final frame = tag.frames.firstWhereOrNull((f) => f.frameName == 'CHAP');
+    expect(frame, isNotNull);
+  });
+
+  test('Tag should contain picture', () {
+    final parser = ID3Parser(File('test/apic.mp3'));
+    final tag = parser.readTagSync();
+    final frame = tag.frames.firstWhereOrNull((f) => f.frameName == 'APIC');
+    expect(frame, isNotNull);
+  });
 }