Initial commit

.gitignore

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+.dart_tool/
+.packages
+pubspec.lock

CONTRIBUTING.md

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+# gsettings.dart Contribution Guide
+
+If you have a problem, please [file an issue](https://github.com/canonical/gsettings.dart/issues/new).
+
+If you have a solution, then we accept contributions via [pull requests](https://github.com/canonical/gsettings.dart/pulls).
+All contributions require the author(s) to sign the [contributor license agreement](http://www.ubuntu.com/legal/contributors/).
+
+Thanks for your help!

README.md

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+[![Pub Package](https://img.shields.io/pub/v/dpkg.svg)](https://pub.dev/packages/dpkg)
+
+Provides classes to extract Debian packages.
+
+```dart
+import 'package:dpkg/dpkg.dart';
+
+void main() async {
+}
+```
+
+## Contributing to dpkg.dart
+
+We welcome contributions! See the [contribution guide](CONTRIBUTING.md) for more details.

analysis_options.yaml

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+include: package:pedantic/analysis_options.yaml

lib/dpkg.dart

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+export 'src/deb_file.dart';

lib/src/ar_archive.dart

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+import 'dart:convert';
+import 'dart:io';
+import 'dart:typed_data';
+
+/// An object used for accessing Ar format archives.
+class ArArchive {
+  final String _path;
+  RandomAccessFile? _file;
+  List<ArFile>? _headers;
+  bool _signatureChecked = false;
+  bool _signatureIsValid = false;
+
+  /// Creates an object access an Ar achive at [path].
+  ArArchive(String path) : _path = path;
+
+  /// Gets the files present in this archive.
+  Future<List<ArFile>> getFiles() async {
+    if (_headers == null) {
+      _headers = await _readFileHeaders();
+    }
+
+    return _headers!;
+  }
+
+  /// Close the archive.
+  Future<void> close() async {
+    if (_file != null) {
+      await _file!.close();
+    }
+  }
+
+  // Reads [length] bytes from [offset].
+  Future<Uint8List> _read(int offset, int length) async {
+    if (_file == null) {
+      _file = await File(_path).open();
+    }
+    await _file!.setPosition(offset);
+    return _file!.read(length);
+  }
+
+  // Checks if the archive file has the correct signature.
+  Future<bool> _checkSignature() async {
+    if (_signatureChecked) {
+      return _signatureIsValid;
+    }
+    _signatureChecked = true;
+
+    var data = await _read(0, 8);
+    _signatureIsValid = data == ascii.encode('!<arch>\n');
+
+    return _signatureIsValid;
+  }
+
+  // Reads all the file headers from the archive.
+  Future<List<ArFile>> _readFileHeaders() async {
+    await _checkSignature();
+    var offset = 8;
+    var headers = <ArFile>[];
+    while (true) {
+      var header = await _readFileHeader(offset);
+      if (header == null) {
+        return headers;
+      }
+      headers.add(header);
+      offset += 60 + header.size;
+
+      // Align to 2 byte boundaries.
+      if (offset % 2 != 0) {
+        offset++;
+      }
+    }
+  }
+
+  // Reads a single file header from [offset].
+  Future<ArFile?> _readFileHeader(int offset) async {
+    var data = await _read(offset, 60);
+    if (data.isEmpty) {
+      return null;
+    }
+    if (data.length != 60) {
+      throw 'Invalid Ar header length';
+    }
+    var identifier = _getField(data, 0, 16);
+    var modificationTimestamp = int.parse(_getField(data, 16, 12));
+    var ownerId = int.parse(_getField(data, 28, 6));
+    var groupId = int.parse(_getField(data, 34, 6));
+    var mode = int.parse(_getField(data, 40, 8), radix: 8);
+    var size = int.parse(_getField(data, 48, 10));
+
+    if (data[58] != 0x60 && data[59] != 0x0a) {
+      throw 'Invalid Ar trailer';
+    }
+    return ArFile(
+        identifier: identifier,
+        modificationTimestamp: modificationTimestamp,
+        ownerId: ownerId,
+        groupId: groupId,
+        mode: mode,
+        offset: offset + 60,
+        size: size);
+  }
+
+  // Decodes a ascii encoded field.
+  String _getField(Uint8List data, int offset, int length) {
+    return ascii.decode(data.sublist(offset, offset + length)).trimRight();
+  }
+}
+
+/// Represents a file in an Ar archive.
+class ArFile {
+  /// Identifier
+  final String identifier;
+
+  /// Unix timestamp file for when file was last modified.
+  final int modificationTimestamp;
+
+  /// Owner user ID of this file.
+  final int ownerId;
+
+  /// Group ID for this file.
+  final int groupId;
+
+  /// Unix file type and permissions.
+  final int mode;
+
+  /// Offset inside the archive in bytes.
+  final int offset;
+
+  // Size of the file in bytes.
+  final int size;
+
+  ArFile(
+      {required this.identifier,
+      required this.modificationTimestamp,
+      required this.ownerId,
+      required this.groupId,
+      required this.mode,
+      required this.offset,
+      required this.size});
+
+  @override
+  String toString() =>
+      "ArFile(identifier: '$identifier', modificationTimestamp: $modificationTimestamp, ownerId: $ownerId, groupId: $groupId, mode: $mode, offset: $offset, size: $size)";
+}

lib/src/deb_file.dart

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+import 'ar_archive.dart';
+
+class DebFile {
+  // The archive that is the .deb file.
+  final ArArchive _archive;
+
+  DebFile(String path) : _archive = ArArchive(path);
+
+  Future<DebControl> getControl() async {
+    var files = await _archive.getFiles();
+
+    for (var file in files) {
+      if (file.identifier == 'control.tar.gz' || file.identifier == 'control.tar.xz') {
+        return DebControl();
+      }
+    }
+
+    throw 'Missing Debian control information';
+  }
+
+  /// Close the deb file.
+  Future<void> close() async {
+    await _archive.close();
+  }
+}
+
+class DebControl {}

pubspec.yaml

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+name: dpkg
+version: 0.0.1
+
+description:
+  Debian Package library
+
+homepage: https://github.com/canonical/dpkg.dart
+
+environment:
+  sdk: '>=2.12.0 <3.0.0'
+
+dev_dependencies:
+  pedantic: ^1.9.0
+  test: ^1.16.8

test/dpkg_test.dart

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+import 'package:dpkg/dpkg.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('FIXME', () async {});
+}