gasaichandesu
65 lines
1.9 KiB
Dart
65 lines
1.9 KiB
Dart
import 'dart:async';
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import 'dart:io';
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import 'package:crypto/crypto.dart' as c;
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import 'package:injectable/injectable.dart';
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import 'package:moonwell_launcher/features/downloader/domain/repositories/file_system.dart';
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@LazySingleton(as: FileSystem)
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class IoFileSystem implements FileSystem {
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@override
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Future<void> ensureParentExists(String path) =>
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File(path).parent.create(recursive: true);
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@override
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Future<bool> exists(String path) => File(path).exists();
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@override
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Future<int> sizeOf(String path) async => (await File(path).stat()).size;
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@override
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Future<void> truncate(String path) async =>
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File(path).writeAsBytes(const [], flush: true);
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@override
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Future<void> createEmpty(String path) => File(path).create(recursive: true);
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@override
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Future<StreamSink<List<int>>> openAppend(String path) async =>
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File(path).openWrite(mode: FileMode.append);
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@override
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Future<bool> verifyFile(
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String path, {
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required String expected,
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required String algo,
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}) async {
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final file = File(path);
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if (!await file.exists()) return false;
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final digestHex = await _computeDigestHex(file, algo);
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return _constantTimeEquals(digestHex.toLowerCase(), expected.toLowerCase());
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}
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Future<String> _computeDigestHex(File file, String algo) async {
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final hash = switch (algo.toLowerCase()) {
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'md5' => c.md5,
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'sha256' => c.sha256,
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_ => throw ArgumentError('Unsupported checksum algo: $algo'),
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};
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// Stream the file into the hash converter; no extra buffers.
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final digest = await hash.bind(file.openRead()).first; // -> c.Digest
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return digest.toString(); // lowercase hex
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}
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bool _constantTimeEquals(String a, String b) {
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if (a.length != b.length) return false;
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var result = 0;
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for (var i = 0; i < a.length; i++) {
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result |= a.codeUnitAt(i) ^ b.codeUnitAt(i);
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}
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return result == 0;
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}
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}
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