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[cross_file] readAsString assumes bytes are UTF-16 #165120
Description
Steps to reproduce
If XFile is created with ut8 bytes and then file.readAsString() is called then it returns incorrect output.
Responsible code from cross_file:
@override
Future<String> readAsString({Encoding encoding = utf8}) {
if (_bytes != null) {
// TODO(kevmoo): Remove ignore and fix when the MIN Dart SDK is 3.3
// ignore: unnecessary_non_null_assertion
return Future<String>.value(String.fromCharCodes(_bytes!));
}
return _file.readAsString(encoding: encoding);
}This happens on IO, haven't tested web.
Expected results
Output
😀
Actual results
Output
�
Code sample
Code sample
// Doesn't Work
void main() async {
final String text ="😀";
final file = XFile.fromData(utf8.encode(text));
print(await file.readAsString()); // should print 😀 but it doesn't.
}
// Works
void main() async {
final String text ="😀";
File('emoji.txt').writeAsStringSync(text);
final file = XFile('emoji.txt');
print(await file.readAsString()); // should print 😀 and it does.
}Screenshots or Video
Screenshots / Video demonstration
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Logs
Logs
[Paste your logs here]Flutter Doctor output
Doctor output
[✓] Flutter (Channel stable, 3.29.1, on macOS 15.3.2 24D81 darwin-arm64, locale en-IN) [1,306ms]
• Flutter version 3.29.1 on channel stable at /Users/birjuvachhani/.puro/envs/stable/flutter
• Upstream repository https://github.com/flutter/flutter.git
• Framework revision 09de023485 (13 days ago), 2025-02-28 13:44:05 -0800
• Engine revision 010c8a806b
• Dart version 3.7.0 (build 3.7.0-323.0.dev)
• DevTools version 2.42.0
[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0) [3.5s]
• Android SDK at /Users/birjuvachhani/Library/Android/sdk
• Platform android-35, build-tools 35.0.0
• ANDROID_HOME = /Users/birjuvachhani/Library/Android/sdk
• Java binary at: /Users/birjuvachhani/Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
This is the JDK bundled with the latest Android Studio installation on this machine.
To manually set the JDK path, use: `flutter config --jdk-dir="path/to/jdk"`.
• Java version OpenJDK Runtime Environment (build 21.0.4+-12422083-b607.1)
• All Android licenses accepted.
[✓] Xcode - develop for iOS and macOS (Xcode 16.2) [2.7s]
• Xcode at /Applications/Xcode.app/Contents/Developer
• Build 16C5032a
• CocoaPods version 1.16.2
[✓] Chrome - develop for the web [102ms]
• Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
[✓] Android Studio (version 2024.2) [101ms]
• Android Studio at /Users/birjuvachhani/Applications/Android Studio.app/Contents
• Flutter plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/9212-flutter
• Dart plugin can be installed from:
🔨 https://plugins.jetbrains.com/plugin/6351-dart
• Java version OpenJDK Runtime Environment (build 21.0.4+-12422083-b607.1)
[✓] IntelliJ IDEA Community Edition (version 2024.3.4.1) [99ms]
• IntelliJ at /Users/birjuvachhani/Applications/IntelliJ IDEA Community Edition.app
• Flutter plugin version 83.0.4
• Dart plugin version 243.23654.44
[✓] VS Code (version 1.98.1) [9ms]
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.106.0
[✓] Connected device (4 available) [6.7s]
• Birju’s iPhone (wireless) (mobile) • 00008110-000E35A83A82401E • ios • iOS 18.3.2 22D82
• macOS (desktop) • macos • darwin-arm64 • macOS 15.3.2 24D81 darwin-arm64
• Mac Designed for iPad (desktop) • mac-designed-for-ipad • darwin • macOS 15.3.2 24D81 darwin-arm64
• Chrome (web) • chrome • web-javascript • Google Chrome 134.0.6998.89
[✓] Network resources [583ms]
• All expected network resources are available.
• No issues found!Reacted by Ruble
Activity
maheshj01 commentedon Mar 13, 2025
Reproducible on latest stable and the master channel across all platforms except the web
flutter doctor -v
BirjuVachhani commentedon Mar 15, 2025
Why is it doing
String.fromCharCodes(_bytes!)if bytes are provided?[-][cross_file] Reading data back from a populated file breaks with Emojis.[/-][+][cross_file] `readAsString` assumes bytes are UTF-16[/+]stuartmorgan-g commentedon Mar 17, 2025
fromCharCodesexpects UTF-16 input; we should probably either detect the encoding, or make it a constructor param.BananaMasterz commentedon Apr 24, 2025
BirjuVachhani commentedon Apr 25, 2025
@BananaMasterz Your issue doesn't seem to be related to this package in any way.
raju-muliyashiya commentedon Nov 11, 2025
@stuartmorgan-g What can we do after we detect encoding?
[cross_file] fixed `readAsString` decoding in-memory bytes as UTF-16 (f…
[cross_file] fixed `readAsString` decoding in-memory bytes as UTF-16 (f…
[cross_file] fixed `readAsString` decoding in-memory bytes as UTF-16 (f…
github-actions commentedon Sep 8, 2026
This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of
flutter doctor -vand a minimal reproduction of the issue.