[cross_file] `readAsString` assumes bytes are UTF-16

[BirjuVachhani]

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

[Upload media here]

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!

[maheshj01]

Reproducible on latest stable and the master channel across all platforms except the web

import 'dart:convert';

import 'package:cross_file/cross_file.dart';
import 'package:flutter/material.dart';

Future<void> main() async {
 final String emojisToEncode = "😀 🔥 🚀 🦋 👋🏻";
 final String symbolsToEncode = "© ® ™";
 final file = XFile.fromData(utf8.encode(emojisToEncode), name: 'emojis.txt');
 final file2 =
 XFile.fromData(utf8.encode(symbolsToEncode), name: 'symbols.txt');

 print(await file.readAsString()); // should print 😀 but it doesn't.
 print(await file2.readAsString()); 
 runApp(const MyApp());
}

mahesh@MacBook-Pro-10 sample_app % flutterm run -d macOS 
Could not load custom device from config index 0: Expected enabled to be a boolean.
Launching lib/main.dart on macOS in debug mode...
--- xcodebuild: WARNING: Using the first of multiple matching destinations:
{ platform:macOS, arch:arm64, id:00008132-0009284E1E39001C, name:My Mac }
{ platform:macOS, arch:x86_64, id:00008132-0009284E1E39001C, name:My Mac }
Building macOS application... 
✓ Built build/macos/Build/Products/Debug/sample_app.app
[IMPORTANT:flutter/shell/platform/embedder/embedder_surface_metal_impeller.mm(50)] Using the Impeller rendering backend (Metal).
2025-03-13 19:28:05.843 sample_app[71666:892695] +[IMKClient subclass]: chose IMKClient_Modern
2025-03-13 19:28:05.843 sample_app[71666:892695] +[IMKInputSession subclass]: chose IMKInputSession_Modern
flutter: ð ð¥ ð ð ðð»
flutter: © ® â
 ¢
Syncing files to device macOS... 125ms

Flutter run key commands.
r Hot reload. 🔥🔥🔥
R Hot restart.
h List all available interactive commands.
d Detach (terminate "flutter run" but leave application running).
c Clear the screen
q Quit (terminate the application on the device).

flutter doctor -v

[!] Flutter (Channel stable, 3.29.1, on macOS 15.1.1 24B2091 darwin-arm64, locale en-US) [834ms]
 • Flutter version 3.29.1 on channel stable at /Users/mahesh/Development/flutter
 ! Warning: `flutter` on your path resolves to /Users/mahesh/Development/flutter_master/bin/flutter, which is not inside your current Flutter
 SDK checkout at /Users/mahesh/Development/flutter. Consider adding /Users/mahesh/Development/flutter/bin to the front of your path.
 ! Warning: `dart` on your path resolves to /Users/mahesh/Development/flutter_master/bin/dart, which is not inside your current Flutter SDK
 checkout at /Users/mahesh/Development/flutter. Consider adding /Users/mahesh/Development/flutter/bin to the front of your path.
 • Upstream repository https://github.com/flutter/flutter.git
 • Framework revision 09de023485 (13 days ago), 2025-02-28 13:44:05 -0800
 • Engine revision 871f65ac1b
 • Dart version 3.7.0
 • DevTools version 2.42.2
 • If those were intentional, you can disregard the above warnings; however it is recommended to use "git" directly to perform update checks
 and upgrades.

[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0) [2.6s]
 • Android SDK at /Users/mahesh/Library/Android/sdk
 • Platform android-35, build-tools 35.0.0
 • ANDROID_HOME = /Users/mahesh/Library/Android/sdk
 • Java binary at: /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 21.0.5+-12932927-b750.29)
 • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 16.0) [1,220ms]
 • Xcode at /Applications/Xcode.app/Contents/Developer
 • Build 16A242d
 • CocoaPods version 1.16.2

[✓] Chrome - develop for the web [144ms]
 • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2024.3) [143ms]
 • Android Studio at /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 21.0.5+-12932927-b750.29)

[✓] IntelliJ IDEA Community Edition (version 2021.2.1) [142ms]
 • IntelliJ at /Applications/IntelliJ IDEA CE.app
 • Flutter plugin version 61.2.4
 • Dart plugin version 212.5080.8

[✓] VS Code (version 1.96.2) [20ms]
 • VS Code at /Applications/Visual Studio Code.app/Contents
 • Flutter extension version 3.102.0

[✓] Connected device (4 available) [6.7s]
 • iPhone 16 Pro (mobile) • 34497AEA-B6B0-4F79-99A3-6E40007745A3 • ios • com.apple.CoreSimulator.SimRuntime.iOS-18-0
 (simulator)
 • macOS (desktop) • macos • darwin-arm64 • macOS 15.1.1 24B2091 darwin-arm64
 • Mac Designed for iPad (desktop) • mac-designed-for-ipad • darwin • macOS 15.1.1 24B2091 darwin-arm64
 • Chrome (web) • chrome • web-javascript • Google Chrome 131.0.6778.265

[✓] Network resources [432ms]
 • All expected network resources are available.

! Doctor found issues in 1 category.

 • Flutter version 3.30.0-1.0.pre.560 on channel master at /Users/mahesh/Development/flutter_master
 • Upstream repository https://github.com/flutter/flutter.git
 • Framework revision 25e5ffd8c2 (2 days ago), 2025-03-11 19:27:32 -0400
 • Engine revision 25e5ffd8c2
 • Dart version 3.8.0 (build 3.8.0-171.0.dev)
 • DevTools version 2.44.0

[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0) [2.1s]
 • Android SDK at /Users/mahesh/Library/Android/sdk
 • Platform android-35, build-tools 35.0.0
 • ANDROID_HOME = /Users/mahesh/Library/Android/sdk
 • Java binary at: /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 21.0.5+-12932927-b750.29)
 • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 16.0) [1,381ms]
 • Xcode at /Applications/Xcode.app/Contents/Developer
 • Build 16A242d
 • CocoaPods version 1.16.2

[✓] Chrome - develop for the web [145ms]
 • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2024.3) [144ms]
 • Android Studio at /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 21.0.5+-12932927-b750.29)

[✓] IntelliJ IDEA Community Edition (version 2021.2.1) [139ms]
 • IntelliJ at /Applications/IntelliJ IDEA CE.app
 • Flutter plugin version 61.2.4
 • Dart plugin version 212.5080.8

[✓] VS Code (version 1.96.2) [21ms]
 • VS Code at /Applications/Visual Studio Code.app/Contents
 • Flutter extension version 3.102.0

[✓] Connected device (3 available) [6.6s]
 • iPhone 16 Pro (mobile) • 34497AEA-B6B0-4F79-99A3-6E40007745A3 • ios • com.apple.CoreSimulator.SimRuntime.iOS-18-0 (simulator)
 • macOS (desktop) • macos • darwin-arm64 • macOS 15.1.1 24B2091 darwin-arm64
 • Chrome (web) • chrome • web-javascript • Google Chrome 131.0.6778.265

[✓] Network resources [300ms]
 • All expected network resources are available.

• No issues found!

[BirjuVachhani]

Why is it doing String.fromCharCodes(_bytes!) if bytes are provided?