Utility function added to check permissions on directory (#95)

* Utility function added to check permissions on directory

* dart format fix

* Update changelog

* Using fakes for tests

* Handle null returns from `getHomeDirectory()`

* Bump version to 2.0.0 due to breaking change on default constructor

pkgs/unified_analytics/CHANGELOG.md

@@ -1,9 +1,10 @@
-## 1.1.1
+## 2.0.0
 
 - Refactoring `dateStamp` utility function to be defined in `utils.dart` instead of having static methods in `Initializer` and `ConfigHandler`
 - Remove the `pddFlag` now that the revisions to the PDD have been finalized to persist data in the log file and session json file
 - Opting out will now delete the contents of the CLIENT ID, session json, and log files; opting back in will regenerate them as events send
 - `enableAsserts` parameter added to constructors for `Analytics` to check body of POST request for Google Analytics 4 limitations
+- Now checking if write permissions are enabled for user's home directory, if not allowed, `NoOpAnalytics` returned by `Analytics` factory constructor
 
 ## 1.1.0
 

pkgs/unified_analytics/lib/src/analytics.dart

@@ -40,6 +40,13 @@ abstract class Analytics {
     // resolve on their own
     const FileSystem fs = LocalFileSystem();
 
+    // Ensure that the home directory has permissions enabled to write
+    final Directory? homeDirectory = getHomeDirectory(fs);
+    if (homeDirectory == null ||
+        !checkDirectoryForWritePermissions(homeDirectory)) {
+      return NoOpAnalytics();
+    }
+
     // Resolve the OS using dart:io
     final DevicePlatform platform;
     if (io.Platform.operatingSystem == 'linux') {
@@ -59,7 +66,7 @@ abstract class Analytics {
 
     return AnalyticsImpl(
       tool: tool,
-      homeDirectory: getHomeDirectory(fs),
+      homeDirectory: homeDirectory,
       flutterChannel: flutterChannel,
       flutterVersion: flutterVersion,
       dartVersion: dartVersion,
@@ -88,6 +95,13 @@ abstract class Analytics {
     // resolve on their own
     const FileSystem fs = LocalFileSystem();
 
+    // Ensure that the home directory has permissions enabled to write
+    final Directory? homeDirectory = getHomeDirectory(fs);
+    if (homeDirectory == null ||
+        !checkDirectoryForWritePermissions(homeDirectory)) {
+      return NoOpAnalytics();
+    }
+
     // Resolve the OS using dart:io
     final DevicePlatform platform;
     if (io.Platform.operatingSystem == 'linux') {
@@ -111,7 +125,7 @@ abstract class Analytics {
 
     return AnalyticsImpl(
       tool: tool,
-      homeDirectory: getHomeDirectory(fs),
+      homeDirectory: homeDirectory,
       flutterChannel: flutterChannel,
       flutterVersion: flutterVersion,
       dartVersion: dartVersion,

pkgs/unified_analytics/lib/src/constants.dart

@@ -70,7 +70,7 @@ const int kLogFileLength = 2500;
 const String kLogFileName = 'dart-flutter-telemetry.log';
 
 /// The current version of the package, should be in line with pubspec version.
-const String kPackageVersion = '1.1.1';
+const String kPackageVersion = '2.0.0';
 
 /// The minimum length for a session
 const int kSessionDurationMinutes = 30;

pkgs/unified_analytics/lib/src/utils.dart

@@ -20,6 +20,18 @@ String get dateStamp {
   return DateFormat('yyyy-MM-dd').format(clock.now());
 }
 
+/// Reads in a directory and returns `true` if write permissions are enabled
+///
+/// Uses the [FileStat] method `modeString()` to return a string in the form
+/// of `rwxrwxrwx` where the second character in the string indicates if write
+/// is enabled with a `w` or disabled with `-`
+bool checkDirectoryForWritePermissions(Directory directory) {
+  if (!directory.existsSync()) return false;
+
+  final FileStat fileStat = directory.statSync();
+  return fileStat.modeString()[1] == 'w';
+}
+
 /// Format time as 'yyyy-MM-dd HH:mm:ss Z' where Z is the difference between the
 /// timezone of t and UTC formatted according to RFC 822.
 String formatDateTime(DateTime t) {
@@ -76,7 +88,7 @@ Map<String, Object?> generateRequestBody({
 /// This will use environment variables to get the user's
 /// home directory where all the directory will be created that will
 /// contain all of the analytics files
-Directory getHomeDirectory(FileSystem fs) {
+Directory? getHomeDirectory(FileSystem fs) {
   String? home;
   Map<String, String> envVars = io.Platform.environment;
 
@@ -88,7 +100,9 @@ Directory getHomeDirectory(FileSystem fs) {
     home = envVars['AppData'];
   }
 
-  return fs.directory(home!);
+  if (home == null) return null;
+
+  return fs.directory(home);
 }
 
 /// Returns `true` if user has opted out of legacy analytics in Dart or Flutter

pkgs/unified_analytics/pubspec.yaml

@@ -4,7 +4,7 @@ description: >-
   to Google Analytics.
 # When updating this, keep the version consistent with the changelog and the
 # value in lib/src/constants.dart.
-version: 1.1.1
+version: 2.0.0
 repository: https://github.com/dart-lang/tools/tree/main/pkgs/unified_analytics
 
 environment:

pkgs/unified_analytics/test/no_op_analytics_test.dart

@@ -2,8 +2,11 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'package:file/file.dart';
+import 'package:test/fake.dart';
 import 'package:test/test.dart';
 
+import 'package:unified_analytics/src/utils.dart';
 import 'package:unified_analytics/unified_analytics.dart';
 
 void main() {
@@ -45,4 +48,49 @@ void main() {
 
     expect(analytics.logFileStats(), isNull);
   });
+
+  test('Home directory without write permissions', () {
+    final FakeDirectory home = FakeDirectory(writeEnabled: false);
+
+    expect(checkDirectoryForWritePermissions(home), false);
+  });
+
+  test('Home directory with write permissions', () {
+    final FakeDirectory home = FakeDirectory(writeEnabled: true);
+
+    expect(checkDirectoryForWritePermissions(home), true);
+  });
+}
+
+class FakeDirectory extends Fake implements Directory {
+  final String _fakeModeString;
+
+  /// This fake directory class allows you to pass the permissions for
+  /// the user level, the group and global permissions will default to
+  /// being denied as indicated by the last 6 characters in [modeString]
+  FakeDirectory({
+    required bool writeEnabled,
+    bool readEnabled = true,
+    bool executeEnabled = true,
+  }) : _fakeModeString = '${readEnabled ? "r" : "-"}'
+            '${writeEnabled ? "w" : "-"}'
+            '${executeEnabled ? "x" : "-"}'
+            '------' {
+    assert(_fakeModeString.length == 9);
+  }
+
+  @override
+  bool existsSync() => true;
+
+  @override
+  FileStat statSync() => FakeFileStat(_fakeModeString);
+}
+
+class FakeFileStat extends Fake implements FileStat {
+  final String _fakeModeString;
+
+  FakeFileStat(this._fakeModeString);
+
+  @override
+  String modeString() => _fakeModeString;
 }