Validate git is clean when publishing

lib/src/git.dart

@@ -50,6 +50,37 @@ class GitException implements ApplicationException {
 /// Tests whether or not the git command-line app is available for use.
 bool get isInstalled => command != null;
 
+/// Splits the [output] of a git -z command at \0.
+///
+/// The first [skipPrefix] bytes of each substring will be ignored (useful for
+/// `git status -z`). If there are not enough bytes to skip, throws a
+/// [FormatException].
+List<Uint8List> splitZeroTerminated(Uint8List output, {int skipPrefix = 0}) {
+  final result = <Uint8List>[];
+  var start = 0;
+
+  for (var i = 0; i < output.length; i++) {
+    if (output[i] != 0) {
+      continue;
+    }
+    if (start + skipPrefix > i) {
+      throw FormatException('Substring too short for prefix at $start');
+    }
+    result.add(
+      Uint8List.sublistView(
+        output,
+        // The first 3 bytes are the modification status.
+        // Skip those.
+        start + skipPrefix,
+        i,
+      ),
+    );
+
+    start = i + 1;
+  }
+  return result;
+}
+
 /// Run a git process with [args] from [workingDir].
 ///
 /// Returns the stdout if it succeeded. Completes to ans exception if it failed.

lib/src/validator.dart

@@ -25,6 +25,7 @@ import 'validator/executable.dart';
 import 'validator/file_case.dart';
 import 'validator/flutter_constraint.dart';
 import 'validator/flutter_plugin_format.dart';
+import 'validator/git_status.dart';
 import 'validator/gitignore.dart';
 import 'validator/leak_detection.dart';
 import 'validator/license.dart';
@@ -143,6 +144,7 @@ abstract class Validator {
       FileCaseValidator(),
       AnalyzeValidator(),
       GitignoreValidator(),
+      GitStatusValidator(),
       PubspecValidator(),
       LicenseValidator(),
       NameValidator(),

lib/src/validator/git_status.dart

@@ -0,0 +1,96 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// 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 'dart:async';
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:path/path.dart' as p;
+
+import '../git.dart' as git;
+import '../log.dart' as log;
+import '../utils.dart';
+import '../validator.dart';
+
+/// A validator that validates that no checked in files are modified in git.
+///
+/// Doesn't report on newly added files, as generated files might not be checked
+/// in to git.
+class GitStatusValidator extends Validator {
+  @override
+  Future<void> validate() async {
+    if (!package.inGitRepo) {
+      return;
+    }
+    final Uint8List output;
+    final String reporoot;
+    try {
+      final maybeReporoot = git.repoRoot(package.dir);
+      if (maybeReporoot == null) {
+        log.fine(
+          'Could not determine the repository root from ${package.dir}.',
+        );
+        // This validation is only a warning.
+        return;
+      }
+      reporoot = maybeReporoot;
+      output = git.runSyncBytes(
+        [
+          'status',
+          '-z', // Machine parsable
+          '--no-renames', // We don't care about renames.
+
+          '--untracked-files=no', // Don't show untracked files.
+        ],
+        workingDir: package.dir,
+      );
+    } on git.GitException catch (e) {
+      log.fine('Could not run `git status` files in repo (${e.message}).');
+      // This validation is only a warning.
+      // If git is not supported on the platform, we just continue silently.
+      return;
+    }
+    final List<String> modifiedFiles;
+    try {
+      modifiedFiles = git
+          .splitZeroTerminated(output, skipPrefix: 3)
+          .map((bytes) {
+            try {
+              final filename = utf8.decode(bytes);
+              final fullPath = p.join(reporoot, filename);
+              if (!files.any((f) => p.equals(fullPath, f))) {
+                // File is not in the published set - ignore.
+                return null;
+              }
+              return p.relative(fullPath);
+            } on FormatException catch (e) {
+              // Filename is not utf8 - ignore.
+              log.fine('Cannot decode file name: $e');
+              return null;
+            }
+          })
+          .nonNulls
+          .toList();
+    } on FormatException catch (e) {
+      // Malformed output from `git status`. Skip this validation.
+      log.fine('Malformed output from `git status -z`: $e');
+      return;
+    }
+    if (modifiedFiles.isNotEmpty) {
+      warnings.add('''
+${modifiedFiles.length} checked-in ${pluralize('file', modifiedFiles.length)} ${modifiedFiles.length == 1 ? 'is' : 'are'} modified in git.
+
+Usually you want to publish from a clean git state.
+
+Consider committing these files or reverting the changes.
+
+Modified files:
+
+${modifiedFiles.take(10).map(p.relative).join('\n')}
+${modifiedFiles.length > 10 ? '...\n' : ''}
+Run `git status` for more information.
+''');
+    }
+  }
+}

lib/src/validator/gitignore.dart

@@ -44,16 +44,15 @@ class GitignoreValidator extends Validator {
         // --recurse-submodules we just continue silently.
         return;
       }
-      final checkedIntoGit = <String>[];
-      // Split at \0.
-      var start = 0;
-      for (var i = 0; i < output.length; i++) {
-        if (output[i] == 0) {
-          checkedIntoGit.add(
-            utf8.decode(Uint8List.sublistView(output, start, i)),
-          );
-          start = i + 1;
-        }
+
+      final List<String> checkedIntoGit;
+      try {
+        checkedIntoGit = git.splitZeroTerminated(output).map((b) {
+          return utf8.decode(b);
+        }).toList();
+      } on FormatException catch (e) {
+        log.fine('Failed decoding git output. Skipping validation. $e.');
+        return;
       }
       final root = git.repoRoot(package.dir) ?? package.dir;
       var beneath = p.posix.joinAll(

test/git_test.dart

@@ -0,0 +1,48 @@
+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// 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 'dart:typed_data';
+
+import 'package:pub/src/git.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('splitZeroTerminated works', () {
+    expect(splitZeroTerminated(Uint8List.fromList([])), <Uint8List>[]);
+    expect(
+      splitZeroTerminated(Uint8List.fromList([0])),
+      <Uint8List>[Uint8List.fromList([])],
+    );
+
+    expect(splitZeroTerminated(Uint8List.fromList([1, 0, 1])), <Uint8List>[
+      Uint8List.fromList([1]),
+    ]);
+    expect(
+      splitZeroTerminated(Uint8List.fromList([2, 1, 0, 1, 0, 0])),
+      <Uint8List>[
+        Uint8List.fromList([2, 1]),
+        Uint8List.fromList([1]),
+        Uint8List.fromList([]),
+      ],
+    );
+    expect(
+      splitZeroTerminated(
+        Uint8List.fromList([2, 1, 0, 1, 0, 2, 3, 0]),
+        skipPrefix: 1,
+      ),
+      <Uint8List>[
+        Uint8List.fromList([1]),
+        Uint8List.fromList([]),
+        Uint8List.fromList([3]),
+      ],
+    );
+    expect(
+      () => splitZeroTerminated(
+        Uint8List.fromList([2, 1, 0, 1, 0, 0]),
+        skipPrefix: 1,
+      ),
+      throwsA(isA<FormatException>()),
+    );
+  });
+}