Update setAssetDirectory service extension to fail if provided path i…

…s invalid (flutter#35178)

assets/asset_manager.cc

@@ -13,20 +13,22 @@ AssetManager::AssetManager() = default;
 
 AssetManager::~AssetManager() = default;
 
-void AssetManager::PushFront(std::unique_ptr<AssetResolver> resolver) {
+bool AssetManager::PushFront(std::unique_ptr<AssetResolver> resolver) {
   if (resolver == nullptr || !resolver->IsValid()) {
-    return;
+    return false;
   }
 
   resolvers_.push_front(std::move(resolver));
+  return true;
 }
 
-void AssetManager::PushBack(std::unique_ptr<AssetResolver> resolver) {
+bool AssetManager::PushBack(std::unique_ptr<AssetResolver> resolver) {
   if (resolver == nullptr || !resolver->IsValid()) {
-    return;
+    return false;
   }
 
   resolvers_.push_back(std::move(resolver));
+  return true;
 }
 
 void AssetManager::UpdateResolverByType(

assets/asset_manager.h

@@ -22,9 +22,23 @@ class AssetManager final : public AssetResolver {
 
   ~AssetManager() override;
 
-  void PushFront(std::unique_ptr<AssetResolver> resolver);
+  //--------------------------------------------------------------------------
+  /// @brief      Adds an asset resolver to the front of the resolver queue.
+  ///             Assets would be loaded from this resolver before any follwing
+  ///             resolvers.
+  ///
+  /// @return     Returns whether this resolver is valid and has been added to
+  ///             the resolver queue.
+  bool PushFront(std::unique_ptr<AssetResolver> resolver);
 
-  void PushBack(std::unique_ptr<AssetResolver> resolver);
+  //--------------------------------------------------------------------------
+  /// @brief      Adds an asset resolver to the end of the resolver queue.
+  ///             Assets would be loaded from this resolver after any previous
+  ///             resolvers.
+  ///
+  /// @return     Returns whether this resolver is valid and has been added to
+  ///             the resolver queue.
+  bool PushBack(std::unique_ptr<AssetResolver> resolver);
 
   //--------------------------------------------------------------------------
   /// @brief      Replaces an asset resolver of the specified `type` with

shell/common/shell.cc

@@ -1773,10 +1773,15 @@ bool Shell::OnServiceProtocolSetAssetBundlePath(
 
   auto asset_manager = std::make_shared<AssetManager>();
 
-  asset_manager->PushFront(std::make_unique<DirectoryAssetBundle>(
-      fml::OpenDirectory(params.at("assetDirectory").data(), false,
-                         fml::FilePermission::kRead),
-      false));
+  if (!asset_manager->PushFront(std::make_unique<DirectoryAssetBundle>(
+          fml::OpenDirectory(params.at("assetDirectory").data(), false,
+                             fml::FilePermission::kRead),
+          false))) {
+    // The new asset directory path was invalid.
+    FML_DLOG(ERROR) << "Could not update asset directory.";
+    ServiceProtocolFailureError(response, "Could not update asset directory.");
+    return false;
+  }
 
   // Preserve any original asset resolvers to avoid syncing unchanged assets
   // over the DevFS connection.

testing/dart/observatory/BUILD.gn

@@ -8,6 +8,7 @@ tests = [
   "skp_test.dart",
   "tracing_test.dart",
   "shader_reload_test.dart",
+  "vmservice_methods_test.dart",
 ]
 
 foreach(test, tests) {

testing/dart/observatory/vmservice_methods_test.dart

@@ -0,0 +1,44 @@
+// Copyright 2013 The Flutter Authors. 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:developer' as developer;
+
+import 'package:litetest/litetest.dart';
+import 'package:vm_service/vm_service.dart' as vms;
+import 'package:vm_service/vm_service_io.dart';
+
+void main() {
+  test('Setting invalid directory returns an error', () async {
+    vms.VmService? vmService;
+    try {
+      final developer.ServiceProtocolInfo info = await developer.Service.getInfo();
+      if (info.serverUri == null) {
+        fail('This test must not be run with --disable-observatory.');
+      }
+
+      vmService = await vmServiceConnectUri(
+        'ws://localhost:${info.serverUri!.port}${info.serverUri!.path}ws',
+      );
+      final vms.Response response = await vmService.callMethod('_flutter.listViews');
+      final List<Object?>? rawViews = response.json!['views'] as List<Object?>?;
+      final String viewId = (rawViews![0]! as Map<String, Object?>?)!['id']! as String;
+
+      dynamic error;
+      try {
+        final vms.Response setAssetDirectoryPath = await vmService.callMethod(
+          '_flutter.setAssetBundlePath',
+          args: <String, Object>{
+            'viewId': viewId,
+            'assetDirectory': ''
+          },
+        );
+      } catch (err) {
+        error = err;
+      }
+      expect(error != null, true);
+    } finally {
+      await vmService?.dispose();
+    }
+  });
+}