Check for shader data validity and add tests (flutter/engine#34793)

engine/src/flutter/impeller/runtime_stage/runtime_stage.cc

@@ -65,9 +65,6 @@ RuntimeStage::RuntimeStage(std::shared_ptr<fml::Mapping> payload)
     return;
   }
   if (!fb::RuntimeStageBufferHasIdentifier(payload_->GetMapping())) {
-    VALIDATION_LOG
-        << "Impeller Runtime stage has invalid magic. Perhaps the stage "
-           "information is for the incorrect backend or the data is corrupted?";
     return;
   }
   auto runtime_stage = fb::GetRuntimeStage(payload_->GetMapping());

engine/src/flutter/lib/ui/painting.dart

@@ -4126,7 +4126,10 @@ class FragmentProgram extends NativeFieldWrapperClass1 {
   @pragma('vm:entry-point')
   FragmentProgram._fromAsset(String assetKey) {
     _constructor();
-    _initFromAsset(assetKey);
+    final String result = _initFromAsset(assetKey);
+    if (result.isNotEmpty) {
+      throw result;
+    }
   }
 
   static void _reinitializeShader(String assetKey) {
@@ -4145,7 +4148,10 @@ class FragmentProgram extends NativeFieldWrapperClass1 {
       return;
     }
 
-    program._initFromAsset(assetKey);
+    final result = program._initFromAsset(assetKey);
+    if (result.isNotEmpty) {
+      throw result;
+    }
   }
 
   late final int _uniformFloatCount;
@@ -4157,8 +4163,8 @@ class FragmentProgram extends NativeFieldWrapperClass1 {
   @FfiNative<Void Function(Pointer<Void>, Handle, Bool)>('FragmentProgram::init')
   external void _init(String sksl, bool debugPrint);
 
-  @FfiNative<Void Function(Pointer<Void>, Handle)>('FragmentProgram::initFromAsset')
-  external void _initFromAsset(String assetKey);
+  @FfiNative<Handle Function(Pointer<Void>, Handle)>('FragmentProgram::initFromAsset')
+  external String _initFromAsset(String assetKey);
 
   /// Constructs a [Shader] object suitable for use by [Paint.shader] with
   /// the given uniforms.

engine/src/flutter/lib/ui/painting/fragment_program.cc

@@ -22,18 +22,21 @@ namespace flutter {
 
 IMPLEMENT_WRAPPERTYPEINFO(ui, FragmentProgram);
 
-void FragmentProgram::initFromAsset(std::string asset_name) {
+std::string FragmentProgram::initFromAsset(std::string asset_name) {
   std::shared_ptr<AssetManager> asset_manager = UIDartState::Current()
                                                     ->platform_configuration()
                                                     ->client()
                                                     ->GetAssetManager();
   std::unique_ptr<fml::Mapping> data = asset_manager->GetAsMapping(asset_name);
   if (data == nullptr) {
-    Dart_ThrowException(tonic::ToDart("Asset '" + asset_name + "' not found"));
-    return;
+    return std::string("Asset '") + asset_name + std::string("' not found");
   }
 
   auto runtime_stage = impeller::RuntimeStage(std::move(data));
+  if (!runtime_stage.IsValid()) {
+    return std::string("Asset '") + asset_name +
+           std::string("' does not contain valid shader data.");
+  }
   {
     auto code_mapping = runtime_stage.GetCodeMapping();
     auto code_size = code_mapping->GetSize();
@@ -43,10 +46,8 @@ void FragmentProgram::initFromAsset(std::string asset_name) {
     SkRuntimeEffect::Result result =
         SkRuntimeEffect::MakeForShader(SkString(sksl, code_size));
     if (result.effect == nullptr) {
-      Dart_ThrowException(tonic::ToDart(std::string("Invalid SkSL:\n") + sksl +
-                                        std::string("\nSkSL Error:\n") +
-                                        result.errorText.c_str()));
-      return;
+      return std::string("Invalid SkSL:\n") + sksl +
+             std::string("\nSkSL Error:\n") + result.errorText.c_str();
     }
     runtime_effect_ = result.effect;
   }
@@ -84,6 +85,8 @@ void FragmentProgram::initFromAsset(std::string asset_name) {
   if (Dart_IsError(result)) {
     Dart_PropagateError(result);
   }
+
+  return "";
 }
 
 void FragmentProgram::init(std::string sksl, bool debugPrintSksl) {

engine/src/flutter/lib/ui/painting/fragment_program.h

@@ -24,7 +24,7 @@ class FragmentProgram : public RefCountedDartWrappable<FragmentProgram> {
   ~FragmentProgram() override;
   static void Create(Dart_Handle wrapper);
 
-  void initFromAsset(std::string asset_name);
+  std::string initFromAsset(std::string asset_name);
 
   void init(std::string sksl, bool debugPrintSksl);
 

engine/src/flutter/testing/dart/fragment_shader_test.dart

@@ -295,6 +295,30 @@ void main() {
     await _expectShaderRendersGreen(shader);
   });
 
+  test('iplr throws an exception on invalid assetKey', () async {
+    bool throws = false;
+    try {
+      final FragmentProgram program = FragmentProgram.fromAsset(
+        '<invalid>',
+      );
+    } catch (e) {
+      throws = true;
+    }
+    expect(throws, equals(true));
+  });
+
+  test('iplr throws an exception on invalid data', () async {
+    bool throws = false;
+    try {
+      final FragmentProgram program = FragmentProgram.fromAsset(
+        'DashInNooglerHat.jpg',
+      );
+    } catch (e) {
+      throws = true;
+    }
+    expect(throws, equals(true));
+  });
+
   // Test all supported GLSL ops. See lib/spirv/lib/src/constants.dart
   final Map<String, ByteBuffer> supportedGLSLOpShaders = _loadShaders(
     path.join('supported_glsl_op_shaders', 'spirv'),