Dart exceptions

jni/example/android/app/build.gradle

@@ -8,7 +8,7 @@ if (localPropertiesFile.exists()) {
 
 def flutterRoot = localProperties.getProperty('flutter.sdk')
 if (flutterRoot == null) {
-    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
+    throw new FileNotFoundException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
 }
 
 def flutterVersionCode = localProperties.getProperty('flutter.versionCode')

jni/java/src/main/java/com/github/dart_lang/jni/PortProxy.java

@@ -73,10 +73,19 @@ public static Object newInstance(String binaryName, long port, long isolateId, l
     return obj;
   }
 
+  private static final class DartException extends Exception {
+    private DartException(String message) {
+      super(message);
+    }
+  }
+
   @Override
-  public Object invoke(Object proxy, Method method, Object[] args) {
+  public Object invoke(Object proxy, Method method, Object[] args) throws DartException {
     Object[] result = _invoke(port, isolateId, functionPtr, proxy, getDescriptor(method), args);
     _cleanUp((Long) result[0]);
+    if (result[1] instanceof DartException) {
+      throw (DartException) result[1];
+    }
     return result[1];
   }
 

jni/lib/src/jni.dart

@@ -299,6 +299,13 @@ extension ProtectedJniExtensions on Jni {
     return lookup;
   }
 
+  /// Returns a new DartException.
+  static JObjectPtr newDartException(String message) {
+    return Jni._bindings
+        .DartException__ctor(Jni.env.toJStringPtr(message))
+        .object;
+  }
+
   /// Returns a new PortContinuation.
   static JObjectPtr newPortContinuation(ReceivePort port) {
     return Jni._bindings
@@ -323,7 +330,7 @@ extension ProtectedJniExtensions on Jni {
         .object;
   }
 
-  /// Return the result of a callback..
+  /// Returns the result of a callback..
   static void returnResult(
       Pointer<CallbackResult> result, JObjectPtr object) async {
     Jni._bindings.resultFor(result, object);
@@ -334,28 +341,30 @@ extension AdditionalEnvMethods on GlobalJniEnv {
   /// Convenience method for converting a [JStringPtr]
   /// to dart string.
   /// if [deleteOriginal] is specified, jstring passed will be deleted using
-  /// DeleteLocalRef.
+  /// DeleteGlobalRef.
   String toDartString(JStringPtr jstringPtr, {bool deleteOriginal = false}) {
     if (jstringPtr == nullptr) {
       throw const JNullException();
     }
-    final chars = GetStringUTFChars(jstringPtr, nullptr);
+    final chars = GetStringChars(jstringPtr, nullptr);
     if (chars == nullptr) {
       throw InvalidJStringException(jstringPtr);
     }
-    final result = chars.cast<Utf8>().toDartString();
-    ReleaseStringUTFChars(jstringPtr, chars);
+    final result = chars.cast<Utf16>().toDartString();
+    ReleaseStringChars(jstringPtr, chars);
     if (deleteOriginal) {
       DeleteGlobalRef(jstringPtr);
     }
     return result;
   }
 
-  /// Return a new [JStringPtr] from contents of [s].
+  /// Returns a new [JStringPtr] from contents of [s].
   JStringPtr toJStringPtr(String s) => using((arena) {
-        final utf = s.toNativeUtf8().cast<Char>();
-        final result = NewStringUTF(utf);
-        malloc.free(utf);
+        final utf = s.toNativeUtf16(allocator: arena).cast<Uint16>();
+        final result = NewString(utf, s.length);
+        if (utf == nullptr) {
+          throw 'Fatal: cannot convert string to Java string: $s';
+        }
         return result;
       });
 

jni/lib/src/lang/jstring.dart

@@ -47,20 +47,11 @@ class JString extends JObject {
   /// Construct a new [JString] with [reference] as its underlying reference.
   JString.fromRef(JStringPtr reference) : super.fromRef(reference);
 
-  static JStringPtr _toJavaString(String s) => using((arena) {
-        final chars = s.toNativeUtf16(allocator: arena).cast<Uint16>();
-        final jstr = Jni.env.NewString(chars, s.length);
-        if (jstr == nullptr) {
-          throw 'Fatal: cannot convert string to Java string: $s';
-        }
-        return jstr;
-      });
-
   /// The number of Unicode characters in this Java string.
   int get length => Jni.env.GetStringLength(reference);
 
   /// Construct a [JString] from the contents of Dart string [s].
-  JString.fromString(String s) : super.fromRef(_toJavaString(s));
+  JString.fromString(String s) : super.fromRef(Jni.env.toJStringPtr(s));
 
   /// Returns the contents as a Dart String.
   ///

jni/lib/src/third_party/jni_bindings_generated.dart

@@ -178,22 +178,19 @@ class JniBindings {
   late final _InitDartApiDL =
       _InitDartApiDLPtr.asFunction<int Function(ffi.Pointer<ffi.Void>)>();
 
-  void resultFor(
-    ffi.Pointer<CallbackResult> result,
-    JObjectPtr object,
+  JniResult DartException__ctor(
+    JStringPtr message,
   ) {
-    return _resultFor(
-      result,
-      object,
+    return _DartException__ctor(
+      message,
     );
   }
 
-  late final _resultForPtr = _lookup<
-      ffi.NativeFunction<
-          ffi.Void Function(
-              ffi.Pointer<CallbackResult>, JObjectPtr)>>('resultFor');
-  late final _resultFor = _resultForPtr
-      .asFunction<void Function(ffi.Pointer<CallbackResult>, JObjectPtr)>();
+  late final _DartException__ctorPtr =
+      _lookup<ffi.NativeFunction<JniResult Function(JStringPtr)>>(
+          'DartException__ctor');
+  late final _DartException__ctor =
+      _DartException__ctorPtr.asFunction<JniResult Function(JStringPtr)>();
 
   JniResult PortContinuation__ctor(
     int j,
@@ -228,6 +225,23 @@ class JniBindings {
   late final _PortProxy__newInstance = _PortProxy__newInstancePtr.asFunction<
       JniResult Function(JObjectPtr, int, int)>();
 
+  void resultFor(
+    ffi.Pointer<CallbackResult> result,
+    JObjectPtr object,
+  ) {
+    return _resultFor(
+      result,
+      object,
+    );
+  }
+
+  late final _resultForPtr = _lookup<
+      ffi.NativeFunction<
+          ffi.Void Function(
+              ffi.Pointer<CallbackResult>, JObjectPtr)>>('resultFor');
+  late final _resultFor = _resultForPtr
+      .asFunction<void Function(ffi.Pointer<CallbackResult>, JObjectPtr)>();
+
   ffi.Pointer<GlobalJniEnvStruct> GetGlobalEnv() {
     return _GetGlobalEnv();
   }

jni/src/dartjni.c

@@ -569,6 +569,29 @@ FFI_PLUGIN_EXPORT intptr_t InitDartApiDL(void* data) {
   return Dart_InitializeApiDL(data);
 }
 
+// com.github.dart_lang.jni.DartException
+jclass _c_DartException = NULL;
+
+jmethodID _m_DartException__ctor = NULL;
+FFI_PLUGIN_EXPORT JniResult DartException__ctor(jstring message) {
+  attach_thread();
+  load_class_global_ref(&_c_DartException,
+                        "com/github/dart_lang/jni/PortProxy$DartException");
+  if (_c_DartException == NULL)
+    return (JniResult){.value = {.j = 0}, .exception = check_exception()};
+  load_method(_c_DartException, &_m_DartException__ctor, "<init>",
+              "(Ljava/lang/String;)V");
+  if (_m_DartException__ctor == NULL)
+    return (JniResult){.value = {.j = 0}, .exception = check_exception()};
+  jobject _result = (*jniEnv)->NewObject(jniEnv, _c_DartException,
+                                         _m_DartException__ctor, message);
+  jthrowable exception = check_exception();
+  if (exception == NULL) {
+    _result = to_global_ref(_result);
+  }
+  return (JniResult){.value = {.l = _result}, .exception = check_exception()};
+}
+
 JNIEXPORT void JNICALL
 Java_com_github_dart_1lang_jni_PortContinuation__1resumeWith(JNIEnv* env,
                                                              jclass clazz,

jni/src/dartjni.h

@@ -410,7 +410,8 @@ static inline JniResult to_global_ref_result(jobject ref) {
 
 FFI_PLUGIN_EXPORT intptr_t InitDartApiDL(void* data);
 
-FFI_PLUGIN_EXPORT void resultFor(CallbackResult* result, jobject object);
+FFI_PLUGIN_EXPORT
+JniResult DartException__ctor(jstring message);
 
 FFI_PLUGIN_EXPORT
 JniResult PortContinuation__ctor(int64_t j);
@@ -419,3 +420,5 @@ FFI_PLUGIN_EXPORT
 JniResult PortProxy__newInstance(jobject binaryName,
                                  int64_t port,
                                  int64_t functionPtr);
+
+FFI_PLUGIN_EXPORT void resultFor(CallbackResult* result, jobject object);

jnigen/android_test_runner/android/app/build.gradle

@@ -8,7 +8,7 @@ if (localPropertiesFile.exists()) {
 
 def flutterRoot = localProperties.getProperty('flutter.sdk')
 if (flutterRoot == null) {
-    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
+    throw new FileNotFoundException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
 }
 
 def flutterVersionCode = localProperties.getProperty('flutter.versionCode')

jnigen/example/in_app_java/android/app/build.gradle

@@ -8,7 +8,7 @@ if (localPropertiesFile.exists()) {
 
 def flutterRoot = localProperties.getProperty('flutter.sdk')
 if (flutterRoot == null) {
-    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
+    throw new FileNotFoundException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
 }
 
 def flutterVersionCode = localProperties.getProperty('flutter.versionCode')

jnigen/example/in_app_java/src/android_utils/dartjni.h

@@ -410,7 +410,8 @@ static inline JniResult to_global_ref_result(jobject ref) {
 
 FFI_PLUGIN_EXPORT intptr_t InitDartApiDL(void* data);
 
-FFI_PLUGIN_EXPORT void resultFor(CallbackResult* result, jobject object);
+FFI_PLUGIN_EXPORT
+JniResult DartException__ctor(jstring message);
 
 FFI_PLUGIN_EXPORT
 JniResult PortContinuation__ctor(int64_t j);
@@ -419,3 +420,5 @@ FFI_PLUGIN_EXPORT
 JniResult PortProxy__newInstance(jobject binaryName,
                                  int64_t port,
                                  int64_t functionPtr);
+
+FFI_PLUGIN_EXPORT void resultFor(CallbackResult* result, jobject object);

jnigen/example/kotlin_plugin/example/android/app/build.gradle

@@ -8,7 +8,7 @@ if (localPropertiesFile.exists()) {
 
 def flutterRoot = localProperties.getProperty('flutter.sdk')
 if (flutterRoot == null) {
-    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
+    throw new FileNotFoundException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
 }
 
 def flutterVersionCode = localProperties.getProperty('flutter.versionCode')

jnigen/example/kotlin_plugin/src/dartjni.h

@@ -410,7 +410,8 @@ static inline JniResult to_global_ref_result(jobject ref) {
 
 FFI_PLUGIN_EXPORT intptr_t InitDartApiDL(void* data);
 
-FFI_PLUGIN_EXPORT void resultFor(CallbackResult* result, jobject object);
+FFI_PLUGIN_EXPORT
+JniResult DartException__ctor(jstring message);
 
 FFI_PLUGIN_EXPORT
 JniResult PortContinuation__ctor(int64_t j);
@@ -419,3 +420,5 @@ FFI_PLUGIN_EXPORT
 JniResult PortProxy__newInstance(jobject binaryName,
                                  int64_t port,
                                  int64_t functionPtr);
+
+FFI_PLUGIN_EXPORT void resultFor(CallbackResult* result, jobject object);

jnigen/example/notification_plugin/example/android/app/build.gradle

@@ -8,7 +8,7 @@ if (localPropertiesFile.exists()) {
 
 def flutterRoot = localProperties.getProperty('flutter.sdk')
 if (flutterRoot == null) {
-    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
+    throw new FileNotFoundException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
 }
 
 def flutterVersionCode = localProperties.getProperty('flutter.versionCode')

jnigen/example/notification_plugin/src/dartjni.h

@@ -410,7 +410,8 @@ static inline JniResult to_global_ref_result(jobject ref) {
 
 FFI_PLUGIN_EXPORT intptr_t InitDartApiDL(void* data);
 
-FFI_PLUGIN_EXPORT void resultFor(CallbackResult* result, jobject object);
+FFI_PLUGIN_EXPORT
+JniResult DartException__ctor(jstring message);
 
 FFI_PLUGIN_EXPORT
 JniResult PortContinuation__ctor(int64_t j);
@@ -419,3 +420,5 @@ FFI_PLUGIN_EXPORT
 JniResult PortProxy__newInstance(jobject binaryName,
                                  int64_t port,
                                  int64_t functionPtr);
+
+FFI_PLUGIN_EXPORT void resultFor(CallbackResult* result, jobject object);

jnigen/example/pdfbox_plugin/example/android/app/build.gradle

@@ -8,7 +8,7 @@ if (localPropertiesFile.exists()) {
 
 def flutterRoot = localProperties.getProperty('flutter.sdk')
 if (flutterRoot == null) {
-    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
+    throw new FileNotFoundException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
 }
 
 def flutterVersionCode = localProperties.getProperty('flutter.versionCode')

jnigen/example/pdfbox_plugin/src/third_party/dartjni.h

@@ -410,7 +410,8 @@ static inline JniResult to_global_ref_result(jobject ref) {
 
 FFI_PLUGIN_EXPORT intptr_t InitDartApiDL(void* data);
 
-FFI_PLUGIN_EXPORT void resultFor(CallbackResult* result, jobject object);
+FFI_PLUGIN_EXPORT
+JniResult DartException__ctor(jstring message);
 
 FFI_PLUGIN_EXPORT
 JniResult PortContinuation__ctor(int64_t j);
@@ -419,3 +420,5 @@ FFI_PLUGIN_EXPORT
 JniResult PortProxy__newInstance(jobject binaryName,
                                  int64_t port,
                                  int64_t functionPtr);
+
+FFI_PLUGIN_EXPORT void resultFor(CallbackResult* result, jobject object);

jnigen/lib/src/bindings/dart_generator.dart

@@ -439,14 +439,18 @@ class $name$typeParamsDef extends $superName {
     int $p,
     $MethodInvocation $i,
   ) {
-    final $d = $i.methodDescriptor.toDartString(deleteOriginal: true);
-    final $a = $i.args;
+    try {
+      final $d = $i.methodDescriptor.toDartString(deleteOriginal: true);
+      final $a = $i.args;
     ''');
       final proxyMethodIf = _InterfaceMethodIf(resolver, s);
       for (final method in node.methods) {
         method.accept(proxyMethodIf);
       }
       s.write('''
+    } catch (e) {
+      return $_protectedExtension.newDartException(e.toString());
+    }
     return jni.nullptr;
   }
 
@@ -469,19 +473,17 @@ class $name$typeParamsDef extends $superName {
     ).._\$p = \$p;
     final \$a = \$p.sendPort.nativePort; 
     _\$impls[\$a] = \$impl;
-''');
-      s.write(r'''
-    $p.listen(($m) {
-      if ($m == null) {
-        _$impls.remove($p.sendPort.nativePort);
-        $p.close();
+    \$p.listen((\$m) {
+      if (\$m == null) {
+        _\$impls.remove(\$p.sendPort.nativePort);
+        \$p.close();
         return;
       }
-      final $i = $MethodInvocation.fromMessage($m);
-      final $r = _$invokeMethod($p.sendPort.nativePort, $i);
-      ProtectedJniExtensions.returnResult($i.result, $r);
+      final \$i = \$MethodInvocation.fromMessage(\$m);
+      final \$r = _\$invokeMethod(\$p.sendPort.nativePort, \$i);
+      $_protectedExtension.returnResult(\$i.result, \$r);
     });
-    return $x;
+    return \$x;
   }
   ''');
     }
@@ -1645,17 +1647,17 @@ class _InterfaceMethodIf extends Visitor<Method, void> {
     final saveResult = isVoid ? '' : 'final \$r = ';
     final name = node.finalName;
     s.write('''
-      if (\$d == r"$signature") {
-        ${saveResult}_\$impls[\$p]!.$name(
+        if (\$d == r"$signature") {
+          ${saveResult}_\$impls[\$p]!.$name(
 ''');
     for (var i = 0; i < node.params.length; ++i) {
       node.params[i].accept(_InterfaceParamCast(resolver, s, paramIndex: i));
     }
     const returnBox = _InterfaceReturnBox();
     s.write('''
-        );
-        return ${node.returnType.accept(returnBox)};
-      }
+          );
+          return ${node.returnType.accept(returnBox)};
+        }
 ''');
   }
 }