Cherry-pick Java utf8 change.

java/src/main/java/com/google/protobuf/Descriptors.java

@@ -31,6 +31,7 @@
 package com.google.protobuf;
 
 import com.google.protobuf.DescriptorProtos.*;
+import com.google.protobuf.Descriptors.FileDescriptor.Syntax;
 
 import java.lang.ref.WeakReference;
 import java.util.ArrayList;
@@ -912,7 +913,17 @@ public final class Descriptors {
 
     /** For internal use only. */
     public boolean needsUtf8Check() {
-      return (type == Type.STRING) && (getFile().getOptions().getJavaStringCheckUtf8());
+      if (type != Type.STRING) {
+        return false;
+      }
+      if (getContainingType().getOptions().getMapEntry()) {
+        // Always enforce strict UTF-8 checking for map fields.
+        return true;
+      }
+      if (getFile().getSyntax() == Syntax.PROTO3) {
+        return true;
+      }
+      return getFile().getOptions().getJavaStringCheckUtf8();
     }
 
     public boolean isMapField() {

java/src/main/java/com/google/protobuf/Proto3Utf8Test.java

+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+package com.google.protobuf;
+
+import com.google.protobuf.testing.UnittestProto3Utf8.TestData;
+import com.google.protobuf.testing.UnittestProto3Utf8.TestUtf8Checked;
+import com.google.protobuf.testing.UnittestProto3Utf8.TestUtf8Unchecked;
+
+import junit.framework.TestCase;
+
+/**
+ * Test the UTF-8 checking semantics in proto3.
+ */
+public class Proto3Utf8Test extends TestCase {
+
+  private static final ByteString INVALID_UTF8_BYTES =
+      ByteString.copyFrom(new byte[]{(byte) 0xff});
+  private static final ByteString VALID_UTF8_BYTES =
+      ByteString.copyFrom(Internal.toByteArray("Hello world!"));
+
+  private void assertAccepted(Message defaultInstance, ByteString data)
+      throws Exception {
+    defaultInstance.newBuilderForType().mergeFrom(data).build();
+  }
+
+  private void assertRejected(Message defaultInstance, ByteString data)
+      throws Exception {
+    try {
+      defaultInstance.newBuilderForType().mergeFrom(data).build();
+      fail("Expects exceptions.");
+    } catch (Exception e) {
+      // Expected.
+    }
+  }
+  
+  private void assertAcceptedByUncheckedMessage(ByteString data)
+      throws Exception {
+  }
+  
+  private void assertRejectedByUncheckedMessage(ByteString data)
+      throws Exception {
+  }
+  
+  private void assertRejectedByCheckedMessage(ByteString data)
+      throws Exception {
+    assertRejected(TestUtf8Checked.getDefaultInstance(), data);
+    assertRejected(DynamicMessage.getDefaultInstance(
+        TestUtf8Checked.getDescriptor()), data);
+  }
+  
+  public void testOptionalFields() throws Exception {
+    TestData.Builder builder = TestData.newBuilder();
+    builder.setOptionalValue(INVALID_UTF8_BYTES);
+    TestData data = builder.build();
+
+    assertAcceptedByUncheckedMessage(data.toByteString());
+    assertRejectedByCheckedMessage(data.toByteString());
+  }
+  
+  public void testRepeatedFields() throws Exception {
+    TestData.Builder builder = TestData.newBuilder();
+    builder.addRepeatedValue(VALID_UTF8_BYTES);
+    builder.setOptionalValue(INVALID_UTF8_BYTES);
+    TestData data = builder.build();
+
+    assertAcceptedByUncheckedMessage(data.toByteString());
+    assertRejectedByCheckedMessage(data.toByteString());
+  }
+  
+  public void testOneofFields() throws Exception {
+    TestData.Builder builder = TestData.newBuilder();
+    builder.setOneofValue(INVALID_UTF8_BYTES);
+    TestData data = builder.build();
+
+    assertAcceptedByUncheckedMessage(data.toByteString());
+    assertRejectedByCheckedMessage(data.toByteString());
+  }
+  
+  public void testMapKey() throws Exception {
+    TestData.Builder builder = TestData.newBuilder();
+    builder.addMapValue(
+        TestData.MapValueEntry.newBuilder()
+            .setKey(INVALID_UTF8_BYTES)
+            .setValue(VALID_UTF8_BYTES).build());
+    TestData data = builder.build();
+
+    // Map fields in Java are enforcing UTF-8 checking already.
+    assertRejectedByUncheckedMessage(data.toByteString());
+    assertRejectedByCheckedMessage(data.toByteString());
+  }
+  
+  public void testMapValue() throws Exception {
+    TestData.Builder builder = TestData.newBuilder();
+    builder.addMapValue(
+        TestData.MapValueEntry.newBuilder()
+            .setKey(VALID_UTF8_BYTES)
+            .setValue(INVALID_UTF8_BYTES).build());
+    TestData data = builder.build();
+
+    // Map fields in Java are enforcing UTF-8 checking already.
+    assertRejectedByUncheckedMessage(data.toByteString());
+    assertRejectedByCheckedMessage(data.toByteString());
+  }
+}

src/google/protobuf/compiler/java/java_helpers.h

@@ -336,6 +336,11 @@ inline bool IsAnyMessage(const Descriptor* descriptor) {
   return descriptor->full_name() == "google.protobuf.Any";
 }
 
+inline bool CheckUtf8(const FieldDescriptor* descriptor) {
+  return descriptor->file()->syntax() == FileDescriptor::SYNTAX_PROTO3 ||
+      descriptor->file()->options().java_string_check_utf8();
+}
+
 }  // namespace java
 }  // namespace compiler
 }  // namespace protobuf

src/google/protobuf/compiler/java/java_string_field.cc

@@ -131,10 +131,6 @@ void SetPrimitiveVariables(const FieldDescriptor* descriptor,
       GenerateSetBitToLocal(messageBitIndex);
 }
 
-bool CheckUtf8(const FieldDescriptor* descriptor) {
-  return descriptor->file()->options().java_string_check_utf8();
-}
-
 }  // namespace
 
 // ===================================================================

src/google/protobuf/compiler/java/java_string_field_lite.cc

@@ -115,10 +115,6 @@ void SetPrimitiveVariables(const FieldDescriptor* descriptor,
       GenerateSetBitToLocal(messageBitIndex);
 }
 
-bool CheckUtf8(const FieldDescriptor* descriptor) {
-  return descriptor->file()->options().java_string_check_utf8();
-}
-
 }  // namespace
 
 // ===================================================================