Update protobuf to r428, part 1.

third_party/protobuf/src/google/protobuf/compiler/java/java_file.cc

Index: third_party/protobuf/src/google/protobuf/compiler/java/java_file.cc
===================================================================
--- third_party/protobuf/src/google/protobuf/compiler/java/java_file.cc	(revision 216642)
+++ third_party/protobuf/src/google/protobuf/compiler/java/java_file.cc	(working copy)
@@ -42,6 +42,7 @@
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/descriptor.pb.h>
+#include <google/protobuf/dynamic_message.h>
 #include <google/protobuf/stubs/strutil.h>
 
 namespace google {
@@ -51,18 +52,24 @@
 
 namespace {
 
-// Recursively searches the given message to see if it contains any extensions.
-bool UsesExtensions(const Message& message) {
+
+// Recursively searches the given message to collect extensions.
+// Returns true if all the extensions can be recognized. The extensions will be
+// appended in to the extensions parameter.
+// Returns false when there are unknown fields, in which case the data in the
+// extensions output parameter is not reliable and should be discarded.
+bool CollectExtensions(const Message& message,
+                       vector<const FieldDescriptor*>* extensions) {
   const Reflection* reflection = message.GetReflection();
 
-  // We conservatively assume that unknown fields are extensions.
-  if (reflection->GetUnknownFields(message).field_count() > 0) return true;
+  // There are unknown fields that could be extensions, thus this call fails.
+  if (reflection->GetUnknownFields(message).field_count() > 0) return false;
 
   vector<const FieldDescriptor*> fields;
   reflection->ListFields(message, &fields);
 
   for (int i = 0; i < fields.size(); i++) {
-    if (fields[i]->is_extension()) return true;
+    if (fields[i]->is_extension()) extensions->push_back(fields[i]);
 
     if (GetJavaType(fields[i]) == JAVATYPE_MESSAGE) {
       if (fields[i]->is_repeated()) {
@@ -70,19 +77,59 @@
         for (int j = 0; j < size; j++) {
           const Message& sub_message =
             reflection->GetRepeatedMessage(message, fields[i], j);
-          if (UsesExtensions(sub_message)) return true;
+          if (!CollectExtensions(sub_message, extensions)) return false;
         }
       } else {
         const Message& sub_message = reflection->GetMessage(message, fields[i]);
-        if (UsesExtensions(sub_message)) return true;
+        if (!CollectExtensions(sub_message, extensions)) return false;
       }
     }
   }
 
-  return false;
+  return true;
 }
 
+// Finds all extensions in the given message and its sub-messages.  If the
+// message contains unknown fields (which could be extensions), then those
+// extensions are defined in alternate_pool.
+// The message will be converted to a DynamicMessage backed by alternate_pool
+// in order to handle this case.
+void CollectExtensions(const FileDescriptorProto& file_proto,
+                       const DescriptorPool& alternate_pool,
+                       vector<const FieldDescriptor*>* extensions,
+                       const string& file_data) {
+  if (!CollectExtensions(file_proto, extensions)) {
+    // There are unknown fields in the file_proto, which are probably
+    // extensions. We need to parse the data into a dynamic message based on the
+    // builder-pool to find out all extensions.
+    const Descriptor* file_proto_desc = alternate_pool.FindMessageTypeByName(
+        file_proto.GetDescriptor()->full_name());
+    GOOGLE_CHECK(file_proto_desc)
+        << "Find unknown fields in FileDescriptorProto when building "
+        << file_proto.name()
+        << ". It's likely that those fields are custom options, however, "
+           "descriptor.proto is not in the transitive dependencies. "
+           "This normally should not happen. Please report a bug.";
+    DynamicMessageFactory factory;
+    scoped_ptr<Message> dynamic_file_proto(
+        factory.GetPrototype(file_proto_desc)->New());
+    GOOGLE_CHECK(dynamic_file_proto.get() != NULL);
+    GOOGLE_CHECK(dynamic_file_proto->ParseFromString(file_data));
 
+    // Collect the extensions again from the dynamic message. There should be no
+    // more unknown fields this time, i.e. all the custom options should be
+    // parsed as extensions now.
+    extensions->clear();
+    GOOGLE_CHECK(CollectExtensions(*dynamic_file_proto, extensions))
+        << "Find unknown fields in FileDescriptorProto when building "
+        << file_proto.name()
+        << ". It's likely that those fields are custom options, however, "
+           "those options cannot be recognized in the builder pool. "
+           "This normally should not happen. Please report a bug.";
+  }
+}
+
+
 }  // namespace
 
 FileGenerator::FileGenerator(const FileDescriptor* file)
@@ -306,19 +353,32 @@
         .GenerateNonNestedInitializationCode(printer);
   }
 
-  if (UsesExtensions(file_proto)) {
-    // Must construct an ExtensionRegistry containing all possible extensions
+  // Proto compiler builds a DescriptorPool, which holds all the descriptors to
+  // generate, when processing the ".proto" files. We call this DescriptorPool
+  // the parsed pool (a.k.a. file_->pool()).
+  //
+  // Note that when users try to extend the (.*)DescriptorProto in their
+  // ".proto" files, it does not affect the pre-built FileDescriptorProto class
+  // in proto compiler. When we put the descriptor data in the file_proto, those
+  // extensions become unknown fields.
+  //
+  // Now we need to find out all the extension value to the (.*)DescriptorProto
+  // in the file_proto message, and prepare an ExtensionRegistry to return.
+  //
+  // To find those extensions, we need to parse the data into a dynamic message
+  // of the FileDescriptor based on the builder-pool, then we can use
+  // reflections to find all extension fields
+  vector<const FieldDescriptor*> extensions;
+  CollectExtensions(file_proto, *file_->pool(), &extensions, file_data);
+
+  if (extensions.size() > 0) {
+    // Must construct an ExtensionRegistry containing all existing extensions
     // and return it.
     printer->Print(
       "com.google.protobuf.ExtensionRegistry registry =\n"
-      "  com.google.protobuf.ExtensionRegistry.newInstance();\n"
-      "registerAllExtensions(registry);\n");
-    for (int i = 0; i < file_->dependency_count(); i++) {
-      if (ShouldIncludeDependency(file_->dependency(i))) {
-        printer->Print(
-            "$dependency$.registerAllExtensions(registry);\n",
-            "dependency", ClassName(file_->dependency(i)));
-      }
+      "  com.google.protobuf.ExtensionRegistry.newInstance();\n");
+    for (int i = 0; i < extensions.size(); i++) {
+      ExtensionGenerator(extensions[i]).GenerateRegistrationCode(printer);
     }
     printer->Print(
       "return registry;\n");
@@ -375,7 +435,9 @@
 
   printer.Print(
     "// Generated by the protocol buffer compiler.  DO NOT EDIT!\n"
-    "\n");
+    "// source: $filename$\n"
+    "\n",
+    "filename", descriptor->file()->name());
   if (!java_package.empty()) {
     printer.Print(
       "package $package$;\n"