Avoid trusting the length encoded in the Snapshot if there is an

runtime/vm/dart_api_message.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_DART_API_MESSAGE_H_
 #define VM_DART_API_MESSAGE_H_
 
 #include "vm/dart_api_state.h"
 #include "vm/snapshot.h"
 
 namespace dart {
 
 // Use this C structure for reading internal objects in the serialized
 // data. These are objects that we need to process in order to
 // generate the Dart_CObject graph but that we don't want to expose in
 // that graph.
 // TODO(sjesse): Remove this when message serialization format is
 // updated.
 struct Dart_CObject_Internal : public Dart_CObject {
   enum Type {
     kTypeArguments = Dart_CObject::kNumberOfTypes,
     kDynamicType,
   };
 };
 
 
 // Reads a message snapshot into a C structure.
 class ApiMessageReader : public BaseReader {
  public:
-  ApiMessageReader(const uint8_t* buffer, intptr_t length, ReAlloc alloc);
+  ApiMessageReader(const Snapshot* snapshot, ReAlloc alloc);
   ~ApiMessageReader() { }
 
   Dart_CObject* ReadMessage();
 
  private:
   class BackRefNode {
    public:
     BackRefNode(Dart_CObject* reference, DeserializeState state)
         : reference_(reference), state_(state) {}
     Dart_CObject* reference() const { return reference_; }
@@ skipping 74 matching lines @@
   ApiMessageWriter(uint8_t** buffer, ReAlloc alloc)
       : BaseWriter(buffer, alloc), object_id_(0),
         forward_list_(NULL), forward_list_length_(0), forward_id_(0) {
     ASSERT(kDartCObjectTypeMask >= Dart_CObject::kNumberOfTypes - 1);
   }
   ~ApiMessageWriter() {
     ::free(forward_list_);
   }
 
   // Writes a message of integers.
-  void WriteMessage(intptr_t field_count, intptr_t *data);
+  intptr_t WriteMessage(intptr_t field_count, intptr_t *data);
 
-  void WriteCMessage(Dart_CObject* object);
+  intptr_t WriteCMessage(Dart_CObject* object);
 
-  void FinalizeBuffer() {
-    BaseWriter::FinalizeBuffer(Snapshot::kMessage);
+  intptr_t FinalizeBuffer() {
+    return BaseWriter::FinalizeBuffer(Snapshot::kMessage);
   }
 
  private:
   static const intptr_t kDartCObjectTypeBits = 4;
   static const intptr_t kDartCObjectTypeMask = (1 << kDartCObjectTypeBits) - 1;
   static const intptr_t kDartCObjectMarkMask = ~kDartCObjectTypeMask;
   static const intptr_t kDartCObjectMarkOffset = 1;
 
   void MarkCObject(Dart_CObject* object, intptr_t object_id);
   void UnmarkCObject(Dart_CObject* object);
@@ skipping 17 matching lines @@
   Dart_CObject** forward_list_;
   intptr_t forward_list_length_;
   intptr_t forward_id_;
 
   DISALLOW_COPY_AND_ASSIGN(ApiMessageWriter);
 };
 
 }  // namespace dart
 
 #endif  // VM_DART_API_MESSAGE_H_