Support posting of external data into dart as external uint8 arrays through the Dart API.

runtime/vm/dart_api_message.cc

 // 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.
 
 #include "vm/dart_api_message.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 
 namespace dart {
 
@@ skipping 697 matching lines @@
       // Write out the class and tags information.
       WriteObjectHeader(ObjectStore::kUint8ArrayClass, 0);
       uint8_t* bytes = object->value.as_byte_array.values;
       intptr_t len = object->value.as_byte_array.length;
       WriteSmi(len);
       for (intptr_t i = 0; i < len; i++) {
         Write<uint8_t>(bytes[i]);
       }
       break;
     }
+    case Dart_CObject::kExternalUint8Array: {
+      // Write out serialization header value for this object.
+      WriteInlinedHeader(object);
+      // Write out the class and tag information.
+      WriteObjectHeader(ObjectStore::kExternalUint8ArrayClass, 0);
+      int length = object->value.as_external_byte_array.length;
+      uint8_t* data = object->value.as_external_byte_array.data;
+      void* peer = object->value.as_external_byte_array.peer;
+      Dart_PeerFinalizer callback =
+          object->value.as_external_byte_array.callback;
+      WriteSmi(length);
+      WriteIntptrValue(reinterpret_cast<intptr_t>(data));
+      WriteIntptrValue(reinterpret_cast<intptr_t>(peer));
+      WriteIntptrValue(reinterpret_cast<intptr_t>(callback));

[siva, 2012/06/28 16:44:05]

As discussed offline we need some mechanism to ensure that this message is not
posted to an external process. maybe you could add a TODO here to that effect.

[Mads Ager (google), 2012/06/28 18:06:51]

Done.

+      break;
+    }
     default:
       UNREACHABLE();
   }
 }
 
 
 void ApiMessageWriter::WriteCMessage(Dart_CObject* object) {
   WriteCObject(object);
   // Write out all objects that were added to the forward list and have
   // not been serialized yet. These would typically be fields of arrays.
   // NOTE: The forward list might grow as we process the list.
   for (intptr_t i = 0; i < forward_id_; i++) {
     WriteForwardedCObject(forward_list_[i]);
   }
   UnmarkAllCObjects(object);
   FinalizeBuffer();
 }
 
 }  // namespace dart