Mojo: More plumbing required to transfer handles over MessagePipes.

mojo/system/message_pipe.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mojo/system/message_pipe.h"
 
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "mojo/system/channel.h"
 #include "mojo/system/local_message_pipe_endpoint.h"
@@ skipping 118 matching lines @@
 
   base::AutoLock locker(lock_);
   DCHECK(endpoints_[GetPeerPort(port)].get());
 
   // The destination port need not be open, unlike the source port.
   if (!endpoints_[port].get()) {
     message->Destroy();
     return MOJO_RESULT_FAILED_PRECONDITION;
   }
 
-  return endpoints_[port]->EnqueueMessage(message, dispatchers);
+  MojoResult result = endpoints_[port]->CanEnqueueMessage(message, dispatchers);
+  if (result != MOJO_RESULT_OK) {
+    message->Destroy();
+    return result;
+  }
+
+  // TODO(vtl): No endpoints currently support transferring dispatchers, so we
+  // can get away with this. What we really need to do is create equivalent
+  // dispatchers here (and close the original dispatchers).
+  DCHECK(!dispatchers);
+
+  endpoints_[port]->EnqueueMessage(message, NULL);
+  return MOJO_RESULT_OK;
 }
 
 void MessagePipe::Attach(unsigned port,
                          scoped_refptr<Channel> channel,
                          MessageInTransit::EndpointId local_id) {
   DCHECK(port == 0 || port == 1);
   DCHECK(channel.get());
   DCHECK_NE(local_id, MessageInTransit::kInvalidEndpointId);
 
   base::AutoLock locker(lock_);
@@ skipping 50 matching lines @@
       rv = MOJO_RESULT_UNKNOWN;
       break;
   }
 
   message->Destroy();
   return rv;
 }
 
 }  // namespace system
 }  // namespace mojo