Mojo: Implement local passing of MessagePipes.

mojo/system/message_pipe_dispatcher.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_dispatcher.h"
 
 #include "base/logging.h"
 #include "mojo/system/limits.h"
 #include "mojo/system/memory.h"
 #include "mojo/system/message_pipe.h"
 
 namespace mojo {
 namespace system {
 
-MessagePipeDispatcher::MessagePipeDispatcher() {
+const unsigned kInvalidPort = static_cast<unsigned>(-1);
+
+MessagePipeDispatcher::MessagePipeDispatcher()
+    : port_(kInvalidPort) {
 }
 
 void MessagePipeDispatcher::Init(scoped_refptr<MessagePipe> message_pipe,
                                  unsigned port) {
   DCHECK(message_pipe.get());
   DCHECK(port == 0 || port == 1);
 
   message_pipe_ = message_pipe;
   port_ = port;
 }
 
 MessagePipeDispatcher::~MessagePipeDispatcher() {
   // |Close()|/|CloseImplNoLock()| should have taken care of the pipe.
   DCHECK(!message_pipe_.get());
 }
 
 void MessagePipeDispatcher::CancelAllWaitersNoLock() {
   lock().AssertAcquired();
   message_pipe_->CancelAllWaiters(port_);
 }
 
 MojoResult MessagePipeDispatcher::CloseImplNoLock() {
   lock().AssertAcquired();
   message_pipe_->Close(port_);
   message_pipe_ = NULL;
+  port_ = kInvalidPort;
   return MOJO_RESULT_OK;
 }
 
 MojoResult MessagePipeDispatcher::WriteMessageImplNoLock(
     const void* bytes, uint32_t num_bytes,
     const std::vector<Dispatcher*>* dispatchers,
     MojoWriteMessageFlags flags) {
   DCHECK(!dispatchers || (dispatchers->size() > 0 &&
                           dispatchers->size() <= kMaxMessageNumHandles));
 
   lock().AssertAcquired();
 
   if (!VerifyUserPointer<void>(bytes, num_bytes))
     return MOJO_RESULT_INVALID_ARGUMENT;
   if (num_bytes > kMaxMessageNumBytes)
     return MOJO_RESULT_RESOURCE_EXHAUSTED;
 
   return message_pipe_->WriteMessage(port_,
                                      bytes, num_bytes,
                                      dispatchers,
                                      flags);
 }
 
 MojoResult MessagePipeDispatcher::ReadMessageImplNoLock(
     void* bytes, uint32_t* num_bytes,
-    uint32_t max_num_dispatchers,
     std::vector<scoped_refptr<Dispatcher> >* dispatchers,
+    uint32_t* num_dispatchers,
     MojoReadMessageFlags flags) {
   lock().AssertAcquired();
 
   if (num_bytes) {
     if (!VerifyUserPointer<uint32_t>(num_bytes, 1))
       return MOJO_RESULT_INVALID_ARGUMENT;
     if (!VerifyUserPointer<void>(bytes, *num_bytes))
       return MOJO_RESULT_INVALID_ARGUMENT;
   }
 
   return message_pipe_->ReadMessage(port_,
                                     bytes, num_bytes,
-                                    max_num_dispatchers, dispatchers,
+                                    dispatchers, num_dispatchers,
                                     flags);
 }
 
 MojoResult MessagePipeDispatcher::AddWaiterImplNoLock(Waiter* waiter,
                                                       MojoWaitFlags flags,
                                                       MojoResult wake_result) {
   lock().AssertAcquired();
   return message_pipe_->AddWaiter(port_, waiter, flags, wake_result);
 }
 
 void MessagePipeDispatcher::RemoveWaiterImplNoLock(Waiter* waiter) {
   lock().AssertAcquired();
   message_pipe_->RemoveWaiter(port_, waiter);
 }
 
+scoped_refptr<Dispatcher>
+MessagePipeDispatcher::CreateEquivalentDispatcherAndCloseImplNoLock() {
+  lock().AssertAcquired();
+
+  scoped_refptr<MessagePipeDispatcher> rv = new MessagePipeDispatcher;
+  rv->Init(message_pipe_, port_);
+  message_pipe_ = NULL;
+  port_ = kInvalidPort;
+  return scoped_refptr<Dispatcher>(rv.get());
+}
+
 }  // namespace system
 }  // namespace mojo