Convert ReadMessage...() to use the new user pointer handling (see r285350).

mojo/system/local_message_pipe_endpoint.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/local_message_pipe_endpoint.h"
 
 #include <string.h>
 
 #include "base/logging.h"
 #include "mojo/system/dispatcher.h"
@@ skipping 45 matching lines @@
   DCHECK(is_open_);
   is_open_ = false;
   message_queue_.Clear();
 }
 
 void LocalMessagePipeEndpoint::CancelAllWaiters() {
   DCHECK(is_open_);
   waiter_list_.CancelAllWaiters();
 }
 
-MojoResult LocalMessagePipeEndpoint::ReadMessage(void* bytes,
-                                                 uint32_t* num_bytes,
-                                                 DispatcherVector* dispatchers,
-                                                 uint32_t* num_dispatchers,
-                                                 MojoReadMessageFlags flags) {
+MojoResult LocalMessagePipeEndpoint::ReadMessage(
+    UserPointer<void> bytes,
+    UserPointer<uint32_t> num_bytes,
+    DispatcherVector* dispatchers,
+    uint32_t* num_dispatchers,
+    MojoReadMessageFlags flags) {
   DCHECK(is_open_);
   DCHECK(!dispatchers || dispatchers->empty());
 
-  const uint32_t max_bytes = num_bytes ? *num_bytes : 0;
+  const uint32_t max_bytes = num_bytes.IsNull() ? 0 : num_bytes.Get();
   const uint32_t max_num_dispatchers = num_dispatchers ? *num_dispatchers : 0;
 
   if (message_queue_.IsEmpty()) {
     return is_peer_open_ ? MOJO_RESULT_SHOULD_WAIT :
                            MOJO_RESULT_FAILED_PRECONDITION;
   }
 
   // TODO(vtl): If |flags & MOJO_READ_MESSAGE_FLAG_MAY_DISCARD|, we could pop
   // and release the lock immediately.
   bool enough_space = true;
   MessageInTransit* message = message_queue_.PeekMessage();
-  if (num_bytes)
-    *num_bytes = message->num_bytes();
+  if (!num_bytes.IsNull())
+    num_bytes.Put(message->num_bytes());
   if (message->num_bytes() <= max_bytes)
-    memcpy(bytes, message->bytes(), message->num_bytes());
+    bytes.PutArray(message->bytes(), message->num_bytes());
   else
     enough_space = false;
 
   if (DispatcherVector* queued_dispatchers = message->dispatchers()) {
     if (num_dispatchers)
       *num_dispatchers = static_cast<uint32_t>(queued_dispatchers->size());
     if (enough_space) {
       if (queued_dispatchers->empty()) {
         // Nothing to do.
       } else if (queued_dispatchers->size() <= max_num_dispatchers) {
@@ skipping 56 matching lines @@
   if (is_peer_open_) {
     rv.satisfied_signals |= MOJO_HANDLE_SIGNAL_WRITABLE;
     rv.satisfiable_signals |=
         MOJO_HANDLE_SIGNAL_READABLE | MOJO_HANDLE_SIGNAL_WRITABLE;
   }
   return rv;
 }
 
 }  // namespace system
 }  // namespace mojo