Add a Mojo EDK for Chrome that uses one OS pipe per message pipe.

mojo/edk/system/core.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 "third_party/mojo/src/mojo/edk/system/core.h"
+#include "mojo/edk/system/core.h"
 
 #include <vector>
 
 #include "base/logging.h"
 #include "base/time/time.h"
+#include "mojo/edk/embedder/platform_channel_pair.h"
+#include "mojo/edk/embedder/platform_shared_buffer.h"
+#include "mojo/edk/embedder/platform_support.h"
+#include "mojo/edk/system/async_waiter.h"
+#include "mojo/edk/system/configuration.h"
+#include "mojo/edk/system/data_pipe.h"
+#include "mojo/edk/system/data_pipe_consumer_dispatcher.h"
+#include "mojo/edk/system/data_pipe_producer_dispatcher.h"
+#include "mojo/edk/system/dispatcher.h"
+#include "mojo/edk/system/handle_signals_state.h"
+#include "mojo/edk/system/message_pipe_dispatcher.h"
+#include "mojo/edk/system/shared_buffer_dispatcher.h"
+#include "mojo/edk/system/waiter.h"
 #include "mojo/public/c/system/macros.h"
 #include "mojo/public/cpp/system/macros.h"
-#include "third_party/mojo/src/mojo/edk/embedder/platform_shared_buffer.h"
-#include "third_party/mojo/src/mojo/edk/embedder/platform_support.h"
-#include "third_party/mojo/src/mojo/edk/system/async_waiter.h"
-#include "third_party/mojo/src/mojo/edk/system/configuration.h"
-#include "third_party/mojo/src/mojo/edk/system/data_pipe.h"
-#include "third_party/mojo/src/mojo/edk/system/data_pipe_consumer_dispatcher.h"
-#include "third_party/mojo/src/mojo/edk/system/data_pipe_producer_dispatcher.h"
-#include "third_party/mojo/src/mojo/edk/system/dispatcher.h"
-#include "third_party/mojo/src/mojo/edk/system/handle_signals_state.h"
-#include "third_party/mojo/src/mojo/edk/system/memory.h"
-#include "third_party/mojo/src/mojo/edk/system/message_pipe.h"
-#include "third_party/mojo/src/mojo/edk/system/message_pipe_dispatcher.h"
-#include "third_party/mojo/src/mojo/edk/system/shared_buffer_dispatcher.h"
-#include "third_party/mojo/src/mojo/edk/system/waiter.h"
 
 namespace mojo {
-namespace system {
+namespace edk {
 
 // Implementation notes
 //
 // Mojo primitives are implemented by the singleton |Core| object. Most calls
 // are for a "primary" handle (the first argument). |Core::GetDispatcher()| is
 // used to look up a |Dispatcher| object for a given handle. That object
 // implements most primitives for that object. The wait primitives are not
 // attached to objects and are implemented by |Core| itself.
 //
 // Some objects have multiple handles associated to them, e.g., message pipes
@@ skipping 31 matching lines @@
 //
 // Notes:
 //    - While holding a |Dispatcher| lock, you may not unconditionally attempt
 //      to take another |Dispatcher| lock. (This has consequences on the
 //      concurrency semantics of |MojoWriteMessage()| when passing handles.)
 //      Doing so would lead to deadlock.
 //    - Locks at the "INF" level may not have any locks taken while they are
 //      held.
 
 // TODO(vtl): This should take a |scoped_ptr<PlatformSupport>| as a parameter.
-Core::Core(embedder::PlatformSupport* platform_support)
+Core::Core(PlatformSupport* platform_support)
     : platform_support_(platform_support) {
 }
 
 Core::~Core() {
 }
 
 MojoHandle Core::AddDispatcher(const scoped_refptr<Dispatcher>& dispatcher) {
-  MutexLocker locker(&handle_table_mutex_);
+  base::AutoLock locker(handle_table_lock_);
   return handle_table_.AddDispatcher(dispatcher);
 }
 
 scoped_refptr<Dispatcher> Core::GetDispatcher(MojoHandle handle) {
   if (handle == MOJO_HANDLE_INVALID)
     return nullptr;
 
-  MutexLocker locker(&handle_table_mutex_);
+  base::AutoLock locker(handle_table_lock_);
   return handle_table_.GetDispatcher(handle);
 }
 
 MojoResult Core::GetAndRemoveDispatcher(MojoHandle handle,
                                         scoped_refptr<Dispatcher>* dispatcher) {
   if (handle == MOJO_HANDLE_INVALID)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
-  MutexLocker locker(&handle_table_mutex_);
+  base::AutoLock locker(handle_table_lock_);
   return handle_table_.GetAndRemoveDispatcher(handle, dispatcher);
 }
 
 MojoResult Core::AsyncWait(MojoHandle handle,
                            MojoHandleSignals signals,
                            const base::Callback<void(MojoResult)>& callback) {
   scoped_refptr<Dispatcher> dispatcher = GetDispatcher(handle);
   DCHECK(dispatcher);
 
   scoped_ptr<AsyncWaiter> waiter = make_scoped_ptr(new AsyncWaiter(callback));
   MojoResult rv = dispatcher->AddAwakable(waiter.get(), signals, 0, nullptr);
   if (rv == MOJO_RESULT_OK)
     ignore_result(waiter.release());
   return rv;
 }
 
 MojoTimeTicks Core::GetTimeTicksNow() {
   return base::TimeTicks::Now().ToInternalValue();
 }
 
 MojoResult Core::Close(MojoHandle handle) {
   if (handle == MOJO_HANDLE_INVALID)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   scoped_refptr<Dispatcher> dispatcher;
   {
-    MutexLocker locker(&handle_table_mutex_);
+    base::AutoLock locker(handle_table_lock_);
     MojoResult result =
         handle_table_.GetAndRemoveDispatcher(handle, &dispatcher);
     if (result != MOJO_RESULT_OK)
       return result;
   }
 
   // The dispatcher doesn't have a say in being closed, but gets notified of it.
-  // Note: This is done outside of |handle_table_mutex_|. As a result, there's a
+  // Note: This is done outside of |handle_table_lock_|. As a result, there's a
   // race condition that the dispatcher must handle; see the comment in
   // |Dispatcher| in dispatcher.h.
   return dispatcher->Close();
 }
 
 MojoResult Core::Wait(MojoHandle handle,
                       MojoHandleSignals signals,
                       MojoDeadline deadline,
-                      UserPointer<MojoHandleSignalsState> signals_state) {
+                      MojoHandleSignalsState* signals_state) {
   uint32_t unused = static_cast<uint32_t>(-1);
   HandleSignalsState hss;
   MojoResult rv = WaitManyInternal(&handle, &signals, 1, deadline, &unused,
-                                   signals_state.IsNull() ? nullptr : &hss);
-  if (rv != MOJO_RESULT_INVALID_ARGUMENT && !signals_state.IsNull())
-    signals_state.Put(hss);
+                                   signals_state ? &hss : nullptr);
+  if (rv != MOJO_RESULT_INVALID_ARGUMENT && signals_state)
+    *signals_state = hss;
   return rv;
 }
 
-MojoResult Core::WaitMany(UserPointer<const MojoHandle> handles,
-                          UserPointer<const MojoHandleSignals> signals,
+MojoResult Core::WaitMany(const MojoHandle* handles,
+                          const MojoHandleSignals* signals,
                           uint32_t num_handles,
                           MojoDeadline deadline,
-                          UserPointer<uint32_t> result_index,
-                          UserPointer<MojoHandleSignalsState> signals_states) {
+                          uint32_t* result_index,
+                          MojoHandleSignalsState* signals_state) {
   if (num_handles < 1)
     return MOJO_RESULT_INVALID_ARGUMENT;
   if (num_handles > GetConfiguration().max_wait_many_num_handles)
     return MOJO_RESULT_RESOURCE_EXHAUSTED;
 
-  UserPointer<const MojoHandle>::Reader handles_reader(handles, num_handles);
-  UserPointer<const MojoHandleSignals>::Reader signals_reader(signals,
-                                                              num_handles);
   uint32_t index = static_cast<uint32_t>(-1);
   MojoResult rv;
-  if (signals_states.IsNull()) {
-    rv = WaitManyInternal(handles_reader.GetPointer(),
-                          signals_reader.GetPointer(), num_handles, deadline,
-                          &index, nullptr);
+  if (!signals_state) {
+    rv = WaitManyInternal(handles, signals, num_handles, deadline, &index,
+                          nullptr);
   } else {
-    UserPointer<MojoHandleSignalsState>::Writer signals_states_writer(
-        signals_states, num_handles);
     // Note: The |reinterpret_cast| is safe, since |HandleSignalsState| is a
     // subclass of |MojoHandleSignalsState| that doesn't add any data members.
-    rv = WaitManyInternal(handles_reader.GetPointer(),
-                          signals_reader.GetPointer(), num_handles, deadline,
-                          &index, reinterpret_cast<HandleSignalsState*>(
-                                      signals_states_writer.GetPointer()));
-    if (rv != MOJO_RESULT_INVALID_ARGUMENT)
-      signals_states_writer.Commit();
+    rv = WaitManyInternal(handles, signals, num_handles, deadline, &index,
+                          reinterpret_cast<HandleSignalsState*>(signals_state));
   }
-  if (index != static_cast<uint32_t>(-1) && !result_index.IsNull())
-    result_index.Put(index);
+  if (index != static_cast<uint32_t>(-1) && result_index)
+    *result_index = index;
   return rv;
 }
 
 MojoResult Core::CreateMessagePipe(
-    UserPointer<const MojoCreateMessagePipeOptions> options,
-    UserPointer<MojoHandle> message_pipe_handle0,
-    UserPointer<MojoHandle> message_pipe_handle1) {
+    const MojoCreateMessagePipeOptions* options,
+    MojoHandle* message_pipe_handle0,
+    MojoHandle* message_pipe_handle1) {
+  CHECK(message_pipe_handle0);
+  CHECK(message_pipe_handle1);
   MojoCreateMessagePipeOptions validated_options = {};
   MojoResult result =
       MessagePipeDispatcher::ValidateCreateOptions(options, &validated_options);
   if (result != MOJO_RESULT_OK)
     return result;
 
   scoped_refptr<MessagePipeDispatcher> dispatcher0 =
       MessagePipeDispatcher::Create(validated_options);
   scoped_refptr<MessagePipeDispatcher> dispatcher1 =
       MessagePipeDispatcher::Create(validated_options);
 
   std::pair<MojoHandle, MojoHandle> handle_pair;
   {
-    MutexLocker locker(&handle_table_mutex_);
+    base::AutoLock locker(handle_table_lock_);
     handle_pair = handle_table_.AddDispatcherPair(dispatcher0, dispatcher1);
   }
   if (handle_pair.first == MOJO_HANDLE_INVALID) {
     DCHECK_EQ(handle_pair.second, MOJO_HANDLE_INVALID);
     LOG(ERROR) << "Handle table full";
     dispatcher0->Close();
     dispatcher1->Close();
     return MOJO_RESULT_RESOURCE_EXHAUSTED;
   }
 
-  scoped_refptr<MessagePipe> message_pipe(MessagePipe::CreateLocalLocal());
-  dispatcher0->Init(message_pipe, 0);
-  dispatcher1->Init(message_pipe, 1);
+  PlatformChannelPair channel_pair;
+  dispatcher0->Init(channel_pair.PassServerHandle());
+  dispatcher1->Init(channel_pair.PassClientHandle());
 
-  message_pipe_handle0.Put(handle_pair.first);
-  message_pipe_handle1.Put(handle_pair.second);
+  *message_pipe_handle0 = handle_pair.first;
+  *message_pipe_handle1 = handle_pair.second;
   return MOJO_RESULT_OK;
 }
 
 // Implementation note: To properly cancel waiters and avoid other races, this
 // does not transfer dispatchers from one handle to another, even when sending a
 // message in-process. Instead, it must transfer the "contents" of the
 // dispatcher to a new dispatcher, and then close the old dispatcher. If this
 // isn't done, in the in-process case, calls on the old handle may complete
 // after the the message has been received and a new handle created (and
 // possibly even after calls have been made on the new handle).
 MojoResult Core::WriteMessage(MojoHandle message_pipe_handle,
-                              UserPointer<const void> bytes,
+                              const void* bytes,
                               uint32_t num_bytes,
-                              UserPointer<const MojoHandle> handles,
+                              const MojoHandle* handles,
                               uint32_t num_handles,
                               MojoWriteMessageFlags flags) {
   scoped_refptr<Dispatcher> dispatcher(GetDispatcher(message_pipe_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   // Easy case: not sending any handles.
   if (num_handles == 0)
     return dispatcher->WriteMessage(bytes, num_bytes, nullptr, flags);
 
   // We have to handle |handles| here, since we have to mark them busy in the
   // global handle table. We can't delegate this to the dispatcher, since the
   // handle table lock must be acquired before the dispatcher lock.
   //
   // (This leads to an oddity: |handles|/|num_handles| are always verified for
   // validity, even for dispatchers that don't support |WriteMessage()| and will
   // simply return failure unconditionally. It also breaks the usual
   // left-to-right verification order of arguments.)
   if (num_handles > GetConfiguration().max_message_num_handles)
     return MOJO_RESULT_RESOURCE_EXHAUSTED;
 
-  UserPointer<const MojoHandle>::Reader handles_reader(handles, num_handles);
-
   // We'll need to hold on to the dispatchers so that we can pass them on to
   // |WriteMessage()| and also so that we can unlock their locks afterwards
   // without accessing the handle table. These can be dumb pointers, since their
   // entries in the handle table won't get removed (since they'll be marked as
   // busy).
   std::vector<DispatcherTransport> transports(num_handles);
 
   // When we pass handles, we have to try to take all their dispatchers' locks
   // and mark the handles as busy. If the call succeeds, we then remove the
   // handles from the handle table.
   {
-    MutexLocker locker(&handle_table_mutex_);
+    base::AutoLock locker(handle_table_lock_);
     MojoResult result = handle_table_.MarkBusyAndStartTransport(
-        message_pipe_handle, handles_reader.GetPointer(), num_handles,
-        &transports);
+        message_pipe_handle, handles, num_handles, &transports);
     if (result != MOJO_RESULT_OK)
       return result;
   }
 
   MojoResult rv =
       dispatcher->WriteMessage(bytes, num_bytes, &transports, flags);
 
   // We need to release the dispatcher locks before we take the handle table
   // lock.
   for (uint32_t i = 0; i < num_handles; i++)
     transports[i].End();
 
   {
-    MutexLocker locker(&handle_table_mutex_);
+    base::AutoLock locker(handle_table_lock_);
     if (rv == MOJO_RESULT_OK) {
-      handle_table_.RemoveBusyHandles(handles_reader.GetPointer(), num_handles);
+      handle_table_.RemoveBusyHandles(handles, num_handles);
     } else {
-      handle_table_.RestoreBusyHandles(handles_reader.GetPointer(),
-                                       num_handles);
+      handle_table_.RestoreBusyHandles(handles, num_handles);
     }
   }
 
   return rv;
 }
 
 MojoResult Core::ReadMessage(MojoHandle message_pipe_handle,
-                             UserPointer<void> bytes,
-                             UserPointer<uint32_t> num_bytes,
-                             UserPointer<MojoHandle> handles,
-                             UserPointer<uint32_t> num_handles,
+                             void* bytes,
+                             uint32_t* num_bytes,
+                             MojoHandle* handles,
+                             uint32_t* num_handles,
                              MojoReadMessageFlags flags) {
   scoped_refptr<Dispatcher> dispatcher(GetDispatcher(message_pipe_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
-  uint32_t num_handles_value = num_handles.IsNull() ? 0 : num_handles.Get();
-
   MojoResult rv;
+  uint32_t num_handles_value = num_handles ? *num_handles : 0;
   if (num_handles_value == 0) {
     // Easy case: won't receive any handles.
     rv = dispatcher->ReadMessage(bytes, num_bytes, nullptr, &num_handles_value,
                                  flags);
   } else {
     DispatcherVector dispatchers;
     rv = dispatcher->ReadMessage(bytes, num_bytes, &dispatchers,
                                  &num_handles_value, flags);
     if (!dispatchers.empty()) {
       DCHECK_EQ(rv, MOJO_RESULT_OK);
-      DCHECK(!num_handles.IsNull());
+      DCHECK(num_handles);
       DCHECK_LE(dispatchers.size(), static_cast<size_t>(num_handles_value));
 
       bool success;
-      UserPointer<MojoHandle>::Writer handles_writer(handles,
-                                                     dispatchers.size());
       {
-        MutexLocker locker(&handle_table_mutex_);
-        success = handle_table_.AddDispatcherVector(
-            dispatchers, handles_writer.GetPointer());
+        base::AutoLock locker(handle_table_lock_);
+        success = handle_table_.AddDispatcherVector(dispatchers, handles);
       }
-      if (success) {
-        handles_writer.Commit();
-      } else {
+      if (!success) {
         LOG(ERROR) << "Received message with " << dispatchers.size()
                    << " handles, but handle table full";
         // Close dispatchers (outside the lock).
         for (size_t i = 0; i < dispatchers.size(); i++) {
           if (dispatchers[i])
             dispatchers[i]->Close();
         }
         if (rv == MOJO_RESULT_OK)
           rv = MOJO_RESULT_RESOURCE_EXHAUSTED;
       }
     }
   }
 
-  if (!num_handles.IsNull())
-    num_handles.Put(num_handles_value);
+  if (num_handles)
+    *num_handles = num_handles_value;
   return rv;
 }
 
 MojoResult Core::CreateDataPipe(
-    UserPointer<const MojoCreateDataPipeOptions> options,
-    UserPointer<MojoHandle> data_pipe_producer_handle,
-    UserPointer<MojoHandle> data_pipe_consumer_handle) {
+    const MojoCreateDataPipeOptions* options,
+    MojoHandle* data_pipe_producer_handle,
+    MojoHandle* data_pipe_consumer_handle) {
   MojoCreateDataPipeOptions validated_options = {};
   MojoResult result =
       DataPipe::ValidateCreateOptions(options, &validated_options);
   if (result != MOJO_RESULT_OK)
     return result;
 
   scoped_refptr<DataPipeProducerDispatcher> producer_dispatcher =
-      DataPipeProducerDispatcher::Create();
+      DataPipeProducerDispatcher::Create(validated_options);
   scoped_refptr<DataPipeConsumerDispatcher> consumer_dispatcher =
-      DataPipeConsumerDispatcher::Create();
+      DataPipeConsumerDispatcher::Create(validated_options);
 
   std::pair<MojoHandle, MojoHandle> handle_pair;
   {
-    MutexLocker locker(&handle_table_mutex_);
+    base::AutoLock locker(handle_table_lock_);
     handle_pair = handle_table_.AddDispatcherPair(producer_dispatcher,
                                                   consumer_dispatcher);
   }
   if (handle_pair.first == MOJO_HANDLE_INVALID) {
     DCHECK_EQ(handle_pair.second, MOJO_HANDLE_INVALID);
     LOG(ERROR) << "Handle table full";
     producer_dispatcher->Close();
     consumer_dispatcher->Close();
     return MOJO_RESULT_RESOURCE_EXHAUSTED;
   }
   DCHECK_NE(handle_pair.second, MOJO_HANDLE_INVALID);
 
-  scoped_refptr<DataPipe> data_pipe(DataPipe::CreateLocal(validated_options));
-  producer_dispatcher->Init(data_pipe);
-  consumer_dispatcher->Init(data_pipe);
+  PlatformChannelPair channel_pair;
+  producer_dispatcher->Init(channel_pair.PassServerHandle());
+  consumer_dispatcher->Init(channel_pair.PassClientHandle());
 
-  data_pipe_producer_handle.Put(handle_pair.first);
-  data_pipe_consumer_handle.Put(handle_pair.second);
+  *data_pipe_producer_handle = handle_pair.first;
+  *data_pipe_consumer_handle = handle_pair.second;
   return MOJO_RESULT_OK;
 }
 
 MojoResult Core::WriteData(MojoHandle data_pipe_producer_handle,
-                           UserPointer<const void> elements,
-                           UserPointer<uint32_t> num_bytes,
+                           const void* elements,
+                           uint32_t* num_bytes,
                            MojoWriteDataFlags flags) {
   scoped_refptr<Dispatcher> dispatcher(
       GetDispatcher(data_pipe_producer_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   return dispatcher->WriteData(elements, num_bytes, flags);
 }
 
 MojoResult Core::BeginWriteData(MojoHandle data_pipe_producer_handle,
-                                UserPointer<void*> buffer,
-                                UserPointer<uint32_t> buffer_num_bytes,
+                                void** buffer,
+                                uint32_t* buffer_num_bytes,
                                 MojoWriteDataFlags flags) {
   scoped_refptr<Dispatcher> dispatcher(
       GetDispatcher(data_pipe_producer_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   return dispatcher->BeginWriteData(buffer, buffer_num_bytes, flags);
 }
 
 MojoResult Core::EndWriteData(MojoHandle data_pipe_producer_handle,
                               uint32_t num_bytes_written) {
   scoped_refptr<Dispatcher> dispatcher(
       GetDispatcher(data_pipe_producer_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   return dispatcher->EndWriteData(num_bytes_written);
 }
 
 MojoResult Core::ReadData(MojoHandle data_pipe_consumer_handle,
-                          UserPointer<void> elements,
-                          UserPointer<uint32_t> num_bytes,
+                          void* elements,
+                          uint32_t* num_bytes,
                           MojoReadDataFlags flags) {
   scoped_refptr<Dispatcher> dispatcher(
       GetDispatcher(data_pipe_consumer_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   return dispatcher->ReadData(elements, num_bytes, flags);
 }
 
 MojoResult Core::BeginReadData(MojoHandle data_pipe_consumer_handle,
-                               UserPointer<const void*> buffer,
-                               UserPointer<uint32_t> buffer_num_bytes,
+                               const void** buffer,
+                               uint32_t* buffer_num_bytes,
                                MojoReadDataFlags flags) {
   scoped_refptr<Dispatcher> dispatcher(
       GetDispatcher(data_pipe_consumer_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   return dispatcher->BeginReadData(buffer, buffer_num_bytes, flags);
 }
 
 MojoResult Core::EndReadData(MojoHandle data_pipe_consumer_handle,
                              uint32_t num_bytes_read) {
   scoped_refptr<Dispatcher> dispatcher(
       GetDispatcher(data_pipe_consumer_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   return dispatcher->EndReadData(num_bytes_read);
 }
 
 MojoResult Core::CreateSharedBuffer(
-    UserPointer<const MojoCreateSharedBufferOptions> options,
+    const MojoCreateSharedBufferOptions* options,
     uint64_t num_bytes,
-    UserPointer<MojoHandle> shared_buffer_handle) {
+    MojoHandle* shared_buffer_handle) {
   MojoCreateSharedBufferOptions validated_options = {};
   MojoResult result = SharedBufferDispatcher::ValidateCreateOptions(
       options, &validated_options);
   if (result != MOJO_RESULT_OK)
     return result;
 
   scoped_refptr<SharedBufferDispatcher> dispatcher;
   result = SharedBufferDispatcher::Create(platform_support_, validated_options,
                                           num_bytes, &dispatcher);
   if (result != MOJO_RESULT_OK) {
     DCHECK(!dispatcher);
     return result;
   }
 
-  MojoHandle h = AddDispatcher(dispatcher);
-  if (h == MOJO_HANDLE_INVALID) {
+  *shared_buffer_handle = AddDispatcher(dispatcher);
+  if (*shared_buffer_handle == MOJO_HANDLE_INVALID) {
     LOG(ERROR) << "Handle table full";
     dispatcher->Close();
     return MOJO_RESULT_RESOURCE_EXHAUSTED;
   }
 
-  shared_buffer_handle.Put(h);
   return MOJO_RESULT_OK;
 }
 
 MojoResult Core::DuplicateBufferHandle(
     MojoHandle buffer_handle,
-    UserPointer<const MojoDuplicateBufferHandleOptions> options,
-    UserPointer<MojoHandle> new_buffer_handle) {
+    const MojoDuplicateBufferHandleOptions* options,
+    MojoHandle* new_buffer_handle) {
   scoped_refptr<Dispatcher> dispatcher(GetDispatcher(buffer_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
   // Don't verify |options| here; that's the dispatcher's job.
   scoped_refptr<Dispatcher> new_dispatcher;
   MojoResult result =
       dispatcher->DuplicateBufferHandle(options, &new_dispatcher);
   if (result != MOJO_RESULT_OK)
     return result;
 
-  MojoHandle new_handle = AddDispatcher(new_dispatcher);
-  if (new_handle == MOJO_HANDLE_INVALID) {
+  *new_buffer_handle = AddDispatcher(new_dispatcher);
+  if (*new_buffer_handle == MOJO_HANDLE_INVALID) {
     LOG(ERROR) << "Handle table full";
     dispatcher->Close();
     return MOJO_RESULT_RESOURCE_EXHAUSTED;
   }
 
-  new_buffer_handle.Put(new_handle);
   return MOJO_RESULT_OK;
 }
 
 MojoResult Core::MapBuffer(MojoHandle buffer_handle,
                            uint64_t offset,
                            uint64_t num_bytes,
-                           UserPointer<void*> buffer,
+                           void** buffer,
                            MojoMapBufferFlags flags) {
   scoped_refptr<Dispatcher> dispatcher(GetDispatcher(buffer_handle));
   if (!dispatcher)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
-  scoped_ptr<embedder::PlatformSharedBufferMapping> mapping;
+  scoped_ptr<PlatformSharedBufferMapping> mapping;
   MojoResult result = dispatcher->MapBuffer(offset, num_bytes, flags, &mapping);
   if (result != MOJO_RESULT_OK)
     return result;
 
   DCHECK(mapping);
   void* address = mapping->GetBase();
   {
-    MutexLocker locker(&mapping_table_mutex_);
+    base::AutoLock locker(mapping_table_lock_);
     result = mapping_table_.AddMapping(mapping.Pass());
   }
   if (result != MOJO_RESULT_OK)
     return result;
 
-  buffer.Put(address);
+  *buffer = address;
   return MOJO_RESULT_OK;
 }
 
-MojoResult Core::UnmapBuffer(UserPointer<void> buffer) {
-  MutexLocker locker(&mapping_table_mutex_);
-  return mapping_table_.RemoveMapping(buffer.GetPointerValue());
+MojoResult Core::UnmapBuffer(void* buffer) {
+  base::AutoLock locker(mapping_table_lock_);
+  return mapping_table_.RemoveMapping(buffer);
 }
 
 // Note: We allow |handles| to repeat the same handle multiple times, since
 // different flags may be specified.
 // TODO(vtl): This incurs a performance cost in |Remove()|. Analyze this
 // more carefully and address it if necessary.
 MojoResult Core::WaitManyInternal(const MojoHandle* handles,
                                   const MojoHandleSignals* signals,
                                   uint32_t num_handles,
                                   MojoDeadline deadline,
                                   uint32_t* result_index,
                                   HandleSignalsState* signals_states) {
+  CHECK(handles);
+  CHECK(signals);
   DCHECK_GT(num_handles, 0u);
-  DCHECK_EQ(*result_index, static_cast<uint32_t>(-1));
+  if (result_index) {
+    DCHECK_EQ(*result_index, static_cast<uint32_t>(-1));
+  }
 
   DispatcherVector dispatchers;
   dispatchers.reserve(num_handles);
   for (uint32_t i = 0; i < num_handles; i++) {
     scoped_refptr<Dispatcher> dispatcher = GetDispatcher(handles[i]);
     if (!dispatcher) {
-      *result_index = i;
+      if (result_index && result_index)
+        *result_index = i;
       return MOJO_RESULT_INVALID_ARGUMENT;
     }
     dispatchers.push_back(dispatcher);
   }
 
   // TODO(vtl): Should make the waiter live (permanently) in TLS.
   Waiter waiter;
   waiter.Init();
 
   uint32_t i;
   MojoResult rv = MOJO_RESULT_OK;
   for (i = 0; i < num_handles; i++) {
     rv = dispatchers[i]->AddAwakable(
         &waiter, signals[i], i, signals_states ? &signals_states[i] : nullptr);
     if (rv != MOJO_RESULT_OK) {
-      *result_index = i;
+      if (result_index)
+        *result_index = i;
       break;
     }
   }
   uint32_t num_added = i;
 
   if (rv == MOJO_RESULT_ALREADY_EXISTS)
     rv = MOJO_RESULT_OK;  // The i-th one is already "triggered".
   else if (rv == MOJO_RESULT_OK)
     rv = waiter.Wait(deadline, result_index);
 
   // Make sure no other dispatchers try to wake |waiter| for the current
   // |Wait()|/|WaitMany()| call. (Only after doing this can |waiter| be
   // destroyed, but this would still be required if the waiter were in TLS.)
   for (i = 0; i < num_added; i++) {
     dispatchers[i]->RemoveAwakable(
         &waiter, signals_states ? &signals_states[i] : nullptr);
   }
   if (signals_states) {
     for (; i < num_handles; i++)
       signals_states[i] = dispatchers[i]->GetHandleSignalsState();
   }
 
   return rv;
 }
 
-}  // namespace system
+}  // namespace edk
 }  // namespace mojo