Create a broker interface for the new Mojo EDK so that the browser can create and duplicate messa...

mojo/edk/system/child_token_serializer_win.cc

+// Copyright 2015 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/edk/system/child_token_serializer_win.h"
+
+#include "base/logging.h"
+#include "mojo/edk/embedder/embedder_internal.h"
+#include "mojo/edk/system/token_serializer_messages_win.h"
+
+namespace mojo {
+namespace edk {
+
+ChildTokenSerializer* ChildTokenSerializer::GetInstance() {
+  return base::Singleton<
+      ChildTokenSerializer,
+      base::LeakySingletonTraits<ChildTokenSerializer>>::get();
+}
+
+void ChildTokenSerializer::SetParentTokenSerializerHandle(
+    ScopedPlatformHandle handle)  {
+  handle_ = handle.Pass();
+  lock_.Unlock();
+}
+
+void ChildTokenSerializer::CreatePlatformChannelPair(
+    ScopedPlatformHandle* server, ScopedPlatformHandle* client) {
+  TokenSerializerMessage message;
+  message.size = kTokenSerializerMessageHeaderSize;
+  message.id = CREATE_PLATFORM_CHANNEL_PAIR;
+
+  uint32_t response_size = 2 * sizeof(HANDLE);
+  HANDLE handles[2];
+  if (WriteAndReadResponse(&message, handles, response_size)) {
+    server->reset(PlatformHandle(handles[0]));
+    client->reset(PlatformHandle(handles[1]));
+  }
+}
+
+void ChildTokenSerializer::HandleToToken(const PlatformHandle* platform_handles,
+                                         size_t count,
+                                         uint64_t* tokens) {
+  uint32_t size = kTokenSerializerMessageHeaderSize +
+                   static_cast<int>(count) * sizeof(HANDLE);
+  std::vector<char> message_buffer(size);
+  TokenSerializerMessage* message =
+      reinterpret_cast<TokenSerializerMessage*>(&message_buffer[0]);
+  message->size = size;
+  message->id = HANDLE_TO_TOKEN;
+  for (size_t i = 0; i < count; ++i)
+    message->handles[i] = platform_handles[i].handle;
+
+  uint32_t response_size = static_cast<int>(count) * sizeof(uint64_t);
+  WriteAndReadResponse(message, tokens, response_size);

[yzshen1, 2015/11/20 20:39:55]

Is there any error handling needed if this call fails?

[jam, 2015/11/21 01:26:09]

it'll fail because bogus handles are passed in. but in that case, the receiver
should handle this case i think. there's not really a mechanism to bubble back
this error from what i can see, looking at HandleToToken's callsites.

+}
+
+void ChildTokenSerializer::TokenToHandle(const uint64_t* tokens,
+                                         size_t count,
+                                         PlatformHandle* handles) {
+  uint32_t size = kTokenSerializerMessageHeaderSize +
+                  static_cast<int>(count) * sizeof(uint64_t);
+  std::vector<char> message_buffer(size);
+  TokenSerializerMessage* message =
+      reinterpret_cast<TokenSerializerMessage*>(&message_buffer[0]);
+  message->size = size;
+  message->id = TOKEN_TO_HANDLE;
+  memcpy(&message->tokens[0], tokens, count * sizeof(uint64_t));
+
+  std::vector<HANDLE> handles_temp(count);
+  uint32_t response_size =
+      static_cast<uint32_t>(handles_temp.size()) * sizeof(HANDLE);
+  if (WriteAndReadResponse(message, &handles_temp[0], response_size)) {
+    for (uint32_t i = 0; i < count; ++i)
+      handles[i].handle = handles_temp[i];
+  }
+}
+
+ChildTokenSerializer::ChildTokenSerializer() {
+  DCHECK(!internal::g_token_serializer);
+  internal::g_token_serializer = this;
+  // Block any threads from calling this until we have a pipe to the parent.
+  lock_.Lock();
+}
+
+ChildTokenSerializer::~ChildTokenSerializer() {
+}
+
+bool ChildTokenSerializer::WriteAndReadResponse(TokenSerializerMessage* message,
+                                                void* response,
+                                                uint32_t response_size) {
+  lock_.Lock();
+  CHECK(handle_.is_valid());
+
+  bool result = false;
+  DWORD bytes_written = 0;
+  BOOL rv = WriteFile(handle_.get().handle, message, message->size,
+                      &bytes_written, NULL);

[yzshen1, 2015/11/20 20:39:55]

Do we need to handle partial read/write as non-error? IIUC, blocking read/write
doesn't guaratee reading/writing the full input buffer.

[jam, 2015/11/21 01:26:09]

per
https://msdn.microsoft.com/en-us/library/windows/desktop/aa365747(v=vs.85).aspx
and
https://msdn.microsoft.com/en-us/library/windows/desktop/aa365150(v=vs.85).aspx,
I don't see write will return earlier (it'll block per doc). i also just tried
this now, and tried writing 120K and it worked synchronously. however you're
right read could return earlier. I'll fix that (I had made parent support this,
but overlooked this file)https://codereview.chromium.org/static/zippyplus.gif

+  if (!rv || bytes_written != message->size) {
+    LOG(ERROR) << "Child token serializer couldn't write message.";
+  } else {
+    DWORD bytes_read = 0;
+    rv = ReadFile(handle_.get().handle, response, response_size, &bytes_read,
+                  NULL);
+    if (!rv || bytes_read != response_size) {
+      LOG(ERROR) << "Child token serializer couldn't read result.";
+    } else {
+      result = true;
+    }
+  }
+
+  lock_.Unlock();
+
+  return result;
+}
+
+}  // namespace edk
+}  // namespace mojo