PPAPI/NaCl: Support Handle passing in ipc_channel_nacl

ipc/ipc_channel_nacl.h

 // Copyright (c) 2012 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.
 
 #ifndef IPC_IPC_CHANNEL_NACL_H_
 #define IPC_IPC_CHANNEL_NACL_H_
 #pragma once
 
 #include <deque>
 #include <string>
 
 #include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/process.h"
 #include "base/threading/simple_thread.h"
 #include "ipc/ipc_channel.h"
 #include "ipc/ipc_channel_reader.h"
 
 namespace IPC {
 
+// Contains the results from one call to imc_recvmsg (data and file
+// descriptors).
+struct MessageContents;
+
 // Similar to the Posix version of ChannelImpl but for Native Client code.
 // This is somewhat different because sendmsg/recvmsg here do not follow POSIX
 // semantics. Instead, they are implemented by a custom embedding of
 // NaClDescCustom. See NaClIPCAdapter for the trusted-side implementation.
 //
 // We don't need to worry about complicated set up and READWRITE mode for
 // sharing handles. We also currently do not support passing file descriptors or
 // named pipes, and we use background threads to emulate signaling when we can
 // read or write without blocking.
 class Channel::ChannelImpl : public internal::ChannelReader {
  public:
   // Mirror methods of Channel, see ipc_channel.h for description.
   ChannelImpl(const IPC::ChannelHandle& channel_handle,
               Mode mode,
               Listener* listener);
   virtual ~ChannelImpl();
 
   // Channel implementation.
   bool Connect();
   void Close();
   bool Send(Message* message);
 
   // Posted to the main thread by ReaderThreadRunner.
-  void DidRecvMsg(scoped_ptr<std::vector<char> > buffer);
+  void DidRecvMsg(scoped_ptr<MessageContents> contents);
   void ReadDidFail();
 
  private:
   class ReaderThreadRunner;
 
   bool CreatePipe(const IPC::ChannelHandle& channel_handle);
   bool ProcessOutgoingMessages();
 
   // ChannelReader implementation.
   virtual ReadState ReadData(char* buffer,
@@ skipping 21 matching lines @@
   //
   // imc_recvmsg supports non-blocking reads, but there's no easy way to be
   // informed when a write or read can be done without blocking (this is handled
   // by libevent in Posix).
   scoped_ptr<ReaderThreadRunner> reader_thread_runner_;
   scoped_ptr<base::DelegateSimpleThread> reader_thread_;
 
   // IPC::ChannelReader expects to be able to call ReadData on us to
   // synchronously read data waiting in the pipe's buffer without blocking.
   // Since we can't do that (see 1 and 2 above), the reader thread does blocking
-  // reads and posts the data over to the main thread in byte vectors. Each byte
-  // vector is the result of one call to "recvmsg". When ReadData is called, it
-  // pulls the bytes out of these vectors in order.
+  // reads and posts the data over to the main thread in MessageContents. Each
+  // MessageContents object is the result of one call to "imc_recvmsg".
+  // DidRecvMsg breaks the MessageContents out in to the data and the file
+  // descriptors, and puts them on these two queues.
   // TODO(dmichael): There's probably a more efficient way to emulate this with
   //                 a circular buffer or something, so we don't have to do so
   //                 many heap allocations. But it maybe isn't worth
   //                 the trouble given that we probably want to implement 1 and
   //                 2 above in NaCl eventually.
+  // When ReadData is called, it pulls the bytes out of this queue in order.
   std::deque<linked_ptr<std::vector<char> > > read_queue_;
+  // Queue of file descriptors extracted from imc_recvmsg messages.
+  // NOTE: The implementation assumes underlying storage here is contiguous, so
+  // don't change to something like std::deque<> without changing the
+  // implementation!
+  std::vector<int> input_fds_;
 
   // This queue is used when a message is sent prior to Connect having been
   // called. Normally after we're connected, the queue is empty.
   std::deque<linked_ptr<Message> > output_queue_;
 
   base::WeakPtrFactory<ChannelImpl> weak_ptr_factory_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(ChannelImpl);
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_CHANNEL_NACL_H_