ipc/ipc_channel_nacl.h - chromium/src - Git at Google

 // 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_

 #include <memory>
 #include <string>

 #include "base/containers/circular_deque.h"
 #include "base/memory/weak_ptr.h"
 #include "base/process/process.h"
 #include "base/threading/simple_thread.h"
 #include "ipc/ipc_channel.h"
 #include "ipc/ipc_channel_reader.h"

 namespace IPC {

 class MessageAttachment;

 // Contains the results from one call to imc_recvmsg (data and file
 // descriptors).
 struct MessageContents;

 // Similar to the ChannelPosix 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 ChannelNacl : public Channel,
                     public internal::ChannelReader {
  public:
   ChannelNacl() = delete;

   // Mirror methods of Channel, see ipc_channel.h for description.
   ChannelNacl(const IPC::ChannelHandle& channel_handle,
               Mode mode,
               Listener* listener);

   ChannelNacl(const ChannelNacl&) = delete;
   ChannelNacl& operator=(const ChannelNacl&) = delete;

   ~ChannelNacl() override;

   // Channel implementation.
   bool Connect() override;
   void Close() override;
   bool Send(Message* message) override;

   // Posted to the main thread by ReaderThreadRunner.
   void DidRecvMsg(std::unique_ptr<MessageContents> contents);
   void ReadDidFail();

  private:
   class ReaderThreadRunner;

   bool CreatePipe(const IPC::ChannelHandle& channel_handle);
   bool ProcessOutgoingMessages();
   void CallOnChannelConnected();

   // ChannelReader implementation.
   ReadState ReadData(char* buffer,
                      int buffer_len,
                      int* bytes_read) override;
   bool ShouldDispatchInputMessage(Message* msg) override;
   bool GetAttachments(Message* msg) override;
   bool DidEmptyInputBuffers() override;
   void HandleInternalMessage(const Message& msg) override;

   Mode mode_;
   bool waiting_connect_;

   // The pipe used for communication.
   int pipe_;

   // We use a thread for reading, so that we can simply block on reading and
   // post the received data back to the main thread to be properly interleaved
   // with other tasks in the MessagePump.
   //
   // 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).
   std::unique_ptr<ReaderThreadRunner> reader_thread_runner_;
   std::unique_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 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.
   base::circular_deque<std::unique_ptr<std::vector<char>>> read_queue_;
   // Queue of file descriptor attachments extracted from imc_recvmsg messages.
   std::vector<scoped_refptr<MessageAttachment>> input_attachments_;

   // This queue is used when a message is sent prior to Connect having been
   // called. Normally after we're connected, the queue is empty.
   base::circular_deque<std::unique_ptr<Message>> output_queue_;

   base::WeakPtrFactory<ChannelNacl> weak_ptr_factory_;
 };

 }  // namespace IPC

 #endif  // 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_

	#include <memory>
	#include <string>

	#include "base/containers/circular_deque.h"
	#include "base/memory/weak_ptr.h"
	#include "base/process/process.h"
	#include "base/threading/simple_thread.h"
	#include "ipc/ipc_channel.h"
	#include "ipc/ipc_channel_reader.h"

	namespace IPC {

	class MessageAttachment;

	// Contains the results from one call to imc_recvmsg (data and file
	// descriptors).
	struct MessageContents;

	// Similar to the ChannelPosix 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 ChannelNacl : public Channel,
	public internal::ChannelReader {
	public:
	ChannelNacl() = delete;

	// Mirror methods of Channel, see ipc_channel.h for description.
	ChannelNacl(const IPC::ChannelHandle& channel_handle,
	Mode mode,
	Listener* listener);

	ChannelNacl(const ChannelNacl&) = delete;
	ChannelNacl& operator=(const ChannelNacl&) = delete;

	~ChannelNacl() override;

	// Channel implementation.
	bool Connect() override;
	void Close() override;
	bool Send(Message* message) override;

	// Posted to the main thread by ReaderThreadRunner.
	void DidRecvMsg(std::unique_ptr<MessageContents> contents);
	void ReadDidFail();

	private:
	class ReaderThreadRunner;

	bool CreatePipe(const IPC::ChannelHandle& channel_handle);
	bool ProcessOutgoingMessages();
	void CallOnChannelConnected();

	// ChannelReader implementation.
	ReadState ReadData(char* buffer,
	int buffer_len,
	int* bytes_read) override;
	bool ShouldDispatchInputMessage(Message* msg) override;
	bool GetAttachments(Message* msg) override;
	bool DidEmptyInputBuffers() override;
	void HandleInternalMessage(const Message& msg) override;

	Mode mode_;
	bool waiting_connect_;

	// The pipe used for communication.
	int pipe_;

	// We use a thread for reading, so that we can simply block on reading and
	// post the received data back to the main thread to be properly interleaved
	// with other tasks in the MessagePump.
	//
	// 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).
	std::unique_ptr<ReaderThreadRunner> reader_thread_runner_;
	std::unique_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 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.
	base::circular_deque<std::unique_ptr<std::vector<char>>> read_queue_;
	// Queue of file descriptor attachments extracted from imc_recvmsg messages.
	std::vector<scoped_refptr<MessageAttachment>> input_attachments_;

	// This queue is used when a message is sent prior to Connect having been
	// called. Normally after we're connected, the queue is empty.
	base::circular_deque<std::unique_ptr<Message>> output_queue_;

	base::WeakPtrFactory<ChannelNacl> weak_ptr_factory_;
	};

	} // namespace IPC

	#endif // IPC_IPC_CHANNEL_NACL_H_