ipc/ipc_channel_posix.h

// Copyright (c) 2008 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_POSIX_H_
#define IPC_IPC_CHANNEL_POSIX_H_
#pragma once

#include "ipc/ipc_channel.h"

#include <sys/socket.h>  // for CMSG macros

#include <queue>
#include <string>
#include <vector>

#include "base/message_loop.h"
#include "ipc/file_descriptor_set_posix.h"

namespace IPC {

// Store that channel name |name| is available via socket |socket|.
// Used when the channel has been precreated by another process on
// our behalf and they've just shipped us the socket.
void AddChannelSocket(const std::string& name, int socket);

// Remove the channel name mapping, and close the corresponding socket.
void RemoveAndCloseChannelSocket(const std::string& name);

// Returns true if a channel named |name| is available.
bool ChannelSocketExists(const std::string& name);

// Construct a socket pair appropriate for IPC: UNIX domain, nonblocking.
// Returns false on error.
bool SocketPair(int* fd1, int* fd2);

// An implementation of ChannelImpl for POSIX systems that works via
// socketpairs.  See the .cc file for an overview of the implementation.
class Channel::ChannelImpl : public MessageLoopForIO::Watcher {
 public:
  // Mirror methods of Channel, see ipc_channel.h for description.
  ChannelImpl(const std::string& channel_id, Mode mode, Listener* listener);
  ~ChannelImpl();
  bool Connect();
  void Close();
  void set_listener(Listener* listener) { listener_ = listener; }
  bool Send(Message* message);
  int GetClientFileDescriptor() const;

 private:
  bool CreatePipe(const std::string& channel_id, Mode mode);

  bool ProcessIncomingMessages();
  bool ProcessOutgoingMessages();

  // MessageLoopForIO::Watcher implementation.
  virtual void OnFileCanReadWithoutBlocking(int fd);
  virtual void OnFileCanWriteWithoutBlocking(int fd);

  Mode mode_;

  // After accepting one client connection on our server socket we want to
  // stop listening.
  MessageLoopForIO::FileDescriptorWatcher server_listen_connection_watcher_;
  MessageLoopForIO::FileDescriptorWatcher read_watcher_;
  MessageLoopForIO::FileDescriptorWatcher write_watcher_;

  // Indicates whether we're currently blocked waiting for a write to complete.
  bool is_blocked_on_write_;

  // If sending a message blocks then we use this variable
  // to keep track of where we are.
  size_t message_send_bytes_written_;

  // If the kTestingChannelID flag is specified, we use a FIFO instead of
  // a socketpair().
  bool uses_fifo_;

  // File descriptor we're listening on for new connections in the FIFO case;
  // unused otherwise.
  int server_listen_pipe_;

  // The pipe used for communication.
  int pipe_;

  // For a server, the client end of our socketpair() -- the other end of our
  // pipe_ that is passed to the client.
  int client_pipe_;

#if !defined(OS_MACOSX)
  // Linux/BSD use a dedicated socketpair() for passing file descriptors.
  int fd_pipe_;
  int remote_fd_pipe_;
#endif

  // The "name" of our pipe.  On Windows this is the global identifier for
  // the pipe.  On POSIX it's used as a key in a local map of file descriptors.
  std::string pipe_name_;

  Listener* listener_;

  // Messages to be sent are queued here.
  std::queue<Message*> output_queue_;

  // We read from the pipe into this buffer
  char input_buf_[Channel::kReadBufferSize];

  enum {
    // We assume a worst case: kReadBufferSize bytes of messages, where each
    // message has no payload and a full complement of descriptors.
    MAX_READ_FDS = (Channel::kReadBufferSize / sizeof(IPC::Message::Header)) *
                   FileDescriptorSet::MAX_DESCRIPTORS_PER_MESSAGE,
  };

  // This is a control message buffer large enough to hold kMaxReadFDs
#if defined(OS_MACOSX)
  // TODO(agl): OSX appears to have non-constant CMSG macros!
  char input_cmsg_buf_[1024];
#else
  char input_cmsg_buf_[CMSG_SPACE(sizeof(int) * MAX_READ_FDS)];
#endif

  // Large messages that span multiple pipe buffers, get built-up using
  // this buffer.
  std::string input_overflow_buf_;
  std::vector<int> input_overflow_fds_;

  // In server-mode, we have to wait for the client to connect before we
  // can begin reading.  We make use of the input_state_ when performing
  // the connect operation in overlapped mode.
  bool waiting_connect_;

  ScopedRunnableMethodFactory<ChannelImpl> factory_;

  DISALLOW_COPY_AND_ASSIGN(ChannelImpl);
};

}  // namespace IPC

#endif  // IPC_IPC_CHANNEL_POSIX_H_