1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef IPC_IPC_CHANNEL_NACL_H_
6#define IPC_IPC_CHANNEL_NACL_H_
7
8#include <deque>
9#include <string>
10
11#include "base/memory/linked_ptr.h"
12#include "base/memory/scoped_ptr.h"
13#include "base/memory/weak_ptr.h"
14#include "base/process/process.h"
15#include "base/threading/simple_thread.h"
16#include "ipc/ipc_channel.h"
17#include "ipc/ipc_channel_reader.h"
18
19namespace IPC {
20
21// Contains the results from one call to imc_recvmsg (data and file
22// descriptors).
23struct MessageContents;
24
25// Similar to the Posix version of ChannelImpl but for Native Client code.
26// This is somewhat different because sendmsg/recvmsg here do not follow POSIX
27// semantics. Instead, they are implemented by a custom embedding of
28// NaClDescCustom. See NaClIPCAdapter for the trusted-side implementation.
29//
30// We don't need to worry about complicated set up and READWRITE mode for
31// sharing handles. We also currently do not support passing file descriptors or
32// named pipes, and we use background threads to emulate signaling when we can
33// read or write without blocking.
34class Channel::ChannelImpl : public internal::ChannelReader {
35 public:
36  // Mirror methods of Channel, see ipc_channel.h for description.
37  ChannelImpl(const IPC::ChannelHandle& channel_handle,
38              Mode mode,
39              Listener* listener);
40  virtual ~ChannelImpl();
41
42  // Channel implementation.
43  bool Connect();
44  void Close();
45  bool Send(Message* message);
46
47  // Posted to the main thread by ReaderThreadRunner.
48  void DidRecvMsg(scoped_ptr<MessageContents> contents);
49  void ReadDidFail();
50
51 private:
52  class ReaderThreadRunner;
53
54  bool CreatePipe(const IPC::ChannelHandle& channel_handle);
55  bool ProcessOutgoingMessages();
56
57  // ChannelReader implementation.
58  virtual ReadState ReadData(char* buffer,
59                             int buffer_len,
60                             int* bytes_read) OVERRIDE;
61  virtual bool WillDispatchInputMessage(Message* msg) OVERRIDE;
62  virtual bool DidEmptyInputBuffers() OVERRIDE;
63  virtual void HandleInternalMessage(const Message& msg) OVERRIDE;
64
65  Mode mode_;
66  bool waiting_connect_;
67
68  // The pipe used for communication.
69  int pipe_;
70
71  // The "name" of our pipe.  On Windows this is the global identifier for
72  // the pipe.  On POSIX it's used as a key in a local map of file descriptors.
73  // For NaCl, we don't actually support looking up file descriptors by name,
74  // and it's only used for debug information.
75  std::string pipe_name_;
76
77  // We use a thread for reading, so that we can simply block on reading and
78  // post the received data back to the main thread to be properly interleaved
79  // with other tasks in the MessagePump.
80  //
81  // imc_recvmsg supports non-blocking reads, but there's no easy way to be
82  // informed when a write or read can be done without blocking (this is handled
83  // by libevent in Posix).
84  scoped_ptr<ReaderThreadRunner> reader_thread_runner_;
85  scoped_ptr<base::DelegateSimpleThread> reader_thread_;
86
87  // IPC::ChannelReader expects to be able to call ReadData on us to
88  // synchronously read data waiting in the pipe's buffer without blocking.
89  // Since we can't do that (see 1 and 2 above), the reader thread does blocking
90  // reads and posts the data over to the main thread in MessageContents. Each
91  // MessageContents object is the result of one call to "imc_recvmsg".
92  // DidRecvMsg breaks the MessageContents out in to the data and the file
93  // descriptors, and puts them on these two queues.
94  // TODO(dmichael): There's probably a more efficient way to emulate this with
95  //                 a circular buffer or something, so we don't have to do so
96  //                 many heap allocations. But it maybe isn't worth
97  //                 the trouble given that we probably want to implement 1 and
98  //                 2 above in NaCl eventually.
99  // When ReadData is called, it pulls the bytes out of this queue in order.
100  std::deque<linked_ptr<std::vector<char> > > read_queue_;
101  // Queue of file descriptors extracted from imc_recvmsg messages.
102  // NOTE: The implementation assumes underlying storage here is contiguous, so
103  // don't change to something like std::deque<> without changing the
104  // implementation!
105  std::vector<int> input_fds_;
106
107  // This queue is used when a message is sent prior to Connect having been
108  // called. Normally after we're connected, the queue is empty.
109  std::deque<linked_ptr<Message> > output_queue_;
110
111  base::WeakPtrFactory<ChannelImpl> weak_ptr_factory_;
112
113  DISALLOW_IMPLICIT_CONSTRUCTORS(ChannelImpl);
114};
115
116}  // namespace IPC
117
118#endif  // IPC_IPC_CHANNEL_NACL_H_
119