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 ChannelPosix 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 ChannelNacl : public Channel,
35                    public internal::ChannelReader {
36 public:
37  // Mirror methods of Channel, see ipc_channel.h for description.
38  ChannelNacl(const IPC::ChannelHandle& channel_handle,
39              Mode mode,
40              Listener* listener);
41  virtual ~ChannelNacl();
42
43  // Channel implementation.
44  virtual base::ProcessId GetPeerPID() const OVERRIDE;
45  virtual base::ProcessId GetSelfPID() const OVERRIDE;
46  virtual bool Connect() OVERRIDE;
47  virtual void Close() OVERRIDE;
48  virtual bool Send(Message* message) OVERRIDE;
49
50  // Posted to the main thread by ReaderThreadRunner.
51  void DidRecvMsg(scoped_ptr<MessageContents> contents);
52  void ReadDidFail();
53
54 private:
55  class ReaderThreadRunner;
56
57  bool CreatePipe(const IPC::ChannelHandle& channel_handle);
58  bool ProcessOutgoingMessages();
59  void CallOnChannelConnected();
60
61  // ChannelReader implementation.
62  virtual ReadState ReadData(char* buffer,
63                             int buffer_len,
64                             int* bytes_read) OVERRIDE;
65  virtual bool WillDispatchInputMessage(Message* msg) OVERRIDE;
66  virtual bool DidEmptyInputBuffers() OVERRIDE;
67  virtual void HandleInternalMessage(const Message& msg) OVERRIDE;
68
69  Mode mode_;
70  bool waiting_connect_;
71
72  // The pipe used for communication.
73  int pipe_;
74
75  // The "name" of our pipe.  On Windows this is the global identifier for
76  // the pipe.  On POSIX it's used as a key in a local map of file descriptors.
77  // For NaCl, we don't actually support looking up file descriptors by name,
78  // and it's only used for debug information.
79  std::string pipe_name_;
80
81  // We use a thread for reading, so that we can simply block on reading and
82  // post the received data back to the main thread to be properly interleaved
83  // with other tasks in the MessagePump.
84  //
85  // imc_recvmsg supports non-blocking reads, but there's no easy way to be
86  // informed when a write or read can be done without blocking (this is handled
87  // by libevent in Posix).
88  scoped_ptr<ReaderThreadRunner> reader_thread_runner_;
89  scoped_ptr<base::DelegateSimpleThread> reader_thread_;
90
91  // IPC::ChannelReader expects to be able to call ReadData on us to
92  // synchronously read data waiting in the pipe's buffer without blocking.
93  // Since we can't do that (see 1 and 2 above), the reader thread does blocking
94  // reads and posts the data over to the main thread in MessageContents. Each
95  // MessageContents object is the result of one call to "imc_recvmsg".
96  // DidRecvMsg breaks the MessageContents out in to the data and the file
97  // descriptors, and puts them on these two queues.
98  // TODO(dmichael): There's probably a more efficient way to emulate this with
99  //                 a circular buffer or something, so we don't have to do so
100  //                 many heap allocations. But it maybe isn't worth
101  //                 the trouble given that we probably want to implement 1 and
102  //                 2 above in NaCl eventually.
103  // When ReadData is called, it pulls the bytes out of this queue in order.
104  std::deque<linked_ptr<std::vector<char> > > read_queue_;
105  // Queue of file descriptors extracted from imc_recvmsg messages.
106  // NOTE: The implementation assumes underlying storage here is contiguous, so
107  // don't change to something like std::deque<> without changing the
108  // implementation!
109  std::vector<int> input_fds_;
110
111  // This queue is used when a message is sent prior to Connect having been
112  // called. Normally after we're connected, the queue is empty.
113  std::deque<linked_ptr<Message> > output_queue_;
114
115  base::WeakPtrFactory<ChannelNacl> weak_ptr_factory_;
116
117  DISALLOW_IMPLICIT_CONSTRUCTORS(ChannelNacl);
118};
119
120}  // namespace IPC
121
122#endif  // IPC_IPC_CHANNEL_NACL_H_
123