ipc/ipc_channel_nacl.h

   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
  19 namespace IPC {
  20
  21 // Contains the results from one call to imc_recvmsg (data and file
  22 // descriptors).
  23 struct 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.
  34 class 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   ~ChannelNacl() override;
  42
  43   // Channel implementation.
  44   base::ProcessId GetPeerPID() const override;
  45   base::ProcessId GetSelfPID() const override;
  46   bool Connect() override;
  47   void Close() override;
  48   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   ReadState ReadData(char* buffer,
  63                      int buffer_len,
  64                      int* bytes_read) override;
  65   bool WillDispatchInputMessage(Message* msg) override;
  66   bool DidEmptyInputBuffers() override;
  67   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_