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