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 <memory> 9 #include <string> 10 11 #include "base/containers/circular_deque.h" 12 #include "base/macros.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 class MessageAttachment; 22 23 // Contains the results from one call to imc_recvmsg (data and file 24 // descriptors). 25 struct MessageContents; 26 27 // Similar to the ChannelPosix but for Native Client code. 28 // This is somewhat different because sendmsg/recvmsg here do not follow POSIX 29 // semantics. Instead, they are implemented by a custom embedding of 30 // NaClDescCustom. See NaClIPCAdapter for the trusted-side implementation. 31 // 32 // We don't need to worry about complicated set up and READWRITE mode for 33 // sharing handles. We also currently do not support passing file descriptors or 34 // named pipes, and we use background threads to emulate signaling when we can 35 // read or write without blocking. 36 class ChannelNacl : public Channel, 37 public internal::ChannelReader { 38 public: 39 // Mirror methods of Channel, see ipc_channel.h for description. 40 ChannelNacl(const IPC::ChannelHandle& channel_handle, 41 Mode mode, 42 Listener* listener); 43 ~ChannelNacl() override; 44 45 // Channel implementation. 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(std::unique_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 ShouldDispatchInputMessage(Message* msg) override; 66 bool GetAttachments(Message* msg) override; 67 bool DidEmptyInputBuffers() override; 68 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 // We use a thread for reading, so that we can simply block on reading and 77 // post the received data back to the main thread to be properly interleaved 78 // with other tasks in the MessagePump. 79 // 80 // imc_recvmsg supports non-blocking reads, but there's no easy way to be 81 // informed when a write or read can be done without blocking (this is handled 82 // by libevent in Posix). 83 std::unique_ptr<ReaderThreadRunner> reader_thread_runner_; 84 std::unique_ptr<base::DelegateSimpleThread> reader_thread_; 85 86 // IPC::ChannelReader expects to be able to call ReadData on us to 87 // synchronously read data waiting in the pipe's buffer without blocking. 88 // Since we can't do that (see 1 and 2 above), the reader thread does blocking 89 // reads and posts the data over to the main thread in MessageContents. Each 90 // MessageContents object is the result of one call to "imc_recvmsg". 91 // DidRecvMsg breaks the MessageContents out in to the data and the file 92 // descriptors, and puts them on these two queues. 93 // TODO(dmichael): There's probably a more efficient way to emulate this with 94 // a circular buffer or something, so we don't have to do so 95 // many heap allocations. But it maybe isn't worth 96 // the trouble given that we probably want to implement 1 and 97 // 2 above in NaCl eventually. 98 // When ReadData is called, it pulls the bytes out of this queue in order. 99 base::circular_deque<std::unique_ptr<std::vector<char>>> read_queue_; 100 // Queue of file descriptor attachments extracted from imc_recvmsg messages. 101 std::vector<scoped_refptr<MessageAttachment>> input_attachments_; 102 103 // This queue is used when a message is sent prior to Connect having been 104 // called. Normally after we're connected, the queue is empty. 105 base::circular_deque<std::unique_ptr<Message>> output_queue_; 106 107 base::WeakPtrFactory<ChannelNacl> weak_ptr_factory_; 108 109 DISALLOW_IMPLICIT_CONSTRUCTORS(ChannelNacl); 110 }; 111 112 } // namespace IPC 113 114 #endif // IPC_IPC_CHANNEL_NACL_H_ 115