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| 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_READER_H_ |
| 6 #define IPC_IPC_CHANNEL_READER_H_ |
| 7 |
| 8 #include "base/basictypes.h" |
| 9 #include "ipc/ipc_channel.h" |
| 10 |
| 11 namespace IPC { |
| 12 namespace internal { |
| 13 |
| 14 // This class provides common pipe reading functionality for the |
| 15 // platform-specific IPC channel implementations. |
| 16 // |
| 17 // It does the common input buffer management and message dispatch, while the |
| 18 // platform-specific parts provide the pipe management through a virtual |
| 19 // interface implemented on a per-platform basis. |
| 20 // |
| 21 // Note that there is no "writer" corresponding to this because the code for |
| 22 // writing to the channel is much simpler and has very little common |
| 23 // functionality that would benefit from being factored out. If we add |
| 24 // something like that in the future, it would be more appropriate to add it |
| 25 // here (and rename appropriately) rather than writing a different class. |
| 26 class ChannelReader { |
| 27 public: |
| 28 explicit ChannelReader(Channel::Listener* listener); |
| 29 virtual ~ChannelReader(); |
| 30 |
| 31 void set_listener(Channel::Listener* listener) { listener_ = listener; } |
| 32 |
| 33 // Call to process messages received from the IPC connection and dispatch |
| 34 // them. Returns false on channel error. True indicates that everything |
| 35 // succeeded, although there may not have been any messages processed. |
| 36 bool ProcessIncomingMessages(); |
| 37 |
| 38 // Handles asynchronously read data. |
| 39 // |
| 40 // Optionally call this after returning READ_PENDING from ReadData to |
| 41 // indicate that buffer was filled with the given number of bytes of |
| 42 // data. See ReadData for more. |
| 43 bool AsyncReadComplete(int bytes_read); |
| 44 |
| 45 // Returns true if the given message is the "hello" message sent on channel |
| 46 // set-up. |
| 47 bool IsHelloMessage(const Message& m) const; |
| 48 |
| 49 protected: |
| 50 enum ReadState { READ_SUCCEEDED, READ_FAILED, READ_PENDING }; |
| 51 |
| 52 Channel::Listener* listener() const { return listener_; } |
| 53 |
| 54 // Populates the given buffer with data from the pipe. |
| 55 // |
| 56 // Returns the state of the read. On READ_SUCCESS, the number of bytes |
| 57 // read will be placed into |*bytes_read| (which can be less than the |
| 58 // buffer size). On READ_FAILED, the channel will be closed. |
| 59 // |
| 60 // If the return value is READ_PENDING, it means that there was no data |
| 61 // ready for reading. The implementation is then responsible for either |
| 62 // calling AsyncReadComplete with the number of bytes read into the |
| 63 // buffer, or ProcessIncomingMessages to try the read again (depending |
| 64 // on whether the platform's async I/O is "try again" or "write |
| 65 // asynchronously into your buffer"). |
| 66 virtual ReadState ReadData(char* buffer, int buffer_len, int* bytes_read) = 0; |
| 67 |
| 68 // Loads the required file desciptors into the given message. Returns true |
| 69 // on success. False means a fatal channel error. |
| 70 // |
| 71 // This will read from the input_fds_ and read more handles from the FD |
| 72 // pipe if necessary. |
| 73 virtual bool WillDispatchInputMessage(Message* msg) = 0; |
| 74 |
| 75 // Performs post-dispatch checks. Called when all input buffers are empty, |
| 76 // though there could be more data ready to be read from the OS. |
| 77 virtual bool DidEmptyInputBuffers() = 0; |
| 78 |
| 79 // Handles the first message sent over the pipe which contains setup info. |
| 80 virtual void HandleHelloMessage(const Message& msg) = 0; |
| 81 |
| 82 private: |
| 83 // Takes the given data received from the IPC channel and dispatches any |
| 84 // fully completed messages. |
| 85 // |
| 86 // Returns true on success. False means channel error. |
| 87 bool DispatchInputData(const char* input_data, int input_data_len); |
| 88 |
| 89 Channel::Listener* listener_; |
| 90 |
| 91 // We read from the pipe into this buffer. Managed by DispatchInputData, do |
| 92 // not access directly outside that function. |
| 93 char input_buf_[Channel::kReadBufferSize]; |
| 94 |
| 95 // Large messages that span multiple pipe buffers, get built-up using |
| 96 // this buffer. |
| 97 std::string input_overflow_buf_; |
| 98 |
| 99 DISALLOW_COPY_AND_ASSIGN(ChannelReader); |
| 100 }; |
| 101 |
| 102 } // namespace internal |
| 103 } // namespace IPC |
| 104 |
| 105 #endif // IPC_IPC_CHANNEL_READER_H_ |
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