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      1 // Copyright 2014 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 LIBRARIES_NACL_IO_DEVFS_JSPIPE_NODE_H_
      6 #define LIBRARIES_NACL_IO_DEVFS_JSPIPE_NODE_H_
      7 
      8 #include <ppapi/c/pp_var.h>
      9 #include <string>
     10 
     11 #include "nacl_io/devfs/jspipe_event_emitter.h"
     12 #include "nacl_io/stream/stream_node.h"
     13 
     14 namespace nacl_io {
     15 
     16 class MessagingInterface;
     17 class VarInterface;
     18 class VarArrayInterface;
     19 class VarArrayBufferInterface;
     20 class VarDictionaryInterface;
     21 
     22 /**
     23  * JSPipeNode represents a two-way channel for communicating with JavaScript
     24  * via calls to PostMessage.  In order to use these some amount of logic on
     25  * the JavaScript side is also required.  The protocol to the communication
     26  * looks the same in both directions and consists of two message types:
     27  * 'write' and 'ack'.
     28  * The messages are formated as JavaScript dictionary objects and take the
     29  * following form:
     30  * {
     31  *   pipe: <pipe_name>,
     32  *   operation: <operation_name>,
     33  *   payload: <operations_payload>
     34  * }
     35  * The payload for 'write' message is a ArrayBuffer containing binary data.
     36  * The payload for 'ack' messages is the total number of bytes recieved at
     37  * the other end.
     38  * For example: { pipe: 'jspipe1', operation: 'ack', payload: 234 }
     39  *
     40  * Messages coming from JavaScript must be delivered using the
     41  * NACL_IOC_HANDLEMESSAGE ioctl on the file handle.
     42  */
     43 class JSPipeNode : public Node {
     44  public:
     45   explicit JSPipeNode(Filesystem* filesystem);
     46 
     47   virtual void Destroy() {
     48     LOG_TRACE("JSPipeNode: Destroy");
     49   }
     50 
     51   virtual JSPipeEventEmitter* GetEventEmitter();
     52 
     53   virtual Error VIoctl(int request, va_list args);
     54 
     55   virtual Error Read(const HandleAttr& attr,
     56                      void* buf,
     57                      size_t count,
     58                      int* out_bytes);
     59   virtual Error Write(const HandleAttr& attr,
     60                       const void* buf,
     61                       size_t count,
     62                       int* out_bytes);
     63 
     64  protected:
     65   Error SendAck();
     66 
     67   ScopedJSPipeEventEmitter pipe_;
     68 };
     69 
     70 }  // namespace nacl_io
     71 
     72 #endif  // LIBRARIES_NACL_IO_DEVFS_JSPIPE_NODE_H_
     73