native_client_sdk/src/libraries/nacl_io/devfs/jspipe_node.h

   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_