gecko-dev/dom/system/gonk/VolumeCommand.h

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_system_volumecommand_h__
#define mozilla_system_volumecommand_h__

#include "nsString.h"
#include "mozilla/RefPtr.h"
#include <algorithm>
#include <vold/ResponseCode.h>

namespace mozilla {
namespace system {

class Volume;
class VolumeCommand;

/***************************************************************************
*
*   The VolumeResponseCallback class is an abstract base class. The ResponseReceived
*   method will be called for each response received.
*
*   Depending on the command, there may be multiple responses for the
*   command. Done() will return true if this is the last response.
*
*   The responses from vold are all of the form:
*
*     <ResponseCode> <String>
*
*   Valid Response codes can be found in the vold/ResponseCode.h header.
*
***************************************************************************/

class VolumeResponseCallback : public RefCounted<VolumeResponseCallback>
{
public:
  VolumeResponseCallback()
    : mResponseCode(0), mPending(false) {}

  virtual ~VolumeResponseCallback() {}

  bool Done() const
  {
    // Response codes from the 200, 400, and 500 series all indicated that
    // the command has completed.

    return (mResponseCode >= ResponseCode::CommandOkay)
        && (mResponseCode < ResponseCode::UnsolicitedInformational);
  }

  bool WasSuccessful() const
  {
    return mResponseCode == ResponseCode::CommandOkay;
  }

  bool              IsPending() const     { return mPending; }
  int               ResponseCode() const  { return mResponseCode; }
  const nsCString  &ResponseStr() const   { return mResponseStr; }

protected:
  virtual void ResponseReceived(const VolumeCommand* aCommand) = 0;

private:
  friend  class VolumeCommand;  // Calls HandleResponse and SetPending

  void HandleResponse(const VolumeCommand* aCommand,
                      int aResponseCode,
                      nsACString& aResponseStr)
  {
    mResponseCode = aResponseCode;
#if ANDROID_VERSION >= 17
    // There's a sequence number here that we don't care about
    // We expect it to be 0. See VolumeCommand::SetCmd
    mResponseStr = Substring(aResponseStr, 2);
#else
    mResponseStr = aResponseStr;
#endif
    if (mResponseCode >= ResponseCode::CommandOkay) {
      // This is a final response.
      mPending = false;
    }
    ResponseReceived(aCommand);
  }

  void SetPending(bool aPending) { mPending = aPending; }

  int       mResponseCode;  // The response code parsed from vold
  nsCString mResponseStr;   // The rest of the line.
  bool      mPending;       // Waiting for response?
};

/***************************************************************************
*
*   The VolumeCommand class is an abstract base class used to encapsulate
*   volume commands send to vold.
*
*   See VolumeManager.h for a list of the volume commands.
*
*   Commands sent to vold need an explicit null character so we add one
*   to the command to ensure that it's included in the length.
*
*   All of these commands are asynchronous in nature, and the
*   ResponseReceived callback will be called when a response is available.
*
***************************************************************************/

class VolumeCommand : public RefCounted<VolumeCommand>
{
public:
  VolumeCommand(VolumeResponseCallback* aCallback)
    : mBytesConsumed(0),
      mCallback(aCallback)
  {
    SetCmd(NS_LITERAL_CSTRING(""));
  }

  VolumeCommand(const nsACString& aCommand, VolumeResponseCallback* aCallback)
    : mBytesConsumed(0),
      mCallback(aCallback)
  {
    SetCmd(aCommand);
  }

  virtual ~VolumeCommand() {}

  void SetCmd(const nsACString& aCommand)
  {
    mCmd.Truncate();
#if ANDROID_VERSION >= 17
    // JB requires a sequence number at the beginning of messages.
    // It doesn't matter what we use, so we use 0.
    mCmd = "0 ";
#endif
    mCmd.Append(aCommand);
    // Add a null character. We want this to be included in the length since
    // vold uses it to determine the end of the command.
    mCmd.Append('\0');
  }

  const char* CmdStr() const    { return mCmd.get(); }
  const char* Data() const      { return mCmd.Data() + mBytesConsumed; }
  size_t BytesConsumed() const  { return mBytesConsumed; }

  size_t BytesRemaining() const
  {
    return mCmd.Length() - std::min(mCmd.Length(), mBytesConsumed);
  }

  void ConsumeBytes(size_t aNumBytes)
  {
    mBytesConsumed += std::min(BytesRemaining(), aNumBytes);
  }

private:
  friend class VolumeManager;   // Calls SetPending & HandleResponse

  void SetPending(bool aPending)
  {
    if (mCallback) {
      mCallback->SetPending(aPending);
    }
  }

  void HandleResponse(int aResponseCode, nsACString& aResponseStr)
  {
    if (mCallback) {
      mCallback->HandleResponse(this, aResponseCode, aResponseStr);
    }
  }

  nsCString mCmd;           // Command being sent
  size_t    mBytesConsumed; // How many bytes have been sent

  // Called when a response to the command is received.
  RefPtr<VolumeResponseCallback>  mCallback;
};

class VolumeActionCommand : public VolumeCommand
{
public:
  VolumeActionCommand(Volume* aVolume, const char* aAction,
                      const char* aExtraArgs, VolumeResponseCallback* aCallback);

private:
  RefPtr<Volume>  mVolume;
};

class VolumeListCommand : public VolumeCommand
{
public:
  VolumeListCommand(VolumeResponseCallback* aCallback);
};

} // system
} // mozilla

#endif  // mozilla_system_volumecommand_h__