/*

* Copyright (c) 2008 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:  Handler for File IO Operations

 *

*/

#ifndef NATIVEFILEIOHANDLER_H

#define NATIVEFILEIOHANDLER_H

#include <string>

namespace java

{

namespace fileutils

{

/**

 * Implements methods to read/write data from the native file system.

 */

OS_NONSHARABLE_CLASS(NativeFileIOHandler)

{

public:

    NativeFileIOHandler(const std::wstring aName);

    virtual ~NativeFileIOHandler();

    /**

     * Reads data from the file into aBuffer upto aLength bytes.

     * Returns the amount of data read.

     * In case of errors, exception is thrown with errno value.

     */

    virtual int readBytes(char* aBuffer, int aLength);

    /**

     * Writes data from aBuffer into the file upto aLength bytes.

     * Returns the amount of data written.

     * In case of errors, exception is thrown with errno value.

     */

    virtual int writeBytes(char* aBuffer, int aLength);

    /**

     * Stops read operation. In case the file is opened in read-write mode and

     * if the write operations are in progress, the file is kept open to allow

     * for write operations. Else the file is closed.

     */

    virtual void stopReading();

    /**

     * Stops write operation. In case the file is opened in read-write mode and

     * if the read operations are in progress, the file is kept open to allow

     * for read operations. Else the file is closed.

     */

    virtual void stopWriting();

    /**

     * Opens the file specified during the construction of the object for read

     * operations.

     * @throws errno value in case open failed.

     */

    virtual void openForReading();

    /**

     * Opens the file specified during the construction of the object for write

     * operations.

     * @throws errno value in case open failed.

     */

    virtual void openForWriting(const long aOffset);

    /**

     * Skips aOffset number of bytes.

     * Positive value of aOffset moves the position forward and negatve backwards.

     * Return value is the actual value that can be skipped.

     */

    virtual long skip(const long aOffset);

    /**

     * Closes the file descriptors but will not delete all data.

     * On next call to read or write, we continue from previous offset.

     */

    virtual void closeFileToReopen();

    /**

     * Returns the amount of data available in the file from current read offset.

     */

    virtual long available();

protected:

    virtual void handleReopenCase();

private:

    void closeStream();

    NativeFileIOHandler();

protected:

    // Name of the file to which the stream is opened

    std::wstring mFileName;

    // Will be set in case the descriptors were closed temporarily. On next call

    // to read or write, we re-open the file and continue with previous offset.

    bool mClosedTemporarily;

private:

    // Stream to do read and write

    int mFileDescriptor;

    // Holds the mode in which the file has to be opened

    int mFileAccessMode;

    // Holds the current read position

    long mReadPosition;

    // Holds the current write position

    long mWritePosition;

};

} // end namespace fileutils

} // end namespace java

#endif // NATIVEFILEIOHANDLER_H