path: root/src/include/usr/util/utilstream.H

/* IBM_PROLOG_BEGIN_TAG                                                   */
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/* $Source: src/include/usr/util/utilstream.H $                           */
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/* OpenPOWER HostBoot Project                                             */
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/* Contributors Listed Below - COPYRIGHT 2012,2015                        */
/* [+] International Business Machines Corp.                              */
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/* IBM_PROLOG_END_TAG                                                     */

#ifndef UTILSTREAM_H
#define UTILSTREAM_H

/**
 * @file utilstream.H
 *
 * @brief       Stream manipulation
 *
 * Used for creating and manipulating streams
 *
 */

/*****************************************************************************/
// I n c l u d e s
/*****************************************************************************/
#include <stdint.h>
#include <errl/errlentry.H>

/*****************************************************************************/
// User Types
/*****************************************************************************/

//*****************************************************************************/
// C o n s t a n t s
/*****************************************************************************/

/*****************************************************************************/
// Stream class
/*****************************************************************************/
/**
 *  @brief  Stream Base class
 *
 *  Stream interface specification
 *
 */
class UtilStream
{
  public:

    enum whence
    {
        CURRENT = 0,
        START = 1,
        END = 2
    };


    /**
     *  @brief Default constructor
     *
     *  Initializes internals of the stream object.
     *
     */
    UtilStream();

    /**
     *  @brief Destructor
     *
     */
    virtual ~UtilStream();

    /**
     *  @brief Reads data from current position of the stream
     *
     *  Reads data from the current position of the stream for the
     *  specified number of bytes.
     *
     *  @return # of bytes read or zero if none.
     *
     *  @note Errors are not reported by this interface, instead
     *        the user must call getLastError.
     *
     */
    virtual uint32_t read(
        void *      o_buffer,   ///< Buffer data is read into
        uint32_t    i_size      ///< Size in bytes of data to be read
        ) = 0;

    /**
     *  @brief Writes data to current position of the stream
     *
     *  Writes data to the current position of the stream for the
     *  specified number of bytes.
     *
     *  @return # of bytes written or zero if none.
     *
     *  @note Errors are not reported by this interface, instead
     *        the user must call getLastError.
     *
     */
    virtual uint32_t write(
        const void *i_buffer,   ///< Source buffer data is written from
        uint32_t    i_size      ///< Size in bytes of data to be written
        ) = 0;

    /**
     *  @brief Seek to the specified position in the stream
     *
     *  Performs a seek based on the specified position and offset.
     *
     *  @return Current file position after the interface completes.
     *
     *  @note Errors are not reported by this interface, instead
     *        the user must call getLastError.
     *
     *  @example
     *  // To Get the current file position
     *
     *  UtilFile    l_file;
     *  ...
     *  uint32_t l_curpos = l_file.seek( 0, l_file.CURRENT );
     *
     *  @endexample
     *
     */
    virtual uint32_t seek(
        int32_t     i_pos,      ///< Seek offset in bytes
        whence      i_whence    ///< Position to seek from
        ) = 0;

    /**
     *  @brief Return the current size of the stream
     *
     *  Returns the current size of the stream.
     *
     */
    virtual uint32_t size() const = 0;

    /**
     *  @brief Return EOF status
     *
     *  Returns true if EOF has been reached, and false if it has not been
     *  reached.
     *
     */
    bool eof();

    /**
     *  @brief Get the last error received.
     *
     *  Returns the last error received and clears error status.
     *
     *  @note clearing the error status involves returning the last
     *        error and setting eof to false.  In other words, it wipes
     *        the slate clean.
     *
     */
    errlHndl_t getLastError();

    /**
     *  @brief Set the last error received.
     *
     *  Replaces the last error with the user supplied parameter.
     *
     *  @note If an error exists, it will be deleted and replaced by this
     *        call.  For this reason, the user should normally do one
     *        of the following:
     *        1. getLastError & append then setLastError, or
     *        2. peekLastError & append, or if it's null, just setLastError
     *
     */
    void setLastError( errlHndl_t i_error );

    /**
     *  @brief Peek last error
     *
     *  Returns the last error received but does NOT clear the error status.
     *
     *  @note
     *      The returned handle should not be:
     *      1. committed
     *      2. deleted
     *
     *      under any circumstances since it belongs to the UtilStream
     *      object.
     *
     */
    errlHndl_t peekLastError() const;

    /**
     *  @brief General Insertion to cover all outstanding cases
     *
     *  Writes the data value to the stream
     *
     *  @return A reference to the stream
     *
     *  @note Errors are not reported by this interface, instead
     *        the user must call getLastError.
     *
     */
    template< class D >
    UtilStream & operator<< ( const D & i_right )
    {
        write( &i_right, sizeof(D) );
        return *this;
    }

    /**
     *  @brief General Extraction to cover all outstanding cases
     *
     *  Reads the data value from the stream
     *
     *  @return A reference to the stream
     *
     *  @note Errors are not reported by this interface, instead
     *        the user must call getLastError.
     *
     */
    template< class D >
    UtilStream & operator>> ( D & i_right )
    {
        read( &i_right, sizeof(D) );
        return *this;
    }

protected:

    /**
     * @brief   Assignment operator
     *
     * Deletes any pending errors, and copies the eof file
     * from the right hand operand.
     *
     * @return A stream reference
     *
    */
    UtilStream & operator = ( const UtilStream & i_right );


    bool                iv_eof;                 ///<Stream EOF
    mutable errlHndl_t  iv_lastError;           ///<Last Error


private:

    // Disable assignment & copy-constructor until the meaning is defined
    UtilStream( const UtilStream & i_right );


};


/*****************************************************************************/
// I n l i n e s
/*****************************************************************************/

/*****************************************************************************/
// Query End of File
/*****************************************************************************/
inline bool UtilStream::eof()
{
    return iv_eof;
}


/*****************************************************************************/
// Get the last Error Log
/*****************************************************************************/
inline errlHndl_t UtilStream::getLastError()
{
    errlHndl_t l_lastError;

    l_lastError = iv_lastError;

    // Clear the error condition
    iv_lastError = 0;
    iv_eof = false;

    return l_lastError;
}


/*****************************************************************************/
// Peek last Error Log
/*****************************************************************************/
inline errlHndl_t UtilStream::peekLastError() const
{
    return iv_lastError;
}

#endif //UTILSTREAM_H