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include/blockio.h

Go to the documentation of this file.

/**********************************************************************
 * Copyright 2002 Jeff Rush <jrush@taupro.com>
 * Original Copyright 1979-2002 Udanax.com
 *
 * This file is part of the Udanax xanalogical storage system.
 *
 * Udanax is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Udanax is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Udanax; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 **********************************************************************/

/* Modification History:
 * $Log: blockio.h,v $
 * Revision 1.5  2004/08/28 13:35:25  jrush
 * Catching up CVS to various incomplete versions on local disk.
 *
 *
 */

#ifndef __UDANAX_BLOCKIO_H__
#define __UDANAX_BLOCKIO_H__

typedef unsigned int BlockNum;
#define NULLBLOCKNUM static_cast<BlockNum>(~0) //Invalid Disk Address: All Ones

// Usage Note: if you try to get a block that hasn't been written, you get a block of garbage.

class BlockIO
{
  protected:
    struct stats {
        unsigned long blocks_read;    
        unsigned long blocks_written; 
    } stats;

    int blocksize;      

  public:
    enum OpenStatus {
        OS_FAILED  = -1,  
        OS_OPENED  =  0,  
        OS_CREATED =  1,  
    };

    BlockIO(int blocksize=4096)
    : blocksize(blocksize)
    {}

//    virtual ~BlockIO() { if (isopen) close(); }

    virtual OpenStatus  open(const char *name) = 0;
    virtual bool const  is_open() = 0;
    virtual void        close() = 0;

    virtual bool get(void *buf, int buflen, BlockNum blockno) = 0;
    virtual bool put(void *buf, int buflen, BlockNum blockno) = 0;

    unsigned long blocksRead()    const { return stats.blocks_read; }
    unsigned long blocksWritten() const { return stats.blocks_written; }
};

class FileBlockIO: public BlockIO
{
  protected:

  public:
    int blockfd; //fixme: temporarily public during code transition

    FileBlockIO(int blocksize=4096)
    : BlockIO(blocksize), blockfd(-1) { }
//    virtual ~FileBlockIO() {}

    virtual OpenStatus  open(const char *filename="enf.enf");
    virtual bool const  is_open() { return blockfd >= 0; }
    virtual void        close();

    virtual bool get(void *buf, int buflen, BlockNum blockno);
    virtual bool put(void *buf, int buflen, BlockNum blockno);
};

#endif /* !__UDANAX_BLOCKIO_H__*/

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