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ext2_io.h

/*
 * io.h --- the I/O manager abstraction
 * 
 * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#ifndef _EXT2FS_EXT2_IO_H
#define _EXT2FS_EXT2_IO_H

/*
 * ext2_loff_t is defined here since unix_io.c needs it.
 */
#if defined(__GNUC__) || defined(HAS_LONG_LONG)
typedef long long ext2_loff_t;
#else
typedef long            ext2_loff_t;
#endif

/* llseek.c */
ext2_loff_t ext2fs_llseek (int, ext2_loff_t, int);

typedef struct struct_io_manager *io_manager;
typedef struct struct_io_channel *io_channel;

struct struct_io_channel {
      errcode_t   magic;
      io_manager  manager;
      char        *name;
      int         block_size;
      errcode_t   (*read_error)(io_channel channel,
                              unsigned long block,
                              int count,
                              void *data,
                              size_t size,
                              int actual_bytes_read,
                              errcode_t   error);
      errcode_t   (*write_error)(io_channel channel,
                               unsigned long block,
                               int count,
                               const void *data,
                               size_t size,
                               int actual_bytes_written,
                               errcode_t error);
      int         refcount;
      int         reserved[15];
      void        *private_data;
      void        *app_data;
};

struct struct_io_manager {
      errcode_t magic;
      const char *name;
      errcode_t (*open)(const char *name, int flags, io_channel *channel);
      errcode_t (*close)(io_channel channel);
      errcode_t (*set_blksize)(io_channel channel, int blksize);
      errcode_t (*read_blk)(io_channel channel, unsigned long block,
                        int count, void *data);
      errcode_t (*write_blk)(io_channel channel, unsigned long block,
                         int count, const void *data);
      errcode_t (*flush)(io_channel channel);
      int         reserved[16];
};

#define IO_FLAG_RW      1

/*
 * Convenience functions....
 */
#define io_channel_close(c)         ((c)->manager->close((c)))
#define io_channel_set_blksize(c,s) ((c)->manager->set_blksize((c),s))
#define io_channel_read_blk(c,b,n,d)      ((c)->manager->read_blk((c),b,n,d))
#define io_channel_write_blk(c,b,n,d)     ((c)->manager->write_blk((c),b,n,d))
#define io_channel_flush(c)         ((c)->manager->flush((c)))
#define io_channel_bumpcount(c)           ((c)->refcount++)
      
/* unix_io.c */
extern io_manager unix_io_manager;

/* test_io.c */
extern io_manager test_io_manager, test_io_backing_manager;
extern void (*test_io_cb_read_blk)
      (unsigned long block, int count, errcode_t err);
extern void (*test_io_cb_write_blk)
      (unsigned long block, int count, errcode_t err);
extern void (*test_io_cb_set_blksize)
      (int blksize, errcode_t err);

#endif /* _EXT2FS_EXT2_IO_H */
      

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