include/ext2fs/ext2_io.h

   1 /*
   2  * io.h --- the I/O manager abstraction
   3  *
   4  * Copyright (C) 1993, 1994, 1995, 1996 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the GNU Public
   8  * License.
   9  * %End-Header%
  10  */
  11
  12 #ifndef _EXT2FS_EXT2_IO_H
  13 #define _EXT2FS_EXT2_IO_H
  14
  15 /*
  16  * ext2_loff_t is defined here since unix_io.c needs it.
  17  */
  18 #if defined(__GNUC__) || defined(HAS_LONG_LONG)
  19 typedef long long       ext2_loff_t;
  20 #else
  21 typedef long            ext2_loff_t;
  22 #endif
  23
  24 /* llseek.c */
  25 ext2_loff_t ext2fs_llseek (int, ext2_loff_t, int);
  26
  27 typedef struct struct_io_manager *io_manager;
  28 typedef struct struct_io_channel *io_channel;
  29
  30 struct struct_io_channel {
  31         errcode_t       magic;
  32         io_manager      manager;
  33         char            *name;
  34         int             block_size;
  35         errcode_t       (*read_error)(io_channel channel,
  36                                       unsigned long block,
  37                                       int count,
  38                                       void *data,
  39                                       size_t size,
  40                                       int actual_bytes_read,
  41                                       errcode_t error);
  42         errcode_t       (*write_error)(io_channel channel,
  43                                        unsigned long block,
  44                                        int count,
  45                                        const void *data,
  46                                        size_t size,
  47                                        int actual_bytes_written,
  48                                        errcode_t error);
  49         int             refcount;
  50         int             reserved[15];
  51         void            *private_data;
  52         void            *app_data;
  53 };
  54
  55 struct struct_io_manager {
  56         errcode_t magic;
  57         const char *name;
  58         errcode_t (*open)(const char *name, int flags, io_channel *channel);
  59         errcode_t (*close)(io_channel channel);
  60         errcode_t (*set_blksize)(io_channel channel, int blksize);
  61         errcode_t (*read_blk)(io_channel channel, unsigned long block,
  62                               int count, void *data);
  63         errcode_t (*write_blk)(io_channel channel, unsigned long block,
  64                                int count, const void *data);
  65         errcode_t (*flush)(io_channel channel);
  66         int             reserved[16];
  67 };
  68
  69 #define IO_FLAG_RW      1
  70
  71 /*
  72  * Convenience functions....
  73  */
  74 #define io_channel_close(c)             ((c)->manager->close((c)))
  75 #define io_channel_set_blksize(c,s)     ((c)->manager->set_blksize((c),s))
  76 #define io_channel_read_blk(c,b,n,d)    ((c)->manager->read_blk((c),b,n,d))
  77 #define io_channel_write_blk(c,b,n,d)   ((c)->manager->write_blk((c),b,n,d))
  78 #define io_channel_flush(c)             ((c)->manager->flush((c)))
  79 #define io_channel_bumpcount(c)         ((c)->refcount++)
  80
  81 /* unix_io.c */
  82 extern io_manager unix_io_manager;
  83
  84 /* test_io.c */
  85 extern io_manager test_io_manager, test_io_backing_manager;
  86 extern void (*test_io_cb_read_blk)
  87         (unsigned long block, int count, errcode_t err);
  88 extern void (*test_io_cb_write_blk)
  89         (unsigned long block, int count, errcode_t err);
  90 extern void (*test_io_cb_set_blksize)
  91         (int blksize, errcode_t err);
  92
  93 #endif /* _EXT2FS_EXT2_IO_H */
  94