lib/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 Library
   8  * General Public License, version 2.
   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 typedef struct struct_io_stats *io_stats;
  30
  31 #define CHANNEL_FLAGS_WRITETHROUGH      0x01
  32 #define CHANNEL_FLAGS_DISCARD_ZEROES    0x02
  33 #define CHANNEL_FLAGS_BLOCK_DEVICE      0x04
  34
  35 #define io_channel_discard_zeroes_data(i) (i->flags & CHANNEL_FLAGS_DISCARD_ZEROES)
  36
  37 struct struct_io_channel {
  38         errcode_t       magic;
  39         io_manager      manager;
  40         char            *name;
  41         int             block_size;
  42         errcode_t       (*read_error)(io_channel channel,
  43                                       unsigned long block,
  44                                       int count,
  45                                       void *data,
  46                                       size_t size,
  47                                       int actual_bytes_read,
  48                                       errcode_t error);
  49         errcode_t       (*write_error)(io_channel channel,
  50                                        unsigned long block,
  51                                        int count,
  52                                        const void *data,
  53                                        size_t size,
  54                                        int actual_bytes_written,
  55                                        errcode_t error);
  56         int             refcount;
  57         int             flags;
  58         long            reserved[14];
  59         void            *private_data;
  60         void            *app_data;
  61         int             align;
  62 };
  63
  64 struct struct_io_stats {
  65         int                     num_fields;
  66         int                     reserved;
  67         unsigned long long      bytes_read;
  68         unsigned long long      bytes_written;
  69 };
  70
  71 struct struct_io_manager {
  72         errcode_t magic;
  73         const char *name;
  74         errcode_t (*open)(const char *name, int flags, io_channel *channel);
  75         errcode_t (*close)(io_channel channel);
  76         errcode_t (*set_blksize)(io_channel channel, int blksize);
  77         errcode_t (*read_blk)(io_channel channel, unsigned long block,
  78                               int count, void *data);
  79         errcode_t (*write_blk)(io_channel channel, unsigned long block,
  80                                int count, const void *data);
  81         errcode_t (*flush)(io_channel channel);
  82         errcode_t (*write_byte)(io_channel channel, unsigned long offset,
  83                                 int count, const void *data);
  84         errcode_t (*set_option)(io_channel channel, const char *option,
  85                                 const char *arg);
  86         errcode_t (*get_stats)(io_channel channel, io_stats *io_stats);
  87         errcode_t (*read_blk64)(io_channel channel, unsigned long long block,
  88                                         int count, void *data);
  89         errcode_t (*write_blk64)(io_channel channel, unsigned long long block,
  90                                         int count, const void *data);
  91         errcode_t (*discard)(io_channel channel, unsigned long long block,
  92                              unsigned long long count);
  93         errcode_t (*cache_readahead)(io_channel channel,
  94                                      unsigned long long block,
  95                                      unsigned long long count);
  96         long    reserved[15];
  97 };
  98
  99 #define IO_FLAG_RW              0x0001
 100 #define IO_FLAG_EXCLUSIVE       0x0002
 101 #define IO_FLAG_DIRECT_IO       0x0004
 102
 103 /*
 104  * Convenience functions....
 105  */
 106 #define io_channel_close(c)             ((c)->manager->close((c)))
 107 #define io_channel_set_blksize(c,s)     ((c)->manager->set_blksize((c),s))
 108 #define io_channel_read_blk(c,b,n,d)    ((c)->manager->read_blk((c),b,n,d))
 109 #define io_channel_write_blk(c,b,n,d)   ((c)->manager->write_blk((c),b,n,d))
 110 #define io_channel_flush(c)             ((c)->manager->flush((c)))
 111 #define io_channel_bumpcount(c)         ((c)->refcount++)
 112
 113 /* io_manager.c */
 114 extern errcode_t io_channel_set_options(io_channel channel,
 115                                         const char *options);
 116 extern errcode_t io_channel_write_byte(io_channel channel,
 117                                        unsigned long offset,
 118                                        int count, const void *data);
 119 extern errcode_t io_channel_read_blk64(io_channel channel,
 120                                        unsigned long long block,
 121                                        int count, void *data);
 122 extern errcode_t io_channel_write_blk64(io_channel channel,
 123                                         unsigned long long block,
 124                                         int count, const void *data);
 125 extern errcode_t io_channel_discard(io_channel channel,
 126                                     unsigned long long block,
 127                                     unsigned long long count);
 128 extern errcode_t io_channel_alloc_buf(io_channel channel,
 129                                       int count, void *ptr);
 130 extern errcode_t io_channel_cache_readahead(io_channel io,
 131                                             unsigned long long block,
 132                                             unsigned long long count);
 133
 134 /* unix_io.c */
 135 extern io_manager unix_io_manager;
 136
 137 /* undo_io.c */
 138 extern io_manager undo_io_manager;
 139 extern errcode_t set_undo_io_backing_manager(io_manager manager);
 140 extern errcode_t set_undo_io_backup_file(char *file_name);
 141
 142 /* test_io.c */
 143 extern io_manager test_io_manager, test_io_backing_manager;
 144 extern void (*test_io_cb_read_blk)
 145         (unsigned long block, int count, errcode_t err);
 146 extern void (*test_io_cb_write_blk)
 147         (unsigned long block, int count, errcode_t err);
 148 extern void (*test_io_cb_read_blk64)
 149         (unsigned long long block, int count, errcode_t err);
 150 extern void (*test_io_cb_write_blk64)
 151         (unsigned long long block, int count, errcode_t err);
 152 extern void (*test_io_cb_set_blksize)
 153         (int blksize, errcode_t err);
 154
 155 #endif /* _EXT2FS_EXT2_IO_H */
 156