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      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 
     33 struct struct_io_channel {
     34 	errcode_t	magic;
     35 	io_manager	manager;
     36 	char		*name;
     37 	int		block_size;
     38 	errcode_t	(*read_error)(io_channel channel,
     39 				      unsigned long block,
     40 				      int count,
     41 				      void *data,
     42 				      size_t size,
     43 				      int actual_bytes_read,
     44 				      errcode_t	error);
     45 	errcode_t	(*write_error)(io_channel channel,
     46 				       unsigned long block,
     47 				       int count,
     48 				       const void *data,
     49 				       size_t size,
     50 				       int actual_bytes_written,
     51 				       errcode_t error);
     52 	int		refcount;
     53 	int		flags;
     54 	long		reserved[14];
     55 	void		*private_data;
     56 	void		*app_data;
     57 };
     58 
     59 struct struct_io_stats {
     60 	int			num_fields;
     61 	int			reserved;
     62 	unsigned long long	bytes_read;
     63 	unsigned long long	bytes_written;
     64 };
     65 
     66 struct struct_io_manager {
     67 	errcode_t magic;
     68 	const char *name;
     69 	errcode_t (*open)(const char *name, int flags, io_channel *channel);
     70 	errcode_t (*close)(io_channel channel);
     71 	errcode_t (*set_blksize)(io_channel channel, int blksize);
     72 	errcode_t (*read_blk)(io_channel channel, unsigned long block,
     73 			      int count, void *data);
     74 	errcode_t (*write_blk)(io_channel channel, unsigned long block,
     75 			       int count, const void *data);
     76 	errcode_t (*flush)(io_channel channel);
     77 	errcode_t (*write_byte)(io_channel channel, unsigned long offset,
     78 				int count, const void *data);
     79 	errcode_t (*set_option)(io_channel channel, const char *option,
     80 				const char *arg);
     81 	errcode_t (*get_stats)(io_channel channel, io_stats *io_stats);
     82 	errcode_t (*read_blk64)(io_channel channel, unsigned long long block,
     83 					int count, void *data);
     84 	errcode_t (*write_blk64)(io_channel channel, unsigned long long block,
     85 					int count, const void *data);
     86 	long	reserved[16];
     87 };
     88 
     89 #define IO_FLAG_RW		0x0001
     90 #define IO_FLAG_EXCLUSIVE	0x0002
     91 #define IO_FLAG_DIRECT_IO	0x0004
     92 
     93 /*
     94  * Convenience functions....
     95  */
     96 #define io_channel_close(c) 		((c)->manager->close((c)))
     97 #define io_channel_set_blksize(c,s)	((c)->manager->set_blksize((c),s))
     98 #define io_channel_read_blk(c,b,n,d)	((c)->manager->read_blk((c),b,n,d))
     99 #define io_channel_write_blk(c,b,n,d)	((c)->manager->write_blk((c),b,n,d))
    100 #define io_channel_flush(c) 		((c)->manager->flush((c)))
    101 #define io_channel_bumpcount(c)		((c)->refcount++)
    102 
    103 /* io_manager.c */
    104 extern errcode_t io_channel_set_options(io_channel channel,
    105 					const char *options);
    106 extern errcode_t io_channel_write_byte(io_channel channel,
    107 				       unsigned long offset,
    108 				       int count, const void *data);
    109 extern errcode_t io_channel_read_blk64(io_channel channel,
    110 				       unsigned long long block,
    111 				       int count, void *data);
    112 extern errcode_t io_channel_write_blk64(io_channel channel,
    113 					unsigned long long block,
    114 					int count, const void *data);
    115 
    116 /* unix_io.c */
    117 extern io_manager unix_io_manager;
    118 
    119 /* undo_io.c */
    120 extern io_manager undo_io_manager;
    121 extern errcode_t set_undo_io_backing_manager(io_manager manager);
    122 extern errcode_t set_undo_io_backup_file(char *file_name);
    123 
    124 /* test_io.c */
    125 extern io_manager test_io_manager, test_io_backing_manager;
    126 extern void (*test_io_cb_read_blk)
    127 	(unsigned long block, int count, errcode_t err);
    128 extern void (*test_io_cb_write_blk)
    129 	(unsigned long block, int count, errcode_t err);
    130 extern void (*test_io_cb_set_blksize)
    131 	(int blksize, errcode_t err);
    132 
    133 #endif /* _EXT2FS_EXT2_IO_H */
    134 
    135