ext2_io.h revision d2bfdc7ff15ce7b6b40c087021528ce190ef43c3 
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)
19typedef long long	ext2_loff_t;
20#else
21typedef long		ext2_loff_t;
22#endif
23
24/* llseek.c */
25ext2_loff_t ext2fs_llseek (int, ext2_loff_t, int);
26
27typedef struct struct_io_manager *io_manager;
28typedef struct struct_io_channel *io_channel;
29typedef 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
37struct 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};
62
63struct struct_io_stats {
64	int			num_fields;
65	int			reserved;
66	unsigned long long	bytes_read;
67	unsigned long long	bytes_written;
68};
69
70struct struct_io_manager {
71	errcode_t magic;
72	const char *name;
73	errcode_t (*open)(const char *name, int flags, io_channel *channel);
74	errcode_t (*close)(io_channel channel);
75	errcode_t (*set_blksize)(io_channel channel, int blksize);
76	errcode_t (*read_blk)(io_channel channel, unsigned long block,
77			      int count, void *data);
78	errcode_t (*write_blk)(io_channel channel, unsigned long block,
79			       int count, const void *data);
80	errcode_t (*flush)(io_channel channel);
81	errcode_t (*write_byte)(io_channel channel, unsigned long offset,
82				int count, const void *data);
83	errcode_t (*set_option)(io_channel channel, const char *option,
84				const char *arg);
85	errcode_t (*get_stats)(io_channel channel, io_stats *io_stats);
86	errcode_t (*read_blk64)(io_channel channel, unsigned long long block,
87					int count, void *data);
88	errcode_t (*write_blk64)(io_channel channel, unsigned long long block,
89					int count, const void *data);
90	errcode_t (*discard)(io_channel channel, unsigned long long block,
91			     unsigned long long count);
92	long	reserved[16];
93};
94
95#define IO_FLAG_RW		0x0001
96#define IO_FLAG_EXCLUSIVE	0x0002
97#define IO_FLAG_DIRECT_IO	0x0004
98
99/*
100 * Convenience functions....
101 */
102#define io_channel_close(c) 		((c)->manager->close((c)))
103#define io_channel_set_blksize(c,s)	((c)->manager->set_blksize((c),s))
104#define io_channel_read_blk(c,b,n,d)	((c)->manager->read_blk((c),b,n,d))
105#define io_channel_write_blk(c,b,n,d)	((c)->manager->write_blk((c),b,n,d))
106#define io_channel_flush(c) 		((c)->manager->flush((c)))
107#define io_channel_bumpcount(c)		((c)->refcount++)
108
109/* io_manager.c */
110extern errcode_t io_channel_set_options(io_channel channel,
111					const char *options);
112extern errcode_t io_channel_write_byte(io_channel channel,
113				       unsigned long offset,
114				       int count, const void *data);
115extern errcode_t io_channel_read_blk64(io_channel channel,
116				       unsigned long long block,
117				       int count, void *data);
118extern errcode_t io_channel_write_blk64(io_channel channel,
119					unsigned long long block,
120					int count, const void *data);
121extern errcode_t io_channel_discard(io_channel channel,
122				    unsigned long long block,
123				    unsigned long long count);
124
125/* unix_io.c */
126extern io_manager unix_io_manager;
127
128/* undo_io.c */
129extern io_manager undo_io_manager;
130extern errcode_t set_undo_io_backing_manager(io_manager manager);
131extern errcode_t set_undo_io_backup_file(char *file_name);
132
133/* test_io.c */
134extern io_manager test_io_manager, test_io_backing_manager;
135extern void (*test_io_cb_read_blk)
136	(unsigned long block, int count, errcode_t err);
137extern void (*test_io_cb_write_blk)
138	(unsigned long block, int count, errcode_t err);
139extern void (*test_io_cb_read_blk64)
140	(unsigned long long block, int count, errcode_t err);
141extern void (*test_io_cb_write_blk64)
142	(unsigned long long block, int count, errcode_t err);
143extern void (*test_io_cb_set_blksize)
144	(int blksize, errcode_t err);
145
146#endif /* _EXT2FS_EXT2_IO_H */
147
148