ext2_io.h revision 2e8ca9a26b0bd7dae546a3f9a98df67b043fe3be 
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)
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;
29
30#define CHANNEL_FLAGS_WRITETHROUGH	0x01
31
32struct struct_io_channel {
33	errcode_t	magic;
34	io_manager	manager;
35	char		*name;
36	int		block_size;
37	errcode_t	(*read_error)(io_channel channel,
38				      unsigned long block,
39				      int count,
40				      void *data,
41				      size_t size,
42				      int actual_bytes_read,
43				      errcode_t	error);
44	errcode_t	(*write_error)(io_channel channel,
45				       unsigned long block,
46				       int count,
47				       const void *data,
48				       size_t size,
49				       int actual_bytes_written,
50				       errcode_t error);
51	int		refcount;
52	int		flags;
53	int		reserved[14];
54	void		*private_data;
55	void		*app_data;
56};
57
58struct struct_io_manager {
59	errcode_t magic;
60	const char *name;
61	errcode_t (*open)(const char *name, int flags, io_channel *channel);
62	errcode_t (*close)(io_channel channel);
63	errcode_t (*set_blksize)(io_channel channel, int blksize);
64	errcode_t (*read_blk)(io_channel channel, unsigned long block,
65			      int count, void *data);
66	errcode_t (*write_blk)(io_channel channel, unsigned long block,
67			       int count, const void *data);
68	errcode_t (*flush)(io_channel channel);
69	errcode_t (*write_byte)(io_channel channel, unsigned long offset,
70				int count, const void *data);
71	errcode_t (*set_option)(io_channel channel, const char *option,
72				const char *arg);
73	int		reserved[14];
74};
75
76#define IO_FLAG_RW	1
77
78/*
79 * Convenience functions....
80 */
81#define io_channel_close(c) 		((c)->manager->close((c)))
82#define io_channel_set_blksize(c,s)	((c)->manager->set_blksize((c),s))
83#define io_channel_read_blk(c,b,n,d)	((c)->manager->read_blk((c),b,n,d))
84#define io_channel_write_blk(c,b,n,d)	((c)->manager->write_blk((c),b,n,d))
85#define io_channel_flush(c) 		((c)->manager->flush((c)))
86#define io_channel_bumpcount(c)		((c)->refcount++)
87
88/* io_manager.c */
89extern errcode_t io_channel_set_options(io_channel channel,
90					const char *options);
91extern errcode_t io_channel_write_byte(io_channel channel,
92				       unsigned long offset,
93				       int count, const void *data);
94
95/* unix_io.c */
96extern io_manager unix_io_manager;
97
98/* test_io.c */
99extern io_manager test_io_manager, test_io_backing_manager;
100extern void (*test_io_cb_read_blk)
101	(unsigned long block, int count, errcode_t err);
102extern void (*test_io_cb_write_blk)
103	(unsigned long block, int count, errcode_t err);
104extern void (*test_io_cb_set_blksize)
105	(int blksize, errcode_t err);
106
107#endif /* _EXT2FS_EXT2_IO_H */
108
109