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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef __CRAMFS_H
2#define __CRAMFS_H
3
David Woodhouse05f75fd2006-05-04 17:50:04 +01004#include <linux/types.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -07005
6#define CRAMFS_MAGIC 0x28cd3d45 /* some random number */
7#define CRAMFS_SIGNATURE "Compressed ROMFS"
8
9/*
10 * Width of various bitfields in struct cramfs_inode.
11 * Primarily used to generate warnings in mkcramfs.
12 */
13#define CRAMFS_MODE_WIDTH 16
14#define CRAMFS_UID_WIDTH 16
15#define CRAMFS_SIZE_WIDTH 24
16#define CRAMFS_GID_WIDTH 8
17#define CRAMFS_NAMELEN_WIDTH 6
18#define CRAMFS_OFFSET_WIDTH 26
19
20/*
21 * Since inode.namelen is a unsigned 6-bit number, the maximum cramfs
22 * path length is 63 << 2 = 252.
23 */
24#define CRAMFS_MAXPATHLEN (((1 << CRAMFS_NAMELEN_WIDTH) - 1) << 2)
25
26/*
27 * Reasonably terse representation of the inode data.
28 */
29struct cramfs_inode {
David Woodhouse05f75fd2006-05-04 17:50:04 +010030 __u32 mode:CRAMFS_MODE_WIDTH, uid:CRAMFS_UID_WIDTH;
Linus Torvalds1da177e2005-04-16 15:20:36 -070031 /* SIZE for device files is i_rdev */
David Woodhouse05f75fd2006-05-04 17:50:04 +010032 __u32 size:CRAMFS_SIZE_WIDTH, gid:CRAMFS_GID_WIDTH;
Linus Torvalds1da177e2005-04-16 15:20:36 -070033 /* NAMELEN is the length of the file name, divided by 4 and
34 rounded up. (cramfs doesn't support hard links.) */
35 /* OFFSET: For symlinks and non-empty regular files, this
36 contains the offset (divided by 4) of the file data in
37 compressed form (starting with an array of block pointers;
38 see README). For non-empty directories it is the offset
39 (divided by 4) of the inode of the first file in that
40 directory. For anything else, offset is zero. */
David Woodhouse05f75fd2006-05-04 17:50:04 +010041 __u32 namelen:CRAMFS_NAMELEN_WIDTH, offset:CRAMFS_OFFSET_WIDTH;
Linus Torvalds1da177e2005-04-16 15:20:36 -070042};
43
44struct cramfs_info {
David Woodhouse05f75fd2006-05-04 17:50:04 +010045 __u32 crc;
46 __u32 edition;
47 __u32 blocks;
48 __u32 files;
Linus Torvalds1da177e2005-04-16 15:20:36 -070049};
50
51/*
52 * Superblock information at the beginning of the FS.
53 */
54struct cramfs_super {
David Woodhouse05f75fd2006-05-04 17:50:04 +010055 __u32 magic; /* 0x28cd3d45 - random number */
56 __u32 size; /* length in bytes */
57 __u32 flags; /* feature flags */
58 __u32 future; /* reserved for future use */
59 __u8 signature[16]; /* "Compressed ROMFS" */
Linus Torvalds1da177e2005-04-16 15:20:36 -070060 struct cramfs_info fsid; /* unique filesystem info */
David Woodhouse05f75fd2006-05-04 17:50:04 +010061 __u8 name[16]; /* user-defined name */
Linus Torvalds1da177e2005-04-16 15:20:36 -070062 struct cramfs_inode root; /* root inode data */
63};
64
65/*
66 * Feature flags
67 *
68 * 0x00000000 - 0x000000ff: features that work for all past kernels
69 * 0x00000100 - 0xffffffff: features that don't work for past kernels
70 */
71#define CRAMFS_FLAG_FSID_VERSION_2 0x00000001 /* fsid version #2 */
72#define CRAMFS_FLAG_SORTED_DIRS 0x00000002 /* sorted dirs */
73#define CRAMFS_FLAG_HOLES 0x00000100 /* support for holes */
74#define CRAMFS_FLAG_WRONG_SIGNATURE 0x00000200 /* reserved */
75#define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400 /* shifted root fs */
76
77/*
78 * Valid values in super.flags. Currently we refuse to mount
79 * if (flags & ~CRAMFS_SUPPORTED_FLAGS). Maybe that should be
80 * changed to test super.future instead.
81 */
82#define CRAMFS_SUPPORTED_FLAGS ( 0x000000ff \
83 | CRAMFS_FLAG_HOLES \
84 | CRAMFS_FLAG_WRONG_SIGNATURE \
85 | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET )
86
87/* Uncompression interfaces to the underlying zlib */
88int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen);
89int cramfs_uncompress_init(void);
Alexey Dobriyan368bdb32006-09-29 02:01:05 -070090void cramfs_uncompress_exit(void);
Linus Torvalds1da177e2005-04-16 15:20:36 -070091
92#endif