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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef __CRAMFS_H
2#define __CRAMFS_H
3
4#ifndef __KERNEL__
5
6typedef unsigned char u8;
7typedef unsigned short u16;
8typedef unsigned int u32;
9
10#endif
11
12#define CRAMFS_MAGIC 0x28cd3d45 /* some random number */
13#define CRAMFS_SIGNATURE "Compressed ROMFS"
14
15/*
16 * Width of various bitfields in struct cramfs_inode.
17 * Primarily used to generate warnings in mkcramfs.
18 */
19#define CRAMFS_MODE_WIDTH 16
20#define CRAMFS_UID_WIDTH 16
21#define CRAMFS_SIZE_WIDTH 24
22#define CRAMFS_GID_WIDTH 8
23#define CRAMFS_NAMELEN_WIDTH 6
24#define CRAMFS_OFFSET_WIDTH 26
25
26/*
27 * Since inode.namelen is a unsigned 6-bit number, the maximum cramfs
28 * path length is 63 << 2 = 252.
29 */
30#define CRAMFS_MAXPATHLEN (((1 << CRAMFS_NAMELEN_WIDTH) - 1) << 2)
31
32/*
33 * Reasonably terse representation of the inode data.
34 */
35struct cramfs_inode {
36 u32 mode:CRAMFS_MODE_WIDTH, uid:CRAMFS_UID_WIDTH;
37 /* SIZE for device files is i_rdev */
38 u32 size:CRAMFS_SIZE_WIDTH, gid:CRAMFS_GID_WIDTH;
39 /* NAMELEN is the length of the file name, divided by 4 and
40 rounded up. (cramfs doesn't support hard links.) */
41 /* OFFSET: For symlinks and non-empty regular files, this
42 contains the offset (divided by 4) of the file data in
43 compressed form (starting with an array of block pointers;
44 see README). For non-empty directories it is the offset
45 (divided by 4) of the inode of the first file in that
46 directory. For anything else, offset is zero. */
47 u32 namelen:CRAMFS_NAMELEN_WIDTH, offset:CRAMFS_OFFSET_WIDTH;
48};
49
50struct cramfs_info {
51 u32 crc;
52 u32 edition;
53 u32 blocks;
54 u32 files;
55};
56
57/*
58 * Superblock information at the beginning of the FS.
59 */
60struct cramfs_super {
61 u32 magic; /* 0x28cd3d45 - random number */
62 u32 size; /* length in bytes */
63 u32 flags; /* feature flags */
64 u32 future; /* reserved for future use */
65 u8 signature[16]; /* "Compressed ROMFS" */
66 struct cramfs_info fsid; /* unique filesystem info */
67 u8 name[16]; /* user-defined name */
68 struct cramfs_inode root; /* root inode data */
69};
70
71/*
72 * Feature flags
73 *
74 * 0x00000000 - 0x000000ff: features that work for all past kernels
75 * 0x00000100 - 0xffffffff: features that don't work for past kernels
76 */
77#define CRAMFS_FLAG_FSID_VERSION_2 0x00000001 /* fsid version #2 */
78#define CRAMFS_FLAG_SORTED_DIRS 0x00000002 /* sorted dirs */
79#define CRAMFS_FLAG_HOLES 0x00000100 /* support for holes */
80#define CRAMFS_FLAG_WRONG_SIGNATURE 0x00000200 /* reserved */
81#define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400 /* shifted root fs */
82
83/*
84 * Valid values in super.flags. Currently we refuse to mount
85 * if (flags & ~CRAMFS_SUPPORTED_FLAGS). Maybe that should be
86 * changed to test super.future instead.
87 */
88#define CRAMFS_SUPPORTED_FLAGS ( 0x000000ff \
89 | CRAMFS_FLAG_HOLES \
90 | CRAMFS_FLAG_WRONG_SIGNATURE \
91 | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET )
92
93/* Uncompression interfaces to the underlying zlib */
94int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen);
95int cramfs_uncompress_init(void);
96int cramfs_uncompress_exit(void);
97
98#endif