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/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef __CRAMFS_H
#define __CRAMFS_H
#include <linux/types.h>
#include <linux/magic.h>
#define CRAMFS_SIGNATURE "Compressed ROMFS"
/*
* Width of various bitfields in struct cramfs_inode.
* Primarily used to generate warnings in mkcramfs.
*/
#define CRAMFS_MODE_WIDTH 16
#define CRAMFS_UID_WIDTH 16
#define CRAMFS_SIZE_WIDTH 24
#define CRAMFS_GID_WIDTH 8
#define CRAMFS_NAMELEN_WIDTH 6
#define CRAMFS_OFFSET_WIDTH 26
/*
* Since inode.namelen is a unsigned 6-bit number, the maximum cramfs
* path length is 63 << 2 = 252.
*/
#define CRAMFS_MAXPATHLEN (((1 << CRAMFS_NAMELEN_WIDTH) - 1) << 2)
/*
* Reasonably terse representation of the inode data.
*/
struct cramfs_inode {
__u32 mode:CRAMFS_MODE_WIDTH, uid:CRAMFS_UID_WIDTH;
/* SIZE for device files is i_rdev */
__u32 size:CRAMFS_SIZE_WIDTH, gid:CRAMFS_GID_WIDTH;
/* NAMELEN is the length of the file name, divided by 4 and
rounded up. (cramfs doesn't support hard links.) */
/* OFFSET: For symlinks and non-empty regular files, this
contains the offset (divided by 4) of the file data in
compressed form (starting with an array of block pointers;
see README). For non-empty directories it is the offset
(divided by 4) of the inode of the first file in that
directory. For anything else, offset is zero. */
__u32 namelen:CRAMFS_NAMELEN_WIDTH, offset:CRAMFS_OFFSET_WIDTH;
};
struct cramfs_info {
__u32 crc;
__u32 edition;
__u32 blocks;
__u32 files;
};
/*
* Superblock information at the beginning of the FS.
*/
struct cramfs_super {
__u32 magic; /* 0x28cd3d45 - random number */
__u32 size; /* length in bytes */
__u32 flags; /* feature flags */
__u32 future; /* reserved for future use */
__u8 signature[16]; /* "Compressed ROMFS" */
struct cramfs_info fsid; /* unique filesystem info */
__u8 name[16]; /* user-defined name */
struct cramfs_inode root; /* root inode data */
};
/*
* Feature flags
*
* 0x00000000 - 0x000000ff: features that work for all past kernels
* 0x00000100 - 0xffffffff: features that don't work for past kernels
*/
#define CRAMFS_FLAG_FSID_VERSION_2 0x00000001 /* fsid version #2 */
#define CRAMFS_FLAG_SORTED_DIRS 0x00000002 /* sorted dirs */
#define CRAMFS_FLAG_HOLES 0x00000100 /* support for holes */
#define CRAMFS_FLAG_WRONG_SIGNATURE 0x00000200 /* reserved */
#define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400 /* shifted root fs */
#define CRAMFS_FLAG_EXT_BLOCK_POINTERS 0x00000800 /* block pointer extensions */
/*
* Valid values in super.flags. Currently we refuse to mount
* if (flags & ~CRAMFS_SUPPORTED_FLAGS). Maybe that should be
* changed to test super.future instead.
*/
#define CRAMFS_SUPPORTED_FLAGS ( 0x000000ff \
| CRAMFS_FLAG_HOLES \
| CRAMFS_FLAG_WRONG_SIGNATURE \
| CRAMFS_FLAG_SHIFTED_ROOT_OFFSET \
| CRAMFS_FLAG_EXT_BLOCK_POINTERS )
/*
* Block pointer flags
*
* The maximum block offset that needs to be represented is roughly:
*
* (1 << CRAMFS_OFFSET_WIDTH) * 4 +
* (1 << CRAMFS_SIZE_WIDTH) / PAGE_SIZE * (4 + PAGE_SIZE)
* = 0x11004000
*
* That leaves room for 3 flag bits in the block pointer table.
*/
#define CRAMFS_BLK_FLAG_UNCOMPRESSED (1 << 31)
#define CRAMFS_BLK_FLAG_DIRECT_PTR (1 << 30)
#define CRAMFS_BLK_FLAGS ( CRAMFS_BLK_FLAG_UNCOMPRESSED \
| CRAMFS_BLK_FLAG_DIRECT_PTR )
/*
* Direct blocks are at least 4-byte aligned.
* Pointers to direct blocks are shifted down by 2 bits.
*/
#define CRAMFS_BLK_DIRECT_PTR_SHIFT 2
#endif /* __CRAMFS_H */
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