[linux.git] / include / linux / cramfs_fs.h

#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 */

/*
 * 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 )

#ifdef __KERNEL__
/* Uncompression interfaces to the underlying zlib */
int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen);
int cramfs_uncompress_init(void);
void cramfs_uncompress_exit(void);
#endif /* __KERNEL__ */

#endif
Commit	Line	Data
1da177e4 LT	1	#ifndef __CRAMFS_H
	2	#define __CRAMFS_H
	3
05f75fd3	4	#include <linux/types.h>
8688b863	5	#include <linux/magic.h>
1da177e4	6
1da177e4 LT	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	*/
	29	struct cramfs_inode {
05f75fd3	30	__u32 mode:CRAMFS_MODE_WIDTH, uid:CRAMFS_UID_WIDTH;
1da177e4	31	/* SIZE for device files is i_rdev */
05f75fd3	32	__u32 size:CRAMFS_SIZE_WIDTH, gid:CRAMFS_GID_WIDTH;
1da177e4 LT	33	/* 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. */
05f75fd3	41	__u32 namelen:CRAMFS_NAMELEN_WIDTH, offset:CRAMFS_OFFSET_WIDTH;
1da177e4 LT	42	};
	43
	44	struct cramfs_info {
05f75fd3 DW	45	__u32 crc;
	46	__u32 edition;
	47	__u32 blocks;
	48	__u32 files;
1da177e4 LT	49	};
	50
	51	/*
	52	* Superblock information at the beginning of the FS.
	53	*/
	54	struct cramfs_super {
05f75fd3 DW	55	__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" */
1da177e4	60	struct cramfs_info fsid; /* unique filesystem info */
05f75fd3	61	__u8 name[16]; /* user-defined name */
1da177e4 LT	62	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
beeae051	87	#ifdef __KERNEL__
1da177e4 LT	88	/* Uncompression interfaces to the underlying zlib */
	89	int cramfs_uncompress_block(void dst, int dstlen, void src, int srclen);
	90	int cramfs_uncompress_init(void);
368bdb3d	91	void cramfs_uncompress_exit(void);
beeae051	92	#endif /* __KERNEL__ */
1da177e4 LT	93
1da177e4 LT	94	#endif