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Diffstat (limited to 'fs/cramfs/cramfs_fs.h')
| -rw-r--r-- | fs/cramfs/cramfs_fs.h | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/fs/cramfs/cramfs_fs.h b/fs/cramfs/cramfs_fs.h new file mode 100644 index 0000000..78cc9ec --- /dev/null +++ b/fs/cramfs/cramfs_fs.h @@ -0,0 +1,133 @@ +#ifndef __CRAMFS_FS_H +#define __CRAMFS_FS_H + +/* Uncompression interfaces to the underlying zlib */ +int cramfs_uncompress_block (void *dst, void *src, int srclen); +int cramfs_uncompress_init (void); + +#define CRAMFS_MAGIC 0x28cd3d45 /* some random number */ +#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 ) + +/* + * Since cramfs is little-endian, provide macros to swab the bitfields. + */ + +#ifndef __BYTE_ORDER +#if defined(__LITTLE_ENDIAN) && !defined(__BIG_ENDIAN) +#define __BYTE_ORDER __LITTLE_ENDIAN +#elif defined(__BIG_ENDIAN) && !defined(__LITTLE_ENDIAN) +#define __BYTE_ORDER __BIG_ENDIAN +#else +#error "unable to define __BYTE_ORDER" +#endif +#endif /* not __BYTE_ORDER */ + +#if __BYTE_ORDER == __LITTLE_ENDIAN +#define CRAMFS_16(x) (x) +#define CRAMFS_24(x) (x) +#define CRAMFS_32(x) (x) +#define CRAMFS_GET_NAMELEN(x) ((x)->namelen) +#define CRAMFS_GET_OFFSET(x) ((x)->offset) +#define CRAMFS_SET_OFFSET(x,y) ((x)->offset = (y)) +#define CRAMFS_SET_NAMELEN(x,y) ((x)->namelen = (y)) +#elif __BYTE_ORDER == __BIG_ENDIAN +#ifdef __KERNEL__ +#define CRAMFS_16(x) swab16(x) +#define CRAMFS_24(x) ((swab32(x)) >> 8) +#define CRAMFS_32(x) swab32(x) +#else /* not __KERNEL__ */ +#define CRAMFS_16(x) bswap_16(x) +#define CRAMFS_24(x) ((bswap_32(x)) >> 8) +#define CRAMFS_32(x) bswap_32(x) +#endif /* not __KERNEL__ */ +#define CRAMFS_GET_NAMELEN(x) (((u8*)(x))[8] & 0x3f) +#define CRAMFS_GET_OFFSET(x) ((CRAMFS_24(((u32*)(x))[2] & 0xffffff) << 2) |\ + ((((u32*)(x))[2] & 0xc0000000) >> 30)) +#define CRAMFS_SET_NAMELEN(x,y) (((u8*)(x))[8] = (((0x3f & (y))) | \ + (0xc0 & ((u8*)(x))[8]))) +#define CRAMFS_SET_OFFSET(x,y) (((u32*)(x))[2] = (((y) & 3) << 30) | \ + CRAMFS_24((((y) & 0x03ffffff) >> 2)) | \ + (((u32)(((u8*)(x))[8] & 0x3f)) << 24)) +#else +#error "__BYTE_ORDER must be __LITTLE_ENDIAN or __BIG_ENDIAN" +#endif + +#endif /* not __CRAMFS_FS_H */ |