1 #ifndef __CRAMFS_H 2 #define __CRAMFS_H 3 4 #include <linux/types.h> 5 6 #define CRAMFS_MAGIC 0x28cd3d45 /* some random number */ 7 #define CRAMFS_MAGIC_WEND 0x453dcd28 /* magic number with the wrong endianess */ 8 #define CRAMFS_SIGNATURE "Compressed ROMFS" 9 10 /* 11 * Width of various bitfields in struct cramfs_inode. 12 * Primarily used to generate warnings in mkcramfs. 13 */ 14 #define CRAMFS_MODE_WIDTH 16 15 #define CRAMFS_UID_WIDTH 16 16 #define CRAMFS_SIZE_WIDTH 24 17 #define CRAMFS_GID_WIDTH 8 18 #define CRAMFS_NAMELEN_WIDTH 6 19 #define CRAMFS_OFFSET_WIDTH 26 20 21 /* 22 * Since inode.namelen is a unsigned 6-bit number, the maximum cramfs 23 * path length is 63 << 2 = 252. 24 */ 25 #define CRAMFS_MAXPATHLEN (((1 << CRAMFS_NAMELEN_WIDTH) - 1) << 2) 26 27 /* 28 * Reasonably terse representation of the inode data. 29 */ 30 struct cramfs_inode { 31 __u32 mode:CRAMFS_MODE_WIDTH, uid:CRAMFS_UID_WIDTH; 32 /* SIZE for device files is i_rdev */ 33 __u32 size:CRAMFS_SIZE_WIDTH, gid:CRAMFS_GID_WIDTH; 34 /* NAMELEN is the length of the file name, divided by 4 and 35 rounded up. (cramfs doesn't support hard links.) */ 36 /* OFFSET: For symlinks and non-empty regular files, this 37 contains the offset (divided by 4) of the file data in 38 compressed form (starting with an array of block pointers; 39 see README). For non-empty directories it is the offset 40 (divided by 4) of the inode of the first file in that 41 directory. For anything else, offset is zero. */ 42 __u32 namelen:CRAMFS_NAMELEN_WIDTH, offset:CRAMFS_OFFSET_WIDTH; 43 }; 44 45 struct cramfs_info { 46 __u32 crc; 47 __u32 edition; 48 __u32 blocks; 49 __u32 files; 50 }; 51 52 /* 53 * Superblock information at the beginning of the FS. 54 */ 55 struct cramfs_super { 56 __u32 magic; /* 0x28cd3d45 - random number */ 57 __u32 size; /* length in bytes */ 58 __u32 flags; /* feature flags */ 59 __u32 future; /* reserved for future use */ 60 __u8 signature[16]; /* "Compressed ROMFS" */ 61 struct cramfs_info fsid; /* unique filesystem info */ 62 __u8 name[16]; /* user-defined name */ 63 struct cramfs_inode root; /* root inode data */ 64 }; 65 66 /* 67 * Feature flags 68 * 69 * 0x00000000 - 0x000000ff: features that work for all past kernels 70 * 0x00000100 - 0xffffffff: features that don't work for past kernels 71 */ 72 #define CRAMFS_FLAG_FSID_VERSION_2 0x00000001 /* fsid version #2 */ 73 #define CRAMFS_FLAG_SORTED_DIRS 0x00000002 /* sorted dirs */ 74 #define CRAMFS_FLAG_HOLES 0x00000100 /* support for holes */ 75 #define CRAMFS_FLAG_WRONG_SIGNATURE 0x00000200 /* reserved */ 76 #define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400 /* shifted root fs */ 77 78 /* 79 * Valid values in super.flags. Currently we refuse to mount 80 * if (flags & ~CRAMFS_SUPPORTED_FLAGS). Maybe that should be 81 * changed to test super.future instead. 82 */ 83 #define CRAMFS_SUPPORTED_FLAGS ( 0x000000ff \ 84 | CRAMFS_FLAG_HOLES \ 85 | CRAMFS_FLAG_WRONG_SIGNATURE \ 86 | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET ) 87 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); 91 void cramfs_uncompress_exit(void); 92 93 #endif 94