1 #ifndef __CRAMFS_H 2 #define __CRAMFS_H 3 4 #include <linux/types.h> 5 #include <linux/magic.h> 6 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 { 30 __u32 mode:CRAMFS_MODE_WIDTH, uid:CRAMFS_UID_WIDTH; 31 /* SIZE for device files is i_rdev */ 32 __u32 size:CRAMFS_SIZE_WIDTH, gid:CRAMFS_GID_WIDTH; 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. */ 41 __u32 namelen:CRAMFS_NAMELEN_WIDTH, offset:CRAMFS_OFFSET_WIDTH; 42 }; 43 44 struct cramfs_info { 45 __u32 crc; 46 __u32 edition; 47 __u32 blocks; 48 __u32 files; 49 }; 50 51 /* 52 * Superblock information at the beginning of the FS. 53 */ 54 struct cramfs_super { 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" */ 60 struct cramfs_info fsid; /* unique filesystem info */ 61 __u8 name[16]; /* user-defined name */ 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 87 88 #endif 89
