include/linux/cramfs_fs.h

   1 #ifndef __CRAMFS_H
   2 #define __CRAMFS_H
   3
   4 #ifndef __KERNEL__
   5
   6 typedef unsigned char u8;
   7 typedef unsigned short u16;
   8 typedef unsigned int u32;
   9
  10 #endif
  11
  12 #define CRAMFS_MAGIC            0x28cd3d45      /* some random number */
  13 #define CRAMFS_SIGNATURE        "Compressed ROMFS"
  14
  15 /*
  16  * Width of various bitfields in struct cramfs_inode.
  17  * Primarily used to generate warnings in mkcramfs.
  18  */
  19 #define CRAMFS_MODE_WIDTH 16
  20 #define CRAMFS_UID_WIDTH 16
  21 #define CRAMFS_SIZE_WIDTH 24
  22 #define CRAMFS_GID_WIDTH 8
  23 #define CRAMFS_NAMELEN_WIDTH 6
  24 #define CRAMFS_OFFSET_WIDTH 26
  25
  26 /*
  27  * Since inode.namelen is a unsigned 6-bit number, the maximum cramfs
  28  * path length is 63 << 2 = 252.
  29  */
  30 #define CRAMFS_MAXPATHLEN (((1 << CRAMFS_NAMELEN_WIDTH) - 1) << 2)
  31
  32 /*
  33  * Reasonably terse representation of the inode data.
  34  */
  35 struct cramfs_inode {
  36         u32 mode:CRAMFS_MODE_WIDTH, uid:CRAMFS_UID_WIDTH;
  37         /* SIZE for device files is i_rdev */
  38         u32 size:CRAMFS_SIZE_WIDTH, gid:CRAMFS_GID_WIDTH;
  39         /* NAMELEN is the length of the file name, divided by 4 and
  40            rounded up.  (cramfs doesn't support hard links.) */
  41         /* OFFSET: For symlinks and non-empty regular files, this
  42            contains the offset (divided by 4) of the file data in
  43            compressed form (starting with an array of block pointers;
  44            see README).  For non-empty directories it is the offset
  45            (divided by 4) of the inode of the first file in that
  46            directory.  For anything else, offset is zero. */
  47         u32 namelen:CRAMFS_NAMELEN_WIDTH, offset:CRAMFS_OFFSET_WIDTH;
  48 };
  49
  50 struct cramfs_info {
  51         u32 crc;
  52         u32 edition;
  53         u32 blocks;
  54         u32 files;
  55 };
  56
  57 /*
  58  * Superblock information at the beginning of the FS.
  59  */
  60 struct cramfs_super {
  61         u32 magic;                      /* 0x28cd3d45 - random number */
  62         u32 size;                       /* length in bytes */
  63         u32 flags;                      /* feature flags */
  64         u32 future;                     /* reserved for future use */
  65         u8 signature[16];               /* "Compressed ROMFS" */
  66         struct cramfs_info fsid;        /* unique filesystem info */
  67         u8 name[16];                    /* user-defined name */
  68         struct cramfs_inode root;       /* root inode data */
  69 };
  70
  71 /*
  72  * Feature flags
  73  *
  74  * 0x00000000 - 0x000000ff: features that work for all past kernels
  75  * 0x00000100 - 0xffffffff: features that don't work for past kernels
  76  */
  77 #define CRAMFS_FLAG_FSID_VERSION_2      0x00000001      /* fsid version #2 */
  78 #define CRAMFS_FLAG_SORTED_DIRS         0x00000002      /* sorted dirs */
  79 #define CRAMFS_FLAG_HOLES               0x00000100      /* support for holes */
  80 #define CRAMFS_FLAG_WRONG_SIGNATURE     0x00000200      /* reserved */
  81 #define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400      /* shifted root fs */
  82
  83 /*
  84  * Valid values in super.flags.  Currently we refuse to mount
  85  * if (flags & ~CRAMFS_SUPPORTED_FLAGS).  Maybe that should be
  86  * changed to test super.future instead.
  87  */
  88 #define CRAMFS_SUPPORTED_FLAGS  ( 0x000000ff \
  89                                 | CRAMFS_FLAG_HOLES \
  90                                 | CRAMFS_FLAG_WRONG_SIGNATURE \
  91                                 | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET )
  92
  93 /* Uncompression interfaces to the underlying zlib */
  94 int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen);
  95 int cramfs_uncompress_init(void);
  96 int cramfs_uncompress_exit(void);
  97
  98 #endif