disk-utils/cramfs.h

   1 /*
   2  * cramfs_common - cramfs common code
   3  *
   4  * Copyright (c) 2008 Roy Peled, the.roy.peled  -at-  gmail
   5  * Copyright (c) 2004-2006 by Juliane Holzt, kju -at- fqdn.org
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  */
  18
  19 #ifndef __CRAMFS_H
  20 #define __CRAMFS_H
  21
  22 #include <stdint.h>
  23
  24 #define CRAMFS_MAGIC            0x28cd3d45      /* some random number */
  25 #define CRAMFS_SIGNATURE        "Compressed ROMFS"
  26
  27 /*
  28  * Width of various bitfields in struct cramfs_inode.
  29  * Primarily used to generate warnings in mkcramfs.
  30  */
  31 #define CRAMFS_MODE_WIDTH 16
  32 #define CRAMFS_UID_WIDTH 16
  33 #define CRAMFS_SIZE_WIDTH 24
  34 #define CRAMFS_GID_WIDTH 8
  35 #define CRAMFS_NAMELEN_WIDTH 6
  36 #define CRAMFS_OFFSET_WIDTH 26
  37
  38 #ifndef HOST_IS_BIG_ENDIAN
  39 #ifdef WORDS_BIGENDIAN
  40 #define HOST_IS_BIG_ENDIAN 1
  41 #else
  42 #define HOST_IS_BIG_ENDIAN 0
  43 #endif
  44 #endif
  45
  46 /*
  47  * Reasonably terse representation of the inode data.
  48  */
  49 struct cramfs_inode {
  50         uint32_t mode:16, uid:16;
  51         /* SIZE for device files is i_rdev */
  52         uint32_t size:24, gid:8;
  53         /*
  54          * NAMELEN is the length of the file name, divided by 4 and
  55          * rounded up.  (cramfs doesn't support hard links.)
  56          *
  57          * OFFSET: For symlinks and non-empty regular files, this
  58          * contains the offset (divided by 4) of the file data in
  59          * compressed form (starting with an array of block pointers;
  60          * see README).  For non-empty directories it is the offset
  61          * (divided by 4) of the inode of the first file in that
  62          * directory.  For anything else, offset is zero.
  63          */
  64         uint32_t namelen:6, offset:26;
  65 };
  66
  67 struct cramfs_info {
  68         uint32_t crc;
  69         uint32_t edition;
  70         uint32_t blocks;
  71         uint32_t files;
  72 };
  73
  74 /*
  75  * Superblock information at the beginning of the FS.
  76  */
  77 struct cramfs_super {
  78         uint32_t magic;         /* 0x28cd3d45 - random number */
  79         uint32_t size;          /* Not used.  mkcramfs currently
  80                                    writes a constant 1<<16 here. */
  81         uint32_t flags;         /* 0 */
  82         uint32_t future;                /* 0 */
  83         uint8_t signature[16];  /* "Compressed ROMFS" */
  84         struct cramfs_info fsid;/* unique filesystem info */
  85         uint8_t name[16];               /* user-defined name */
  86         struct cramfs_inode root;       /* Root inode data */
  87 };
  88
  89 #define CRAMFS_FLAG_FSID_VERSION_2      0x00000001      /* fsid version #2 */
  90 #define CRAMFS_FLAG_SORTED_DIRS         0x00000002      /* sorted dirs */
  91 #define CRAMFS_FLAG_HOLES               0x00000100      /* support for holes */
  92 #define CRAMFS_FLAG_WRONG_SIGNATURE     0x00000200      /* reserved */
  93 #define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400      /* shifted root fs */
  94
  95 /*
  96  * Valid values in super.flags.  Currently we refuse to mount
  97  * if (flags & ~CRAMFS_SUPPORTED_FLAGS).  Maybe that should be
  98  * changed to test super.future instead.
  99  */
 100 #define CRAMFS_SUPPORTED_FLAGS (0xff)
 101
 102 /* Uncompression interfaces to the underlying zlib */
 103 int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen);
 104 int cramfs_uncompress_init(void);
 105 int cramfs_uncompress_exit(void);
 106
 107 uint32_t u32_toggle_endianness(int big_endian, uint32_t what);
 108 void super_toggle_endianness(int from_big_endian, struct cramfs_super *super);
 109 void inode_to_host(int from_big_endian, struct cramfs_inode *inode_in,
 110                    struct cramfs_inode *inode_out);
 111 void inode_from_host(int to_big_endian, struct cramfs_inode *inode_in,
 112                      struct cramfs_inode *inode_out);
 113
 114 #endif