lib/ext2fs/ext2_ext_attr.h

   1 /*
   2   File: linux/ext2_ext_attr.h
   3
   4   On-disk format of extended attributes for the ext2 filesystem.
   5
   6   (C) 2000 Andreas Gruenbacher, <a.gruenbacher@computer.org>
   7 */
   8
   9 #ifndef _EXT2_EXT_ATTR_H
  10 #define _EXT2_EXT_ATTR_H
  11 /* Magic value in attribute blocks */
  12 #define EXT2_EXT_ATTR_MAGIC_v1          0xEA010000
  13 #define EXT2_EXT_ATTR_MAGIC             0xEA020000
  14
  15 /* Maximum number of references to one attribute block */
  16 #define EXT2_EXT_ATTR_REFCOUNT_MAX      1024
  17
  18 struct ext2_ext_attr_header {
  19         __u32   h_magic;        /* magic number for identification */
  20         __u32   h_refcount;     /* reference count */
  21         __u32   h_blocks;       /* number of disk blocks used */
  22         __u32   h_hash;         /* hash value of all attributes */
  23         __u32   h_checksum;     /* crc32c(uuid+id+xattrs) */
  24                                 /* id = inum if refcount = 1, else blknum */
  25         __u32   h_reserved[3];  /* zero right now */
  26 };
  27
  28 struct ext2_ext_attr_entry {
  29         __u8    e_name_len;     /* length of name */
  30         __u8    e_name_index;   /* attribute name index */
  31         __u16   e_value_offs;   /* offset in disk block of value */
  32         __u32   e_value_inum;   /* inode in which the value is stored */
  33         __u32   e_value_size;   /* size of attribute value */
  34         __u32   e_hash;         /* hash value of name and value */
  35 #if 0
  36         char    e_name[0];      /* attribute name */
  37 #endif
  38 };
  39
  40 #define EXT2_EXT_ATTR_PAD_BITS          2
  41 #define EXT2_EXT_ATTR_PAD               ((unsigned) 1<<EXT2_EXT_ATTR_PAD_BITS)
  42 #define EXT2_EXT_ATTR_ROUND             (EXT2_EXT_ATTR_PAD-1)
  43 #define EXT2_EXT_ATTR_LEN(name_len) \
  44         (((name_len) + EXT2_EXT_ATTR_ROUND + \
  45         sizeof(struct ext2_ext_attr_entry)) & ~EXT2_EXT_ATTR_ROUND)
  46 #define EXT2_EXT_ATTR_NEXT(entry) \
  47         ( (struct ext2_ext_attr_entry *)( \
  48           (char *)(entry) + EXT2_EXT_ATTR_LEN((entry)->e_name_len)) )
  49 #define EXT2_EXT_ATTR_SIZE(size) \
  50         (((size) + EXT2_EXT_ATTR_ROUND) & ~EXT2_EXT_ATTR_ROUND)
  51 #define EXT2_EXT_IS_LAST_ENTRY(entry) (*((__u32 *)(entry)) == 0UL)
  52 #define EXT2_EXT_ATTR_NAME(entry) \
  53         (((char *) (entry)) + sizeof(struct ext2_ext_attr_entry))
  54 #define EXT2_XATTR_LEN(name_len) \
  55         (((name_len) + EXT2_EXT_ATTR_ROUND + \
  56         sizeof(struct ext2_xattr_entry)) & ~EXT2_EXT_ATTR_ROUND)
  57 #define EXT2_XATTR_SIZE(size) \
  58         (((size) + EXT2_EXT_ATTR_ROUND) & ~EXT2_EXT_ATTR_ROUND)
  59
  60 /*
  61  * XATTR_SIZE_MAX is currently 64k, but for the purposes of checking
  62  * for file system consistency errors, we use a somewhat bigger value.
  63  * This allows XATTR_SIZE_MAX to grow in the future, but by using this
  64  * instead of INT_MAX for certain consistency checks, we don't need to
  65  * worry about arithmetic overflows.  (Actually XATTR_SIZE_MAX is
  66  * defined in include/uapi/linux/limits.h, so changing it is going
  67  * not going to be trivial....)
  68  */
  69 #define EXT2_XATTR_SIZE_MAX (1 << 24)
  70
  71 #ifdef __KERNEL__
  72 # ifdef CONFIG_EXT2_FS_EXT_ATTR
  73 extern int ext2_get_ext_attr(struct inode *, const char *, char *, size_t, int);
  74 extern int ext2_set_ext_attr(struct inode *, const char *, char *, size_t, int);
  75 extern void ext2_ext_attr_free_inode(struct inode *inode);
  76 extern void ext2_ext_attr_put_super(struct super_block *sb);
  77 extern int ext2_ext_attr_init(void);
  78 extern void ext2_ext_attr_done(void);
  79 # else
  80 #  define ext2_get_ext_attr NULL
  81 #  define ext2_set_ext_attr NULL
  82 # endif
  83 #endif  /* __KERNEL__ */
  84 #endif  /* _EXT2_EXT_ATTR_H */