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/* Ext2 support for extended attributes
Copyright (C) 2006, 2016 Free Software Foundation, Inc.
Written by Thadeu Lima de Souza Cascardo <cascardo@dcc.ufmg.br>
and Shengyu Zhang <lastavengers@outlook.com>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#ifndef EXT2_XATTR_H
#define EXT2_XATTR_H
#include "ext2fs.h"
/* Identifies whether a block is a proper xattr block. */
#define EXT2_XATTR_BLOCK_MAGIC 0xEA020000
/* xattr block header. */
struct ext2_xattr_header
{
__u32 h_magic; /* h_magic number for identification */
__u32 h_refcount; /* reference count */
__u32 h_blocks; /* number of disk blocks used */
__u32 h_hash; /* hash value of all attributes */
__u32 h_reserved[4]; /* zero right now */
};
/* xattr entry in xattr block. */
struct ext2_xattr_entry
{
__u8 e_name_len; /* length of name */
__u8 e_name_index; /* attribute name index */
__u16 e_value_offs; /* offset in disk block of value */
__u32 e_value_block; /* disk block attribute is stored on (n/i) */
__u32 e_value_size; /* size of attribute value */
__u32 e_hash; /* hash value of name and value */
char e_name[0]; /* attribute name */
};
#define EXT2_XATTR_PAD_BITS 2
#define EXT2_XATTR_PAD (1 << EXT2_XATTR_PAD_BITS)
#define EXT2_XATTR_ROUND (EXT2_XATTR_PAD - 1)
/* Entry alignment in xattr block. */
#define EXT2_XATTR_ALIGN(x) (((unsigned long) (x) + \
EXT2_XATTR_ROUND) & \
(~EXT2_XATTR_ROUND))
/* Given a fs block, return the xattr header. */
#define EXT2_XATTR_HEADER(block) ((struct ext2_xattr_header *) block)
/* Aligned size of entry, including the name length. */
#define EXT2_XATTR_ENTRY_SIZE(len) EXT2_XATTR_ALIGN ((sizeof \
(struct ext2_xattr_entry) + \
len))
/* Offset of entry, given the block header. */
#define EXT2_XATTR_ENTRY_OFFSET(header, entry) ((off_t) ((char *) entry - \
(char *) header))
/* First entry of xattr block, given its header. */
#define EXT2_XATTR_ENTRY_FIRST(header) ((struct ext2_xattr_entry *) (header + 1))
/* Next entry, giving an entry. */
#define EXT2_XATTR_ENTRY_NEXT(entry) ((struct ext2_xattr_entry *) \
((char *) entry + \
EXT2_XATTR_ENTRY_SIZE \
(entry->e_name_len)))
/* Checks if this entry is the last (not valid) one. */
#define EXT2_XATTR_ENTRY_LAST(entry) (*(unsigned long *) entry == 0UL)
#endif
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