ext2fs: Add support for xattr

* ext2fs/Makefile (SRCS): Add xattr.c.
* ext2fs/ext2_fs.h: Define EXT2_FEATURE_COMPAT_EXT_ATTR.
* ext2fs/ext2fs.h: Add xattr functions.
* ext2fs/ialloc.c (diskfs_free_node): Free xattr block.
* ext2fs/xattr.c: xattr implement.
* ext2fs/xattr.h: Likewise.

1 files changed, 85 insertions, 0 deletions

diff --git a/ext2fs/xattr.h b/ext2fs/xattr.h
new file mode 100644
index 00000000..245f896e
--- /dev/null
+++ b/ext2fs/xattr.h
@@ -0,0 +1,85 @@
+ /* 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