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/*
* csum.c --- checksumming of ext3 structures
*
* Copyright (C) 2006 Cluster File Systems, Inc.
* Copyright (C) 2006, 2007 by Andreas Dilger <adilger@clusterfs.com>
*
* %Begin-Header%
* This file may be redistributed under the terms of the GNU Library
* General Public License, version 2.
* %End-Header%
*/
#include <common.h>
//#include <ext_common.h>
//#include <ext4fs.h>
#include <malloc.h>
#include <stddef.h>
#include <linux/stat.h>
#include <linux/time.h>
#include "ext2_fs.h"
#include "ext2fs.h"
#include "crc16.h"
#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif
#ifdef DEBUG
#define STATIC
#else
#define STATIC static
#endif
STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
{
__u16 crc = 0;
struct ext2_group_desc *desc;
desc = &fs->group_desc[group];
if (fs->super->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
int offset = offsetof(struct ext2_group_desc, bg_checksum);
#ifdef WORDS_BIGENDIAN
struct ext2_group_desc swabdesc = *desc;
/* Have to swab back to little-endian to do the checksum */
ext2fs_swap_group_desc(&swabdesc);
desc = &swabdesc;
group = ext2fs_swab32(group);
#endif
crc = ext2fs_crc16(~0, fs->super->s_uuid,
sizeof(fs->super->s_uuid));
crc = ext2fs_crc16(crc, &group, sizeof(group));
crc = ext2fs_crc16(crc, desc, offset);
offset += sizeof(desc->bg_checksum); /* skip checksum */
assert(offset == sizeof(*desc));
/* for checksum of struct ext4_group_desc do the rest...*/
if (offset < fs->super->s_desc_size) {
crc = ext2fs_crc16(crc, (char *)desc + offset,
fs->super->s_desc_size - offset);
}
}
return crc;
}
int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group)
{
if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
EXT4_FEATURE_RO_COMPAT_GDT_CSUM) &&
(fs->group_desc[group].bg_checksum !=
ext2fs_group_desc_csum(fs, group)))
return 0;
return 1;
}
void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group)
{
if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
fs->group_desc[group].bg_checksum =
ext2fs_group_desc_csum(fs, group);
}
static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap,
__u32 inodes_per_grp, dgrp_t grp_no)
{
ext2_ino_t i, start_ino, end_ino;
start_ino = grp_no * inodes_per_grp + 1;
end_ino = start_ino + inodes_per_grp - 1;
for (i = end_ino; i >= start_ino; i--) {
if (ext2fs_fast_test_inode_bitmap(bitmap, i))
return i - start_ino + 1;
}
return inodes_per_grp;
}
/* update the bitmap flags, set the itable high watermark, and calculate
* checksums for the group descriptors */
errcode_t ext2fs_set_gdt_csum(ext2_filsys fs)
{
struct ext2_super_block *sb = fs->super;
struct ext2_group_desc *bg = fs->group_desc;
int dirty = 0;
dgrp_t i;
if (!fs->inode_map)
return EXT2_ET_NO_INODE_BITMAP;
if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
return 0;
for (i = 0; i < fs->group_desc_count; i++, bg++) {
int old_csum = bg->bg_checksum;
int old_unused = bg->bg_itable_unused;
int old_flags = bg->bg_flags;
if (bg->bg_free_inodes_count == sb->s_inodes_per_group) {
bg->bg_flags |= EXT2_BG_INODE_UNINIT;
bg->bg_itable_unused = sb->s_inodes_per_group;
} else {
bg->bg_flags &= ~EXT2_BG_INODE_UNINIT;
bg->bg_itable_unused = sb->s_inodes_per_group -
find_last_inode_ingrp(fs->inode_map,
sb->s_inodes_per_group,i);
}
ext2fs_group_desc_csum_set(fs, i);
if (old_flags != bg->bg_flags)
dirty = 1;
if (old_unused != bg->bg_itable_unused)
dirty = 1;
if (old_csum != bg->bg_checksum)
dirty = 1;
}
if (dirty)
ext2fs_mark_super_dirty(fs);
return 0;
}
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