mirror of https://github.com/vitalif/e2fsprogs
157 lines
4.4 KiB
C
157 lines
4.4 KiB
C
/*
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* csum.c --- checksumming of ext3 structures
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*
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* Copyright (C) 2006 Cluster File Systems, Inc.
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*
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* %Begin-Header%
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* This file may be redistributed under the terms of the GNU Public
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* License.
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* %End-Header%
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*/
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#include "ext2_fs.h"
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#include "ext2fs.h"
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#include "crc16.h"
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#include <assert.h>
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#ifndef offsetof
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#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
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#endif
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#ifdef DEBUG
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#define STATIC
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#else
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#define STATIC static
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#endif
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STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
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{
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__u16 crc = 0;
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struct ext2_group_desc *desc;
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desc = &fs->group_desc[group];
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if (fs->super->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
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int offset = offsetof(struct ext2_group_desc, bg_checksum);
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#ifdef WORDS_BIGENDIAN
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struct ext2_group_desc swabdesc = *desc;
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/* Have to swab back to little-endian to do the checksum */
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ext2fs_swap_group_desc(&swabdesc);
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desc = &swabdesc;
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group = ext2fs_swab32(group);
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#endif
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crc = crc16(~0, fs->super->s_uuid, sizeof(fs->super->s_uuid));
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crc = crc16(crc, &group, sizeof(group));
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crc = crc16(crc, desc, offset);
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offset += sizeof(desc->bg_checksum); /* skip checksum */
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assert(offset == sizeof(*desc));
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/* for checksum of struct ext4_group_desc do the rest...*/
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if (offset < fs->super->s_desc_size) {
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crc = crc16(crc, (char *)desc + offset,
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fs->super->s_desc_size - offset);
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}
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}
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return crc;
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}
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int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group)
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{
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if (fs->group_desc[group].bg_checksum !=
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ext2fs_group_desc_csum(fs, group))
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return 0;
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return 1;
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}
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void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group)
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{
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fs->group_desc[group].bg_checksum = ext2fs_group_desc_csum(fs, group);
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}
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static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap,
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__u32 inodes_per_grp, dgrp_t grp_no)
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{
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ext2_ino_t i, start_ino, end_ino;
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start_ino = grp_no * inodes_per_grp + 1;
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end_ino = start_ino + inodes_per_grp - 1;
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for (i = end_ino; i >= start_ino; i--) {
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if (ext2fs_fast_test_inode_bitmap(bitmap, i))
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return i - start_ino + 1;
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}
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return inodes_per_grp;
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}
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/* update the bitmap flags, set the itable high watermark, and calculate
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* checksums for the group descriptors */
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void ext2fs_set_gdt_csum(ext2_filsys fs)
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{
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struct ext2_super_block *sb = fs->super;
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struct ext2_group_desc *bg = fs->group_desc;
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int blks, csum_flag, dirty = 0;
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dgrp_t i;
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csum_flag = EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
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EXT4_FEATURE_RO_COMPAT_GDT_CSUM);
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if (!EXT2_HAS_COMPAT_FEATURE(fs->super,
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EXT2_FEATURE_COMPAT_LAZY_BG) && !csum_flag)
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return;
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for (i = 0; i < fs->group_desc_count; i++, bg++) {
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int old_csum = bg->bg_checksum;
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int old_unused = bg->bg_itable_unused;
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int old_flags = bg->bg_flags;
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/* Even if it wasn't zeroed, by the time this function is
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* called by e2fsck we have already scanned and corrected
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* the whole inode table so we may as well not overwrite it.
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* This is just a hint to the kernel that it could do lazy
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* zeroing of the inode table if mke2fs didn't do it, to help
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* out if we need to do a full itable scan sometime later. */
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if (!(bg->bg_flags & (EXT2_BG_INODE_UNINIT |
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EXT2_BG_INODE_ZEROED)))
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fs->group_desc[i].bg_flags |= EXT2_BG_INODE_ZEROED;
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if (bg->bg_free_inodes_count == sb->s_inodes_per_group &&
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i > 0 && (i < fs->group_desc_count - 1 || csum_flag)) {
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if (!(bg->bg_flags & EXT2_BG_INODE_UNINIT))
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bg->bg_flags |= EXT2_BG_INODE_UNINIT;
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if (csum_flag)
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bg->bg_itable_unused = sb->s_inodes_per_group;
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} else if (csum_flag) {
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bg->bg_flags &= ~EXT2_BG_INODE_UNINIT;
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bg->bg_itable_unused = sb->s_inodes_per_group -
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find_last_inode_ingrp(fs->inode_map,
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sb->s_inodes_per_group,i);
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}
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/* skip first and last groups, or groups with GDT backups
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* because the resize inode has blocks allocated in them. */
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if (i == 0 || (i == fs->group_desc_count - 1 && !csum_flag) ||
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(ext2fs_bg_has_super(fs, i) && sb->s_reserved_gdt_blocks))
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goto checksum;
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blks = ext2fs_super_and_bgd_loc(fs, i, 0, 0, 0, 0);
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if (bg->bg_free_blocks_count == blks &&
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bg->bg_flags & EXT2_BG_INODE_UNINIT &&
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!(bg->bg_flags & EXT2_BG_BLOCK_UNINIT))
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bg->bg_flags |= EXT2_BG_BLOCK_UNINIT;
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checksum:
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ext2fs_group_desc_csum_set(fs, i);
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if (old_flags != bg->bg_flags)
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dirty = 1;
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if (old_unused != bg->bg_itable_unused)
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dirty = 1;
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if (old_csum != bg->bg_checksum)
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dirty = 1;
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}
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if (dirty)
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ext2fs_mark_super_dirty(fs);
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}
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