text: /*
   * 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 "config.h"
  #if HAVE_SYS_TYPES_H
  #include <sys/types.h>
  #endif
  
  #include "ext2_fs.h"
  #include "ext2fs.h"
  #include "crc16.h"
  #include <assert.h>
  
  #ifndef offsetof
  #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
  #endif
  
  #ifdef DEBUG
  #define STATIC
  #else
  #define STATIC static
  #endif
  
  void ext2fs_init_csum_seed(ext2_filsys fs)
  {
  	if (ext2fs_has_feature_csum_seed(fs->super))
  		fs->csum_seed = fs->super->s_checksum_seed;
  	else if (ext2fs_has_feature_metadata_csum(fs->super) ||
  		 ext2fs_has_feature_ea_inode(fs->super))
  		fs->csum_seed = ext2fs_crc32c_le(~0, fs->super->s_uuid,
  						 sizeof(fs->super->s_uuid));
  }
  
  static __u32 ext2fs_mmp_csum(ext2_filsys fs, struct mmp_struct *mmp)
  {
  	int offset = offsetof(struct mmp_struct, mmp_checksum);
  
  	return ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)mmp, offset);
  }
  
  int ext2fs_mmp_csum_verify(ext2_filsys fs, struct mmp_struct *mmp)
  {
  	__u32 calculated;
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 1;
  
  	calculated = ext2fs_mmp_csum(fs, mmp);
  
  	return ext2fs_le32_to_cpu(mmp->mmp_checksum) == calculated;
  }
  
  errcode_t ext2fs_mmp_csum_set(ext2_filsys fs, struct mmp_struct *mmp)
  {
  	__u32 crc;
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 0;
  
  	crc = ext2fs_mmp_csum(fs, mmp);
  	mmp->mmp_checksum = ext2fs_cpu_to_le32(crc);
  
  	return 0;
  }
  
  int ext2fs_verify_csum_type(ext2_filsys fs, struct ext2_super_block *sb)
  {
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 1;
  
  	return sb->s_checksum_type == EXT2_CRC32C_CHKSUM;
  }
  
  static __u32 ext2fs_superblock_csum(ext2_filsys fs EXT2FS_ATTR((unused)),
  				    struct ext2_super_block *sb)
  {
  	int offset = offsetof(struct ext2_super_block, s_checksum);
  
  	return ext2fs_crc32c_le(~0, (unsigned char *)sb, offset);
  }
  
  /* NOTE: The input to this function MUST be in LE order */
  int ext2fs_superblock_csum_verify(ext2_filsys fs, struct ext2_super_block *sb)
  {
  	__u32 flag, calculated;
  
  	if (fs->flags & EXT2_FLAG_SWAP_BYTES)
  		flag = EXT4_FEATURE_RO_COMPAT_METADATA_CSUM;
  	else
  		flag = ext2fs_cpu_to_le32(EXT4_FEATURE_RO_COMPAT_METADATA_CSUM);
  
  	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, flag))
  		return 1;
  
  	calculated = ext2fs_superblock_csum(fs, sb);
  
  	return ext2fs_le32_to_cpu(sb->s_checksum) == calculated;
  }
  
  /* NOTE: The input to this function MUST be in LE order */
  errcode_t ext2fs_superblock_csum_set(ext2_filsys fs,
  				     struct ext2_super_block *sb)
  {
  	__u32 flag, crc;
  
  	if (fs->flags & EXT2_FLAG_SWAP_BYTES)
  		flag = EXT4_FEATURE_RO_COMPAT_METADATA_CSUM;
  	else
  		flag = ext2fs_cpu_to_le32(EXT4_FEATURE_RO_COMPAT_METADATA_CSUM);
  
  	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super, flag))
  		return 0;
  
  	crc = ext2fs_superblock_csum(fs, sb);
  	sb->s_checksum = ext2fs_cpu_to_le32(crc);
  
  	return 0;
  }
  
  static errcode_t ext2fs_ext_attr_block_csum(ext2_filsys fs,
  					    ext2_ino_t inum EXT2FS_ATTR((unused)),
  					    blk64_t block,
  					    struct ext2_ext_attr_header *hdr,
  					    __u32 *crc)
  {
  	char *buf = (char *)hdr;
  	__u32 old_crc = hdr->h_checksum;
  
  	hdr->h_checksum = 0;
  	block = ext2fs_cpu_to_le64(block);
  	*crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&block,
  				sizeof(block));
  	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)buf, fs->blocksize);
  	hdr->h_checksum = old_crc;
  
  	return 0;
  }
  
  int ext2fs_ext_attr_block_csum_verify(ext2_filsys fs, ext2_ino_t inum,
  				      blk64_t block,
  				      struct ext2_ext_attr_header *hdr)
  {
  	__u32 calculated;
  	errcode_t retval;
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 1;
  
  	retval = ext2fs_ext_attr_block_csum(fs, inum, block, hdr, &calculated);
  	if (retval)
  		return 0;
  
  	return ext2fs_le32_to_cpu(hdr->h_checksum) == calculated;
  }
  
  errcode_t ext2fs_ext_attr_block_csum_set(ext2_filsys fs, ext2_ino_t inum,
  					 blk64_t block,
  					 struct ext2_ext_attr_header *hdr)
  {
  	errcode_t retval;
  	__u32 crc;
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 0;
  
  	retval = ext2fs_ext_attr_block_csum(fs, inum, block, hdr, &crc);
  	if (retval)
  		return retval;
  	hdr->h_checksum = ext2fs_cpu_to_le32(crc);
  	return 0;
  }
  
  static __u16 do_nothing16(__u16 x)
  {
  	return x;
  }
  
  static __u16 disk_to_host16(__u16 x)
  {
  	return ext2fs_le16_to_cpu(x);
  }
  
  static errcode_t __get_dx_countlimit(ext2_filsys fs,
  				     struct ext2_dir_entry *dirent,
  				     struct ext2_dx_countlimit **cc,
  				     int *offset,
  				     int need_swab)
  {
  	struct ext2_dir_entry *dp;
  	struct ext2_dx_root_info *root;
  	struct ext2_dx_countlimit *c;
  	int count_offset, max_sane_entries;
  	unsigned int rec_len;
  	__u16 (*translate)(__u16) = (need_swab ? disk_to_host16 : do_nothing16);
  
  	rec_len = translate(dirent->rec_len);
  
  	if (rec_len == fs->blocksize && translate(dirent->name_len) == 0)
  		count_offset = 8;
  	else if (rec_len == 12) {
  		dp = (struct ext2_dir_entry *)(((char *)dirent) + rec_len);
  		rec_len = translate(dp->rec_len);
  		if (rec_len != fs->blocksize - 12)
  			return EXT2_ET_DB_NOT_FOUND;
  		root = (struct ext2_dx_root_info *)(((char *)dp + 12));
  		if (root->reserved_zero ||
  		    root->info_length != sizeof(struct ext2_dx_root_info))
  			return EXT2_ET_DB_NOT_FOUND;
  		count_offset = 32;
  	} else
  		return EXT2_ET_DB_NOT_FOUND;
  
  	c = (struct ext2_dx_countlimit *)(((char *)dirent) + count_offset);
  	max_sane_entries = (fs->blocksize - count_offset) /
  			   sizeof(struct ext2_dx_entry);
  	if (ext2fs_le16_to_cpu(c->limit) > max_sane_entries ||
  	    ext2fs_le16_to_cpu(c->count) > max_sane_entries)
  		return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
  
  	if (offset)
  		*offset = count_offset;
  	if (cc)
  		*cc = c;
  
  	return 0;
  }
  
  errcode_t ext2fs_get_dx_countlimit(ext2_filsys fs,
  				   struct ext2_dir_entry *dirent,
  				   struct ext2_dx_countlimit **cc,
  				   int *offset)
  {
  	return __get_dx_countlimit(fs, dirent, cc, offset, 0);
  }
  
  void ext2fs_initialize_dirent_tail(ext2_filsys fs,
  				   struct ext2_dir_entry_tail *t)
  {
  	memset(t, 0, sizeof(struct ext2_dir_entry_tail));
  	ext2fs_set_rec_len(fs, sizeof(struct ext2_dir_entry_tail),
  			   (struct ext2_dir_entry *)t);
  	t->det_reserved_name_len = EXT2_DIR_NAME_LEN_CSUM;
  }
  
  static errcode_t __get_dirent_tail(ext2_filsys fs,
  				   struct ext2_dir_entry *dirent,
  				   struct ext2_dir_entry_tail **tt,
  				   int need_swab)
  {
  	struct ext2_dir_entry *d;
  	void *top;
  	struct ext2_dir_entry_tail *t;
  	unsigned int rec_len;
  	errcode_t retval = 0;
  	__u16 (*translate)(__u16) = (need_swab ? disk_to_host16 : do_nothing16);
  
  	d = dirent;
  	top = EXT2_DIRENT_TAIL(dirent, fs->blocksize);
  
  	rec_len = translate(d->rec_len);
  	while (rec_len && !(rec_len & 0x3)) {
  		d = (struct ext2_dir_entry *)(((char *)d) + rec_len);
  		if ((void *)d >= top)
  			break;
  		rec_len = translate(d->rec_len);
  	}
  
  	if (d != top)
  		return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
  
  	t = (struct ext2_dir_entry_tail *)d;
  	if (t->det_reserved_zero1 ||
  	    translate(t->det_rec_len) != sizeof(struct ext2_dir_entry_tail) ||
  	    translate(t->det_reserved_name_len) != EXT2_DIR_NAME_LEN_CSUM)
  		return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
  
  	if (tt)
  		*tt = t;
  	return retval;
  }
  
  int ext2fs_dirent_has_tail(ext2_filsys fs, struct ext2_dir_entry *dirent)
  {
  	return __get_dirent_tail(fs, dirent, NULL, 0) == 0;
  }
  
  static errcode_t ext2fs_dirent_csum(ext2_filsys fs, ext2_ino_t inum,
  				    struct ext2_dir_entry *dirent, __u32 *crc,
  				    int size)
  {
  	errcode_t retval;
  	char *buf = (char *)dirent;
  	__u32 gen;
  	struct ext2_inode inode;
  
  	retval = ext2fs_read_inode(fs, inum, &inode);
  	if (retval)
  		return retval;
  
  	inum = ext2fs_cpu_to_le32(inum);
  	gen = ext2fs_cpu_to_le32(inode.i_generation);
  	*crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
  				sizeof(inum));
  	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
  	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)buf, size);
  
  	return 0;
  }
  
  int ext2fs_dirent_csum_verify(ext2_filsys fs, ext2_ino_t inum,
  			      struct ext2_dir_entry *dirent)
  {
  	errcode_t retval;
  	__u32 calculated;
  	struct ext2_dir_entry_tail *t;
  
  	retval = __get_dirent_tail(fs, dirent, &t, 1);
  	if (retval)
  		return 1;
  
  	/*
  	 * The checksum field is overlaid with the dirent->name field
  	 * so the swapfs.c functions won't change the endianness.
  	 */
  	retval = ext2fs_dirent_csum(fs, inum, dirent, &calculated,
  				    (char *)t - (char *)dirent);
  	if (retval)
  		return 0;
  	return ext2fs_le32_to_cpu(t->det_checksum) == calculated;
  }
  
  static errcode_t ext2fs_dirent_csum_set(ext2_filsys fs, ext2_ino_t inum,
  					struct ext2_dir_entry *dirent)
  {
  	errcode_t retval;
  	__u32 crc;
  	struct ext2_dir_entry_tail *t;
  
  	retval = __get_dirent_tail(fs, dirent, &t, 1);
  	if (retval)
  		return retval;
  
  	/* swapfs.c functions don't change the checksum endianness */
  	retval = ext2fs_dirent_csum(fs, inum, dirent, &crc,
  				    (char *)t - (char *)dirent);
  	if (retval)
  		return retval;
  	t->det_checksum = ext2fs_cpu_to_le32(crc);
  	return 0;
  }
  
  static errcode_t ext2fs_dx_csum(ext2_filsys fs, ext2_ino_t inum,
  				struct ext2_dir_entry *dirent,
  				__u32 *crc, int count_offset, int count,
  				struct ext2_dx_tail *t)
  {
  	errcode_t retval;
  	char *buf = (char *)dirent;
  	int size;
  	__u32 old_csum, gen;
  	struct ext2_inode inode;
  
  	size = count_offset + (count * sizeof(struct ext2_dx_entry));
  	old_csum = t->dt_checksum;
  	t->dt_checksum = 0;
  
  	retval = ext2fs_read_inode(fs, inum, &inode);
  	if (retval)
  		return retval;
  
  	inum = ext2fs_cpu_to_le32(inum);
  	gen = ext2fs_cpu_to_le32(inode.i_generation);
  	*crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
  				sizeof(inum));
  	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
  	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)buf, size);
  	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)t,
  				sizeof(struct ext2_dx_tail));
  	t->dt_checksum = old_csum;
  
  	return 0;
  }
  
  static int ext2fs_dx_csum_verify(ext2_filsys fs, ext2_ino_t inum,
  				 struct ext2_dir_entry *dirent)
  {
  	__u32 calculated;
  	errcode_t retval;
  	struct ext2_dx_countlimit *c;
  	struct ext2_dx_tail *t;
  	int count_offset, limit, count;
  
  	retval = __get_dx_countlimit(fs, dirent, &c, &count_offset, 1);
  	if (retval)
  		return 1;
  	limit = ext2fs_le16_to_cpu(c->limit);
  	count = ext2fs_le16_to_cpu(c->count);
  	if (count_offset + (limit * sizeof(struct ext2_dx_entry)) >
  	    fs->blocksize - sizeof(struct ext2_dx_tail))
  		return 0;
  	/* htree structs are accessed in LE order */
  	t = (struct ext2_dx_tail *)(((struct ext2_dx_entry *)c) + limit);
  	retval = ext2fs_dx_csum(fs, inum, dirent, &calculated, count_offset,
  				count, t);
  	if (retval)
  		return 0;
  
  	return ext2fs_le32_to_cpu(t->dt_checksum) == calculated;
  }
  
  static errcode_t ext2fs_dx_csum_set(ext2_filsys fs, ext2_ino_t inum,
  				    struct ext2_dir_entry *dirent)
  {
  	__u32 crc;
  	errcode_t retval = 0;
  	struct ext2_dx_countlimit *c;
  	struct ext2_dx_tail *t;
  	int count_offset, limit, count;
  
  	retval = __get_dx_countlimit(fs, dirent, &c, &count_offset, 1);
  	if (retval)
  		return retval;
  	limit = ext2fs_le16_to_cpu(c->limit);
  	count = ext2fs_le16_to_cpu(c->count);
  	if (count_offset + (limit * sizeof(struct ext2_dx_entry)) >
  	    fs->blocksize - sizeof(struct ext2_dx_tail))
  		return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
  	t = (struct ext2_dx_tail *)(((struct ext2_dx_entry *)c) + limit);
  
  	/* htree structs are accessed in LE order */
  	retval = ext2fs_dx_csum(fs, inum, dirent, &crc, count_offset, count, t);
  	if (retval)
  		return retval;
  	t->dt_checksum = ext2fs_cpu_to_le32(crc);
  	return retval;
  }
  
  int ext2fs_dir_block_csum_verify(ext2_filsys fs, ext2_ino_t inum,
  				 struct ext2_dir_entry *dirent)
  {
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 1;
  
  	if (__get_dirent_tail(fs, dirent, NULL, 1) == 0)
  		return ext2fs_dirent_csum_verify(fs, inum, dirent);
  	if (__get_dx_countlimit(fs, dirent, NULL, NULL, 1) == 0)
  		return ext2fs_dx_csum_verify(fs, inum, dirent);
  
  	return 0;
  }
  
  errcode_t ext2fs_dir_block_csum_set(ext2_filsys fs, ext2_ino_t inum,
  				    struct ext2_dir_entry *dirent)
  {
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 0;
  
  	if (__get_dirent_tail(fs, dirent, NULL, 1) == 0)
  		return ext2fs_dirent_csum_set(fs, inum, dirent);
  	if (__get_dx_countlimit(fs, dirent, NULL, NULL, 1) == 0)
  		return ext2fs_dx_csum_set(fs, inum, dirent);
  
  	if (fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS)
  		return 0;
  	return EXT2_ET_DIR_NO_SPACE_FOR_CSUM;
  }
  
  #define EXT3_EXTENT_TAIL_OFFSET(hdr)	(sizeof(struct ext3_extent_header) + \
  	(sizeof(struct ext3_extent) * ext2fs_le16_to_cpu((hdr)->eh_max)))
  
  static struct ext3_extent_tail *get_extent_tail(struct ext3_extent_header *h)
  {
  	return (struct ext3_extent_tail *)(((char *)h) +
  					   EXT3_EXTENT_TAIL_OFFSET(h));
  }
  
  static errcode_t ext2fs_extent_block_csum(ext2_filsys fs, ext2_ino_t inum,
  					  struct ext3_extent_header *eh,
  					  __u32 *crc)
  {
  	int size;
  	__u32 gen;
  	errcode_t retval;
  	struct ext2_inode inode;
  
  	size = EXT3_EXTENT_TAIL_OFFSET(eh) + offsetof(struct ext3_extent_tail,
  						      et_checksum);
  
  	retval = ext2fs_read_inode(fs, inum, &inode);
  	if (retval)
  		return retval;
  	inum = ext2fs_cpu_to_le32(inum);
  	gen = ext2fs_cpu_to_le32(inode.i_generation);
  	*crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
  				sizeof(inum));
  	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
  	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)eh, size);
  
  	return 0;
  }
  
  int ext2fs_extent_block_csum_verify(ext2_filsys fs, ext2_ino_t inum,
  				    struct ext3_extent_header *eh)
  {
  	errcode_t retval;
  	__u32 provided, calculated;
  	struct ext3_extent_tail *t = get_extent_tail(eh);
  
  	/*
  	 * The extent tree structures are accessed in LE order, so we must
  	 * swap the checksum bytes here.
  	 */
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 1;
  
  	provided = ext2fs_le32_to_cpu(t->et_checksum);
  	retval = ext2fs_extent_block_csum(fs, inum, eh, &calculated);
  	if (retval)
  		return 0;
  
  	return provided == calculated;
  }
  
  errcode_t ext2fs_extent_block_csum_set(ext2_filsys fs, ext2_ino_t inum,
  				       struct ext3_extent_header *eh)
  {
  	errcode_t retval;
  	__u32 crc;
  	struct ext3_extent_tail *t = get_extent_tail(eh);
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 0;
  
  	/*
  	 * The extent tree structures are accessed in LE order, so we must
  	 * swap the checksum bytes here.
  	 */
  	retval = ext2fs_extent_block_csum(fs, inum, eh, &crc);
  	if (retval)
  		return retval;
  	t->et_checksum = ext2fs_cpu_to_le32(crc);
  	return retval;
  }
  
  int ext2fs_inode_bitmap_csum_verify(ext2_filsys fs, dgrp_t group,
  				    char *bitmap, int size)
  {
  	struct ext4_group_desc *gdp = (struct ext4_group_desc *)
  			ext2fs_group_desc(fs, fs->group_desc, group);
  	__u32 provided, calculated;
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 1;
  	provided = gdp->bg_inode_bitmap_csum_lo;
  	calculated = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap,
  				      size);
  	if (fs->super->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  		provided |= (__u32)gdp->bg_inode_bitmap_csum_hi << 16;
  	else
  		calculated &= 0xFFFF;
  
  	return provided == calculated;
  }
  
  errcode_t ext2fs_inode_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
  				       char *bitmap, int size)
  {
  	__u32 crc;
  	struct ext4_group_desc *gdp = (struct ext4_group_desc *)
  			ext2fs_group_desc(fs, fs->group_desc, group);
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 0;
  
  	crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap, size);
  	gdp->bg_inode_bitmap_csum_lo = crc & 0xFFFF;
  	if (fs->super->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)
  		gdp->bg_inode_bitmap_csum_hi = crc >> 16;
  
  	return 0;
  }
  
  int ext2fs_block_bitmap_csum_verify(ext2_filsys fs, dgrp_t group,
  				    char *bitmap, int size)
  {
  	struct ext4_group_desc *gdp = (struct ext4_group_desc *)
  			ext2fs_group_desc(fs, fs->group_desc, group);
  	__u32 provided, calculated;
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 1;
  	provided = gdp->bg_block_bitmap_csum_lo;
  	calculated = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap,
  				      size);
  	if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
  		provided |= (__u32)gdp->bg_block_bitmap_csum_hi << 16;
  	else
  		calculated &= 0xFFFF;
  
  	return provided == calculated;
  }
  
  errcode_t ext2fs_block_bitmap_csum_set(ext2_filsys fs, dgrp_t group,
  				       char *bitmap, int size)
  {
  	__u32 crc;
  	struct ext4_group_desc *gdp = (struct ext4_group_desc *)
  			ext2fs_group_desc(fs, fs->group_desc, group);
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 0;
  
  	crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)bitmap, size);
  	gdp->bg_block_bitmap_csum_lo = crc & 0xFFFF;
  	if (fs->super->s_desc_size >= EXT4_BG_BLOCK_BITMAP_CSUM_HI_LOCATION)
  		gdp->bg_block_bitmap_csum_hi = crc >> 16;
  
  	return 0;
  }
  
  static errcode_t ext2fs_inode_csum(ext2_filsys fs, ext2_ino_t inum,
  			       struct ext2_inode_large *inode,
  			       __u32 *crc, int has_hi)
  {
  	__u32 gen;
  	struct ext2_inode_large *desc = inode;
  	size_t size = EXT2_INODE_SIZE(fs->super);
  	__u16 old_lo;
  	__u16 old_hi = 0;
  
  	old_lo = inode->i_checksum_lo;
  	inode->i_checksum_lo = 0;
  	if (has_hi) {
  		old_hi = inode->i_checksum_hi;
  		inode->i_checksum_hi = 0;
  	}
  
  	inum = ext2fs_cpu_to_le32(inum);
  	gen = inode->i_generation;
  	*crc = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&inum,
  				sizeof(inum));
  	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)&gen, sizeof(gen));
  	*crc = ext2fs_crc32c_le(*crc, (unsigned char *)desc, size);
  
  	inode->i_checksum_lo = old_lo;
  	if (has_hi)
  		inode->i_checksum_hi = old_hi;
  	return 0;
  }
  
  int ext2fs_inode_csum_verify(ext2_filsys fs, ext2_ino_t inum,
  			     struct ext2_inode_large *inode)
  {
  	errcode_t retval;
  	__u32 provided, calculated;
  	unsigned int i, has_hi;
  	char *cp;
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 1;
  
  	has_hi = (EXT2_INODE_SIZE(fs->super) > EXT2_GOOD_OLD_INODE_SIZE &&
  		  inode->i_extra_isize >= EXT4_INODE_CSUM_HI_EXTRA_END);
  
  	provided = ext2fs_le16_to_cpu(inode->i_checksum_lo);
  	retval = ext2fs_inode_csum(fs, inum, inode, &calculated, has_hi);
  	if (retval)
  		return 0;
  	if (has_hi) {
  		__u32 hi = ext2fs_le16_to_cpu(inode->i_checksum_hi);
  		provided |= hi << 16;
  	} else
  		calculated &= 0xFFFF;
  
  	if (provided == calculated)
  		return 1;
  
  	/*
  	 * If the checksum didn't match, it's possible it was due to
  	 * the inode being all zero's.  It's unlikely this is the
  	 * case, but it can happen.  So check for it here.  (We only
  	 * check the base inode since that's good enough, and it's not
  	 * worth the bother to figure out how much of the extended
  	 * inode, if any, is present.)
  	 */
  	for (cp = (char *) inode, i = 0;
  	     i < sizeof(struct ext2_inode);
  	     cp++, i++)
  		if (*cp)
  			return 0;
  	return 1;		/* Inode must have been all zero's */
  }
  
  errcode_t ext2fs_inode_csum_set(ext2_filsys fs, ext2_ino_t inum,
  			   struct ext2_inode_large *inode)
  {
  	errcode_t retval;
  	__u32 crc;
  	int has_hi;
  
  	if (!ext2fs_has_feature_metadata_csum(fs->super))
  		return 0;
  
  	has_hi = (EXT2_INODE_SIZE(fs->super) > EXT2_GOOD_OLD_INODE_SIZE &&
  		  inode->i_extra_isize >= EXT4_INODE_CSUM_HI_EXTRA_END);
  
  	retval = ext2fs_inode_csum(fs, inum, inode, &crc, has_hi);
  	if (retval)
  		return retval;
  	inode->i_checksum_lo = ext2fs_cpu_to_le16(crc & 0xFFFF);
  	if (has_hi)
  		inode->i_checksum_hi = ext2fs_cpu_to_le16(crc >> 16);
  	return 0;
  }
  
  __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
  {
  	struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc,
  							 group);
  	size_t offset, size = EXT2_DESC_SIZE(fs->super);
  	__u16 crc = 0;
  #ifdef WORDS_BIGENDIAN
  	struct ext4_group_desc swabdesc;
  	size_t save_size = size;
  	const size_t ext4_bg_size = sizeof(struct ext4_group_desc);
  	struct ext2_group_desc *save_desc = desc;
  
  	/* Have to swab back to little-endian to do the checksum */
  	if (size > ext4_bg_size)
  		size = ext4_bg_size;
  	memcpy(&swabdesc, desc, size);
  	ext2fs_swap_group_desc2(fs, (struct ext2_group_desc *) &swabdesc);
  	desc = (struct ext2_group_desc *) &swabdesc;
  	group = ext2fs_swab32(group);
  #endif
  
  	if (ext2fs_has_feature_metadata_csum(fs->super)) {
  		/* new metadata csum code */
  		__u16 old_crc;
  		__u32 crc32;
  
  		old_crc = desc->bg_checksum;
  		desc->bg_checksum = 0;
  		crc32 = ext2fs_crc32c_le(fs->csum_seed, (unsigned char *)&group,
  					 sizeof(group));
  		crc32 = ext2fs_crc32c_le(crc32, (unsigned char *)desc,
  					 size);
  		desc->bg_checksum = old_crc;
  #ifdef WORDS_BIGENDIAN
  		if (save_size > ext4_bg_size)
  			crc32 = ext2fs_crc32c_le(crc32,
  				     (unsigned char *)save_desc + ext4_bg_size,
  	                             save_size - ext4_bg_size);
  #endif
  		crc = crc32 & 0xFFFF;
  		goto out;
  	}
  
  	/* old crc16 code */
  	offset = offsetof(struct ext2_group_desc, bg_checksum);
  	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 */
  	/* for checksum of struct ext4_group_desc do the rest...*/
  	if (offset < size) {
  		crc = ext2fs_crc16(crc, (char *)desc + offset,
  				   size - offset);
  	}
  #ifdef WORDS_BIGENDIAN
  	/*
  	 * If the size of the bg descriptor is greater than 64
  	 * bytes, which is the size of the traditional ext4 bg
  	 * descriptor, checksum the rest of the descriptor here
  	 */
  	if (save_size > ext4_bg_size)
  		crc = ext2fs_crc16(crc, (char *)save_desc + ext4_bg_size,
  				   save_size - ext4_bg_size);
  #endif
  
  out:
  	return crc;
  }
  
  int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group)
  {
  	if (ext2fs_has_group_desc_csum(fs) &&
  	    (ext2fs_bg_checksum(fs, group) !=
  	     ext2fs_group_desc_csum(fs, group)))
  		return 0;
  
  	return 1;
  }
  
  void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group)
  {
  	if (!ext2fs_has_group_desc_csum(fs))
  		return;
  
  	/* ext2fs_bg_checksum_set() sets the actual checksum field but
  	 * does not calculate the checksum itself. */
  	ext2fs_bg_checksum_set(fs, group, 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_bitmap2(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;
  	int dirty = 0;
  	dgrp_t i;
  
  	if (!fs->inode_map)
  		return EXT2_ET_NO_INODE_BITMAP;
  
  	if (!ext2fs_has_group_desc_csum(fs))
  		return 0;
  
  	for (i = 0; i < fs->group_desc_count; i++) {
  		__u32 old_csum = ext2fs_bg_checksum(fs, i);
  		__u32 old_unused = ext2fs_bg_itable_unused(fs, i);
  		__u32 old_flags = ext2fs_bg_flags(fs, i);
  		__u32 old_free_inodes_count = ext2fs_bg_free_inodes_count(fs, i);
  		__u32 old_free_blocks_count = ext2fs_bg_free_blocks_count(fs, i);
  
  		if (old_free_blocks_count == sb->s_blocks_per_group &&
  		    i != fs->group_desc_count - 1)
  			ext2fs_bg_flags_set(fs, i, EXT2_BG_BLOCK_UNINIT);
  
  		if (old_free_inodes_count == sb->s_inodes_per_group) {
  			ext2fs_bg_flags_set(fs, i, EXT2_BG_INODE_UNINIT);
  			ext2fs_bg_itable_unused_set(fs, i, sb->s_inodes_per_group);
  		} else {
  			int unused =
  				sb->s_inodes_per_group -
  				find_last_inode_ingrp(fs->inode_map,
  						      sb->s_inodes_per_group, i);
  
  			ext2fs_bg_flags_clear(fs, i, EXT2_BG_INODE_UNINIT);
  			ext2fs_bg_itable_unused_set(fs, i, unused);
  		}
  
  		ext2fs_group_desc_csum_set(fs, i);
  		if (old_flags != ext2fs_bg_flags(fs, i))
  			dirty = 1;
  		if (old_unused != ext2fs_bg_itable_unused(fs, i))
  			dirty = 1;
  		if (old_csum != ext2fs_bg_checksum(fs, i))
  			dirty = 1;
  	}
  	if (dirty)
  		ext2fs_mark_super_dirty(fs);
  	return 0;
  }
  
  #ifdef DEBUG
  #include "e2p/e2p.h"
  
  void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
  {
  	__u16 crc1, crc2, crc3;
  	dgrp_t swabgroup;
  	struct ext2_group_desc *desc = ext2fs_group_desc(fs, fs->group_desc,
  							 group);
  	size_t size = EXT2_DESC_SIZE(fs->super);
  	struct ext2_super_block *sb = fs->super;
  	int offset = offsetof(struct ext2_group_desc, bg_checksum);
  #ifdef WORDS_BIGENDIAN
  	struct ext4_group_desc swabdesc;
  	struct ext2_group_desc *save_desc = desc;
  	const size_t ext4_bg_size = sizeof(struct ext4_group_desc);
  	size_t save_size = size;
  #endif
  
  #ifdef WORDS_BIGENDIAN
  	/* Have to swab back to little-endian to do the checksum */
  	if (size > ext4_bg_size)
  		size = ext4_bg_size;
  	memcpy(&swabdesc, desc, size);
  	ext2fs_swap_group_desc2(fs, (struct ext2_group_desc *) &swabdesc);
  	desc = (struct ext2_group_desc *) &swabdesc;
  
  	swabgroup = ext2fs_swab32(group);
  #else
  	swabgroup = group;
  #endif
  
  	crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
  	crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup));
  	crc3 = ext2fs_crc16(crc2, desc, offset);
  	offset += sizeof(desc->bg_checksum); /* skip checksum */
  	/* for checksum of struct ext4_group_desc do the rest...*/
  	if (offset < size)
  		crc3 = ext2fs_crc16(crc3, (char *)desc + offset, size - offset);
  #ifdef WORDS_BIGENDIAN
  	if (save_size > ext4_bg_size)
  		crc3 = ext2fs_crc16(crc3, (char *)save_desc + ext4_bg_size,
  				    save_size - ext4_bg_size);
  #endif
  
  	printf("%s UUID %s=%04x, grp %u=%04x: %04x=%04x\n",
  	       msg, e2p_uuid2str(sb->s_uuid), crc1, group, crc2, crc3,
  	       ext2fs_group_desc_csum(fs, group));
  }
  
  unsigned char sb_uuid[16] = { 0x4f, 0x25, 0xe8, 0xcf, 0xe7, 0x97, 0x48, 0x23,
  			      0xbe, 0xfa, 0xa7, 0x88, 0x4b, 0xae, 0xec, 0xdb };
  
  int main(int argc, char **argv)
  {
  	struct ext2_super_block param;
  	errcode_t		retval;
  	ext2_filsys		fs;
  	int			i;
  	__u16 csum1, csum2, csum_known = 0xd3a4;
  
  	memset(&param, 0, sizeof(param));
  	ext2fs_blocks_count_set(&param, 32768);
  #if 0
  	param.s_feature_incompat |= EXT4_FEATURE_INCOMPAT_64BIT;
  	param.s_desc_size = 128;
  	csum_known = 0x5b6e;
  #endif
  
  	retval = ext2fs_initialize("test fs", EXT2_FLAG_64BITS, &param,
  				   test_io_manager, &fs);
  	if (retval) {
  		com_err("setup", retval,
  			"While initializing filesystem");
  		exit(1);
  	}
  	memcpy(fs->super->s_uuid, sb_uuid, 16);
  	fs->super->s_feature_ro_compat = EXT4_FEATURE_RO_COMPAT_GDT_CSUM;
  
  	for (i=0; i < fs->group_desc_count; i++) {
  		ext2fs_block_bitmap_loc_set(fs, i, 124);
  		ext2fs_inode_bitmap_loc_set(fs, i, 125);
  		ext2fs_inode_table_loc_set(fs, i, 126);
  		ext2fs_bg_free_blocks_count_set(fs, i, 31119);
  		ext2fs_bg_free_inodes_count_set(fs, i, 15701);
  		ext2fs_bg_used_dirs_count_set(fs, i, 2);
  		ext2fs_bg_flags_zap(fs, i);
  	};
  
  	csum1 = ext2fs_group_desc_csum(fs, 0);
  	print_csum("csum0000", fs, 0);
  
  	if (csum1 != csum_known) {
  		printf("checksum for group 0 should be %04x\n", csum_known);
  		exit(1);
  	}
  	csum2 = ext2fs_group_desc_csum(fs, 1);
  	print_csum("csum0001", fs, 1);
  	if (csum1 == csum2) {
  		printf("checksums for different groups shouldn't match\n");
  		exit(1);
  	}
  	csum2 = ext2fs_group_desc_csum(fs, 2);
  	print_csum("csumffff", fs, 2);
  	if (csum1 == csum2) {
  		printf("checksums for different groups shouldn't match\n");
  		exit(1);
  	}
  	ext2fs_bg_checksum_set(fs, 0, csum1);
  	csum2 = ext2fs_group_desc_csum(fs, 0);
  	print_csum("csum_set", fs, 0);
  	if (csum1 != csum2) {
  		printf("checksums should not depend on checksum field\n");
  		exit(1);
  	}
  	if (!ext2fs_group_desc_csum_verify(fs, 0)) {
  		printf("checksums should verify against gd_checksum\n");
  		exit(1);
  	}
  	memset(fs->super->s_uuid, 0x30, sizeof(fs->super->s_uuid));
  	print_csum("new_uuid", fs, 0);
  	if (ext2fs_group_desc_csum_verify(fs, 0) != 0) {
  		printf("checksums for different filesystems shouldn't match\n");
  		exit(1);
  	}
  	csum1 = ext2fs_group_desc_csum(fs, 0);
  	ext2fs_bg_checksum_set(fs, 0, csum1);
  	print_csum("csum_new", fs, 0);
  	ext2fs_bg_free_blocks_count_set(fs, 0, 1);
  	csum2 = ext2fs_group_desc_csum(fs, 0);
  	print_csum("csum_blk", fs, 0);
  	if (csum1 == csum2) {
  		printf("checksums for different data shouldn't match\n");
  		exit(1);
  	}
  	ext2fs_free(fs);
  
  	return 0;
  }
  #endif
  