/*

 * 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);

  if (fs->blocksize < 1024)

    return EXT2_FILSYS_CORRUPTED; /* Should never happen */

  d = dirent;

  top = EXT2_DIRENT_TAIL(dirent, fs->blocksize);

  while ((void *) d < top) {

    rec_len = translate(d->rec_len);

    if ((rec_len < 8) || (rec_len & 0x03))

      return EXT2_ET_DIR_CORRUPTED;

    d = (struct ext2_dir_entry *)(((char *)d) + rec_len);

  }

  if ((char *)d > ((char *)dirent + fs->blocksize))

      return EXT2_ET_DIR_CORRUPTED;

  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) !=

    EXT2_ET_DIR_NO_SPACE_FOR_CSUM;

}

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;

}

errcode_t ext2fs_dx_csum(ext2_filsys fs, ext2_ino_t inum,

       struct ext2_dir_entry *dirent,

       __u32 *crc, struct ext2_dx_tail **ret_t)

{

  errcode_t retval;

  char *buf = (char *)dirent;

  int size;

  __u32 gen, dummy_csum = 0;

  struct ext2_inode inode;

  struct ext2_dx_tail *t;

  struct ext2_dx_countlimit *c;

  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;

  /* htree structs are accessed in LE order */

  t = (struct ext2_dx_tail *)(((struct ext2_dx_entry *)c) + limit);

  size = count_offset + (count * sizeof(struct ext2_dx_entry));

  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, 4);

  *crc = ext2fs_crc32c_le(*crc, (unsigned char *)&dummy_csum, 4);

  if (ret_t)

    *ret_t = t;

  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_tail *t;

  retval = ext2fs_dx_csum(fs, inum, dirent, &calculated, &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_tail *t;

  retval = ext2fs_dx_csum(fs, inum, dirent, &crc, &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 (EXT2_DESC_SIZE(fs->super) >= 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 (EXT2_DESC_SIZE(fs->super) >= 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 (EXT2_DESC_SIZE(fs->super) >= 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 (EXT2_DESC_SIZE(fs->super) >= 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 };