lib/ext2fs/ext_attr.c

   1 /*
   2  * ext_attr.c --- extended attribute blocks
   3  *
   4  * Copyright (C) 2001 Andreas Gruenbacher, <a.gruenbacher@computer.org>
   5  *
   6  * Copyright (C) 2002 Theodore Ts'o.
   7  *
   8  * %Begin-Header%
   9  * This file may be redistributed under the terms of the GNU Library
  10  * General Public License, version 2.
  11  * %End-Header%
  12  */
  13
  14 #include "config.h"
  15 #include <stdio.h>
  16 #if HAVE_UNISTD_H
  17 #include <unistd.h>
  18 #endif
  19 #include <string.h>
  20 #include <time.h>
  21
  22 #include "ext2_fs.h"
  23 #include "ext2_ext_attr.h"
  24
  25 #include "ext2fs.h"
  26
  27 #define NAME_HASH_SHIFT 5
  28 #define VALUE_HASH_SHIFT 16
  29
  30 /*
  31  * ext2_xattr_hash_entry()
  32  *
  33  * Compute the hash of an extended attribute.
  34  */
  35 __u32 ext2fs_ext_attr_hash_entry(struct ext2_ext_attr_entry *entry, void *data)
  36 {
  37         __u32 hash = 0;
  38         char *name = ((char *) entry) + sizeof(struct ext2_ext_attr_entry);
  39         int n;
  40
  41         for (n = 0; n < entry->e_name_len; n++) {
  42                 hash = (hash << NAME_HASH_SHIFT) ^
  43                        (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^
  44                        *name++;
  45         }
  46
  47         /* The hash needs to be calculated on the data in little-endian. */
  48         if (entry->e_value_block == 0 && entry->e_value_size != 0) {
  49                 __u32 *value = (__u32 *)data;
  50                 for (n = (entry->e_value_size + EXT2_EXT_ATTR_ROUND) >>
  51                          EXT2_EXT_ATTR_PAD_BITS; n; n--) {
  52                         hash = (hash << VALUE_HASH_SHIFT) ^
  53                                (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^
  54                                ext2fs_le32_to_cpu(*value++);
  55                 }
  56         }
  57
  58         return hash;
  59 }
  60
  61 #undef NAME_HASH_SHIFT
  62 #undef VALUE_HASH_SHIFT
  63
  64 errcode_t ext2fs_read_ext_attr3(ext2_filsys fs, blk64_t block, void *buf,
  65                                 ext2_ino_t inum)
  66 {
  67         errcode_t       retval;
  68
  69         retval = io_channel_read_blk64(fs->io, block, 1, buf);
  70         if (retval)
  71                 return retval;
  72
  73         if (!(fs->flags & EXT2_FLAG_IGNORE_CSUM_ERRORS) &&
  74             !ext2fs_ext_attr_block_csum_verify(fs, inum, block, buf))
  75                 retval = EXT2_ET_EXT_ATTR_CSUM_INVALID;
  76
  77 #ifdef WORDS_BIGENDIAN
  78         ext2fs_swap_ext_attr(buf, buf, fs->blocksize, 1);
  79 #endif
  80
  81         return retval;
  82 }
  83
  84 errcode_t ext2fs_read_ext_attr2(ext2_filsys fs, blk64_t block, void *buf)
  85 {
  86         return ext2fs_read_ext_attr3(fs, block, buf, 0);
  87 }
  88
  89 errcode_t ext2fs_read_ext_attr(ext2_filsys fs, blk_t block, void *buf)
  90 {
  91         return ext2fs_read_ext_attr2(fs, block, buf);
  92 }
  93
  94 errcode_t ext2fs_write_ext_attr3(ext2_filsys fs, blk64_t block, void *inbuf,
  95                                  ext2_ino_t inum)
  96 {
  97         errcode_t       retval;
  98         char            *write_buf;
  99
 100 #ifdef WORDS_BIGENDIAN
 101         retval = ext2fs_get_mem(fs->blocksize, &write_buf);
 102         if (retval)
 103                 return retval;
 104         ext2fs_swap_ext_attr(write_buf, inbuf, fs->blocksize, 1);
 105 #else
 106         write_buf = (char *) inbuf;
 107 #endif
 108
 109         retval = ext2fs_ext_attr_block_csum_set(fs, inum, block,
 110                         (struct ext2_ext_attr_header *)write_buf);
 111         if (retval)
 112                 return retval;
 113
 114         retval = io_channel_write_blk64(fs->io, block, 1, write_buf);
 115 #ifdef WORDS_BIGENDIAN
 116         ext2fs_free_mem(&write_buf);
 117 #endif
 118         if (!retval)
 119                 ext2fs_mark_changed(fs);
 120         return retval;
 121 }
 122
 123 errcode_t ext2fs_write_ext_attr2(ext2_filsys fs, blk64_t block, void *inbuf)
 124 {
 125         return ext2fs_write_ext_attr3(fs, block, inbuf, 0);
 126 }
 127
 128 errcode_t ext2fs_write_ext_attr(ext2_filsys fs, blk_t block, void *inbuf)
 129 {
 130         return ext2fs_write_ext_attr2(fs, block, inbuf);
 131 }
 132
 133 /*
 134  * This function adjusts the reference count of the EA block.
 135  */
 136 errcode_t ext2fs_adjust_ea_refcount3(ext2_filsys fs, blk64_t blk,
 137                                     char *block_buf, int adjust,
 138                                     __u32 *newcount, ext2_ino_t inum)
 139 {
 140         errcode_t       retval;
 141         struct ext2_ext_attr_header *header;
 142         char    *buf = 0;
 143
 144         if ((blk >= ext2fs_blocks_count(fs->super)) ||
 145             (blk < fs->super->s_first_data_block))
 146                 return EXT2_ET_BAD_EA_BLOCK_NUM;
 147
 148         if (!block_buf) {
 149                 retval = ext2fs_get_mem(fs->blocksize, &buf);
 150                 if (retval)
 151                         return retval;
 152                 block_buf = buf;
 153         }
 154
 155         retval = ext2fs_read_ext_attr3(fs, blk, block_buf, inum);
 156         if (retval)
 157                 goto errout;
 158
 159         header = (struct ext2_ext_attr_header *) block_buf;
 160         header->h_refcount += adjust;
 161         if (newcount)
 162                 *newcount = header->h_refcount;
 163
 164         retval = ext2fs_write_ext_attr3(fs, blk, block_buf, inum);
 165         if (retval)
 166                 goto errout;
 167
 168 errout:
 169         if (buf)
 170                 ext2fs_free_mem(&buf);
 171         return retval;
 172 }
 173
 174 errcode_t ext2fs_adjust_ea_refcount2(ext2_filsys fs, blk64_t blk,
 175                                     char *block_buf, int adjust,
 176                                     __u32 *newcount)
 177 {
 178         return ext2fs_adjust_ea_refcount3(fs, blk, block_buf, adjust,
 179                                           newcount, 0);
 180 }
 181
 182 errcode_t ext2fs_adjust_ea_refcount(ext2_filsys fs, blk_t blk,
 183                                         char *block_buf, int adjust,
 184                                         __u32 *newcount)
 185 {
 186         return ext2fs_adjust_ea_refcount2(fs, blk, block_buf, adjust,
 187                                           newcount);
 188 }