lib/ext2fs/dirblock.c

   1 /*
   2  * dirblock.c --- directory block routines.
   3  *
   4  * Copyright (C) 1995, 1996 Theodore Ts'o.
   5  *
   6  * %Begin-Header%
   7  * This file may be redistributed under the terms of the GNU Public
   8  * License.
   9  * %End-Header%
  10  */
  11
  12 #include <stdio.h>
  13 #if HAVE_UNISTD_H
  14 #include <unistd.h>
  15 #endif
  16 #include <string.h>
  17 #include <time.h>
  18
  19 #include "ext2_fs.h"
  20 #include "ext2fs.h"
  21
  22 errcode_t ext2fs_read_dir_block2(ext2_filsys fs, blk_t block,
  23                                  void *buf, int flags EXT2FS_ATTR((unused)))
  24 {
  25         errcode_t       retval;
  26         char            *p, *end;
  27         struct ext2_dir_entry *dirent;
  28         unsigned int    name_len, rec_len, do_swap;
  29
  30
  31         retval = io_channel_read_blk(fs->io, block, 1, buf);
  32         if (retval)
  33                 return retval;
  34 #ifdef EXT2FS_ENABLE_SWAPFS
  35         do_swap = (fs->flags & (EXT2_FLAG_SWAP_BYTES|
  36                                 EXT2_FLAG_SWAP_BYTES_READ)) != 0;
  37 #endif
  38         p = (char *) buf;
  39         end = (char *) buf + fs->blocksize;
  40         while (p < end-8) {
  41                 dirent = (struct ext2_dir_entry *) p;
  42 #ifdef EXT2FS_ENABLE_SWAPFS
  43                 if (do_swap) {
  44                         dirent->inode = ext2fs_swab32(dirent->inode);
  45                         dirent->rec_len = ext2fs_swab16(dirent->rec_len);
  46                         dirent->name_len = ext2fs_swab16(dirent->name_len);
  47                 }
  48 #endif
  49                 name_len = dirent->name_len;
  50 #ifdef WORDS_BIGENDIAN
  51                 if (flags & EXT2_DIRBLOCK_V2_STRUCT)
  52                         dirent->name_len = ext2fs_swab16(dirent->name_len);
  53 #endif
  54                 rec_len = dirent->rec_len;
  55                 if ((rec_len < 8) || (rec_len % 4)) {
  56                         rec_len = 8;
  57                         retval = EXT2_ET_DIR_CORRUPTED;
  58                 }
  59                 if (((name_len & 0xFF) + 8) > dirent->rec_len)
  60                         retval = EXT2_ET_DIR_CORRUPTED;
  61                 p += rec_len;
  62         }
  63         return retval;
  64 }
  65
  66 errcode_t ext2fs_read_dir_block(ext2_filsys fs, blk_t block,
  67                                  void *buf)
  68 {
  69         return ext2fs_read_dir_block2(fs, block, buf, 0);
  70 }
  71
  72
  73 errcode_t ext2fs_write_dir_block2(ext2_filsys fs, blk_t block,
  74                                   void *inbuf, int flags EXT2FS_ATTR((unused)))
  75 {
  76 #ifdef EXT2FS_ENABLE_SWAPFS
  77         int             do_swap = 0;
  78         errcode_t       retval;
  79         char            *p, *end;
  80         char            *buf = 0;
  81         struct ext2_dir_entry *dirent;
  82
  83         if ((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
  84             (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE))
  85                 do_swap = 1;
  86
  87 #ifndef WORDS_BIGENDIAN
  88         if (!do_swap)
  89                 return io_channel_write_blk(fs->io, block, 1, (char *) inbuf);
  90 #endif
  91
  92         retval = ext2fs_get_mem(fs->blocksize, &buf);
  93         if (retval)
  94                 return retval;
  95         memcpy(buf, inbuf, fs->blocksize);
  96         p = buf;
  97         end = buf + fs->blocksize;
  98         while (p < end) {
  99                 dirent = (struct ext2_dir_entry *) p;
 100                 if ((dirent->rec_len < 8) ||
 101                     (dirent->rec_len % 4)) {
 102                         ext2fs_free_mem(&buf);
 103                         return (EXT2_ET_DIR_CORRUPTED);
 104                 }
 105                 p += dirent->rec_len;
 106                 if (do_swap) {
 107                         dirent->inode = ext2fs_swab32(dirent->inode);
 108                         dirent->rec_len = ext2fs_swab16(dirent->rec_len);
 109                         dirent->name_len = ext2fs_swab16(dirent->name_len);
 110                 }
 111 #ifdef WORDS_BIGENDIAN
 112                 if (flags & EXT2_DIRBLOCK_V2_STRUCT)
 113                         dirent->name_len = ext2fs_swab16(dirent->name_len);
 114 #endif
 115         }
 116         retval = io_channel_write_blk(fs->io, block, 1, buf);
 117         ext2fs_free_mem(&buf);
 118         return retval;
 119 #else
 120         return io_channel_write_blk(fs->io, block, 1, (char *) inbuf);
 121 #endif
 122 }
 123
 124
 125 errcode_t ext2fs_write_dir_block(ext2_filsys fs, blk_t block,
 126                                  void *inbuf)
 127 {
 128         return ext2fs_write_dir_block2(fs, block, inbuf, 0);
 129 }
 130