fs_fat32.c

                    ret = cluster;
                    goto errout_with_semaphore;
                }

                /* Zero means that there is no further clusters available
                 * in the chain.
                 */

                if (cluster == 0)
                {
                    /* At the position to the current locaiton and
                     * break out.
                     */

                    position = clustersize;
                    break;
                }

                if (cluster >= fs->fs_nclusters)
                {
                    ret = -ENOSPC;
                    goto errout_with_semaphore;
                }

                /* Otherwise, update the position and continue looking */

                ff->ff_position += clustersize;
                position        -= clustersize;
            }

            /* We get here after we have found the sector containing
             * the requested position.
             */

            sectoroffset = (position - 1) / fs->fs_hwsectorsize;

            /* And get the current sector from the cluster and
             * the sectoroffset into the cluster.
             */

            ff->ff_currentsector =
                fat_cluster2sector(fs, cluster) + sectoroffset;

            /* Load the sector corresponding to the position */

            if ((position & SEC_NDXMASK(fs)) != 0)
            {
                ret = fat_ffcacheread(fs, ff, ff->ff_currentsector);
                if (ret < 0)
                {
                    goto errout_with_semaphore;
                }
            }

            /* Save the number of sectors left in the cluster */

            ff->ff_sectorsincluster = fs->fs_fatsecperclus - sectoroffset;

            /* And save the new file position */

            ff->ff_position += position;
        }
    }

  /* If we extended the size of the file, then mark the file as modified. */

  if ((ff->ff_oflags & O_WROK) != 0 &&  ff->ff_position > ff->ff_size)
    {
        ff->ff_size    = ff->ff_position;
        ff->ff_bflags |= FFBUFF_MODIFIED;
    }

  fat_semgive(fs);
  return OK;

 errout_with_semaphore:
  fat_semgive(fs);
  return ret;
}

/****************************************************************************
 * Name: fat_ioctl
 ****************************************************************************/

static int fat_ioctl(FAR struct file *filp, int cmd, unsigned long arg)
{
  struct inode         *inode;
  struct fat_mountpt_s *fs;
  struct fat_file_s    *ff;
  int                   ret;

  /* Sanity checks */

  DEBUGASSERT(filp->f_priv != NULL && filp->f_inode != NULL);

  /* Recover our private data from the struct file instance */

  ff    = filp->f_priv;
  inode = filp->f_inode;
  fs    = inode->i_private;

  DEBUGASSERT(fs != NULL);

  /* Make sure that the mount is still healthy */

  fat_semtake(fs);
  ret = fat_checkmount(fs);
  if (ret != OK)
    {
      fat_semgive(fs);
      return ret;
    }

  /* ioctl calls are just passed through to the contained block driver */

  fat_semgive(fs);
  return -ENOSYS;
}

/****************************************************************************
 * Name: fat_sync
 *
 * Description: Synchronize the file state on disk to match internal, in-
 *   memory state.
 *
 ****************************************************************************/

static int fat_sync(FAR struct file *filp)
{
  struct inode         *inode;
  struct fat_mountpt_s *fs;
  struct fat_file_s    *ff;
  uint32                wrttime;
  ubyte                *direntry;
  int                   ret;

  /* Sanity checks */

  DEBUGASSERT(filp->f_priv != NULL && filp->f_inode != NULL);

  /* Recover our private data from the struct file instance */

  ff    = filp->f_priv;
  inode = filp->f_inode;
  fs    = inode->i_private;

  DEBUGASSERT(fs != NULL);

  /* Make sure that the mount is still healthy */

  fat_semtake(fs);
  ret = fat_checkmount(fs);
  if (ret != OK)
    {
      goto errout_with_semaphore;
    }

  /* Check if the has been modified in any way */
  if ((ff->ff_bflags & FFBUFF_MODIFIED) != 0)
    {
      /* Flush any unwritten data in the file buffer */

      ret = fat_ffcacheflush(fs, ff);
      if (ret < 0)
        {
          goto errout_with_semaphore;
        }

      /* Update the directory entry.  First read the directory
       * entry into the fs_buffer (preserving the ff_buffer)
       */

      ret = fat_fscacheread(fs, ff->ff_dirsector);
      if (ret < 0)
        {
          goto errout_with_semaphore;
        }

      /* Recover a pointer to the specific directory entry
       * in the sector using the saved directory index.
       */

      direntry = &fs->fs_buffer[ff->ff_dirindex * 32];

      /* Set the archive bit, set the write time, and update
       * anything that may have* changed in the directory
       * entry: the file size, and the start cluster
       */

      direntry[DIR_ATTRIBUTES] |= FATATTR_ARCHIVE;

      DIR_PUTFILESIZE(direntry, ff->ff_size);
      DIR_PUTFSTCLUSTLO(direntry, ff->ff_startcluster);
      DIR_PUTFSTCLUSTHI(direntry, ff->ff_startcluster >> 16);

      wrttime = fat_systime2fattime();
      DIR_PUTWRTTIME(direntry, wrttime & 0xffff);
      DIR_PUTWRTDATE(direntry, wrttime >> 16);

      /* Clear the modified bit in the flags */

      ff->ff_bflags &= ~FFBUFF_MODIFIED;

      /* Flush these change to disk and update FSINFO (if
       * appropriate.
       */

      fs->fs_dirty = TRUE;
      ret          = fat_updatefsinfo(fs);
    }

 errout_with_semaphore:
  fat_semgive(fs);
  return ret;
}

/****************************************************************************
 * Name: fat_opendir
 *
 * Description: Open a directory for read access
 *
 ****************************************************************************/

static int fat_opendir(struct inode *mountpt, const char *relpath, struct internal_dir_s *dir)
{
  struct fat_mountpt_s *fs;
  struct fat_dirinfo_s  dirinfo;
  int                     ret;

  /* Sanity checks */

  DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);

  /* Recover our private data from the inode instance */

  fs = mountpt->i_private;

  /* Make sure that the mount is still healthy */

  fat_semtake(fs);
  ret = fat_checkmount(fs);
  if (ret != OK)
    {
      goto errout_with_semaphore;
    }

  /* Find the requested directory */

  ret = fat_finddirentry(fs, &dirinfo, relpath);
  if (ret < 0)
    {
      goto errout_with_semaphore;
    }

  /* Check if this is the root directory */

  if (dirinfo.fd_entry == NULL)
    {
      /* Handler the FAT12/16 root directory */

      dir->u.fat.fd_startcluster = 0;
      dir->u.fat.fd_currcluster  = 0;
      dir->u.fat.fd_currsector   = fs->fs_rootbase;
      dir->u.fat.fd_index        = 2;
    }

  /* This is not the root directory.  Verify that it is some kind of directory */

  else if ((DIR_GETATTRIBUTES(dirinfo.fd_entry) & FATATTR_DIRECTORY) == 0)
    {
       /* The entry is not a directory */
       ret = -ENOTDIR;
       goto errout_with_semaphore;
    }
  else
    {
       /* The entry is a directory */

      dir->u.fat.fd_startcluster = 
          ((uint32)DIR_GETFSTCLUSTHI(dirinfo.fd_entry) << 16) |
                   DIR_GETFSTCLUSTLO(dirinfo.fd_entry);
      dir->u.fat.fd_currcluster  = dir->u.fat.fd_startcluster;
      dir->u.fat.fd_currsector   = fat_cluster2sector(fs, dir->u.fat.fd_currcluster);
      dir->u.fat.fd_index        = 2;
    }

  fat_semgive(fs);
  return OK;

errout_with_semaphore:
  fat_semgive(fs);
  return ERROR;
}

/****************************************************************************
 * Name: fat_readdir
 *
 * Description: Read the next directory entry
 *
 ****************************************************************************/

static int fat_readdir(struct inode *mountpt, struct internal_dir_s *dir)
{
  struct fat_mountpt_s *fs;
  unsigned int            dirindex;
  ubyte                  *direntry;
  ubyte                   ch;
  ubyte                   attribute;
  int                     ret;

  /* Sanity checks */

  DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);

  /* Recover our private data from the inode instance */

  fs = mountpt->i_private;

  /* Make sure that the mount is still healthy */

  fat_semtake(fs);
  ret = fat_checkmount(fs);
  if (ret != OK)
    {
      goto errout_with_semaphore;
    }

  /* Read the next directory entry */

  dir->fd_dir.d_name[0] = '\0';
  while (dir->u.fat.fd_currsector && dir->fd_dir.d_name[0] == '\0')
    {
      ret = fat_fscacheread(fs, dir->u.fat.fd_currsector);
      if ( ret < 0)
        {
          goto errout_with_semaphore;
        }

      /* Get a reference to the current directory entry */

      dirindex = (dir->u.fat.fd_index & DIRSEC_NDXMASK(fs)) * 32;
      direntry = &fs->fs_buffer[dirindex];

      /* Has it reached to end of the directory */

      ch = *direntry;
      if (ch == DIR0_ALLEMPTY)
        {
          /* We signal the end of the directory by returning the
           * special error -ENOENT
           */

          ret = -ENOENT;
          goto errout_with_semaphore;
        }

      /* No, is the current entry a valid entry? */

      attribute = DIR_GETATTRIBUTES(direntry);
      if (ch != DIR0_EMPTY && (attribute & FATATTR_VOLUMEID) == 0)
        {
          /* Yes.. get the name from the directory info */

          (void)fat_dirname2path(dir->fd_dir.d_name, direntry);

          /* And the file type */

          if ((attribute & FATATTR_DIRECTORY) == 0)
            {
              dir->fd_dir.d_type = DTYPE_FILE;
            }
          else
            {
              dir->fd_dir.d_type = DTYPE_DIRECTORY;
            }
        }

      /* Set up the next directory index */

      if (fat_nextdirentry(fs, &dir->u.fat) != OK)
        {
          dir->u.fat.fd_currsector = 0;
        }
    }

  fat_semgive(fs);
  return OK;

errout_with_semaphore:
  fat_semgive(fs);
  return ERROR;
}

/****************************************************************************
 * Name: fat_rewindir
 *
 * Description: Reset directory read to the first entry
 *
 ****************************************************************************/

static int fat_rewinddir(struct inode *mountpt, struct internal_dir_s *dir)
{
  struct fat_mountpt_s *fs;
  int ret;

  /* Sanity checks */

  DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);

  /* Recover our private data from the inode instance */

  fs = mountpt->i_private;

  /* Make sure that the mount is still healthy */

  fat_semtake(fs);
  ret = fat_checkmount(fs);
  if (ret != OK)
    {
      goto errout_with_semaphore;
    }

  /* Check if this is the root directory */

  if (dir->u.fat.fd_startcluster == 0)
    {
      /* Handler the FAT12/16 root directory */

      dir->u.fat.fd_currcluster  = 0;
      dir->u.fat.fd_currsector   = fs->fs_rootbase;
      dir->u.fat.fd_index        = 2;
    }

  /* This is not the root directory */

  else
    {
      dir->u.fat.fd_currcluster  = dir->u.fat.fd_startcluster;
      dir->u.fat.fd_currsector   = fat_cluster2sector(fs, dir->u.fat.fd_currcluster);
      dir->u.fat.fd_index        = 2;
    }

  fat_semgive(fs);
  return OK;

errout_with_semaphore:
  fat_semgive(fs);
  return ERROR;
}

/****************************************************************************
 * Name: fat_bind
 *
 * Description: This implements a portion of the mount operation. This
 *  function allocates and initializes the mountpoint private data and
 *  binds the blockdriver inode to the filesystem private data.  The final
 *  binding of the private data (containing the blockdriver) to the
 *  mountpoint is performed by mount().
 *
 ****************************************************************************/

static int fat_bind(FAR struct inode *blkdriver, const void *data,
                    void **handle)
{
  struct fat_mountpt_s *fs;
  int ret;

  /* Open the block driver */

  if (!blkdriver || !blkdriver->u.i_bops)
    {
      return -ENODEV;
    }

  if ( blkdriver->u.i_bops->open &&
       blkdriver->u.i_bops->open(blkdriver) != OK)
    {
      return -ENODEV;
    }

  /* Create an instance of the mountpt state structure */

  fs = (struct fat_mountpt_s *)zalloc(sizeof(struct fat_mountpt_s));
  if ( !fs )
    {
      return -ENOMEM;
    }

  /* Initialize the allocated mountpt state structure.  The filesystem is
   * responsible for one reference ont the blkdriver inode and does not
   * have to addref() here (but does have to release in ubind().
   */

  fs->fs_blkdriver = blkdriver;  /* Save the block driver reference */
  sem_init(&fs->fs_sem, 0, 0);   /* Initialize the semaphore that controls access */

  /* Then get information about the FAT32 filesystem on the devices managed
   * by this block driver.
   */

  ret = fat_mount(fs, TRUE);
  if ( ret != 0 )
    {
      sem_destroy(&fs->fs_sem);
      free(fs);
      return ret;
    }

  *handle = (void*)fs;
  fat_semgive(fs);
  return OK;
}

/****************************************************************************
 * Name: fat_unbind
 *
 * Description: This implements the filesystem portion of the umount
 *   operation.
 *
 ****************************************************************************/

static int fat_unbind(void *handle, FAR struct inode **blkdriver)
{
  struct fat_mountpt_s *fs = (struct fat_mountpt_s*)handle;
  int ret;

  if ( !fs )
    {
      return -EINVAL;
    }

  /* Check if there are sill any files opened on the filesystem. */

  ret = OK; /* Assume success */
  fat_semtake(fs);
  if (fs->fs_head)
    {
      /* We cannot unmount now.. there are open files */

      ret = -EBUSY;
    }
  else
    {
       /* Unmount ... close the block driver */

      if (fs->fs_blkdriver)
        {
          struct inode *inode = fs->fs_blkdriver;
          if (inode)
            {
              if (inode->u.i_bops && inode->u.i_bops->close)
                {
                  (void)inode->u.i_bops->close(inode);
                }

              /* We hold a reference to the block driver but should
               * not but mucking with inodes in this context.  So, we will just return
               * our contained reference to the block driver inode and let the umount
               * logic dispose of it.
               */

              if (blkdriver)
                {
                  *blkdriver = inode;
                }
            }
        }

      /* Release the mountpoint private data */

      if (fs->fs_buffer)
        {
          free(fs->fs_buffer);
        }
      free(fs);
    }

  fat_semgive(fs);
  return ret;
}

/****************************************************************************
 * Name: fat_statfs
 *
 * Description: Return filesystem statistics
 *
 ****************************************************************************/

static int fat_statfs(struct inode *mountpt, struct statfs *buf)
{
  struct fat_mountpt_s *fs;
  int                   ret;

  /* Sanity checks */

  DEBUGASSERT(mountpt && mountpt->i_private);

  /* Get the mountpoint private data from the inode structure */

  fs = mountpt->i_private;

  /* Check if the mount is still healthy */

  fat_semtake(fs);
  ret = fat_checkmount(fs);
  if (ret < 0)
    {
       goto errout_with_semaphore;
    }

  /* Fill in the statfs info */

  memset(buf, 0, sizeof(struct statfs));
  buf->f_type    = MSDOS_SUPER_MAGIC;

  /* We will claim that the optimal transfer size is the size of a cluster in bytes */

  buf->f_bsize   = fs->fs_fatsecperclus * fs->fs_hwsectorsize;

  /* Everything else follows in units of clusters */

  buf->f_blocks  = fs->fs_nclusters;                        /* Total data blocks in the file system */
  ret = fat_nfreeclusters(fs, &buf->f_bfree);               /* Free blocks in the file system */
  buf->f_bavail  = buf->f_bfree;                            /* Free blocks avail to non-superuser */
  buf->f_namelen = (8+1+3);                                 /* Maximum length of filenames */

  fat_semgive(fs);
  return OK;

errout_with_semaphore:
  fat_semgive(fs);
  return ret;
}

/****************************************************************************
 * Name: fat_unlink
 *
 * Description: Remove a file
 *
 ****************************************************************************/

static int fat_unlink(struct inode *mountpt, const char *relpath)
{
  struct fat_mountpt_s *fs;
  int                   ret;

  /* Sanity checks */

  DEBUGASSERT(mountpt && mountpt->i_private);

  /* Get the mountpoint private data from the inode structure */

  fs = mountpt->i_private;

  /* Check if the mount is still healthy */

  fat_semtake(fs);
  ret = fat_checkmount(fs);
  if (ret == OK)
    {
      /* If the file is open, the correct behavior is to remove the file
       * name, but to keep the file cluster chain in place until the last
       * open reference to the file is closed.
       */

#warning "Need to defer deleting cluster chain if the file is open"

      /* Remove the file */

      ret = fat_remove(fs, relpath, FALSE);
    }

  fat_semgive(fs);
  return ret;
}

/****************************************************************************
 * Name: fat_mkdir
 *
 * Description: Create a directory
 *
 ****************************************************************************/

static int fat_mkdir(struct inode *mountpt, const char *relpath, mode_t mode)
{
  struct fat_mountpt_s *fs;
  struct fat_dirinfo_s  dirinfo;
  ubyte       *direntry;
  ubyte       *direntry2;
  size_t       parentsector;
  ssize_t      dirsector;
  sint32       dircluster;
  uint32       parentcluster;
  uint32       crtime;
  unsigned int i;
  int          ret;

  /* Sanity checks */

  DEBUGASSERT(mountpt && mountpt->i_private);

  /* Get the mountpoint private data from the inode structure */

  fs = mountpt->i_private;

  /* Check if the mount is still healthy */

  fat_semtake(fs);
  ret = fat_checkmount(fs);
  if (ret != OK)
    {
      goto errout_with_semaphore;
    }

  /* Find the directory where the new directory should be created. */

  ret = fat_finddirentry(fs, &dirinfo, relpath);

  /* If anything exists at this location, then we fail with EEXIST */

  if (ret == OK)
    {
      ret = -EEXIST;
      goto errout_with_semaphore;
    }

  /* What we want to see is for fat_finddirentry to fail with -ENOENT.
   * This error means that no failure occurred but that nothing exists
   * with this name.
   */

  if (ret != -ENOENT)
    {
      goto errout_with_semaphore;
    }

  /* NOTE: There is no check that dirinfo.fd_name contains the final
   * directory name.  We could be creating an intermediate directory
   * in the full relpath.
   */

  /* Allocate a directory entry for the new directory in this directory */

  ret = fat_allocatedirentry(fs, &dirinfo);
  if (ret != OK)
    {
      goto errout_with_semaphore;
    }
  parentsector = fs->fs_currentsector;

  /* Allocate a cluster for new directory */

  dircluster = fat_createchain(fs);
  if (dircluster < 0)
    {
      ret = dircluster;
      goto errout_with_semaphore;
    }
  else if (dircluster < 2)
    {
      ret = -ENOSPC;
      goto errout_with_semaphore;
    }

  dirsector = fat_cluster2sector(fs, dircluster);
  if (dirsector < 0)
    {
      ret = dirsector;
      goto errout_with_semaphore;
    }

  /* Flush any existing, dirty data in fs_buffer (because we need 
   * it to create the directory entries.
   */

  ret = fat_fscacheflush(fs);
  if (ret < 0)
    {
      goto errout_with_semaphore;
    }

  /* Get a pointer to the first directory entry in the sector */

  direntry = fs->fs_buffer;

  /* Now erase the contents of fs_buffer */

  fs->fs_currentsector = dirsector;
  memset(direntry, 0, fs->fs_hwsectorsize);

  /* Now clear all sectors in the new directory cluster (except for the first) */

  for (i = 1; i < fs->fs_fatsecperclus; i++)
    {
      ret = fat_hwwrite(fs, direntry, ++dirsector, 1);
      if (ret < 0)
        {
          goto errout_with_semaphore;
        }
    }

  /* Now create the "." directory entry in the first directory slot */

  memset(&direntry[DIR_NAME], ' ', 8+3);
  direntry[DIR_NAME] = '.';
  DIR_PUTATTRIBUTES(direntry, FATATTR_DIRECTORY);

  crtime = fat_systime2fattime();
  DIR_PUTCRTIME(direntry, crtime & 0xffff);
  DIR_PUTWRTTIME(direntry, crtime & 0xffff);
  DIR_PUTCRDATE(direntry, crtime >> 16);
  DIR_PUTWRTDATE(direntry, crtime >> 16);

  /* Create ".." directory entry in the second directory slot */

  direntry2 = direntry + 32;

  /* So far, the two entries are nearly the same */

  memcpy(direntry2, direntry, 32);
  direntry2[DIR_NAME+1] = '.';

  /* Now add the cluster information to both directory entries */

  DIR_PUTFSTCLUSTHI(direntry, dircluster >> 16);
  DIR_PUTFSTCLUSTLO(direntry, dircluster);

  parentcluster = dirinfo.dir.fd_startcluster;
  if (fs->fs_type != FSTYPE_FAT32 && parentcluster == fs->fs_rootbase)
    {
      parentcluster = 0;
    }

  DIR_PUTFSTCLUSTHI(direntry2, parentcluster >> 16);
  DIR_PUTFSTCLUSTLO(direntry2, parentcluster);

  /* Save the first sector of the directory cluster and re-read
   *  the parentsector
   */

  fs->fs_dirty = TRUE;
  ret = fat_fscacheread(fs, parentsector);
  if (ret < 0)
    {
      goto errout_with_semaphore;
    }

  /* Initialize the new entry directory entry in the parent directory */

  direntry = dirinfo.fd_entry;
  memset(direntry, 0, 32);

  memcpy(direntry, dirinfo.fd_name, 8+3);
#ifdef CONFIG_FLAT_LCNAMES
  DIR_PUTNTRES(direntry, dirinfo.fd_ntflags);
#endif
  DIR_PUTATTRIBUTES(dirinfo.fd_entry, FATATTR_DIRECTORY);

  /* Same creation time as for . and .. */

  DIR_PUTCRTIME(dirinfo.fd_entry, crtime & 0xffff);
  DIR_PUTWRTTIME(dirinfo.fd_entry, crtime & 0xffff);
  DIR_PUTCRDATE(dirinfo.fd_entry, crtime >> 16);
  DIR_PUTWRTDATE(dirinfo.fd_entry, crtime >> 16);

  /* Set subdirectory start cluster */

  DIR_PUTFSTCLUSTLO(dirinfo.fd_entry, dircluster);
  DIR_PUTFSTCLUSTHI(dirinfo.fd_entry, dircluster >> 16);

  /* Now update the FAT32 FSINFO sector */

  fs->fs_dirty = TRUE;
  ret = fat_updatefsinfo(fs);
  if (ret < 0)
    {
      goto errout_with_semaphore;
    }

  fat_semgive(fs);
  return OK;

 errout_with_semaphore:
  fat_semgive(fs);
  return ret;
}

/****************************************************************************
 * Name: fat_rmdir
 *
 * Description: Remove a directory
 *
 ****************************************************************************/

int fat_rmdir(struct inode *mountpt, const char *relpath)
{
  struct fat_mountpt_s *fs;
  int                   ret;

  /* Sanity checks */

  DEBUGASSERT(mountpt && mountpt->i_private);

  /* Get the mountpoint private data from the inode structure */

  fs = mountpt->i_private;

  /* Check if the mount is still healthy */

  fat_semtake(fs);
  ret = fat_checkmount(fs);
  if (ret == OK)
    {
      /* If the directory is open, the correct behavior is to remove the directory
       * name, but to keep the directory cluster chain in place until the last
       * open reference to the directory is closed.
       */

#warning "Need to defer deleting cluster chain if the directory is open"

      /* Remove the directory */

      ret = fat_remove(fs, relpath, TRUE);
    }

  fat_semgive(fs);
  return ret;
}

/****************************************************************************
 * Name: fat_rename
 *
 * Description: Rename a file or directory
 *
 ****************************************************************************/

int fat_rename(struct inode *mountpt, const char *oldrelpath,
               const char *newrelpath)
{
  struct fat_mountpt_s *fs;
  struct fat_dirinfo_s  dirinfo;
  size_t                oldsector;
  ubyte                *olddirentry;
  ubyte                *newdirentry;
  ubyte                 dirstate[32-11];
  int                   ret;

  /* Sanity checks */

  DEBUGASSERT(mountpt && mountpt->i_private);

  /* Get the mountpoint private data from the inode structure */

  fs = mountpt->i_private;

  /* Check if the mount is still healthy */

  fat_semtake(fs);
  ret = fat_checkmount(fs);
  if (ret != OK)
    {
      goto errout_with_semaphore;
    }

  /* Find the directory entry for the oldrelpath */

  ret = fat_finddirentry(fs, &dirinfo, oldrelpath);
  if (ret != OK)
    {
      /* Some error occurred -- probably -ENOENT */

      goto errout_with_semaphore;
    }

  /* Save the information that will need to recover the
   * directory sector and directory entry offset to the
   * old directory.
   */

  olddirentry = dirinfo.fd_entry;

  /* One more check:  Make sure that the oldrelpath does
   * not refer to the root directory.  We can't rename the
   * root directory.
   */

  if (!olddirentry)
    {
      ret = -EXDEV;
      goto errout_with_semaphore;
    }

  oldsector   = fs->fs_currentsector;
  memcpy(dirstate, &olddirentry[DIR_ATTRIBUTES], 32-11);

  /* No find the directory where we should create the newpath object */

  ret = fat_finddirentry(fs, &dirinfo, newrelpath);
  if (ret == OK)