fs_fat32.c

這是一個實時嵌入式作業系統 實作了MCS51 ARM等MCU

 *
 ****************************************************************************/

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)
    {
      /* It is an error if the object at newrelpath already exists */

      ret = -EEXIST;
      goto errout_with_semaphore;
    }

  /* What we expect is -ENOENT mean that the full directory path was
   * followed but that the object does not exists in the terminal directory.
   */

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

  /* Reserve a directory entry */

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

  /* Create the new directory entry */

  newdirentry = dirinfo.fd_entry;

  memcpy(&newdirentry[DIR_ATTRIBUTES], dirstate, 32-11);
  memcpy(&newdirentry[DIR_NAME], dirinfo.fd_name, 8+3);
#ifdef CONFIG_FLAT_LCNAMES
  DIR_PUTNTRES(newdirentry, dirinfo.fd_ntflags);
#else
  DIR_PUTNTRES(newdirentry, 0);
#endif
  fs->fs_dirty = TRUE;

  /* Now flush the new directory entry to disk and read the sector
   * containing the old directory entry.
   */

  ret = fat_fscacheread(fs, oldsector);
  if (ret < 0)
    {
      goto errout_with_semaphore;
    }

  /* Remove the old entry */

  olddirentry[DIR_NAME] = DIR0_EMPTY;
  fs->fs_dirty = TRUE;

  /* Write the old entry to disk and update FSINFO if necessary */

  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_stat
 *
 * Description: Return information about a file or directory
 *
 ****************************************************************************/

static int fat_stat(struct inode *mountpt, const char *relpath, struct stat *buf)
{
  struct fat_mountpt_s *fs;
  struct fat_dirinfo_s  dirinfo;
  uint16                date;
  uint16                date2;
  uint16                time;
  ubyte                 attribute;
  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 corresponding to relpath. */

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

  /* If nothing was found, then we fail with EEXIST */

  if (ret < 0)
    {
      goto errout_with_semaphore;
    }

  memset(buf, 0, sizeof(struct stat));
  if (!dirinfo.fd_entry)
    {
      /* It's directory name of mount point */

      buf->st_mode = S_IFDIR|S_IROTH|S_IRGRP|S_IRUSR|S_IWOTH|S_IWGRP|S_IWUSR;
      ret = OK;
      goto errout_with_semaphore;
    }

  /* Get the FAT attribute and map it so some meaningful mode_t values */

  attribute = DIR_GETATTRIBUTES(dirinfo.fd_entry);
  if ((attribute & FATATTR_VOLUMEID) != 0)
    {
      ret = -ENOENT;
      goto errout_with_semaphore;
    }

  /* Set the access permissions.  The file/directory is always readable
   * by everyone but may be writeable by no-one.
   */

  buf->st_mode = S_IROTH|S_IRGRP|S_IRUSR;
  if ((attribute & FATATTR_READONLY) == 0)
    {
      buf->st_mode |= S_IWOTH|S_IWGRP|S_IWUSR;
    }

  /* We will report only types file or directory */

  if ((attribute & FATATTR_DIRECTORY) != 0)
    {
      buf->st_mode |= S_IFDIR;
    }
  else
    {
      buf->st_mode |= S_IFREG;
    }

  /* File/directory size, access block size */

  buf->st_size      = DIR_GETFILESIZE(dirinfo.fd_entry);
  buf->st_blksize   = fs->fs_fatsecperclus * fs->fs_hwsectorsize;
  buf->st_blocks    = (buf->st_size + buf->st_blksize - 1) / buf->st_blksize;

  /* Times */

  date              = DIR_GETWRTDATE(dirinfo.fd_entry);
  time              = DIR_GETWRTTIME(dirinfo.fd_entry);
  buf->st_mtime     = fat_fattime2systime(time, date);

  date2             = DIR_GETLASTACCDATE(dirinfo.fd_entry);
  if (date == date2)
    {
      buf->st_atime = buf->st_mtime;
    }
  else
    {
      buf->st_atime = fat_fattime2systime(0, date2);
    }

  date              = DIR_GETCRDATE(dirinfo.fd_entry);
  time              = DIR_GETCRTIME(dirinfo.fd_entry);
  buf->st_ctime     = fat_fattime2systime(time, date);

  ret = OK;

errout_with_semaphore:
  fat_semgive(fs);
  return ret;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/