Update

src/filesys/directory.h

+#ifndef FILESYS_DIRECTORY_H
+#define FILESYS_DIRECTORY_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include "devices/block.h"
+
+/* Maximum length of a file name component.
+   This is the traditional UNIX maximum length.
+   After directories are implemented, this maximum length may be
+   retained, but much longer full path names must be allowed. */
+#define NAME_MAX 14
+
+struct inode;
+
+/* Opening and closing directories. */
+bool dir_create (block_sector_t sector, size_t entry_cnt);
+struct dir *dir_open (struct inode *);
+struct dir *dir_open_root (void);
+struct dir *dir_reopen (struct dir *);
+void dir_close (struct dir *);
+struct inode *dir_get_inode (struct dir *);
+
+/* Reading and writing. */
+bool dir_lookup (const struct dir *, const char *name, struct inode **);
+bool dir_add (struct dir *, const char *name, block_sector_t);
+bool dir_remove (struct dir *, const char *name);
+bool dir_readdir (struct dir *, char name[NAME_MAX + 1]);
+
+#endif /* filesys/directory.h */