provided code

src/filesys/filesys.c

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+#include "filesys/filesys.h"
+#include <debug.h>
+#include <stdio.h>
+#include <string.h>
+#include "filesys/file.h"
+#include "filesys/free-map.h"
+#include "filesys/inode.h"
+#include "filesys/directory.h"
+
+/* Partition that contains the file system. */
+struct block *fs_device;
+
+static void do_format (void);
+
+/* Initializes the file system module.
+   If FORMAT is true, reformats the file system. */
+void
+filesys_init (bool format) 
+{
+  fs_device = block_get_role (BLOCK_FILESYS);
+  if (fs_device == NULL)
+    PANIC ("No file system device found, can't initialize file system.");
+
+  inode_init ();
+  free_map_init ();
+
+  if (format) 
+    do_format ();
+
+  free_map_open ();
+}
+
+/* Shuts down the file system module, writing any unwritten data
+   to disk. */
+void
+filesys_done (void) 
+{
+  free_map_close ();
+}
+
+/* Creates a file named NAME with the given INITIAL_SIZE.
+   Returns true if successful, false otherwise.
+   Fails if a file named NAME already exists,
+   or if internal memory allocation fails. */
+bool
+filesys_create (const char *name, off_t initial_size) 
+{
+  block_sector_t inode_sector = 0;
+  struct dir *dir = dir_open_root ();
+  bool success = (dir != NULL
+                  && free_map_allocate (1, &inode_sector)
+                  && inode_create (inode_sector, initial_size)
+                  && dir_add (dir, name, inode_sector));
+  if (!success && inode_sector != 0) 
+    free_map_release (inode_sector, 1);
+  dir_close (dir);
+
+  return success;
+}
+
+/* Opens the file with the given NAME.
+   Returns the new file if successful or a null pointer
+   otherwise.
+   Fails if no file named NAME exists,
+   or if an internal memory allocation fails. */
+struct file *
+filesys_open (const char *name)
+{
+  struct dir *dir = dir_open_root ();
+  struct inode *inode = NULL;
+
+  if (dir != NULL)
+    dir_lookup (dir, name, &inode);
+  dir_close (dir);
+
+  return file_open (inode);
+}
+
+/* Deletes the file named NAME.
+   Returns true if successful, false on failure.
+   Fails if no file named NAME exists,
+   or if an internal memory allocation fails. */
+bool
+filesys_remove (const char *name) 
+{
+  struct dir *dir = dir_open_root ();
+  bool success = dir != NULL && dir_remove (dir, name);
+  dir_close (dir); 
+
+  return success;
+}
+
+/* Formats the file system. */
+static void
+do_format (void)
+{
+  printf ("Formatting file system...");
+  free_map_create ();
+  if (!dir_create (ROOT_DIR_SECTOR, 16))
+    PANIC ("root directory creation failed");
+  free_map_close ();
+  printf ("done.\n");
+}