diff -u src/userprog/syscall.c~ src/userprog/syscall.c
--- src/userprog/syscall.c~
+++ src/userprog/syscall.c
-@@ -1,20 +1,684 @@
+@@ -1,20 +1,685 @@
#include "userprog/syscall.h"
#include <stdio.h>
+#include <string.h>
+#include "userprog/process.h"
+#include "userprog/pagedir.h"
+#include "devices/input.h"
++#include "devices/shutdown.h"
+#include "filesys/directory.h"
+#include "filesys/filesys.h"
+#include "filesys/file.h"
+static int
+sys_halt (void)
+{
-+ power_off ();
++ shutdown_power_off ();
+}
+
+/* Exit system call. */