Close file with fd always

src/threads/thread.c

@@ -649,6 +649,7 @@ void close_fd(struct thread *cur, int fd) {
         struct sys_file *cur_file = list_entry(e, struct sys_file, file_elem);
         if (cur_file->fd == fd) {
             list_remove(&cur_file->file_elem);
+            file_close(cur_file->file);
             palloc_free_page(cur_file);
             return;
         }

src/userprog/process.c

@@ -190,6 +190,7 @@ void process_exit(void) {
     if (cur->executable != NULL) {
         file_close(cur->executable);
     }
+    cur->executable = NULL;
 
     /* Let parent know it is done. */
     sema_up(&cur->wait_sema);

src/userprog/syscall.c

@@ -416,7 +416,6 @@ void sys_close(int fd) {
     acquire_file_lock();
     /* Delete file from thread */
     close_fd(cur, fd);
-    file_close(open_file);
     release_file_lock();
 }