Update start_process to push pointers to process arguments onto the process thread's stack

src/userprog/process.c

@@ -123,12 +123,13 @@ start_process (void *file_name_)
   struct list_elem *tail = list_tail (&arg_list);
   while (e != tail)
     {
-      /* TODO: Push argument pointers to process stack. */
+      struct arg_elem *arg_elem = list_entry (e, struct arg_elem, elem);
+      
+      if_.esp -= sizeof (char *);
+      memcpy (if_.esp, arg_elem->arg, sizeof (char *));
       
-      struct list_elem *prev_e = e;
       e = list_next (e);
-
-      free (list_entry (prev_e, struct arg_elem, elem));
+      free (arg_elem);
     }
 
   /* If load failed, quit. */