feat: proper cleanup for shared pages

src/userprog/process.c

@@ -172,8 +172,9 @@ start_process (void *proc_start_data)
  to store the command that executed the process. */
   if (data->success)
     {
-      data->success =
-        process_init_stack (data->cmd_saveptr, &if_.esp, data->file_name);
+      data->success = use_shared_file (exec_file)
+                      && process_init_stack (data->cmd_saveptr, &if_.esp,
+                                             data->file_name);
     }
 
   /* Signal that the process has finished attempting to load. */
@@ -366,6 +367,7 @@ process_exit (void)
   /* Clean up all open files */
   hash_destroy (&cur->open_files, fd_cleanup);
   hash_destroy (&cur->pages, page_cleanup);
+  unuse_shared_file (cur->exec_file);
 
   /* Close the executable file, implicitly allowing it to be written to. */
   if (cur->exec_file != NULL)