我发现在使用 VS 的安装项目安装文件之前无法执行自定义操作.这是因为 VS 的安装项目首先复制文件，然后执行自定义操作.这是设计使然.这就是为什么我决定创建一个带有设置界面和所需行为的小型 winforms 应用程序.

I've figured out that it is impossible to execute custom action before installing files using VS's setup project. This is because VS's setup project copies files at first and after that executes custom actions. This is by design. That's why I decided to create a small winforms application with setup's interface and required behavior.