If you’re aborting specifically an io.Copy, then there are better ways to do that: abort in the write path rather than the read path.
It’s not my job to provide you with alternative code. That’s your job.
It is not your job to tell me "that is wrong", yet you do it because it's easy. Suggesting an alternative (not necessarily providing the code) is less easy, so you don't wanna do it. That's fine. I just want you to be aware that the former without the latter is pretty much useless.
Posting detailed instructions on how to identify, purchase and utilise a hammer isn’t something I need to do, and doesn’t negate the correctness of the initial “don’t do that”.