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Comment by None4U | Hacker News Reader

it will execute whatever script you pass it (immutable) and mutate whatever other files you pass it

I think the question is, how do you know C-reduce isn't going to mutate your test case into calling `remove("/path/to/my/important/file");`

C-reduce is meant to... Reduce your files, it would not add stuff that was not there in the first place. Also, I think it's meant to only be run against the "frontend" of most languages, not full execution

Yeah but you could have a shell script that does

    rm -rf /foo/bar

and in theory it could reduce it to

    rm -rf /

The passes are very heuristic, so that doesn't seem like something you can rule out.

(and I actually want to run it on shell scripts! )

While I've used c-reduce before, I've never done it in a way where it could be destructive. However speculating based on what I do know. I think the 2 things I would do would be in the interesting-ness test, grep for already known harmful instructions and force them to be uninteresting (returning 1). And then if I was still unsure of the potential harm of the program and I had to run it to determine if it's interesting or not (segfault or something similar). I think I would hoist the binary/script into a docker container and run it there. That way the log and result can still be checked, but it's access to actual file system is minimized as much as possible.

TLDR; C-Reduce just gives you text to run/compile, if you're worried about things like that sandbox as much as possible.

So just run it inside of a Docker instance.

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