From: Jeff King <peff@peff.net>
Date: Tue, 26 Jun 2018 21:01:00 GMT
Subject: Re: [PATCH 29/29] t/test-lib: teach --chain-lint to detect broken &&-chains in subshells
Message-ID: <20180626210100.GA3682@sigill.intra.peff.net>
In-Reply-To: <CAPig+cRvgsu-6f+mzjGVDWTVhFrhLY5MsNxEQBJYckKDpeaMAg@mail.gmail.com>

On Tue, Jun 26, 2018 at 04:46:18PM -0400, Eric Sunshine wrote:

> > I'm not sure if there's a good solution, though. Even if you retained
> > the subshells and instead did a chain-lint inside each subshell, like
> > this:
> >
> >   (exit 117) &&
> >   one &&
> >   (
> >         (exit 117) &&
> >         cd foo
> >         two
> >   ) &&
> >   three
> 
> I thought of that too, but the inner (exit 117) doesn't even get
> invoked unless there is &&-chain breakage somewhere above that point
> (for instance, if "one" lacks "&&"), so the inner (exit 117) doesn't
> participate in the linting process at all.

Oh, right. Not only does it not fix the problem, it's totally
unworkable. :)

> Some of these dangers can be de-thoothed during the linting phase by
> defining do-nothing shell functions:
> 
>     cp () { :; }
>     mv () { :; }
>     ln () { :; }
> 
> That, at least, makes the scariest case ("rm") much less so.

Now that's an interesting idea. We can't catch every dangerous action
(notably ">" would be hard to override), but it should be pretty cheap
to cover some obvious ones.

-Peff