Ah that makes sense, attached an updated patch. I don't know whether the `umask 077` after making the symlink is strictly necessary but it might avoid nasty surprises later on in the script.

Cheers,

- Tim

On Thu, 1 Feb 2024 at 10:32, Rich Felker <dalias@libc.org> wrote:

On Thu, Feb 01, 2024 at 09:39:56AM +1100, Tim Cuthbertson wrote:
> Yeah, setting it to `chmod 000` in just the symlink branch seems good to me
> too.
>
> Looking at the script more closely, `mode` is always set and so I'm unclear
> why there is also a `umask 077` at all. Whatever permissions we create the
> file with, we `chmod` it explicitly before doing anything else.
>
> Is that line just there to undo the potential change to `umask` in the
> mkdirp branch? If so, maybe that should be done explicitly by capturing the
> old umask? e.g:

No, it's so that the install.sh never exposes a file to users who
should not have access to it via the existing umask being more
permissive than the requested install mode. Normally this does not
matter for use as part of musl's install process, but the script is
written to be general and not have security bugs like that.

Rich