bug#60566: [PATCH] environment: Fix '--emulate-fhs' option overriding $PATH.

[Ludovic Courtès]

Hi John,

John Kehayias <john.kehayias@protonmail.com> skribis:

> From beb6f9255fc62fe52e237f82c7e953a21b7f82f4 Mon Sep 17 00:00:00 2001
> From: John Kehayias <john.kehayias@protonmail.com>
> Date: Thu, 5 Jan 2023 16:06:19 -0500
> Subject: [PATCH] * environment: Fix '--emulate-fhs' option overriding $PATH.
>
> Fixes <https://issues.guix.gnu.org/60566> where even if "--preserve='^PATH$'"
> was passed to 'guix shell' it would be replaced by just the FHS directories
> when '--emulate-fhs' was also set.
>
> * gnu/scripts/environment.scm (launch-environment): Add the FHS directories to
> $PATH rather than overriding $PATH completely.
> * tests/guix-environment-container.sh: Test that FHS directories are in $PATH
> in the container and that $PATH can be preserved.

[...]

> -           (setenv "PATH" "/bin:/usr/bin:/sbin:/usr/sbin")
> +           (setenv "PATH" (string-append "/bin:/usr/bin:/sbin:/usr/sbin"
> +                                         (when (getenv "PATH")
> +                                           (string-append ":" (getenv 
> "PATH")))))

Remember that ‘when’ returns *unspecified* when the condition is false,
so you’d get a type error here when PATH is undefined.

Instead write: (if (getenv "PATH") … "").

> +# Test that $PATH inside the container has FHS directories.
> +guix shell -CF --bootstrap guile-bootstrap \
> +     -- guile -c '(exit (if (string-contains (getenv "PATH")
> +                            "/bin:/usr/bin:/sbin:/usr/sbin")
> +                           0
> +                           1))'

Even (exit (string=? (getenv "PATH") "/bin:/usr/bin:/sbin:/usr/sbin")).

> +# Make sure '--preserve' is honored for $PATH, which the '--emulate-fhs'
> +# option will modify.  We can't (easily) check the whole $PATH as it will
> +# differ inside and outside the container, so just check for an added string.
> +PATH=this-is-a-test:$PATH guix shell -CF --bootstrap guile-bootstrap -E PATH 
> \
> +     -- guile -c '(exit (if (string-contains (getenv "PATH")
> +                            "this-is-a-test")
> +                           0
> +                           1))'

It might be slightly more concise with ‘env’:

  PATH=/foo $(type -P guix) shell -E ^PATH$ -C coreutils -- env |grep 
^PATH=.*:/foo

(I think ‘--bootstrap’ doesn’t buy us much here because we have to
download/build ‘glibc-for-fhs’ anyway.  ‘--bootstrap’ and
‘guile-bootstrap’ are particularly useful for testse that can run
without network access and without building tons of stuff, as in
‘tests/guix-environment.sh’ for instance.)

Otherwise LGTM, thanks!

Ludo’.