Re: [PATCH v2 8/8] shell: restrict BASH_SOURCE_PATH when appropriate

[Matheus Afonso Martins Moreira]

> Or you could simply ignore BASH_SOURCE_PATH in restricted mode.

Then the restricted shells will not have access to this new functionality.
I thought it could be useful if properly integrated.

> Or, at least, this should be an opt-in
> feature that the scripts to set up the
> restricted shells need to explicitly turn on
> instead of being automatically enabled
> through the existence of a variable BASH_SOURCE_PATH.

I think this is a very good idea, especially if we combine it with
the "no defaults" idea.

I'd like to propose that restricted shells disallow manipulation
of this variable, and on top of that set it to the empty string so
that no paths are searchable by default, regardless of which
default value was chosen at compilation time. Then we could
have some mechanism by which other code which prepares
the restricted shell sets the desired BASH_SOURCE_PATH, if any.

This way, the users of restricted shells also have to opt in
to benefit from the new behavior, and compatibility is enhanced.

I'm not sure what form the aforementioned
mechanism would take though. What do you say?

  -- Matheus