[PATCH v2 0/2] env: setenv add resolve value option

Wolfgang Denk wd at denx.de
Sat Nov 20 13:36:09 CET 2021

Dear Artem,

In message <CAKaHn9KZg13r=pGCo=Lv69pBP-s-EW4uxjBVuH9veT+o5j9v+g at mail.gmail.com> you wrote:
> next examples just demonstrate how its works for already defined env
> variables which contain other variables (like storred env variables)

Which next examples?

> sure I know about this ! see my prev message please .

Which exact message are you referring to here?

> Why not have this new opportunity ?

I think the suggested code is adding more problems than it solves.

> > have in mind, as you speak of "deep resolve". But then, I'm first
> > missing an explanation (and documentation) of what "deep resolve"
> recurrent  resolving for variables

Your implementation of recursion has an arbiotrary and undocumented
depth limit. Also, I cannot see a way to prevent resolving in case I
want to keep something like "$foo" in the result.

But that's to be expected from such a non-standard way.

Why don't you stick with what "eval" in a standard shell does?

> > actually means in this context, i. e. how many levels down you
> > evaluat.   Oh...  the code has "int max_loop = 32;" - this is a
> i think its will be enough

It is a reallybad habt to implement code with arbitrary limits, as
it will blow into your face (or more likely that of an innocent
user) rather sooner than later.  It's even worse that this limit is
nowhere documented.

> 1) this option did not broke any exist compatibilities
> 2) there we talk not only about uboot shell, same time will be useful
> to have env_resolve for internal c usage, because env_set dont have
> this feature

I did not say that an "eval" like construct would not be useful.
But uncontrolled recursion with an undocumented depth limit is
a problem.

> yes i'm informed  about this plans  (and think its happens  not  so
> soon - but i provide some simple elegant solution already)
> but again we dont have env_resolve for internal c usage which must be
> very useful

On the CLI, we use the "run" command to get the desired effect. Yes,
this is neither perfect nor elegant. But you can use that in C code
as well.

> will be easy get useful features via simple solution ( deep resolve
> all vars by one line )

I understand what you want, but this is not a good way to solve the
problem.  I'd really rather see such efforts invested in helping
Francis with the hush update - which will make such code unnecessary.

Best regards,

Wolfgang Denk

DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
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