[U-Boot] [PATCH v2 1/2] cmd: nvedit: add whitelist option for env import

[Quentin Schulz]

Hi Stephen,

On Fri, May 18, 2018 at 10:00:27AM -0600, Stephen Warren wrote:
> On 05/18/2018 08:44 AM, Quentin Schulz wrote:
> > While the `env export` can take as parameters variables to be exported,
> > `env import` does not have such a mechanism of variable selection.
> > 
> > Let's add a `-w` option that asks `env import` to look for the
> > `whitelisted_vars` env variable for a space-separated list of variables
> > that are whitelisted.
> 
> Would it be better for the -w option to accept a variable name rather than
> hard-coding it as whitelisted_vars? That way, people could import/export
> different sets of variables at different times, and also could choose a more
> use-case-specific variable name than whitelisted_vars in order to describe
> why those variables are "whitelisted".

This has been raised in the previous version of the patch[1] (of which
you weren't in the mail recipients) and a similar patch[2] made by Alex
Kiernan (Cc of this patch series). I'd say it's an ongoing discussion,
though I should have mentioned it in the comments of the patch?

TL;DR:
Proposition 1: Have -w only which "hardcodedly" checks for
"whitelisting_vars",
+: straightforward implementation of the argument parsing,
-: implicit declaration of the list: you have to know to set
   whitelisted_vars in the environnement,

Proposition 2: Have -w followed by one string-word which is the name of
the env variable where to look for the list of whitelisted env
variables,
+: explicit var to check where whitelist is looked for,
-: a bit of complexity added to the parsing of the parameters of the env
   import function,

Proposition 3: Have -w followed by the list of whitelisted env variable,
+: explicit list
-: the list cannot be separated by comma (valid character for an env
   variable) or a space (would not be able to distinguish the last
   arguments of the commands which are address and size with size being
   optional => how to know if size was passed or not?), what char can be
   used to separate env variables in the list?
   how does it perform with a very long list of whitelisted variables?

I don't know how many features and their complexity we can add to the
env import/export functions, but keeping their arguments simple is
a way to keep features hopefully easy to implement in the future.

I'm not convinced by any of the propositions but proposition 1 is the
one I implemented for now. I just want a consensus towards a solution
(be it among the given 3 or another one) and I'm good with it.

Thanks,
Quentin

[1] https://www.mail-archive.com/u-boot@lists.denx.de/msg286266.html
[2] http://patchwork.ozlabs.org/patch/891422/
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