On Mon, May 21, 2018 at 01:36:49PM +0100, Alex Kiernan wrote:
On Mon, May 21, 2018 at 1:06 PM Quentin Schulz quentin.schulz@bootlin.com wrote:
Hi Alex,
On Mon, May 21, 2018 at 12:56:04PM +0100, Alex Kiernan wrote:
On Mon, May 21, 2018 at 9:02 AM Quentin Schulz <
quentin.schulz@bootlin.com>
wrote:
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 charcan be
used to separate env variables in the list? how does it perform with a very long list of whitelistedvariables?
Two more thoughts, both of which delegate the separator problem to the caller (the second being the one I implemented as it's almost no code)
- specify multiple -w options each specifying a whitelisted env variable
You'll hit the maximum number of arguments/length of the command quickly with this method. Quicker than with the other propositions.
So you just made me go and read the definition for CONFIG_SYS_MAXARGS, the default's clearly pretty small (16). I guess I don't have a feeling for how many args you want to import - my use case is for 4, so even with max args at 16 I'm within that limit.
Same for me, a few variables and that's it. I'm trying not to have a solution that's working only for me/us with a pretty low limitation though. Once we've settled for a solution, IMHO, we've to stick with it and thus if the solution can't be used by others, that's bad design from us.
I guess at worst, we could call multiple times the env import command with different whitelists but that's not really user-friendly.
Quentin