Re: gEDA-user: [RFC 1/6] Non-Turing-complete configuration files.

[Árpád Magosányi <magwas@xxxxxxxxx>]

2009/1/17 Peter Clifton <pcjc2@xxxxxxxxx>:
> On Sat, 2009-01-17 at 17:53 +0100, Árpád Magosányi wrote:
>> Hi!
>>
>> Sorry if I will be too long, but this is an important question.
>> Short version: Don't Do That!
>
> Rebuttal:
>
> Least important reason: Turing complete may present security
> implications.
>
> (BTW: Just saying "sandbox" the interpreter is very easy. Actually doing
> it properly is another matter.)

(It is actually done for most languages which would come to mind in
this context, and using these solutions is not that difficult.)

>
> Real crux of the matter: If you accept free-form input, it becomes
> inordinately more difficult to write any sane GUI, or write-back of
> changed config options. (Since the config file might be arbitrarily
> complex).

Reading configuration for the configurator GUI is a non-issue: a good
configuration GUI never do that. It either uses the configured
program's config reader routines (in our case the interpreter), or
generates the config from a different source.

>
> The time saved in being able to write back configs, or provide a nice
> GUI for some (not necessarily all) of our config  - which is more than
> just firing up $EDITOR and handing the user the file, will more than
> make up for any effort required to handle the conversion to non-turing
> complete configs. In fact Peter B has already done most of the work - so
> that is a non-issue.
>
> Firewall software is in a completely different class to CAD
> applications. A GUI is expected by most users (although not necessarily
> all those on geda-user).
>
> That said, I am surprised you didn't find similar problems in writing
> configs for your firewall. Don't your users demand a GUI / web
> interface?

Unfortunately nowadays the average firewall admin have absolutely no
clue about network, protocols and security, so a GUI is a must.
And yes, firewall config is different than config of some tools: the
configuration in itself is a modelling problem, in a world of several
object classes and their interrelations. So our GUI just writes Zorp
config, does not read it.


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