RE: controlling lua from a c program

[Håkon Evensen <haakon.evensen@...>]

So basicly the answer is no..

If i trusted the script writer, i wouldnt use scripts.  then i would let 
the person write a dll.  the reason for using lua is to create a sandbox 
environment.  I dont want the script writer to be able to crash, nor hang 
the host program.    The host program should have complete control of 
script execution.

I was thinking of using the script for the end user to impement unsupported 
behaviours, so its not a question of trust, because i dont yet have a clue 
who the script writers are.  And the users should be able to create an 
infinite loop, just as long as it doesnt run away with the entire host thread..

I think your last idea is the best, just implement the needed features in 
Lua VM..


h





At 09:37 AM 7/8/2003 -0700, you wrote:
> We have done extensive research and experiments with yielding from hooks 
> in Lua 5. The bottom line is that this doesn't work reliably. Line hooks 
> almost work with little massage. Count hooks are highly unreliable and 
> produce all sorts of undesirable side effects. In all cases the main 
> source of unreliability is that the return values are not handled 
> properly. In the end we had to switch to using explicit yields in our scripts.
>
> Lua is generally perceived (by me:)) as an application extension language. 
> IMHO, it is a programming language, I can't speak Lua nor am I aware of 
> anyone who can, can you?
>
> I think if you are unloading script writing on someone, you already have 
> some degree of trust in them. On the other hand, it would be trivial to 
> add a little piece of code to Lua VM to detect a long running script and 
> throw an assert,  simply call *lua_error* or do something else of sorts.
>
> AB
>
>  -----Original Message-----
> From:   Håkon Evensen [mailto:haakon.evensen@teletopia.no]
> Sent:   Tuesday, July 08, 2003 2:07 AM
> To:     Lua list
> Subject:        Re: controlling lua from a c program
>
> Thx..
>
> But how do all people using lua solve this problem?  If i write a
> singlethreaded game in c, and wants to use lua as scripting, i have to
> trust whoever makes the scripts for the whole games mainthread not to hang
> ? Is lua a scripting or a programming language?  Shouldnt the
> script<->mainprogram intergration almost be the most important property of
> a script?
>
> h
>
> At 09:18 PM 7/7/2003 -0400, you wrote:
>
> >Håkon Evensen wrote:
> >>I want to execute a script but i dont want to leave the entire control of
> >>the host thread in the hands of the script.   is it possible to set a
> >>line hook and break further execution from there?
> >
> >It's messy and I wouldn't do it, but where there is a will there is a
> >way.  Here are some references:
> >
> >http://lua-users.org/lists/lua-l/2003-04/msg00262.html
> >
> >http://lua-users.org/lists/lua-l/2003-04/msg00249.html
> >