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- Subject: Re: Implementing a simple sandbox -- another quirk
- From: Max Ischenko <max@...>
- Date: Tue, 24 Jun 2003 08:55:11 +0300
Luiz Henrique de Figueiredo wrote:
> Max Ischenko wrote:
> >function xxx()
> > SandBox['DATE'] = 1
> > DATE = 1
> > SandBox['Date'] = Date
> > local outcome = sandbox(SandBox, f)
> > return outcome
> >Function f, called by xxx, refers to global variable DATE.
> >The problem is that SandBox.DATEE is not used (and __index is not
> >called) when f is evaluated so I have to assign to global DATEE before
> >calling f.
> Do you mean DATE instead of DATEE?
Yes, sorry, s/DATEE/DATE/.
> Could you please show f? Better
> still, a complete (but short) program that fails? The program below
> works as expected.
[ ... skip ... ]
OK, here it is. It prints nil when line 17 is uncommented and prints 1
when line 19 is uncommented (and line 17 is commented out).
If I change line 23 into f = equals() then it prints 20, as expected.
3 function sandbox(env, f, ...)
4 local g = getfenv(f)
5 setfenv(f, env)
6 local retval = f(unpack(arg))
7 setfenv(f, g)
8 return retval
11 function equals()
12 return DATE
15 function xxx(f)
17 SandBox['DATE'] = 20
18 SandBox['equals'] = equals
19 --DATE = 1
20 print(sandbox(SandBox, f))
23 f = loadstring("return equals()")