Re: Negative table index

[Tom N Harris <telliamed@...>]

On Monday, December 22, 2014 01:13:12 PM Roberto Ierusalimschy wrote:
> The expression 'math.maxinteger*2+1' evaluates to -1 (by the rules
> of arithmetic overflows) before the function is called. The calls
> then become
> 
>   table.move({"a","b","c"},1,3, -1,{})
>   table.move(t,1,-1, -1,{})
> 

I was incorrectly thinking that table indexes were unsigned. The issue then is 
overlapping copies when the sign changes. It's not that the source is 
negative, but that the destination wraps around. What about this check?

    n = e - f;
    luaL_argcheck(L, t+n >= t, 4, "destination index overflows");
    for (i = 0; i <= n; i++)

(skipping the overlap check for brevity)

-- 
tom <telliamed@whoopdedo.org>