Re: Possible bug?

[David Morris-Oliveros <david@...>]

Ok... thanks for the info, doing forensics now...

Rici Lake wrote:

> On 12-Oct-05, at 10:44 PM, David Morris-Oliveros wrote:
>
> > It asserts on line 4 of the code below. Now my question is, is it 
> > supposed to be L->ci->top or just L->top? Because lua_gettop() is 
> > (L->top - L->base), and like 9 below is very similar to this.
>
>
> L->ci->top is the end of the allocated stack (allocated in the sense 
> that you've done lua_checkstack() to make sure that you have that 
> stack space available; if you don't do that, you have 20 slots.) 
> L->top is the top of the actual stack.
>
> If L->ci->top < L->top, something evil has happened (this could happen 
> if you didn't do a lua_checkstack(), but in that case the index would 
> be >20).
>
> It's not an api error to refer to a stack slot that has been 
> allocated, even if it is beyond the end of the current stack. 
> (Although it's highly questionable.) On the other hand, a negative 
> index greater than the current end is clearly a non-existent stack 
> slot. That's why those two lines are different.
>
> I wonder if your problem has to do with the fact that there are two 
> stacks in play when you're doing coroutines. It's pretty easy to use 
> the wrong one by mistake.
>
> Rici

--
// David Morris-Oliveros
// Camera & Lua Coder
// Team Bondi


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