Re: Preventing DOS when executing Lua code ...

[Mark Hamburg <mhamburg@...>]

on 7/3/06 12:14 AM, Andreas Stenius at kaos@explosive.se wrote:

> One way could be to call lua_error instead of longjmp in your hook, but
> then you have to remove pcall from the user environment, or he'll be
> able to catch it.

Or redefine pcall so that it looks for a particular error and always
propagates it. In Lua, I think the following is correct (untested):

    local kMagicError = { }

    local old_pcall = pcall

    function new_pcall

    function new_pcall_finish( success, ... )
        if not success then
            local message = ...
            if message == kMagicError then
                error( kMagicError )
            end
        end
        return success, ...
    end

    pcall = function( ... )
        return new_pcall_finish( old_pcall( ... ) )
    end

    function throwMagicError()
        error( kMagicError )
    end

You would want to access throwMagicError from your hook proc.

Mark