Lua 4 closures

["D Burgess" <db@...>]

Is it possible in Lua4 (or 5) to establish the value of a
function closure?
e.g.

    lua_CFunction fnc;
    lua_getglobal(L,"write");
    fnc=lua_tocfunction(L,-1); /* gives the function pointer */
    /* love to know what its closure values are */