Re: semantics of luaM_growvector?

[Paul Du Bois <paul.dubois@...>]

On Wed, 12 Jan 2005 10:42:14 -0200, Roberto Ierusalimschy
<roberto@inf.puc-rio.br> wrote:
> > In 4.0.1, this call allows kproto to grow until it has MAXARG_A-1
> > elements.
> 
> Are you sure about that?

Hi Roberto, thanks for the reply. Sorry, I should have posted code
snippets as well. Here they are:

#define luaM_growvector(L, v,nelems,inc,t,e,l) \
          ((v)=(t *)luaM_growaux(L, v,nelems,inc,sizeof(t),e,l))

void *luaM_growaux (lua_State *L, void *block, size_t nelems,
               int inc, size_t size, const char *errormsg, size_t limit) {
  size_t newn = nelems+inc;
  if (nelems >= limit-inc) lua_error(L, errormsg);

If one ignores int-overflow problems, the test can be written
  if (nelems+inc >= limit) lua_error(...);
And the problem is more obvious.

paul