Function luaD_reallocstack

third-party/lua-5.4.6/src/ldo.c:219–242

** Reallocate the stack to a new size, correcting all pointers into it. ** In ISO C, any pointer use after the pointer has been deallocated is ** undefined behavior. So, before the reallocation, all pointers are ** changed to offsets, and after the reallocation they are changed back ** to pointers. As during the reallocation the pointers are invalid, the ** reallocation cannot run emergency collec

** to 'raiseerror'.
*/
int luaD_reallocstack (lua_State *L, int newsize, int raiseerror) {
  int oldsize = stacksize(L);
  int i;
  StkId newstack;
  int oldgcstop = G(L)->gcstopem;
  lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
  relstack(L);  /* change pointers to offsets */
  G(L)->gcstopem = 1;  /* stop emergency collection */
  newstack = luaM_reallocvector(L, L->stack.p, oldsize + EXTRA_STACK,
                                   newsize + EXTRA_STACK, StackValue);
  G(L)->gcstopem = oldgcstop;  /* restore emergency collection */
  if (l_unlikely(newstack == NULL)) {  /* reallocation failed? */
    correctstack(L);  /* change offsets back to pointers */
    if (raiseerror)
      luaM_error(L);
    else return 0;  /* do not raise an error */
  }
  L->stack.p = newstack;
  correctstack(L);  /* change offsets back to pointers */
  L->stack_last.p = L->stack.p + newsize;
  for (i = oldsize + EXTRA_STACK; i < newsize + EXTRA_STACK; i++)
    setnilvalue(s2v(newstack + i)); /* erase new segment */
  return 1;
}


/*