There's still a potential problem when Reg2Py calls wcslen(str[index]). This could be addressed by having fixupMultiSZ take an int array to store the length of each string. For example:

    static void
    fixupMultiSZ(wchar_t **strings, int *lengths, wchar_t *data, int len)
    {
        wchar_t *P, *Q = data + len;
        int i;

        for (P = data, i = 0; P < Q && *P; P++, i++) {
            strings[i] = P;
            lengths[i] = 0;
            for (; P < Q && *P; P++) {
                lengths[i]++;
            }
        }
    }

We'd have to allocate the lengths array in Reg2Py, like we do for the strings array. Also, we can remove the overflow error check prior to PyUnicode_FromWideChar. The longest possible length is `retDataSize / 2`, which occurs if a single string is stored without any null terminators.