GeezerVison

if (resize > PY_SSIZE_T_MAX - (2 + digits + 1)) {
    return PyErr_MemoryError();
}

    Py_ssize_t ressize = 0;
    for (Py_ssize_t i = start; i < end; ++i) {
        // The number of characters that each character 'ch' contributes
        // in the result is 2 + k + 1, where k = min{t >= 1 | 10^t > ch}
        // and will be formatted as "&#" + DIGITS + ";". Since the Unicode
        // range is below 10^7, each "block" requires at most 2 + 7 + 1
        // characters.
        int replsize;
        /* object is guaranteed to be "ready" */
        Py_UCS4 ch = PyUnicode_READ_CHAR(obj, i);
        if (ch < 10) {
            replsize = 2 + 1 + 1;
        }
        else if (ch < 100) {
            replsize = 2 + 2 + 1;
        }
        else if (ch < 1000) {
            replsize = 2 + 3 + 1;
        }
        else if (ch < 10000) {
            replsize = 2 + 4 + 1;
        }
        else if (ch < 100000) {
            replsize = 2 + 5 + 1;
        }
        else if (ch < 1000000) {
            replsize = 2 + 6 + 1;
        }
        else {
            assert(ch < 10000000);
            replsize = 2 + 7 + 1;
        }
        if (ressize > PY_SSIZE_T_MAX - replsize) {
            Py_DECREF(obj);
            return PyErr_NoMemory();
        }
        ressize += replsize;

        for (i = start, ressize = 0; i < end; ++i) {
            /* object is guaranteed to be "ready" */
            c = PyUnicode_READ_CHAR(object, i);
            if (ucnhash_capi->getname(c, buffer, sizeof(buffer), 1)) {
                replsize = 1+1+1+(int)strlen(buffer)+1;
            }
            else if (c >= 0x10000) {
                replsize = 1+1+8;
            }
            else if (c >= 0x100) {
                replsize = 1+1+4;
            }
            else
                replsize = 1+1+2;
            if (ressize > PY_SSIZE_T_MAX - replsize)
                break;
            ressize += replsize;
        }