PyBytes_Concat

PyBytes_Concat.c

void
PyBytes_Concat(PyObject **pv, PyObject *w)
{
    assert(pv != NULL);
    if (*pv == NULL)
        return;
    if (w == NULL) {
        Py_CLEAR(*pv);
        return;
    }

    if (Py_REFCNT(*pv) == 1 && PyBytes_CheckExact(*pv)) {
        /* Only one reference, so we can resize in place */
        Py_ssize_t oldsize;
        Py_buffer wb;

        wb.len = -1;
        if (PyObject_GetBuffer(w, &wb, PyBUF_SIMPLE) != 0) {
            PyErr_Format(PyExc_TypeError, "can't concat %.100s to %.100s",
                         Py_TYPE(w)->tp_name, Py_TYPE(*pv)->tp_name);
            Py_CLEAR(*pv);
            return;
        }

        oldsize = PyBytes_GET_SIZE(*pv);
        if (oldsize > PY_SSIZE_T_MAX - wb.len) {
            PyErr_NoMemory();
            goto error;
        }
        if (_PyBytes_Resize(pv, oldsize + wb.len) < 0)
            goto error;

        memcpy(PyBytes_AS_STRING(*pv) + oldsize, wb.buf, wb.len);
        PyBuffer_Release(&wb);
        return;

      error:
        PyBuffer_Release(&wb);
        Py_CLEAR(*pv);
        return;
    }

    else {
        /* Multiple references, need to create new object */
        PyObject *v;
        v = bytes_concat(*pv, w);
        Py_SETREF(*pv, v);
    }
}