Function PyArray_FromBuffer

numpy/core/src/multiarray/ctors.c:3561–3680

NUMPY_API*/

/*NUMPY_API*/
NPY_NO_EXPORT PyObject *
PyArray_FromBuffer(PyObject *buf, PyArray_Descr *type,
                   npy_intp count, npy_intp offset)
{
    PyArrayObject *ret;
    char *data;
    Py_buffer view;
    Py_ssize_t ts;
    npy_intp s, n;
    int itemsize;
    int writeable = 1;

    if (type == NULL) {
        return NULL;
    }

    if (PyDataType_REFCHK(type)) {
        PyErr_SetString(PyExc_ValueError,
                        "cannot create an OBJECT array from memory"\
                        " buffer");
        Py_DECREF(type);
        return NULL;
    }
    if (PyDataType_ISUNSIZED(type)) {
        PyErr_SetString(PyExc_ValueError,
                        "itemsize cannot be zero in type");
        Py_DECREF(type);
        return NULL;
    }

    /*
     * If the object supports `releasebuffer`, the new buffer protocol allows
     * tying the memories lifetime to the `Py_buffer view`.
     * NumPy cannot hold on to the view itself (it is not an object) so it
     * has to wrap the original object in a Python `memoryview` which deals
     * with the lifetime management for us.
     * For backwards compatibility of `arr.base` we try to avoid this when
     * possible.  (For example, NumPy arrays will never get wrapped here!)
     */
    if (Py_TYPE(buf)->tp_as_buffer
            && Py_TYPE(buf)->tp_as_buffer->bf_releasebuffer) {
        buf = PyMemoryView_FromObject(buf);
        if (buf == NULL) {
            return NULL;
        }
    }
    else {
        Py_INCREF(buf);
    }

    if (PyObject_GetBuffer(buf, &view, PyBUF_WRITABLE|PyBUF_SIMPLE) < 0) {
        writeable = 0;
        PyErr_Clear();
        if (PyObject_GetBuffer(buf, &view, PyBUF_SIMPLE) < 0) {
            Py_DECREF(buf);
            Py_DECREF(type);
            return NULL;
        }