Function PyArray_ResolveWritebackIfCopy

numpy/core/src/multiarray/arrayobject.c:362–392

NUMPY_API * * If WRITEBACKIFCOPY and self has data, reset the base WRITEABLE flag, * copy the local data to base, release the local data, and set flags * appropriately. Return 0 if not relevant, 1 if success, < 0 on failure */

 * appropriately. Return 0 if not relevant, 1 if success, < 0 on failure
 */
NPY_NO_EXPORT int
PyArray_ResolveWritebackIfCopy(PyArrayObject * self)
{
    PyArrayObject_fields *fa = (PyArrayObject_fields *)self;
    if (fa && fa->base) {
        if (fa->flags & NPY_ARRAY_WRITEBACKIFCOPY) {
            /*
             * WRITEBACKIFCOPY means that fa->base's data
             * should be updated with the contents
             * of self.
             * fa->base->flags is not WRITEABLE to protect the relationship
             * unlock it.
             */
            int retval = 0;
            PyArray_ENABLEFLAGS(((PyArrayObject *)fa->base),
                                                    NPY_ARRAY_WRITEABLE);
            PyArray_CLEARFLAGS(self, NPY_ARRAY_WRITEBACKIFCOPY);
            retval = PyArray_CopyAnyInto((PyArrayObject *)fa->base, self);
            Py_DECREF(fa->base);
            fa->base = NULL;
            if (retval < 0) {
                /* this should never happen, how did the two copies of data
                 * get out of sync?
                 */
                return retval;
            }
            return 1;
        }
    }
    return 0;
}

/*********************** end C-API functions **********************/