MAINT: Extract `_is_from_ctypes` to a header so that it can be shared

4 files changed, 55 insertions, 13 deletions

diff --git a/numpy/core/_internal.py b/numpy/core/_internal.py
index c4d967dc2..30069f0ca 100644
--- a/numpy/core/_internal.py
+++ b/numpy/core/_internal.py
@@ -796,13 +796,13 @@ def _ufunc_doc_signature_formatter(ufunc):
     )
 
 
-def _is_from_ctypes(obj):
-    # determine if an object comes from ctypes, in order to work around
+def npy_ctypes_check(cls):
+    # determine if a class comes from ctypes, in order to work around
     # a bug in the buffer protocol for those objects, bpo-10746
     try:
         # ctypes class are new-style, so have an __mro__. This probably fails
         # for ctypes classes with multiple inheritance.
-        ctype_base = type(obj).__mro__[-2]
+        ctype_base = cls.__mro__[-2]
         # right now, they're part of the _ctypes module
         return 'ctypes' in ctype_base.__module__
     except Exception:
diff --git a/numpy/core/setup.py b/numpy/core/setup.py
index fc15fe59f..7ff7bd254 100644
--- a/numpy/core/setup.py
+++ b/numpy/core/setup.py
@@ -731,6 +731,7 @@ def configuration(parent_package='',top_path=None):
             join('src', 'common', 'lowlevel_strided_loops.h'),
             join('src', 'common', 'mem_overlap.h'),
             join('src', 'common', 'npy_config.h'),
+            join('src', 'common', 'npy_ctypes.h'),
             join('src', 'common', 'npy_extint128.h'),
             join('src', 'common', 'npy_longdouble.h'),
             join('src', 'common', 'templ_common.h.src'),
diff --git a/numpy/core/src/common/npy_ctypes.h b/numpy/core/src/common/npy_ctypes.h
new file mode 100644
index 000000000..f26db9e05
--- /dev/null
+++ b/numpy/core/src/common/npy_ctypes.h
@@ -0,0 +1,49 @@
+#ifndef NPY_CTYPES_H
+#define NPY_CTYPES_H
+
+#include <Python.h>
+
+#include "npy_import.h"
+
+/*
+ * Check if a python type is a ctypes class.
+ *
+ * Works like the Py<type>_Check functions, returning true if the argument
+ * looks like a ctypes object.
+ *
+ * This entire function is just a wrapper around the Python function of the
+ * same name.
+ */
+NPY_INLINE static int
+npy_ctypes_check(PyTypeObject *obj)
+{
+    static PyObject *py_func = NULL;
+    PyObject *ret_obj;
+    int ret;
+
+    npy_cache_import("numpy.core._internal", "npy_ctypes_check", &py_func);
+    if (py_func == NULL) {
+        goto fail;
+    }
+
+    ret_obj = PyObject_CallFunctionObjArgs(py_func, (PyObject *)obj, NULL);
+    if (ret_obj == NULL) {
+        goto fail;
+    }
+
+    ret = PyObject_IsTrue(ret_obj);
+    if (ret == -1) {
+        goto fail;
+    }
+
+    return ret;
+
+fail:
+    /* If the above fails, then we should just assume that the type is not from
+     * ctypes
+     */
+    PyErr_Clear();
+    return 0;
+}
+
+#endif
diff --git a/numpy/core/src/multiarray/ctors.c b/numpy/core/src/multiarray/ctors.c
index aaaaeee82..bf888659d 100644
--- a/numpy/core/src/multiarray/ctors.c
+++ b/numpy/core/src/multiarray/ctors.c
@@ -11,7 +11,7 @@
 
 #include "npy_config.h"
 
-#include "npy_import.h"
+#include "npy_ctypes.h"
 #include "npy_pycompat.h"
 #include "multiarraymodule.h"
 
@@ -1381,15 +1381,7 @@ _array_from_buffer_3118(PyObject *memoryview)
          * Note that even if the above are fixed in master, we have to drop the
          * early patch versions of python to actually make use of the fixes.
          */
-
-        int is_ctypes = _is_from_ctypes(view->obj);
-        if (is_ctypes < 0) {
-            /* This error is not useful */
-            PyErr_WriteUnraisable(view->obj);
-            is_ctypes = 0;
-        }
-
-        if (!is_ctypes) {
+        if (!npy_ctypes_check(Py_TYPE(view->obj))) {
             /* This object has no excuse for a broken PEP3118 buffer */
             PyErr_Format(
                     PyExc_RuntimeError,