Fixed return of invalid pointer from the fp attribute of encoder/decoder

Fixes #171.

docs/versionhistory.rst

@@ -9,6 +9,9 @@ This library adheres to `Semantic Versioning <http://semver.org/>`_.
 
 - Added support for Python 3.12
 - Dropped support for Python 3.7
+- Fixed bug in the ``fp`` attribute of the built-in version of ``CBORDecoder`` and
+  ``CBOREncoder`` where the getter returns an invalid pointer if the ``read`` method of
+  the file was a built-in method
 
 **5.4.6** (2022-12-07)
 

source/decoder.c

@@ -184,9 +184,12 @@ CBORDecoder_init(CBORDecoderObject *self, PyObject *args, PyObject *kwargs)
 static PyObject *
 _CBORDecoder_get_fp(CBORDecoderObject *self, void *closure)
 {
-    PyObject *ret = PyMethod_GET_SELF(self->read);
-    Py_INCREF(ret);
-    return ret;
+    PyObject *fp = PyObject_GetAttrString(self->read, "__self__");
+    if (fp) {
+        return fp;
+    } else {
+        Py_RETURN_NONE;
+    }
 }
 
 

source/encoder.c

@@ -200,9 +200,12 @@ CBOREncoder_init(CBOREncoderObject *self, PyObject *args, PyObject *kwargs)
 static PyObject *
 _CBOREncoder_get_fp(CBOREncoderObject *self, void *closure)
 {
-    PyObject *ret = PyMethod_GET_SELF(self->write);
-    Py_INCREF(ret);
-    return ret;
+    PyObject *fp = PyObject_GetAttrString(self->write, "__self__");
+    if (fp) {
+        return fp;
+    } else {
+        Py_RETURN_NONE;
+    }
 }