#3946 fix PyObject_CheckBuffer on a memoryview object

reviewed by Antoine

Lib/test/test_builtin.py

@@ -242,6 +242,7 @@ class BuiltinTest(unittest.TestCase):
         compile(source='pass', filename='?', mode='exec')
         compile(dont_inherit=0, filename='tmp', source='0', mode='eval')
         compile('pass', '?', dont_inherit=1, mode='exec')
+        compile(memoryview(b"text"), "name", "exec")
         self.assertRaises(TypeError, compile)
         self.assertRaises(ValueError, compile, 'print(42)\n', '<string>', 'badmode')
         self.assertRaises(ValueError, compile, 'print(42)\n', '<string>', 'single', 0xff)

Misc/NEWS

@@ -12,6 +12,8 @@ What's New in Python 3.0 release candidate 2
 Core and Builtins
 -----------------
 
+- Issue #3946: PyObject_CheckReadBuffer crashed on a memoryview object.
+
 - Issue #1688: On Windows, the input() prompt was not correctly displayed if it
   contains non-ascii characters.
 

Objects/abstract.c

@@ -268,16 +268,16 @@ int
 PyObject_CheckReadBuffer(PyObject *obj)
 {
 	PyBufferProcs *pb = obj->ob_type->tp_as_buffer;
+	Py_buffer view;
 
 	if (pb == NULL ||
 	    pb->bf_getbuffer == NULL)
 		return 0;
-	if ((*pb->bf_getbuffer)(obj, NULL, PyBUF_SIMPLE) == -1) {
+	if ((*pb->bf_getbuffer)(obj, &view, PyBUF_SIMPLE) == -1) {
 		PyErr_Clear();
 		return 0;
 	}
-	if (*pb->bf_releasebuffer != NULL)
-		(*pb->bf_releasebuffer)(obj, NULL);
+	PyBuffer_Release(&view);
 	return 1;
 }