Issue #3258: Fix an assertion error (in debug build) and a crash (in

release build) when the format string of a pointer to an incomplete
structure is created.

diff --git a/Lib/ctypes/test/test_pep3118.py b/Lib/ctypes/test/test_pep3118.py
index cf628d859f7b6cfc87f1f8876a96cee111f9d6ae..119b0ada87a07994ddc785b73450b38f41700e68 100644 (file)
--- a/Lib/ctypes/test/test_pep3118.py
+++ b/Lib/ctypes/test/test_pep3118.py
@@ -33,6 +33,8 @@ class memoryview(object):
 def normalize(format):
     # Remove current endian specifier and white space from a format
     # string
+    if format is None:
+        return ""
     format = format.replace(OTHER_ENDIAN, THIS_ENDIAN)
     return re.sub(r"\s", "", format)
 
@@ -105,6 +107,14 @@ class EmptyStruct(Structure):
 class aUnion(Union):
     _fields_ = [("a", c_int)]
 
+class Incomplete(Structure):
+    pass
+
+class Complete(Structure):
+    pass
+PComplete = POINTER(Complete)
+Complete._fields_ = [("a", c_int)]
+
 ################################################################
 #
 # This table contains format strings as they look on little endian
@@ -162,6 +172,16 @@ native_types = [
     # the pep does't support unions
     (aUnion,                    "B",                    None,           aUnion),
 
+    ## pointer to incomplete structure
+    (Incomplete,                "B",                    None,           Incomplete),
+    (POINTER(Incomplete),       "&B",                   None,           POINTER(Incomplete)),
+
+    # 'Complete' is a structure that starts incomplete, but is completed after the
+    # pointer type to it has been created.
+    (Complete,                  "T{<l:a:}",             None,           Complete),
+    # Unfortunately the pointer format string is not fixed...
+    (POINTER(Complete),         "&B",                   None,           POINTER(Complete)),
+
     ## other
 
     # function signatures are not implemented

diff --git a/Modules/_ctypes/_ctypes.c b/Modules/_ctypes/_ctypes.c
index 73542c7a0417d9d9a2224764b8bbbd9f796ab3c4..9c7355ac9bf1890d11642f762f71a3f09f88e318 100644 (file)
--- a/Modules/_ctypes/_ctypes.c
+++ b/Modules/_ctypes/_ctypes.c
@@ -386,6 +386,11 @@ StructUnionType_new(PyTypeObject *type, PyObject *args, PyObject *kwds, int isSt
        }
        Py_DECREF(result->tp_dict);
        result->tp_dict = (PyObject *)dict;
+       dict->format = alloc_format_string(NULL, "B");
+       if (dict->format == NULL) {
+               Py_DECREF(result);
+               return NULL;
+       }
 
        dict->paramfunc = StructUnionType_paramfunc;
 
@@ -907,7 +912,13 @@ PointerType_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
        if (proto) {
                StgDictObject *itemdict = PyType_stgdict(proto);
                assert(itemdict);
-               stgdict->format = alloc_format_string("&", itemdict->format);
+               /* If itemdict->format is NULL, then this is a pointer to an
+                  incomplete type.  We create a generic format string
+                  'pointer to bytes' in this case.  XXX Better would be to
+                  fix the format string later...
+               */
+               stgdict->format = alloc_format_string("&",
+                             itemdict->format ? itemdict->format : "B");
                if (stgdict->format == NULL) {
                        Py_DECREF((PyObject *)stgdict);
                        return NULL;