bpo-35947: Update Windows to the current version of libffi (GH-11797)

We now use a pre-built libffi binary from our binaries repository, and no longer vendor the full implementation.

Author: paulmon

Lib/ctypes/test/test_win32.py

@@ -6,35 +6,6 @@
 
 import _ctypes_test
 
-# Only windows 32-bit has different calling conventions.
-@unittest.skipUnless(sys.platform == "win32", 'Windows-specific test')
-@unittest.skipUnless(sizeof(c_void_p) == sizeof(c_int),
-                     "sizeof c_void_p and c_int differ")
-class WindowsTestCase(unittest.TestCase):
-    def test_callconv_1(self):
-        # Testing stdcall function
-
-        IsWindow = windll.user32.IsWindow
-        # ValueError: Procedure probably called with not enough arguments
-        # (4 bytes missing)
-        self.assertRaises(ValueError, IsWindow)
-
-        # This one should succeed...
-        self.assertEqual(0, IsWindow(0))
-
-        # ValueError: Procedure probably called with too many arguments
-        # (8 bytes in excess)
-        self.assertRaises(ValueError, IsWindow, 0, 0, 0)
-
-    def test_callconv_2(self):
-        # Calling stdcall function as cdecl
-
-        IsWindow = cdll.user32.IsWindow
-
-        # ValueError: Procedure called with not enough arguments
-        # (4 bytes missing) or wrong calling convention
-        self.assertRaises(ValueError, IsWindow, None)
-
 @unittest.skipUnless(sys.platform == "win32", 'Windows-specific test')
 class FunctionCallTestCase(unittest.TestCase):
     @unittest.skipUnless('MSC' in sys.version, "SEH only supported by MSC")

Misc/NEWS.d/next/Windows/2019-02-11-14-53-17.bpo-35947.9vI4hP.rst

@@ -0,0 +1,2 @@
+Added current version of libffi to cpython-source-deps. 
+Change _ctypes to use current version of libffi on Windows.

Modules/_ctypes/_ctypes.c

@@ -403,24 +403,35 @@ static PyCArgObject *
 StructUnionType_paramfunc(CDataObject *self)
 {
     PyCArgObject *parg;
+    CDataObject *copied_self;
     StgDictObject *stgdict;
 
+    if (self->b_size > sizeof(void*)) {
+        void *new_ptr = PyMem_Malloc(self->b_size);
+        if (new_ptr == NULL)
+            return NULL;
+        memcpy(new_ptr, self->b_ptr, self->b_size);
+        copied_self = (CDataObject *)PyCData_AtAddress(
+            (PyObject *)Py_TYPE(self), new_ptr);
+        copied_self->b_needsfree = 1;
+    } else {
+        copied_self = self;
+        Py_INCREF(copied_self);
+    }
+
     parg = PyCArgObject_new();
-    if (parg == NULL)
+    if (parg == NULL) {
+        Py_DECREF(copied_self);
         return NULL;
+    }
 
     parg->tag = 'V';
-    stgdict = PyObject_stgdict((PyObject *)self);
+    stgdict = PyObject_stgdict((PyObject *)copied_self);
     assert(stgdict); /* Cannot be NULL for structure/union instances */
     parg->pffi_type = &stgdict->ffi_type_pointer;
-    /* For structure parameters (by value), parg->value doesn't contain the structure
-       data itself, instead parg->value.p *points* to the structure's data
-       See also _ctypes.c, function _call_function_pointer().
-    */
-    parg->value.p = self->b_ptr;
-    parg->size = self->b_size;
-    Py_INCREF(self);
-    parg->obj = (PyObject *)self;
+    parg->value.p = copied_self->b_ptr;
+    parg->size = copied_self->b_size;
+    parg->obj = (PyObject *)copied_self;
     return parg;
 }
 

Modules/_ctypes/callproc.c

@@ -729,6 +729,23 @@ static int ConvParam(PyObject *obj, Py_ssize_t index, struct argument *pa)
     }
 }
 
+#if defined(MS_WIN32) && !defined(_WIN32_WCE)
+/*
+Per: https://msdn.microsoft.com/en-us/library/7572ztz4.aspx
+To be returned by value in RAX, user-defined types must have a length 
+of 1, 2, 4, 8, 16, 32, or 64 bits
+*/
+int can_return_struct_as_int(size_t s)
+{
+  return s == 1 || s == 2 || s == 4;
+}
+
+int can_return_struct_as_sint64(size_t s)
+{
+  return s == 8;
+}
+#endif
+
 
 ffi_type *_ctypes_get_ffi_type(PyObject *obj)
 {
@@ -778,12 +795,9 @@ static int _call_function_pointer(int flags,
     int *space;
     ffi_cif cif;
     int cc;
-#ifdef MS_WIN32
-    int delta;
-#ifndef DONT_USE_SEH
+#if defined(MS_WIN32) && !defined(DONT_USE_SEH)
     DWORD dwExceptionCode = 0;
     EXCEPTION_RECORD record;
-#endif
 #endif
     /* XXX check before here */
     if (restype == NULL) {
@@ -828,7 +842,6 @@ static int _call_function_pointer(int flags,
 #ifndef DONT_USE_SEH
     __try {
 #endif
-        delta =
 #endif
                 ffi_call(&cif, (void *)pProc, resmem, avalues);
 #ifdef MS_WIN32
@@ -860,35 +873,6 @@ static int _call_function_pointer(int flags,
         return -1;
     }
 #endif
-#ifdef MS_WIN64
-    if (delta != 0) {
-        PyErr_Format(PyExc_RuntimeError,
-                 "ffi_call failed with code %d",
-                 delta);
-        return -1;
-    }
-#else
-    if (delta < 0) {
-        if (flags & FUNCFLAG_CDECL)
-            PyErr_Format(PyExc_ValueError,
-                     "Procedure called with not enough "
-                     "arguments (%d bytes missing) "
-                     "or wrong calling convention",
-                     -delta);
-        else
-            PyErr_Format(PyExc_ValueError,
-                     "Procedure probably called with not enough "
-                     "arguments (%d bytes missing)",
-                     -delta);
-        return -1;
-    } else if (delta > 0) {
-        PyErr_Format(PyExc_ValueError,
-                 "Procedure probably called with too many "
-                 "arguments (%d bytes in excess)",
-                 delta);
-        return -1;
-    }
-#endif
 #endif
     if ((flags & FUNCFLAG_PYTHONAPI) && PyErr_Occurred())
         return -1;