Index: Lib/test/test_io.py
===================================================================
--- Lib/test/test_io.py	(Revision 67070)
+++ Lib/test/test_io.py	(Arbeitskopie)
@@ -9,6 +9,8 @@
 import unittest
 from itertools import chain, cycle
 from test import support
+import warnings
+import gc
 
 import codecs
 import io  # The module under test
@@ -1237,20 +1239,55 @@
             else:
                 self.assert_(issubclass(obj, io.IOBase))
 
+
+class CloseFDTest(unittest.TestCase):
+    def setUp(sel):
+        with io.open(support.TESTFN, "w") as f:
+            f.write("line1\n")
+            f.write("line2\n")
+
     def test_fileio_warnings(self):
         with support.check_warnings() as w:
             self.assertEqual(w.warnings, [])
             self.assertRaises(TypeError, io.FileIO, [])
             self.assertEqual(w.warnings, [])
-            self.assertRaises(ValueError, io.FileIO, "/some/invalid/name", "rt")
+            self.assertRaises(ValueError, io.FileIO, "support.TESTFN", "rt")
             self.assertEqual(w.warnings, [])
 
+    def testReadClosed(self):
+        with io.open(support.TESTFN, "r") as f:
+            file = io.FileIO(f.fileno(), "r", closefd=False)
+            file.close()
+            self.assertRaises(ValueError, file.readline)
+
+    def testNoClose(self):
+        with support.check_warnings() as w:
+            with io.open(support.TESTFN, "r") as f:
+                self.assertEqual(w.warnings, [])
+                file = io.FileIO(f.fileno(), "r", closefd=False)
+                # destructor should no raise a RuntimeWarning
+                # (close unclosable file)
+                del file
+                gc.collect()
+                self.assertEqual(w.warnings, [])
+
+    def test_no_closefd_with_filename(self):
+        # can't use closefd in combination with a file name
+        self.assertRaises(ValueError, io.open, support.TESTFN, "r", closefd=False)
+
+    def test_closefd_attr(self):
+        with io.open(support.TESTFN, "r") as f:
+            self.assertEqual(f.buffer.raw.closefd, True)
+            file = io.FileIO(f.fileno(), "r", closefd=False)
+            self.assertEqual(file.closefd, False)
+
+
 def test_main():
     support.run_unittest(IOTest, BytesIOTest, StringIOTest,
                               BufferedReaderTest, BufferedWriterTest,
                               BufferedRWPairTest, BufferedRandomTest,
                               StatefulIncrementalDecoderTest,
-                              TextIOWrapperTest, MiscIOTest)
+                              TextIOWrapperTest, MiscIOTest, CloseFDTest)
 
 if __name__ == "__main__":
     unittest.main()
Index: Modules/_fileio.c
===================================================================
--- Modules/_fileio.c	(Revision 67070)
+++ Modules/_fileio.c	(Arbeitskopie)
@@ -61,10 +61,7 @@
 fileio_close(PyFileIOObject *self)
 {
 	if (!self->closefd) {
-		if (PyErr_WarnEx(PyExc_RuntimeWarning,
-				 "Trying to close unclosable fd!", 3) < 0) {
-			return NULL;
-		}
+		self->fd = -1;
 		Py_RETURN_NONE;
 	}
 	errno = internal_close(self);
@@ -821,6 +818,12 @@
 }
 
 static PyObject *
+get_closefd(PyFileIOObject *self, void *closure)
+{
+	return PyBool_FromLong((long)(self->closefd));
+}
+
+static PyObject *
 get_mode(PyFileIOObject *self, void *closure)
 {
 	return PyUnicode_FromString(mode_string(self));
@@ -828,6 +831,8 @@
 
 static PyGetSetDef fileio_getsetlist[] = {
 	{"closed", (getter)get_closed, NULL, "True if the file is closed"},
+	{"closefd", (getter)get_closefd, NULL, 
+		"True if the file descriptor will be closed"},
 	{"mode", (getter)get_mode, NULL, "String giving the file mode"},
 	{0},
 };