Index: Lib/test/test_largefile.py
===================================================================
--- Lib/test/test_largefile.py	(revision 59809)
+++ Lib/test/test_largefile.py	(working copy)
@@ -152,7 +152,7 @@
         newsize -= 1
         f.seek(42)
         f.truncate(newsize)
-        expect(f.tell(), 42)        # else pointer moved
+        expect(f.tell(), newsize)   # pointer should be moved
         f.seek(0, 2)
         expect(f.tell(), newsize)   # else wasn't truncated
 
@@ -161,8 +161,8 @@
         # cut it waaaaay back
         f.seek(0)
         f.truncate(1)
-        expect(f.tell(), 0)         # else pointer moved
-        expect(len(f.read()), 1)    # else wasn't truncated
+        expect(f.tell(), 1)         # pointer should be moved
+        expect(len(f.read()), 0)
 
     finally:
         f.close()
Index: Lib/test/test_io.py
===================================================================
--- Lib/test/test_io.py	(revision 59809)
+++ Lib/test/test_io.py	(working copy)
@@ -94,7 +94,7 @@
         self.assertEqual(f.seek(-1, 2), 13)
         self.assertEqual(f.tell(), 13)
         self.assertEqual(f.truncate(12), 12)
-        self.assertEqual(f.tell(), 13)
+        self.assertEqual(f.tell(), 12)
         self.assertRaises(TypeError, f.seek, 0.0)
 
     def read_ops(self, f, buffered=False):
@@ -139,7 +139,7 @@
         self.assertEqual(f.tell(), self.LARGE + 2)
         self.assertEqual(f.seek(0, 2), self.LARGE + 2)
         self.assertEqual(f.truncate(self.LARGE + 1), self.LARGE + 1)
-        self.assertEqual(f.tell(), self.LARGE + 2)
+        self.assertEqual(f.tell(), self.LARGE + 1)
         self.assertEqual(f.seek(0, 2), self.LARGE + 1)
         self.assertEqual(f.seek(-1, 2), self.LARGE)
         self.assertEqual(f.read(2), b"x")
@@ -580,6 +580,7 @@
             txt.write("BB\nCCC\n")
             txt.write("X\rY\r\nZ")
             txt.flush()
+            self.assertEquals(buf.closed, False)
             self.assertEquals(buf.getvalue(), expected)
 
     def testNewlines(self):
Index: Modules/_fileio.c
===================================================================
--- Modules/_fileio.c	(revision 59809)
+++ Modules/_fileio.c	(working copy)
@@ -560,11 +560,10 @@
 			PyErr_SetString(PyExc_TypeError, "an integer is required");
 			return NULL;
 		}
-#if !defined(HAVE_LARGEFILE_SUPPORT)
-		pos = PyLong_AsLong(posobj);
+#if defined(HAVE_LARGEFILE_SUPPORT)
+		pos = PyLong_AsLongLong(posobj);
 #else
-		pos = PyLong_Check(posobj) ?
-			PyLong_AsLongLong(posobj) : PyLong_AsLong(posobj);
+		pos = PyLong_AsLong(posobj);
 #endif
 		if (PyErr_Occurred())
 			return NULL;
@@ -580,10 +579,10 @@
 	if (res < 0)
 		return PyErr_SetFromErrno(PyExc_IOError);
 
-#if !defined(HAVE_LARGEFILE_SUPPORT)
-	return PyLong_FromLong(res);
-#else
+#if defined(HAVE_LARGEFILE_SUPPORT)
 	return PyLong_FromLongLong(res);
+#else
+	return PyLong_FromLong(res);
 #endif
 }
 
@@ -630,49 +629,30 @@
 		return NULL;
 
 	if (posobj == Py_None || posobj == NULL) {
+		/* Get the current position. */
                 posobj = portable_lseek(fd, NULL, 1);
                 if (posobj == NULL)
-                  return NULL;
+			return NULL;
         }
         else {
-		Py_INCREF(posobj);
+		/* Move to the position to be truncated. */
+                posobj = portable_lseek(fd, posobj, 0);
         }
 
-#if !defined(HAVE_LARGEFILE_SUPPORT)
-	pos = PyLong_AsLong(posobj);
+#if defined(HAVE_LARGEFILE_SUPPORT)
+	pos = PyLong_AsLongLong(posobj);
 #else
-	pos = PyLong_Check(posobj) ?
-		PyLong_AsLongLong(posobj) : PyLong_AsLong(posobj);
+	pos = PyLong_AsLong(posobj);
 #endif
-	if (PyErr_Occurred()) {
-		Py_DECREF(posobj);
+	if (PyErr_Occurred())
 		return NULL;
-	}
 
 #ifdef MS_WINDOWS
 	/* MS _chsize doesn't work if newsize doesn't fit in 32 bits,
 	   so don't even try using it. */
 	{
 		HANDLE hFile;
-		PyObject *pos2, *oldposobj;
 
-		/* store the current position */
-		oldposobj = portable_lseek(self->fd, NULL, 1);
-		if (oldposobj == NULL) {
-			Py_DECREF(posobj);
-			return NULL;
-		}
-
-		/* Have to move current pos to desired endpoint on Windows. */
-		errno = 0;
-		pos2 = portable_lseek(fd, posobj, SEEK_SET);
-		if (pos2 == NULL) {
-			Py_DECREF(posobj);
-			Py_DECREF(oldposobj);
-			return NULL;
-		}
-		Py_DECREF(pos2);
-
 		/* Truncate.  Note that this may grow the file! */
 		Py_BEGIN_ALLOW_THREADS
 		errno = 0;
@@ -684,18 +664,6 @@
 				errno = EACCES;
 		}
 		Py_END_ALLOW_THREADS
-
-		if (ret == 0) {
-			/* Move to the previous position in the file */
-			pos2 = portable_lseek(fd, oldposobj, SEEK_SET);
-			if (pos2 == NULL) {
-				Py_DECREF(posobj);
-				Py_DECREF(oldposobj);
-				return NULL;
-			}
-		}
-		Py_DECREF(pos2);
-		Py_DECREF(oldposobj);
 	}
 #else
 	Py_BEGIN_ALLOW_THREADS
@@ -705,7 +673,6 @@
 #endif /* !MS_WINDOWS */
 
 	if (ret != 0) {
-		Py_DECREF(posobj);
 		PyErr_SetFromErrno(PyExc_IOError);
 		return NULL;
 	}
@@ -799,7 +766,8 @@
 PyDoc_STRVAR(truncate_doc,
 "truncate([size: int]) -> None.	 Truncate the file to at most size bytes.\n"
 "\n"
-"Size defaults to the current file position, as returned by tell().");
+"Size defaults to the current file position, as returned by tell()."
+"The current file position is changed to the value of size.");
 #endif
 
 PyDoc_STRVAR(tell_doc,