Index: Modules/posixmodule.c
===================================================================
--- Modules/posixmodule.c	(revision 66863)
+++ Modules/posixmodule.c	(working copy)
@@ -2384,40 +2384,67 @@
 posix__getfullpathname(PyObject *self, PyObject *args)
 {
 	/* assume encoded strings wont more than double no of chars */
-	char inbuf[MAX_PATH*2];
+	char inbuf[MAX_PATH+1];
 	char *inbufp = inbuf;
-	Py_ssize_t insize = sizeof(inbuf);
-	char outbuf[MAX_PATH*2];
+	Py_ssize_t insize = sizeof(inbuf)/sizeof(inbuf[0]);
+	char outbuf[MAX_PATH+1];
 	char *temp;
+	DWORD result;
+
+	if (PyArg_ParseTuple (args, "et#:_getfullpathname",
+	                       Py_FileSystemDefaultEncoding, &inbufp,
+	                       &insize)) {
+		result = GetFullPathNameA(inbuf, sizeof(outbuf)/sizeof(outbuf[0]),
+					  outbuf, &temp);
+		if (result) {
+			/* In the ANSI API, there should not be any paths longer
+			   than MAX_PATH. */
+			assert(result <= MAX_PATH+1);
+			return PyString_FromString(outbuf);
+		}
+	}
+
+	/* Drop the argument parsing error as narrow strings
+	   are also valid. */
+	PyErr_Clear();
+
 #ifdef Py_WIN_WIDE_FILENAMES
 	if (unicode_file_names()) {
-		PyUnicodeObject *po;
-		if (PyArg_ParseTuple(args, "U|:_getfullpathname", &po)) {
+		PyObject *po;
+		if (PyArg_ParseTuple(args, "O:_getfullpathname", &po)) {
+			Py_UNICODE *wpath;
 			Py_UNICODE woutbuf[MAX_PATH*2];
+			Py_UNICODE *woutbufp = woutbuf;
 			Py_UNICODE *wtemp;
-			if (!GetFullPathNameW(PyUnicode_AS_UNICODE(po),
-						sizeof(woutbuf)/sizeof(woutbuf[0]),
-						 woutbuf, &wtemp))
-				return win32_error("GetFullPathName", "");
-			return PyUnicode_FromUnicode(woutbuf, wcslen(woutbuf));
+			PyObject *v;
+
+			if (!convert_to_unicode(&po))
+				return NULL;
+			wpath = PyUnicode_AS_UNICODE(po);
+
+			result = GetFullPathNameW(wpath, sizeof(woutbuf)/sizeof(woutbuf[0]),
+						   woutbuf, &wtemp);
+			if (result > sizeof(woutbuf)/sizeof(woutbuf[0])) {
+				woutbufp = malloc(result * sizeof(Py_UNICODE));
+				if (!woutbufp)
+					return PyErr_NoMemory();
+				result = GetFullPathNameW(wpath, result, woutbufp, &wtemp);
+			}
+			if (!result)
+				v = win32_error_unicode("GetFullPathName", wpath);
+			else if (PyUnicode_Check(PyTuple_GetItem(args, 0)))
+				v = PyUnicode_FromUnicode(woutbufp, wcslen(woutbufp));
+			else
+				v = PyUnicode_Encode(woutbufp, wcslen(woutbufp),
+					Py_FileSystemDefaultEncoding, NULL);
+			if (woutbufp != woutbuf)
+				free(woutbufp);
+			Py_DECREF(po);
+			return v;
 		}
-		/* Drop the argument parsing error as narrow strings
-		   are also valid. */
-		PyErr_Clear();
 	}
 #endif
-	if (!PyArg_ParseTuple (args, "et#:_getfullpathname",
-	                       Py_FileSystemDefaultEncoding, &inbufp,
-	                       &insize))
-		return NULL;
-	if (!GetFullPathName(inbuf, sizeof(outbuf)/sizeof(outbuf[0]),
-	                     outbuf, &temp))
-		return win32_error("GetFullPathName", inbuf);
-	if (PyUnicode_Check(PyTuple_GetItem(args, 0))) {
-		return PyUnicode_Decode(outbuf, strlen(outbuf),
-			Py_FileSystemDefaultEncoding, NULL);
-	}
-	return PyString_FromString(outbuf);
+	return NULL;
 } /* end of posix__getfullpathname */
 #endif /* MS_WINDOWS */