Index: Lib/ntpath.py
===================================================================
--- Lib/ntpath.py	(revision 75333)
+++ Lib/ntpath.py	(working copy)
@@ -17,6 +17,7 @@
            "basename","dirname","commonprefix","getsize","getmtime",
            "getatime","getctime", "islink","exists","lexists","isdir","isfile",
            "ismount","walk","expanduser","expandvars","normpath","abspath",
+           "samefile","sameopenfile",
            "splitunc","curdir","pardir","sep","pathsep","defpath","altsep",
            "extsep","devnull","realpath","supports_unicode_filenames","relpath"]
 
@@ -496,3 +497,31 @@
     if not rel_list:
         return curdir
     return join(*rel_list)
+
+
+# Are two filenames really pointing to the same file?
+try:
+    from nt import _samefile
+
+except ImportError: # not running on Windows - mock up something sensible
+    from posixpath import samefile # XXX
+
+else:  # use native Windows method on Windows
+    def samefile(f1, f2):
+        """Test whether two pathnames reference the same actual file"""
+        return _samefile(f1, f2)
+
+
+# Are two open files really referencing the same file?
+# (Not necessarily the same file descriptor!)
+try:
+    from nt import _sameopenfile
+
+except ImportError: # not running on Windows - mock up something sensible
+    from posixpath import sameopenfile # XXX
+
+else:  # use native Windows method on Windows
+    def sameopenfile(f1, f2):
+        """Test whether two file handles reference the same actual file"""
+        return _sameopenfile(f1, f2)
+
Index: Modules/posixmodule.c
===================================================================
--- Modules/posixmodule.c	(revision 75333)
+++ Modules/posixmodule.c	(working copy)
@@ -2428,6 +2428,113 @@
 	}
 	return PyString_FromString(outbuf);
 } /* end of posix__getfullpathname */
+
+static HANDLE
+open_file(const char *path)
+{
+	return CreateFileA(path, 0, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, 0);
+}
+
+static HANDLE
+open_file_w(const wchar_t *path)
+{
+	return CreateFileW(path, 0, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, 0);
+}
+
+static PyObject *
+samefile(HANDLE h1, HANDLE h2)
+{
+	BY_HANDLE_FILE_INFORMATION info1, info2;
+
+	if (!GetFileInformationByHandle(h1, &info1))
+		return NULL;
+	if (!GetFileInformationByHandle(h2, &info2))
+		return NULL;
+	if ((info1.dwVolumeSerialNumber == info2.dwVolumeSerialNumber) &&
+	    (info1.nFileIndexHigh == info2.nFileIndexHigh) &&
+	    (info1.nFileIndexLow == info2.nFileIndexLow))
+		Py_RETURN_TRUE;
+	else
+		Py_RETURN_FALSE;
+}
+
+/* A helper function for samefile on win32 */
+static PyObject *
+posix__samefile(PyObject *self, PyObject *args)
+{
+	PyUnicodeObject *po1, *po2;
+	PyObject *v = NULL;
+	HANDLE h1, h2;
+	char inbuf1[MAX_PATH+1], *inbufp1 = inbuf1;
+	char inbuf2[MAX_PATH+1], *inbufp2 = inbuf2;
+	Py_ssize_t insize1 = sizeof(inbuf1);
+	Py_ssize_t insize2 = sizeof(inbuf2);
+
+	if (PyArg_ParseTuple(args, "UU:_samefile", &po1, &po2)) {
+		h1 = open_file_w(PyUnicode_AS_UNICODE(po1));
+		if (h1 != INVALID_HANDLE_VALUE) {
+			h2 = open_file_w(PyUnicode_AS_UNICODE(po2));
+			if (h2 != INVALID_HANDLE_VALUE) {
+				v = samefile(h1, h2);
+				CloseHandle(h2);
+			}
+			CloseHandle(h1);
+		}
+		if (!v)
+			return win32_error("_samefile", NULL);
+		return v;
+	}
+	/* Drop the argument parsing error as narrow strings
+	   are also valid. */
+	PyErr_Clear();
+
+	if (!PyArg_ParseTuple(args, "et#et#:_samefile",
+	                      Py_FileSystemDefaultEncoding, &inbufp1, &insize1,
+	                      Py_FileSystemDefaultEncoding, &inbufp2, &insize2))
+		return NULL;
+	h1 = open_file(inbuf1);
+	if (h1 != INVALID_HANDLE_VALUE) {
+		h2 = open_file(inbuf2);
+		if (h2 != INVALID_HANDLE_VALUE) {
+			v = samefile(h1, h2);
+			CloseHandle(h2);
+		}
+		CloseHandle(h1);
+	}
+	if (!v)
+		return win32_error("_samefile", NULL);
+	return v;
+} /* end of posix__samefile */
+
+/* A helper function for sameopenfile on win32 */
+static PyObject *
+posix__sameopenfile(PyObject *self, PyObject *args)
+{
+	int fd1, fd2;
+	PyObject *v = NULL;
+	HANDLE h1, h2;
+
+	if (!PyArg_ParseTuple(args, "ii:_samefile", &fd1, &fd2))
+		return NULL;
+
+	h1 = (HANDLE)_get_osfhandle(fd1);
+	h2 = (HANDLE)_get_osfhandle(fd2);
+
+	/* Protocol violation: we explicitly clear errno, instead of
+	   setting it to a POSIX error. Callers should use GetLastError. */
+	errno = 0;
+
+	if (h1 == INVALID_HANDLE_VALUE || h2 == INVALID_HANDLE_VALUE)
+    		/* This is really a C library error (invalid file handle).
+		   We set the Win32 error to the closes one matching. */
+		SetLastError(ERROR_INVALID_HANDLE);
+	else
+		v = samefile(h1, h2);
+
+	if (!v)
+		return win32_error("_sameopenfile", NULL);
+	return v;
+} /* end of posix__sameopenfile */
 #endif /* MS_WINDOWS */
 
 PyDoc_STRVAR(posix_mkdir__doc__,
@@ -8686,6 +8793,8 @@
 	{"abort",	posix_abort, METH_NOARGS, posix_abort__doc__},
 #ifdef MS_WINDOWS
 	{"_getfullpathname",	posix__getfullpathname, METH_VARARGS, NULL},
+	{"_samefile",	posix__samefile, METH_VARARGS, NULL},
+	{"_sameopenfile",	posix__sameopenfile, METH_VARARGS, NULL},
 #endif
 #ifdef HAVE_GETLOADAVG
 	{"getloadavg",	posix_getloadavg, METH_NOARGS, posix_getloadavg__doc__},