Index: configure.in
===================================================================
--- configure.in	(revision 76162)
+++ configure.in	(working copy)
@@ -2546,13 +2546,15 @@
 AC_CHECK_FUNCS(alarm setitimer getitimer bind_textdomain_codeset chown \
  clock confstr ctermid execv fchmod fchown fork fpathconf ftime ftruncate \
  gai_strerror getgroups getlogin getloadavg getpeername getpgid getpid \
- getpriority getpwent getspnam getspent getsid getwd \
+ getpriority getresuid getresgid getpwent getspnam getspent getsid getwd \
  kill killpg lchmod lchown lstat mkfifo mknod mktime \
  mremap nice pathconf pause plock poll pthread_init \
  putenv readlink realpath \
  select sem_open sem_timedwait sem_getvalue sem_unlink setegid seteuid \
  setgid \
  setlocale setregid setreuid setsid setpgid setpgrp setuid setvbuf snprintf \
+ setlocale setregid setreuid setresuid setresgid \
+ setsid setpgid setpgrp setuid setvbuf snprintf \
  sigaction siginterrupt sigrelse strftime \
  sysconf tcgetpgrp tcsetpgrp tempnam timegm times tmpfile tmpnam tmpnam_r \
  truncate uname unsetenv utimes waitpid wait3 wait4 wcscoll _getpty)
Index: Lib/test/test_posix.py
===================================================================
--- Lib/test/test_posix.py	(revision 76162)
+++ Lib/test/test_posix.py	(working copy)
@@ -41,6 +41,48 @@
                 posix_func()
                 self.assertRaises(TypeError, posix_func, 1)
 
+    if hasattr(posix, 'getresuid'):
+        def test_getresuid(self):
+            user_ids = posix.getresuid()
+            self.assertEqual(len(user_ids), 3)
+            for val in user_ids:
+                self.assertGreaterEqual(val, 0)
+
+    if hasattr(posix, 'getresgid'):
+        def test_getresgid(self):
+            group_ids = posix.getresgid()
+            self.assertEqual(len(group_ids), 3)
+            for val in group_ids:
+                self.assertGreaterEqual(val, 0)
+
+    if hasattr(posix, 'setresuid'):
+        def test_setresuid(self):
+            current_user_ids = posix.getresuid()
+            self.assertIsNone(posix.setresuid(*current_user_ids))
+            # -1 means don't change that value.
+            self.assertIsNone(posix.setresuid(-1, -1, -1))
+
+        def test_setresuid_exception(self):
+            # Don't do this test if someone is silly enough to run us as root.
+            current_user_ids = posix.getresuid()
+            if 0 not in current_user_ids:
+                new_user_ids = (current_user_ids[0]+1, -1, -1)
+                self.assertRaises(OSError, posix.setresuid, *new_user_ids)
+
+    if hasattr(posix, 'setresgid'):
+        def test_setresgid(self):
+            current_group_ids = posix.getresgid()
+            self.assertIsNone(posix.setresgid(*current_group_ids))
+            # -1 means don't change that value.
+            self.assertIsNone(posix.setresgid(-1, -1, -1))
+
+        def test_setresgid_exception(self):
+            # Don't do this test if someone is silly enough to run us as root.
+            current_group_ids = posix.getresgid()
+            if 0 not in current_group_ids:
+                new_group_ids = (current_group_ids[0]+1, -1, -1)
+                self.assertRaises(OSError, posix.setresgid, *new_group_ids)
+
     def test_statvfs(self):
         if hasattr(posix, 'statvfs'):
             self.assertTrue(posix.statvfs(os.curdir))
Index: Modules/posixmodule.c
===================================================================
--- Modules/posixmodule.c	(revision 76162)
+++ Modules/posixmodule.c	(working copy)
@@ -8386,6 +8386,82 @@
 }
 #endif
 
+#ifdef HAVE_SETRESUID
+PyDoc_STRVAR(posix_setresuid__doc__,
+"setresuid(ruid, euid, suid)\n\n\
+Set the current process's real, effective, and saved user ids.");
+
+static PyObject*
+posix_setresuid (PyObject *self, PyObject *args)
+{
+	/* We assume uid_t is no larger than a long. */
+	long ruid, euid, suid;
+	if (!PyArg_ParseTuple(args, "lll", &ruid, &euid, &suid))
+		return NULL;
+	if (setresuid(ruid, euid, suid) < 0)
+		return posix_error();
+	Py_RETURN_NONE;
+}
+#endif
+
+#ifdef HAVE_SETRESGID
+PyDoc_STRVAR(posix_setresgid__doc__,
+"setresgid(rgid, egid, sgid)\n\n\
+Set the current process's real, effective, and saved group ids.");
+
+static PyObject*
+posix_setresgid (PyObject *self, PyObject *args)
+{
+	/* We assume uid_t is no larger than a long. */
+	long rgid, egid, sgid;
+	if (!PyArg_ParseTuple(args, "lll", &rgid, &egid, &sgid))
+		return NULL;
+	if (setresgid(rgid, egid, sgid) < 0)
+		return posix_error();
+	Py_RETURN_NONE;
+}
+#endif
+
+#ifdef HAVE_GETRESUID
+PyDoc_STRVAR(posix_getresuid__doc__,
+"getresuid() -> (ruid, euid, sgid)\n\n\
+Get tuple of the current process's real, effective, and saved user ids.");
+
+static PyObject*
+posix_getresuid (PyObject *self, PyObject *noargs)
+{
+	uid_t ruid, euid, suid;
+	long l_ruid, l_euid, l_suid;
+	if (getresuid(&ruid, &euid, &suid) < 0)
+		return posix_error();
+	/* Force the values into long's as we don't know the size of uid_t. */
+	l_ruid = ruid;
+	l_euid = euid;
+	l_suid = suid;
+	return Py_BuildValue("(lll)", l_ruid, l_euid, l_suid);
+}
+#endif
+
+#ifdef HAVE_GETRESGID
+PyDoc_STRVAR(posix_getresgid__doc__,
+"getresgid() -> (rgid, egid, sgid)\n\n\
+Get tuple of the current process's real, effective, and saved user ids.");
+
+static PyObject*
+posix_getresgid (PyObject *self, PyObject *noargs)
+{
+	uid_t rgid, egid, sgid;
+	long l_rgid, l_egid, l_sgid;
+	if (getresgid(&rgid, &egid, &sgid) < 0)
+		return posix_error();
+	/* Force the values into long's as we don't know the size of uid_t. */
+	l_rgid = rgid;
+	l_egid = egid;
+	l_sgid = sgid;
+	return Py_BuildValue("(lll)", l_rgid, l_egid, l_sgid);
+}
+#endif
+
 static PyMethodDef posix_methods[] = {
 	{"access",	posix_access, METH_VARARGS, posix_access__doc__},
 #ifdef HAVE_TTYNAME
@@ -8696,6 +8772,19 @@
  #ifdef __VMS
  	{"urandom", vms_urandom, METH_VARARGS, vms_urandom__doc__},
  #endif
+#ifdef HAVE_SETRESUID
+        {"setresuid",	posix_setresuid, METH_VARARGS, posix_setresuid__doc__},
+#endif
+#ifdef HAVE_SETRESGID
+        {"setresgid",	posix_setresgid, METH_VARARGS, posix_setresgid__doc__},
+#endif
+#ifdef HAVE_GETRESUID
+        {"getresuid",	posix_getresuid, METH_NOARGS, posix_getresuid__doc__},
+#endif
+#ifdef HAVE_GETRESGID
+        {"getresgid",	posix_getresgid, METH_NOARGS, posix_getresgid__doc__},
+#endif
+
 	{NULL,		NULL}		 /* Sentinel */
 };
 
Index: pyconfig.h.in
===================================================================
--- pyconfig.h.in	(revision 76162)
+++ pyconfig.h.in	(working copy)
@@ -316,6 +316,12 @@
 /* Define to 1 if you have the `getpwent' function. */
 #undef HAVE_GETPWENT
 
+/* Define to 1 if you have the `getresgid' function. */
+#undef HAVE_GETRESGID
+
+/* Define to 1 if you have the `getresuid' function. */
+#undef HAVE_GETRESUID
+
 /* Define to 1 if you have the `getsid' function. */
 #undef HAVE_GETSID
 
@@ -580,6 +586,12 @@
 /* Define to 1 if you have the `setregid' function. */
 #undef HAVE_SETREGID
 
+/* Define to 1 if you have the `setresgid' function. */
+#undef HAVE_SETRESGID
+
+/* Define to 1 if you have the `setresuid' function. */
+#undef HAVE_SETRESUID
+
 /* Define to 1 if you have the `setreuid' function. */
 #undef HAVE_SETREUID