Index: Modules/posixmodule.c
===================================================================
--- Modules/posixmodule.c	(revision 78265)
+++ Modules/posixmodule.c	(working copy)
@@ -3833,17 +3833,20 @@
 posix_getgroups(PyObject *self, PyObject *noargs)
 {
     PyObject *result = NULL;
+        gid_t *grouplist;
+        int n, nbuf;
 
-#ifdef NGROUPS_MAX
-#define MAX_GROUPS NGROUPS_MAX
-#else
-        /* defined to be 16 on Solaris7, so this should be a small number */
-#define MAX_GROUPS 64
-#endif
-        gid_t grouplist[MAX_GROUPS];
-        int n;
-
-        n = getgroups(MAX_GROUPS, grouplist);
+	nbuf = 16;
+	while (1) {
+	    grouplist = PyMem_MALLOC(nbuf * sizeof(gid_t));
+	    if (grouplist == NULL)
+	        return PyErr_NoMemory();
+	    n = getgroups(nbuf, grouplist);
+	    if (n > 0 || errno != EINVAL)
+		break;
+	    PyMem_FREE(grouplist);
+	    nbuf *= 2;
+	}
         if (n < 0)
             posix_error();
         else {
@@ -3861,6 +3864,7 @@
                 }
             }
         }
+	PyMem_FREE(grouplist);
 
     return result;
 }
@@ -5713,35 +5717,35 @@
 posix_setgroups(PyObject *self, PyObject *groups)
 {
 	int i, len;
-        gid_t grouplist[MAX_GROUPS];
+        gid_t *grouplist;
+	PyObject *ret = NULL;
 
 	if (!PySequence_Check(groups)) {
 		PyErr_SetString(PyExc_TypeError, "setgroups argument must be a sequence");
 		return NULL;
 	}
 	len = PySequence_Size(groups);
-	if (len > MAX_GROUPS) {
-		PyErr_SetString(PyExc_ValueError, "too many groups");
-		return NULL;
-	}
+	grouplist = PyMem_MALLOC(len * sizeof(gid_t));
+	if (grouplist == NULL)
+	        return PyErr_NoMemory();
 	for(i = 0; i < len; i++) {
 		PyObject *elem;
 		elem = PySequence_GetItem(groups, i);
 		if (!elem)
-			return NULL;
+			goto done;
 		if (!PyInt_Check(elem)) {
 			if (!PyLong_Check(elem)) {
 				PyErr_SetString(PyExc_TypeError,
 						"groups must be integers");
 				Py_DECREF(elem);
-				return NULL;
+				goto done;
 			} else {
 				unsigned long x = PyLong_AsUnsignedLong(elem);
 				if (PyErr_Occurred()) {
 					PyErr_SetString(PyExc_TypeError, 
 							"group id too big");
 					Py_DECREF(elem);
-					return NULL;
+					goto done;
 				}
 				grouplist[i] = x;
 				/* read back to see if it fits in gid_t */
@@ -5749,7 +5753,7 @@
 					PyErr_SetString(PyExc_TypeError,
 							"group id too big");
 					Py_DECREF(elem);
-					return NULL;
+					goto done;
 				}
 			}
 		} else {
@@ -5759,7 +5763,7 @@
 				PyErr_SetString(PyExc_TypeError,
 						"group id too big");
 				Py_DECREF(elem);
-				return NULL;
+				goto done;
 			}
 		}
 		Py_DECREF(elem);
@@ -5767,8 +5771,11 @@
 
 	if (setgroups(len, grouplist) < 0)
 		return posix_error();
-	Py_INCREF(Py_None);
-	return Py_None;
+	ret = Py_None;
+	Py_INCREF(ret);
+ done:
+	PyMem_FREE(grouplist);
+	return ret;
 }
 #endif /* HAVE_SETGROUPS */