string_join(): Some cleaning up of reference counting. In the

seqlen==1 clause, before returning item, we need to DECREF seq.  In
the res=PyString... failure clause, we need to goto finally to also
decref seq (and the DECREF of res in finally is changed to a
XDECREF).  Also, we need to DECREF seq just before the
PyUnicode_Join() return.

diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 2667fa9e70f6dd94cf2b3c32e85a16af6b1143a2..dc41122c8a81dcfa9d4c8af381e5467cc9d49c1b 100644 (file)
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -749,24 +749,27 @@ string_join(PyStringObject *self, PyObject *args)
        if (!PyArg_ParseTuple(args, "O:join", &orig))
                return NULL;
 
-       seq = PySequence_Fast(orig, "");
-       if (seq == NULL) {
+       if (!(seq = PySequence_Fast(orig, ""))) {
                if (PyErr_ExceptionMatches(PyExc_TypeError))
                        PyErr_Format(PyExc_TypeError,
                                     "sequence expected, %.80s found",
                                     orig->ob_type->tp_name);
                return NULL;
        }
-
+       /* From here on out, errors go through finally: for proper
+        * reference count manipulations.
+        */
        seqlen = PySequence_Length(seq);
        if (seqlen == 1) {
                item = PySequence_Fast_GET_ITEM(seq, 0);
                Py_INCREF(item);
+               Py_DECREF(seq);
                return item;
        }
 
        if (!(res = PyString_FromStringAndSize((char*)NULL, sz)))
-               return NULL;
+               goto finally;
+
        p = PyString_AsString(res);
 
        for (i = 0; i < seqlen; i++) {
@@ -774,8 +777,8 @@ string_join(PyStringObject *self, PyObject *args)
                if (!PyString_Check(item)){
                        if (PyUnicode_Check(item)) {
                                Py_DECREF(res);
-                               return PyUnicode_Join((PyObject *)self, 
-                                                     seq);
+                               Py_DECREF(seq);
+                               return PyUnicode_Join((PyObject *)self, seq);
                        }
                        PyErr_Format(PyExc_TypeError,
                             "sequence item %i: expected string, %.80s found",
@@ -806,7 +809,7 @@ string_join(PyStringObject *self, PyObject *args)
 
   finally:
        Py_DECREF(seq);
-       Py_DECREF(res);
+       Py_XDECREF(res);
        return NULL;
 }