Fix the refleak in strftime when converting a %Z with a user defined tzinfo.

I inverted some of the conditionals to reduce indent levels.  Hopefully
this makes it a little easier to read.

This code caused the leak:

    class FixedOffset(datetime.tzinfo):
        def tzname(self, dt): return "UTC"

    datetime.time(12, 47, tzinfo=FixedOffset()).strftime('%Z')

This code is very tricky and I'm not positive it works.  However,
it neither crashes nor leaks.

diff --git a/Modules/datetimemodule.c b/Modules/datetimemodule.c
index d220b563c881d3c78428c308e4bb9a344f2605c2..165ddbde315ed5576d1753bc5ae8a54c3f87ddd4 100644 (file)
--- a/Modules/datetimemodule.c
+++ b/Modules/datetimemodule.c
@@ -1131,44 +1131,51 @@ format_utcoffset(char *buf, size_t buflen, const char *sep,
 static PyObject *
 make_Zreplacement(PyObject *object, PyObject *tzinfoarg)
 {
+       PyObject *temp;
        PyObject *tzinfo = get_tzinfo_member(object);
        PyObject *Zreplacement = PyString_FromString("");
        if (Zreplacement == NULL)
                return NULL;
-       if (tzinfo != Py_None && tzinfo != NULL) {
-               PyObject *temp;
-               assert(tzinfoarg != NULL);
-               temp = call_tzname(tzinfo, tzinfoarg);
-               if (temp == NULL)
-                       goto Error;
-               if (temp != Py_None) {
-                       assert(PyUnicode_Check(temp));
-                       /* Since the tzname is getting stuffed into the
-                        * format, we have to double any % signs so that
-                        * strftime doesn't treat them as format codes.
-                        */
+       if (tzinfo == Py_None || tzinfo == NULL)
+               return Zreplacement;
+
+       assert(tzinfoarg != NULL);
+       temp = call_tzname(tzinfo, tzinfoarg);
+       if (temp == NULL)
+               goto Error;
+       if (temp == Py_None) {
+               Py_DECREF(temp);
+               return Zreplacement;
+       }
+
+       assert(PyUnicode_Check(temp));
+       /* Since the tzname is getting stuffed into the
+        * format, we have to double any % signs so that
+        * strftime doesn't treat them as format codes.
+        */
+       Py_DECREF(Zreplacement);
+       Zreplacement = PyObject_CallMethod(temp, "replace", "ss", "%", "%%");
+       Py_DECREF(temp);
+       if (Zreplacement == NULL)
+               return NULL;
+       if (PyUnicode_Check(Zreplacement)) {
+               /* XXX(nnorwitz): this is really convoluted, is it correct? */
+               PyObject *Zreplacement2 =
+                       _PyUnicode_AsDefaultEncodedString(Zreplacement, NULL);
+               if (Zreplacement2 == NULL)
+                       return NULL;
+               Py_INCREF(Zreplacement2);
+               /* Zreplacement is owned, but Zreplacement2 is borrowed.
+                  If they are different, we have to release Zreplacement. */
+               if (Zreplacement != Zreplacement2) {
                        Py_DECREF(Zreplacement);
-                       Zreplacement = PyObject_CallMethod(temp, "replace",
-                                                          "ss", "%", "%%");
-                       Py_DECREF(temp);
-                       if (Zreplacement == NULL)
-                               return NULL;
-                       if (PyUnicode_Check(Zreplacement)) {
-                               Zreplacement =
-                                       _PyUnicode_AsDefaultEncodedString(
-                                               Zreplacement, NULL);
-                               if (Zreplacement == NULL)
-                                       return NULL;
-                                Py_INCREF(Zreplacement);
-                       }
-                       if (!PyString_Check(Zreplacement)) {
-                               PyErr_SetString(PyExc_TypeError,
-                                 "tzname.replace() did not return a string");
-                               goto Error;
-                       }
                }
-               else
-                       Py_DECREF(temp);
+               Zreplacement = Zreplacement2;
+       }
+       if (!PyString_Check(Zreplacement)) {
+               PyErr_SetString(PyExc_TypeError,
+                               "tzname.replace() did not return a string");
+               goto Error;
        }
        return Zreplacement;