Issue #6697: Fixed instances of _PyUnicode_AsString() result not checked for NULL

13 files changed, 145 insertions, 79 deletions

diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py
index 48e5095..dddf0f8 100644
--- a/Lib/test/datetimetester.py
+++ b/Lib/test/datetimetester.py
@@ -2508,11 +2508,17 @@ class TestTimeTZ(TestTime, TZInfoBase, unittest.TestCase):
 
         # Check that an invalid tzname result raises an exception.
         class Badtzname(tzinfo):
-            def tzname(self, dt): return 42
+            tz = 42
+            def tzname(self, dt): return self.tz
         t = time(2, 3, 4, tzinfo=Badtzname())
         self.assertEqual(t.strftime("%H:%M:%S"), "02:03:04")
         self.assertRaises(TypeError, t.strftime, "%Z")
 
+        # Issue #6697:
+        if '_Fast' in str(type(self)):
+            Badtzname.tz = '\ud800'
+            self.assertRaises(ValueError, t.strftime, "%Z")
+
     def test_hash_edge_cases(self):
         # Offsets that overflow a basic time.
         t1 = self.theclass(0, 1, 2, 3, tzinfo=FixedOffset(1439, ""))
diff --git a/Lib/test/test_pyexpat.py b/Lib/test/test_pyexpat.py
index 5a193bb..5bb8c97 100644
--- a/Lib/test/test_pyexpat.py
+++ b/Lib/test/test_pyexpat.py
@@ -203,6 +203,8 @@ class ParseTest(unittest.TestCase):
 
         operations = out.out
         self._verify_parse_output(operations)
+        # Issue #6697.
+        self.assertRaises(AttributeError, getattr, parser, '\uD800')
 
     def test_parse_file(self):
         # Try parsing a file
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 32084da..6bdb6c9 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -667,6 +667,8 @@ class GeneralModuleTests(unittest.TestCase):
                                type=socket.SOCK_STREAM, proto=0,
                                flags=socket.AI_PASSIVE)
         self.assertEqual(a, b)
+        # Issue #6697.
+        self.assertRaises(UnicodeEncodeError, socket.getaddrinfo, 'localhost', '\uD800')
 
     def test_getnameinfo(self):
         # only IP addresses are allowed
diff --git a/Lib/test/test_syslog.py b/Lib/test/test_syslog.py
index 028dcb4..4e7621e5 100644
--- a/Lib/test/test_syslog.py
+++ b/Lib/test/test_syslog.py
@@ -11,6 +11,8 @@ class Test(unittest.TestCase):
 
     def test_openlog(self):
         syslog.openlog('python')
+        # Issue #6697.
+        self.assertRaises(UnicodeEncodeError, syslog.openlog, '\uD800')
 
     def test_syslog(self):
         syslog.openlog('python')
diff --git a/Lib/test/test_xml_etree_c.py b/Lib/test/test_xml_etree_c.py
index ee270f9..5c0bf6c 100644
--- a/Lib/test/test_xml_etree_c.py
+++ b/Lib/test/test_xml_etree_c.py
@@ -8,10 +8,26 @@ cET = support.import_module('xml.etree.cElementTree')
 # cElementTree specific tests
 
 def sanity():
-    """
+    r"""
     Import sanity.
 
     >>> from xml.etree import cElementTree
+
+    Issue #6697.
+
+    >>> e = cElementTree.Element('a')
+    >>> getattr(e, '\uD800')           # doctest: +ELLIPSIS
+    Traceback (most recent call last):
+      ...
+    UnicodeEncodeError: ...
+
+    >>> p = cElementTree.XMLParser()
+    >>> p.version.split()[0]
+    'Expat'
+    >>> getattr(p, '\uD800')
+    Traceback (most recent call last):
+     ...
+    AttributeError: 'XMLParser' object has no attribute '\ud800'
     """
 
 
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 32fe835..16964d8 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -1257,7 +1257,8 @@ wrap_strftime(PyObject *object, PyObject *format, PyObject *timetuple,
             assert(PyUnicode_Check(Zreplacement));
             ptoappend = _PyUnicode_AsStringAndSize(Zreplacement,
                                                   &ntoappend);
-            ntoappend = Py_SIZE(Zreplacement);
+            if (ptoappend == NULL)
+                goto Done;
         }
         else if (ch == 'f') {
             /* format microseconds */
diff --git a/Modules/_elementtree.c b/Modules/_elementtree.c
index 4fed46e..3061d8e 100644
--- a/Modules/_elementtree.c
+++ b/Modules/_elementtree.c
@@ -1483,6 +1483,9 @@ element_getattro(ElementObject* self, PyObject* nameobj)
 
     if (PyUnicode_Check(nameobj))
         name = _PyUnicode_AsString(nameobj);
+    
+    if (name == NULL)
+        return NULL;
 
     /* handle common attributes first */
     if (strcmp(name, "tag") == 0) {
@@ -2139,7 +2142,7 @@ expat_set_error(const char* message, int line, int column)
     PyObject *position;
     char buffer[256];
 
-    sprintf(buffer, "%s: line %d, column %d", message, line, column);
+    sprintf(buffer, "%.100s: line %d, column %d", message, line, column);
 
     error = PyObject_CallFunction(elementtree_parseerror_obj, "s", buffer);
     if (!error)
@@ -2194,8 +2197,8 @@ expat_default_handler(XMLParserObject* self, const XML_Char* data_in,
         Py_XDECREF(res);
     } else if (!PyErr_Occurred()) {
         /* Report the first error, not the last */
-        char message[128];
-        sprintf(message, "undefined entity &%.100s;", _PyUnicode_AsString(key));
+        char message[128] = "undefined entity ";
+        strncat(message, data_in, data_len < 100?data_len:100);
         expat_set_error(
             message,
             EXPAT(GetErrorLineNumber)(self->parser),
@@ -2796,29 +2799,25 @@ static PyMethodDef xmlparser_methods[] = {
 static PyObject*  
 xmlparser_getattro(XMLParserObject* self, PyObject* nameobj)
 {
-    PyObject* res;
-    char *name = "";
-
-    if (PyUnicode_Check(nameobj))
-        name = _PyUnicode_AsString(nameobj);
-
-    PyErr_Clear();
-
-    if (strcmp(name, "entity") == 0)
-        res = self->entity;
-    else if (strcmp(name, "target") == 0)
-        res = self->target;
-    else if (strcmp(name, "version") == 0) {
-        char buffer[100];
-        sprintf(buffer, "Expat %d.%d.%d", XML_MAJOR_VERSION,
+    if (PyUnicode_Check(nameobj)) {
+        PyObject* res;
+        if (PyUnicode_CompareWithASCIIString(nameobj, "entity") == 0)
+            res = self->entity;
+        else if (PyUnicode_CompareWithASCIIString(nameobj, "target") == 0)
+            res = self->target;
+        else if (PyUnicode_CompareWithASCIIString(nameobj, "version") == 0) {
+            return PyUnicode_FromFormat(
+                "Expat %d.%d.%d", XML_MAJOR_VERSION,
                 XML_MINOR_VERSION, XML_MICRO_VERSION);
-        return PyUnicode_DecodeUTF8(buffer, strlen(buffer), "strict");
-    } else {
-        return PyObject_GenericGetAttr((PyObject*) self, nameobj);
-    }
+        }
+        else
+            goto generic;
 
-    Py_INCREF(res);
-    return res;
+        Py_INCREF(res);
+        return res;
+    }
+  generic:
+    return PyObject_GenericGetAttr((PyObject*) self, nameobj);
 }
 
 static PyTypeObject XMLParser_Type = {
diff --git a/Modules/_lsprof.c b/Modules/_lsprof.c
index 048cfc8..cc412bf 100644
--- a/Modules/_lsprof.c
+++ b/Modules/_lsprof.c
@@ -178,7 +178,16 @@ normalizeUserObj(PyObject *obj)
         PyObject *mod = fn->m_module;
         const char *modname;
         if (mod && PyUnicode_Check(mod)) {
+            /* XXX: The following will truncate module names with embedded
+             * null-characters.  It is unlikely that this can happen in
+             * practice and the concequences are not serious enough to
+             * introduce extra checks here.
+             */
             modname = _PyUnicode_AsString(mod);
+            if (modname == NULL) {
+                modname = "<encoding error>";
+                PyErr_Clear();
+            }
         }
         else if (mod && PyModule_Check(mod)) {
             modname = PyModule_GetName(mod);
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 42d0bcd..f0c07ae 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -1741,15 +1741,16 @@ test_string_from_format(PyObject *self, PyObject *args)
 {
     PyObject *result;
     char *msg;
-
-#define CHECK_1_FORMAT(FORMAT, TYPE)                    \
-    result = PyUnicode_FromFormat(FORMAT, (TYPE)1);     \
-    if (result == NULL)                                 \
-        return NULL;                                    \
-    if (strcmp(_PyUnicode_AsString(result), "1")) {     \
-        msg = FORMAT " failed at 1";                    \
-        goto Fail;                                      \
-    }                                                   \
+    static const Py_UNICODE one[] = {'1', 0};
+
+#define CHECK_1_FORMAT(FORMAT, TYPE)                                \
+    result = PyUnicode_FromFormat(FORMAT, (TYPE)1);                 \
+    if (result == NULL)                                             \
+        return NULL;                                                \
+    if (Py_UNICODE_strcmp(PyUnicode_AS_UNICODE(result), one)) {     \
+        msg = FORMAT " failed at 1";                                \
+        goto Fail;                                                  \
+    }                                                               \
     Py_DECREF(result)
 
     CHECK_1_FORMAT("%d", int);
diff --git a/Modules/parsermodule.c b/Modules/parsermodule.c
index 27b680f..e959321 100644
--- a/Modules/parsermodule.c
+++ b/Modules/parsermodule.c
@@ -792,6 +792,11 @@ build_node_children(PyObject *tuple, node *root, int *line_num)
                 }
             }
             temp_str = _PyUnicode_AsStringAndSize(temp, &len);
+            if (temp_str == NULL) {
+                Py_DECREF(temp);
+                Py_XDECREF(elem);
+                return 0;
+            }
             strn = (char *)PyObject_MALLOC(len + 1);
             if (strn != NULL)
                 (void) memcpy(strn, temp_str, len + 1);
@@ -870,6 +875,8 @@ build_node_tree(PyObject *tuple)
             encoding = PySequence_GetItem(tuple, 2);
             /* tuple isn't borrowed anymore here, need to DECREF */
             tuple = PySequence_GetSlice(tuple, 0, 2);
+            if (tuple == NULL)
+                return NULL;
         }
         res = PyNode_New(num);
         if (res != NULL) {
@@ -881,6 +888,12 @@ build_node_tree(PyObject *tuple)
                 Py_ssize_t len;
                 const char *temp;
                 temp = _PyUnicode_AsStringAndSize(encoding, &len);
+                if (temp == NULL) {
+                    Py_DECREF(res);
+                    Py_DECREF(encoding);
+                    Py_DECREF(tuple);
+                    return NULL;
+                }
                 res->n_str = (char *)PyObject_MALLOC(len + 1);
                 if (res->n_str != NULL && temp != NULL)
                     (void) memcpy(res->n_str, temp, len + 1);
diff --git a/Modules/pyexpat.c b/Modules/pyexpat.c
index 5aadcc0..1a00347 100644
--- a/Modules/pyexpat.c
+++ b/Modules/pyexpat.c
@@ -1215,11 +1215,12 @@ xmlparse_dealloc(xmlparseobject *self)
 }
 
 static int
-handlername2int(const char *name)
+handlername2int(PyObject *name)
 {
     int i;
     for (i = 0; handler_info[i].name != NULL; i++) {
-        if (strcmp(name, handler_info[i].name) == 0) {
+        if (PyUnicode_CompareWithASCIIString(
+                name, handler_info[i].name) == 0) {
             return i;
         }
     }
@@ -1237,13 +1238,13 @@ get_pybool(int istrue)
 static PyObject *
 xmlparse_getattro(xmlparseobject *self, PyObject *nameobj)
 {
-    char *name = "";
+    Py_UNICODE *name;
     int handlernum = -1;
 
-    if (PyUnicode_Check(nameobj))
-        name = _PyUnicode_AsString(nameobj);
+    if (!PyUnicode_Check(nameobj))
+        goto generic;
 
-    handlernum = handlername2int(name);
+    handlernum = handlername2int(nameobj);
 
     if (handlernum != -1) {
         PyObject *result = self->handlers[handlernum];
@@ -1252,46 +1253,48 @@ xmlparse_getattro(xmlparseobject *self, PyObject *nameobj)
         Py_INCREF(result);
         return result;
     }
+
+    name = PyUnicode_AS_UNICODE(nameobj);
     if (name[0] == 'E') {
-        if (strcmp(name, "ErrorCode") == 0)
+        if (PyUnicode_CompareWithASCIIString(nameobj, "ErrorCode") == 0)
             return PyLong_FromLong((long)
                                   XML_GetErrorCode(self->itself));
-        if (strcmp(name, "ErrorLineNumber") == 0)
+        if (PyUnicode_CompareWithASCIIString(nameobj, "ErrorLineNumber") == 0)
             return PyLong_FromLong((long)
                                   XML_GetErrorLineNumber(self->itself));
-        if (strcmp(name, "ErrorColumnNumber") == 0)
+        if (PyUnicode_CompareWithASCIIString(nameobj, "ErrorColumnNumber") == 0)
             return PyLong_FromLong((long)
                                   XML_GetErrorColumnNumber(self->itself));
-        if (strcmp(name, "ErrorByteIndex") == 0)
+        if (PyUnicode_CompareWithASCIIString(nameobj, "ErrorByteIndex") == 0)
             return PyLong_FromLong((long)
                                   XML_GetErrorByteIndex(self->itself));
     }
     if (name[0] == 'C') {
-        if (strcmp(name, "CurrentLineNumber") == 0)
+        if (PyUnicode_CompareWithASCIIString(nameobj, "CurrentLineNumber") == 0)
             return PyLong_FromLong((long)
                                   XML_GetCurrentLineNumber(self->itself));
-        if (strcmp(name, "CurrentColumnNumber") == 0)
+        if (PyUnicode_CompareWithASCIIString(nameobj, "CurrentColumnNumber") == 0)
             return PyLong_FromLong((long)
                                   XML_GetCurrentColumnNumber(self->itself));
-        if (strcmp(name, "CurrentByteIndex") == 0)
+        if (PyUnicode_CompareWithASCIIString(nameobj, "CurrentByteIndex") == 0)
             return PyLong_FromLong((long)
                                   XML_GetCurrentByteIndex(self->itself));
     }
     if (name[0] == 'b') {
-        if (strcmp(name, "buffer_size") == 0)
+        if (PyUnicode_CompareWithASCIIString(nameobj, "buffer_size") == 0)
             return PyLong_FromLong((long) self->buffer_size);
-        if (strcmp(name, "buffer_text") == 0)
+        if (PyUnicode_CompareWithASCIIString(nameobj, "buffer_text") == 0)
             return get_pybool(self->buffer != NULL);
-        if (strcmp(name, "buffer_used") == 0)
+        if (PyUnicode_CompareWithASCIIString(nameobj, "buffer_used") == 0)
             return PyLong_FromLong((long) self->buffer_used);
     }
-    if (strcmp(name, "namespace_prefixes") == 0)
+    if (PyUnicode_CompareWithASCIIString(nameobj, "namespace_prefixes") == 0)
         return get_pybool(self->ns_prefixes);
-    if (strcmp(name, "ordered_attributes") == 0)
+    if (PyUnicode_CompareWithASCIIString(nameobj, "ordered_attributes") == 0)
         return get_pybool(self->ordered_attributes);
-    if (strcmp(name, "specified_attributes") == 0)
+    if (PyUnicode_CompareWithASCIIString(nameobj, "specified_attributes") == 0)
         return get_pybool((long) self->specified_attributes);
-    if (strcmp(name, "intern") == 0) {
+    if (PyUnicode_CompareWithASCIIString(nameobj, "intern") == 0) {
         if (self->intern == NULL) {
             Py_INCREF(Py_None);
             return Py_None;
@@ -1301,7 +1304,7 @@ xmlparse_getattro(xmlparseobject *self, PyObject *nameobj)
             return self->intern;
         }
     }
-
+  generic:
     return PyObject_GenericGetAttr((PyObject*)self, nameobj);
 }
 
@@ -1352,7 +1355,7 @@ xmlparse_dir(PyObject *self, PyObject* noargs)
 }
 
 static int
-sethandler(xmlparseobject *self, const char *name, PyObject* v)
+sethandler(xmlparseobject *self, PyObject *name, PyObject* v)
 {
     int handlernum = handlername2int(name);
     if (handlernum >= 0) {
@@ -1388,14 +1391,15 @@ sethandler(xmlparseobject *self, const char *name, PyObject* v)
 }
 
 static int
-xmlparse_setattr(xmlparseobject *self, char *name, PyObject *v)
+xmlparse_setattro(xmlparseobject *self, PyObject *name, PyObject *v)
 {
     /* Set attribute 'name' to value 'v'. v==NULL means delete */
     if (v == NULL) {
         PyErr_SetString(PyExc_RuntimeError, "Cannot delete attribute");
         return -1;
     }
-    if (strcmp(name, "buffer_text") == 0) {
+    assert(PyUnicode_Check(name));
+    if (PyUnicode_CompareWithASCIIString(name, "buffer_text") == 0) {
         if (PyObject_IsTrue(v)) {
             if (self->buffer == NULL) {
                 self->buffer = malloc(self->buffer_size);
@@ -1414,7 +1418,7 @@ xmlparse_setattr(xmlparseobject *self, char *name, PyObject *v)
         }
         return 0;
     }
-    if (strcmp(name, "namespace_prefixes") == 0) {
+    if (PyUnicode_CompareWithASCIIString(name, "namespace_prefixes") == 0) {
         if (PyObject_IsTrue(v))
             self->ns_prefixes = 1;
         else
@@ -1422,14 +1426,14 @@ xmlparse_setattr(xmlparseobject *self, char *name, PyObject *v)
         XML_SetReturnNSTriplet(self->itself, self->ns_prefixes);
         return 0;
     }
-    if (strcmp(name, "ordered_attributes") == 0) {
+    if (PyUnicode_CompareWithASCIIString(name, "ordered_attributes") == 0) {
         if (PyObject_IsTrue(v))
             self->ordered_attributes = 1;
         else
             self->ordered_attributes = 0;
         return 0;
     }
-    if (strcmp(name, "specified_attributes") == 0) {
+    if (PyUnicode_CompareWithASCIIString(name, "specified_attributes") == 0) {
         if (PyObject_IsTrue(v))
             self->specified_attributes = 1;
         else
@@ -1437,7 +1441,7 @@ xmlparse_setattr(xmlparseobject *self, char *name, PyObject *v)
         return 0;
     }
 
-    if (strcmp(name, "buffer_size") == 0) {
+    if (PyUnicode_CompareWithASCIIString(name, "buffer_size") == 0) {
       long new_buffer_size;
       if (!PyLong_Check(v)) {
         PyErr_SetString(PyExc_TypeError, "buffer_size must be an integer");
@@ -1480,7 +1484,7 @@ xmlparse_setattr(xmlparseobject *self, char *name, PyObject *v)
       return 0;
     }
 
-    if (strcmp(name, "CharacterDataHandler") == 0) {
+    if (PyUnicode_CompareWithASCIIString(name, "CharacterDataHandler") == 0) {
         /* If we're changing the character data handler, flush all
          * cached data with the old handler.  Not sure there's a
          * "right" thing to do, though, but this probably won't
@@ -1492,7 +1496,7 @@ xmlparse_setattr(xmlparseobject *self, char *name, PyObject *v)
     if (sethandler(self, name, v)) {
         return 0;
     }
-    PyErr_SetString(PyExc_AttributeError, name);
+    PyErr_SetObject(PyExc_AttributeError, name);
     return -1;
 }
 
@@ -1524,7 +1528,7 @@ static PyTypeObject Xmlparsetype = {
         (destructor)xmlparse_dealloc,   /*tp_dealloc*/
         (printfunc)0,           /*tp_print*/
         0,                      /*tp_getattr*/
-        (setattrfunc)xmlparse_setattr,  /*tp_setattr*/
+        0,  /*tp_setattr*/
         0,                      /*tp_reserved*/
         (reprfunc)0,            /*tp_repr*/
         0,                      /*tp_as_number*/
@@ -1534,7 +1538,7 @@ static PyTypeObject Xmlparsetype = {
         (ternaryfunc)0,         /*tp_call*/
         (reprfunc)0,            /*tp_str*/
         (getattrofunc)xmlparse_getattro, /* tp_getattro */
-        0,              /* tp_setattro */
+        (setattrofunc)xmlparse_setattro,              /* tp_setattro */
         0,              /* tp_as_buffer */
         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /*tp_flags*/
         Xmlparsetype__doc__, /* tp_doc - Documentation string */
diff --git a/Modules/socketmodule.c b/Modules/socketmodule.c
index abdd1b2..327e470 100644
--- a/Modules/socketmodule.c
+++ b/Modules/socketmodule.c
@@ -1406,9 +1406,9 @@ getsockaddrarg(PySocketSockObject *s, PyObject *args,
         {
             struct sockaddr_hci *addr = (struct sockaddr_hci *)addr_ret;
 #if defined(__NetBSD__) || defined(__DragonFly__)
-			char *straddr = PyBytes_AS_STRING(args);
+                        char *straddr = PyBytes_AS_STRING(args);
 
-			_BT_HCI_MEMB(addr, family) = AF_BLUETOOTH;
+                        _BT_HCI_MEMB(addr, family) = AF_BLUETOOTH;
             if (straddr == NULL) {
                 PyErr_SetString(socket_error, "getsockaddrarg: "
                     "wrong format");
@@ -4022,8 +4022,10 @@ socket_getaddrinfo(PyObject *self, PyObject *args, PyObject* kwargs)
         pptr = pbuf;
     } else if (PyUnicode_Check(pobj)) {
         pptr = _PyUnicode_AsString(pobj);
+        if (pptr == NULL)
+            goto err;
     } else if (PyBytes_Check(pobj)) {
-        pptr = PyBytes_AsString(pobj);
+        pptr = PyBytes_AS_STRING(pobj);
     } else if (pobj == Py_None) {
         pptr = (char *)NULL;
     } else {
diff --git a/Modules/syslogmodule.c b/Modules/syslogmodule.c
index 1842dc9..5b86963 100644
--- a/Modules/syslogmodule.c
+++ b/Modules/syslogmodule.c
@@ -68,9 +68,9 @@ syslog_get_argv(void)
      * is optional.
      */
 
-    Py_ssize_t argv_len;
+    Py_ssize_t argv_len, scriptlen;
     PyObject *scriptobj;
-    char *atslash;
+    Py_UNICODE *atslash, *atstart;
     PyObject *argv = PySys_GetObject("argv");
 
     if (argv == NULL) {
@@ -90,13 +90,16 @@ syslog_get_argv(void)
     if (!PyUnicode_Check(scriptobj)) {
         return(NULL);
     }
-    if (PyUnicode_GET_SIZE(scriptobj) == 0) {
+    scriptlen = PyUnicode_GET_SIZE(scriptobj);
+    if (scriptlen == 0) {
         return(NULL);
     }
 
-    atslash = strrchr(_PyUnicode_AsString(scriptobj), SEP);
+    atstart = PyUnicode_AS_UNICODE(scriptobj);
+    atslash = Py_UNICODE_strrchr(atstart, SEP);
     if (atslash) {
-        return(PyUnicode_FromString(atslash + 1));
+        return(PyUnicode_FromUnicode(atslash + 1,
+                                     scriptlen - (atslash - atstart) - 1));
     } else {
         Py_INCREF(scriptobj);
         return(scriptobj);
@@ -113,6 +116,7 @@ syslog_openlog(PyObject * self, PyObject * args, PyObject *kwds)
     long facility = LOG_USER;
     PyObject *new_S_ident_o = NULL;
     static char *keywords[] = {"ident", "logoption", "facility", 0};
+    char *ident = NULL;
 
     if (!PyArg_ParseTupleAndKeywords(args, kwds,
                           "|Ull:openlog", keywords, &new_S_ident_o, &logopt, &facility))
@@ -120,12 +124,12 @@ syslog_openlog(PyObject * self, PyObject * args, PyObject *kwds)
 
     if (new_S_ident_o) {
         Py_INCREF(new_S_ident_o);
-        }
+    }
 
     /*  get sys.argv[0] or NULL if we can't for some reason  */
     if (!new_S_ident_o) {
         new_S_ident_o = syslog_get_argv();
-        }
+    }
 
     Py_XDECREF(S_ident_o);
     S_ident_o = new_S_ident_o;
@@ -134,8 +138,13 @@ syslog_openlog(PyObject * self, PyObject * args, PyObject *kwds)
      * make a copy, and syslog(3) later uses it.  We can't garbagecollect it
      * If NULL, just let openlog figure it out (probably using C argv[0]).
      */
+    if (S_ident_o) {
+        ident = _PyUnicode_AsString(S_ident_o);
+        if (ident == NULL)
+            return NULL;
+    }
 
-    openlog(S_ident_o ? _PyUnicode_AsString(S_ident_o) : NULL, logopt, facility);
+    openlog(ident, logopt, facility);
     S_log_open = 1;
 
     Py_INCREF(Py_None);