Make sure filter() never returns tuple, str or unicode
subclasses. (Discussed in SF patch #665835)
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 2b0c017..92e44d5 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -408,6 +408,29 @@
unicode("345")
)
+ def test_filter_subclasses(self):
+ # test, that filter() never returns tuple, str or unicode subclasses
+ funcs = (None, lambda x: True)
+ class tuple2(tuple):
+ pass
+ class str2(str):
+ pass
+ inputs = {
+ tuple2: [(), (1,2,3)],
+ str2: ["", "123"]
+ }
+ if have_unicode:
+ class unicode2(unicode):
+ pass
+ inputs[unicode2] = [unicode(), unicode("123")]
+
+ for func in funcs:
+ for (cls, inps) in inputs.iteritems():
+ for inp in inps:
+ out = filter(func, cls(inp))
+ self.assertEqual(inp, out)
+ self.assert_(not isinstance(out, cls))
+
def test_float(self):
self.assertEqual(float(3.14), 3.14)
self.assertEqual(float(314), 314.0)
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 2383b4f..b74e09c 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -1838,7 +1838,10 @@
int len = PyTuple_Size(tuple);
if (len == 0) {
- Py_INCREF(tuple);
+ if (PyTuple_CheckExact(tuple))
+ Py_INCREF(tuple);
+ else
+ tuple = PyTuple_New(0);
return tuple;
}
@@ -1895,8 +1898,15 @@
int outlen = len;
if (func == Py_None) {
- /* No character is ever false -- share input string */
- Py_INCREF(strobj);
+ /* No character is ever false -- share input string
+ * (if it's not a subclass) */
+ if (PyString_CheckExact(strobj))
+ Py_INCREF(strobj);
+ else
+ strobj = PyString_FromStringAndSize(
+ PyString_AS_STRING(strobj),
+ len
+ );
return strobj;
}
if ((result = PyString_FromStringAndSize(NULL, len)) == NULL)
@@ -1980,8 +1990,15 @@
int outlen = len;
if (func == Py_None) {
- /* No character is ever false -- share input string */
- Py_INCREF(strobj);
+ /* No character is ever false -- share input string
+ * (it if's not a subclass) */
+ if (PyUnicode_CheckExact(strobj))
+ Py_INCREF(strobj);
+ else
+ strobj = PyUnicode_FromUnicode(
+ PyUnicode_AS_UNICODE(strobj),
+ len
+ );
return strobj;
}
if ((result = PyUnicode_FromUnicode(NULL, len)) == NULL)