issue 2045: Infinite recursion when printing a subclass of defaultdict,

if default_factory is set to a bound method.

Will backport.

diff --git a/Lib/test/test_defaultdict.py b/Lib/test/test_defaultdict.py
index 6108840e7f0df4cff0e42a1189df601596949e95..5935e052f9ab1b1c59dcb7afcac9fc1dc4ab049e 100644 (file)
--- a/Lib/test/test_defaultdict.py
+++ b/Lib/test/test_defaultdict.py
@@ -141,6 +141,29 @@ class TestDefaultDict(unittest.TestCase):
         else:
             self.fail("expected KeyError")
 
+    def test_recursive_repr(self):
+        # Issue2045: stack overflow when default_factory is a bound method
+        class sub(defaultdict):
+            def __init__(self):
+                self.default_factory = self._factory
+            def _factory(self):
+                return []
+        d = sub()
+        self.assert_(repr(d).startswith(
+            "defaultdict(<bound method sub._factory of defaultdict(..."))
+
+        # NOTE: printing a subclass of a builtin type does not call its
+        # tp_print slot. So this part is essentially the same test as above.
+        tfn = tempfile.mktemp()
+        try:
+            f = open(tfn, "w+")
+            try:
+                print >>f, d
+            finally:
+                f.close()
+        finally:
+            os.remove(tfn)
+
 
 def test_main():
     test_support.run_unittest(TestDefaultDict)

diff --git a/Misc/NEWS b/Misc/NEWS
index af9f36452c7cc804db09ec1933892f336c6ac8d1..7975cbb32739d8f93d0601e7dd72967f8311a9d0 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,9 @@ What's New in Python 2.6 alpha 1?
 Core and builtins
 -----------------
 
+- Issue #2045: Fix an infinite recursion triggered when printing a subclass of
+  collections.defaultdict, if its default_factory is set to a bound method.
+
 - Fixed a minor memory leak in dictobject.c. The content of the free
   list was not freed on interpreter shutdown.
 

diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index 05b03b7c550b671797e147349ff2540970843d62..67700de72858f80225b145be00c2b76668b41d10 100644 (file)
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -1300,7 +1300,17 @@ defdict_repr(defdictobject *dd)
        if (dd->default_factory == NULL)
                defrepr = PyString_FromString("None");
        else
-               defrepr = PyObject_Repr(dd->default_factory);
+       {
+               int status = Py_ReprEnter(dd->default_factory);
+               if (status != 0) {
+                       if (status < 0)
+                               return NULL;
+                       defrepr = PyString_FromString("...");
+               }
+               else
+                       defrepr = PyObject_Repr(dd->default_factory);
+               Py_ReprLeave(dd->default_factory);
+       }
        if (defrepr == NULL) {
                Py_DECREF(baserepr);
                return NULL;