#3720: Interpreter crashes when an evil iterator removes its own next function.

Now the slot is filled with a function that always raises.

Will not backport: extensions compiled with 2.6.x would not run on 2.6.0.

2 files changed, 22 insertions, 53 deletions

diff --git a/Lib/test/crashers/iter.py b/Lib/test/crashers/iter.py
deleted file mode 100644
index 081dcbc..0000000
--- a/Lib/test/crashers/iter.py
+++ /dev/null
@@ -1,53 +0,0 @@
-# Calls to PyIter_Next, or direct calls to tp_iternext, on an object
-# which might no longer be an iterable because its 'next' method was
-# removed.  These are all variants of Issue3720.
-
-"""
-Run this script with an argument between 1 and <N> to test for
-different crashes.
-"""
-N = 8
-
-import sys
-
-class Foo(object):
-    def __iter__(self):
-        return self
-    def next(self):
-        del Foo.next
-        return (1, 2)
-
-def case1():
-    list(enumerate(Foo()))
-
-def case2():
-    x, y = Foo()
-
-def case3():
-    filter(None, Foo())
-
-def case4():
-    map(None, Foo(), Foo())
-
-def case5():
-    max(Foo())
-
-def case6():
-    sum(Foo(), ())
-
-def case7():
-    dict(Foo())
-
-def case8():
-    sys.stdout.writelines(Foo())
-
-# etc...
-
-
-if __name__ == '__main__':
-    if len(sys.argv) < 2:
-        print __doc__.replace('<N>', str(N))
-    else:
-        n = int(sys.argv[1])
-        func = globals()['case%d' % n]
-        func()
diff --git a/Lib/test/test_iter.py b/Lib/test/test_iter.py
index f83de78..e847018 100644
--- a/Lib/test/test_iter.py
+++ b/Lib/test/test_iter.py
@@ -120,6 +120,13 @@ class TestCase(unittest.TestCase):
     def test_seq_class_iter(self):
         self.check_iterator(iter(SequenceClass(10)), range(10))
 
+    # Test a new_style class with __iter__ but no next() method
+    def test_new_style_iter_class(self):
+        class IterClass(object):
+            def __iter__(self):
+                return self
+        self.assertRaises(TypeError, iter, IterClass())
+
     # Test two-argument iter() with callable instance
     def test_iter_callable(self):
         class C:
@@ -877,6 +884,21 @@ class TestCase(unittest.TestCase):
         self.assertEqual(list(b), zip(range(5), range(5)))
         self.assertEqual(list(b), [])
 
+    def test_3720(self):
+        # Avoid a crash, when an iterator deletes its next() method.
+        class BadIterator(object):
+            def __iter__(self):
+                return self
+            def next(self):
+                del BadIterator.next
+                return 1
+
+        try:
+            for i in BadIterator() :
+                pass
+        except TypeError:
+            pass
+
 
 def test_main():
     run_unittest(TestCase)