bpo-35714: Reject null characters in struct format strings (GH-16928)

struct.error is now raised if there is a null character in a struct
format string.

1 files changed, 8 insertions, 0 deletions

diff --git a/Lib/test/test_struct.py b/Lib/test/test_struct.py
index 4829fbe..b3f21ea 100644
--- a/Lib/test/test_struct.py
+++ b/Lib/test/test_struct.py
@@ -671,6 +671,14 @@ class StructTest(unittest.TestCase):
         self.assertIn(b"Exception ignored in:", stderr)
         self.assertIn(b"C.__del__", stderr)
 
+    def test_issue35714(self):
+        # Embedded null characters should not be allowed in format strings.
+        for s in '\0', '2\0i', b'\0':
+            with self.assertRaisesRegex(struct.error,
+                                        'embedded null character'):
+                struct.calcsize(s)
+
+
 class UnpackIteratorTest(unittest.TestCase):
     """
     Tests for iterative unpacking (struct.Struct.iter_unpack).