Demonstrate a bug

hexagonrecursion · hexagonrecursion · commit aaf6ed37f1aa · 2021-02-26T09:53:50.000+03:00
diff --git a/test/test_discrepancy.py b/test/test_discrepancy.py
@@ -0,0 +1,25 @@
+import io
+from pytest import raises, mark
+
+try:
+    from msgpack import _cmsgpack
+except ImportError:
+    _cmsgpack = None
+
+
+@mark.skipif(_cmsgpack is None, reason="C extension not awailable")
+@mark.parametrize("use_unpack", [True, False])
+def test_exceed_max_buffer_size(use_unpack):
+    """The C extension used to have a bug: when reading objects that require
+    a buffer bigger than max_buffer_size it would behave as if there is not
+    enough data"""
+    buffer_size = 11
+    max_buffer_size = 10
+    f = io.BytesIO(b"\xc6" + buffer_size.to_bytes(4, "big") + b"z" * buffer_size)
+    u = _cmsgpack.Unpacker(f, max_buffer_size=max_buffer_size)
+
+    with raises(ValueError):
+        if use_unpack:
+            u.unpack()
+        else:
+            next(u)
