Raise DEFAULT_RECURSE_LIMIT from 511 to 1024 (#676)

msgpack/_packer.pyx

@@ -38,7 +38,7 @@ cdef extern from "pack.h":
     int msgpack_pack_timestamp(msgpack_packer* x, long long seconds, unsigned long nanoseconds) except -1
 
 
-cdef int DEFAULT_RECURSE_LIMIT=511
+cdef int DEFAULT_RECURSE_LIMIT=1024
 cdef long long ITEM_LIMIT = (2**32)-1
 
 

msgpack/fallback.py

@@ -52,7 +52,7 @@ TYPE_RAW = 3
 TYPE_BIN = 4
 TYPE_EXT = 5
 
-DEFAULT_RECURSE_LIMIT = 511
+DEFAULT_RECURSE_LIMIT = 1024
 
 
 def _check_type_strict(obj, t, type=type, tuple=tuple):

test/test_limits.py

@@ -153,6 +153,30 @@ def test_auto_max_array_len():
         unpacker.unpack()
 
 
+def test_nest_limit_1024():
+    import sys
+
+    # Build a list nested 1024 levels deep
+    d = None
+    for _ in range(1024):
+        d = [d]
+
+    # Temporarily raise Python's recursion limit so packing 1024 levels succeeds
+    old_limit = sys.getrecursionlimit()
+    sys.setrecursionlimit(max(old_limit, 10000))
+    try:
+        packed = packb(d)
+        result = unpackb(packed)
+    finally:
+        sys.setrecursionlimit(old_limit)
+
+    # Verify structure iteratively to avoid hitting C-level recursion limit in ==
+    for _ in range(1024):
+        assert isinstance(result, list) and len(result) == 1
+        result = result[0]
+    assert result is None
+
+
 def test_auto_max_map_len():
     # len(packed) == 6 -> max_map_len == 3
     packed = b"\xde\x00\x04zzz"