check for recursive Cursor.__init__ calls

2 files changed, 19 insertions, 0 deletions

diff --git a/extra_tests/test_sqlite3.py b/extra_tests/test_sqlite3.py
index 80eff86c4f..04686f4fee 100644
--- a/extra_tests/test_sqlite3.py
+++ b/extra_tests/test_sqlite3.py
@@ -515,3 +515,19 @@ def test_recursive_fetch():
     finally:
         del _sqlite3.converters['ITER']
 
+def test_recursive_init():
+    conn = _sqlite3.connect(":memory:", detect_types=_sqlite3.PARSE_COLNAMES)
+    cursor = conn.cursor()
+    cursor.execute("create table test(x foo)")
+    cursor.executemany("insert into test(x) values (?)",
+                       [("foo",), ("bar",)])
+    def conv(x):
+        cursor.__init__(conn)
+        return x
+    try:
+        _sqlite3.converters['INIT'] = conv
+        with pytest.raises(_sqlite3.ProgrammingError):
+            cursor.execute(f'select x as "x [INIT]", x from test')
+    finally:
+        del _sqlite3.converters['INIT']
+
diff --git a/lib_pypy/_sqlite3.py b/lib_pypy/_sqlite3.py
index 1d31ff80df..8fb44368fd 100644
--- a/lib_pypy/_sqlite3.py
+++ b/lib_pypy/_sqlite3.py
@@ -778,8 +778,11 @@ class Connection(object):
 class Cursor(object):
     __initialized = False
     __statement = None
+    __locked = False
 
     def __init__(self, con):
+        if self.__locked:
+            raise ProgrammingError("Recursive use of cursors not allowed.")
         if not isinstance(con, Connection):
             raise TypeError
         self.__connection = con