bpo-31577: Fix a crash in os.utime() in case of a bad ns argument. (GH-3752)

(cherry picked from commit 0bd1a2dcfdf36b181385ae61361e7692f4ebb0fd)

Co-authored-by: Oren Milman <orenmn@gmail.com>
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index a140ae0..79ddc48 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -635,6 +635,22 @@
         with self.assertRaises(ValueError):
             os.utime(self.fname, (5, 5), ns=(5, 5))
 
+    @support.cpython_only
+    def test_issue31577(self):
+        # The interpreter shouldn't crash in case utime() received a bad
+        # ns argument.
+        def get_bad_int(divmod_ret_val):
+            class BadInt:
+                def __divmod__(*args):
+                    return divmod_ret_val
+            return BadInt()
+        with self.assertRaises(TypeError):
+            os.utime(self.fname, ns=(get_bad_int(42), 1))
+        with self.assertRaises(TypeError):
+            os.utime(self.fname, ns=(get_bad_int(()), 1))
+        with self.assertRaises(TypeError):
+            os.utime(self.fname, ns=(get_bad_int((1, 2, 3)), 1))
+
 
 from test import mapping_tests