Issue #22117: Fix os.utime(), it now rounds the timestamp towards minus

infinity (-inf) instead of rounding towards zero.

Replace _PyTime_ROUND_DOWN with _PyTime_ROUND_FLOOR.

Misc/NEWS

@@ -30,6 +30,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #22117: Fix os.utime(), it now rounds the timestamp towards minus
+  infinity (-inf) instead of rounding towards zero.
+
 - Issue #14260: The groupindex attribute of regular expression pattern object
   now is non-modifiable mapping.
 

Modules/posixmodule.c

@@ -6127,9 +6127,9 @@ os_utime_impl(PyModuleDef *module, path_t *path, PyObject *times, PyObject *ns,
         }
         utime.now = 0;
         if (_PyTime_ObjectToTimespec(PyTuple_GET_ITEM(times, 0),
-                                     &a_sec, &a_nsec, _PyTime_ROUND_DOWN) == -1 ||
+                                     &a_sec, &a_nsec, _PyTime_ROUND_FLOOR) == -1 ||
             _PyTime_ObjectToTimespec(PyTuple_GET_ITEM(times, 1),
-                                     &m_sec, &m_nsec, _PyTime_ROUND_DOWN) == -1) {
+                                     &m_sec, &m_nsec, _PyTime_ROUND_FLOOR) == -1) {
             goto exit;
         }
         utime.atime_s = a_sec;