bpo-41710: Add _PyTime_AsTimespec_clamp() (GH-28629)

Add the _PyTime_AsTimespec_clamp() function: similar to
_PyTime_AsTimespec(), but clamp to _PyTime_t min/max and don't raise
an exception.

PyThread_acquire_lock_timed() now uses _PyTime_AsTimespec_clamp() to
remove the Py_UNREACHABLE() code path.

* Add _PyTime_AsTime_t() function.
* Add PY_TIME_T_MIN and PY_TIME_T_MAX constants.
* Replace _PyTime_AsTimeval_noraise() with _PyTime_AsTimeval_clamp().
* Add pytime_divide_round_up() function.
* Fix integer overflow in pytime_divide().
* Add pytime_divmod() function.

1 files changed, 1 insertions, 5 deletions

diff --git a/Python/thread_pthread.h b/Python/thread_pthread.h
index a45d842ffe7..7f04151ca91 100644
--- a/Python/thread_pthread.h
+++ b/Python/thread_pthread.h
@@ -481,11 +481,7 @@ PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds,
             }
             else if (dt > 0) {
                 _PyTime_t realtime_deadline = _PyTime_GetSystemClock() + dt;
-                if (_PyTime_AsTimespec(realtime_deadline, &ts) < 0) {
-                    /* Cannot occur thanks to (microseconds > PY_TIMEOUT_MAX)
-                       check done above */
-                    Py_UNREACHABLE();
-                }
+                _PyTime_AsTimespec_clamp(realtime_deadline, &ts);
                 /* no need to update microseconds value, the code only care
                    if (microseconds > 0 or (microseconds == 0). */
             }