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, 11 insertions, 5 deletions

diff --git a/Include/cpython/pytime.h b/Include/cpython/pytime.h
index 8c2958501f..04c43ac5d4 100644
--- a/Include/cpython/pytime.h
+++ b/Include/cpython/pytime.h
@@ -16,6 +16,7 @@ extern "C" {
 typedef int64_t _PyTime_t;
 #define _PyTime_MIN INT64_MIN
 #define _PyTime_MAX INT64_MAX
+#define _SIZEOF_PYTIME_T 8
 
 typedef enum {
     /* Round towards minus infinity (-inf).
@@ -136,8 +137,9 @@ PyAPI_FUNC(int) _PyTime_AsTimeval(_PyTime_t t,
     struct timeval *tv,
     _PyTime_round_t round);
 
-/* Similar to _PyTime_AsTimeval(), but don't raise an exception on error. */
-PyAPI_FUNC(int) _PyTime_AsTimeval_noraise(_PyTime_t t,
+/* Similar to _PyTime_AsTimeval() but don't raise an exception on overflow.
+   On overflow, clamp tv_sec to _PyTime_t min/max. */
+PyAPI_FUNC(void) _PyTime_AsTimeval_clamp(_PyTime_t t,
     struct timeval *tv,
     _PyTime_round_t round);
 
@@ -162,6 +164,10 @@ PyAPI_FUNC(int) _PyTime_FromTimespec(_PyTime_t *tp, struct timespec *ts);
    tv_nsec is always positive.
    Raise an exception and return -1 on error, return 0 on success. */
 PyAPI_FUNC(int) _PyTime_AsTimespec(_PyTime_t t, struct timespec *ts);
+
+/* Similar to _PyTime_AsTimespec() but don't raise an exception on overflow.
+   On overflow, clamp tv_sec to _PyTime_t min/max. */
+PyAPI_FUNC(void) _PyTime_AsTimespec_clamp(_PyTime_t t, struct timespec *ts);
 #endif
 
 /* Compute ticks * mul / div.
@@ -181,7 +187,7 @@ typedef struct {
 /* Get the current time from the system clock.
 
    If the internal clock fails, silently ignore the error and return 0.
-   On integer overflow, silently ignore the overflow and truncated the clock to
+   On integer overflow, silently ignore the overflow and clamp the clock to
    _PyTime_MIN or _PyTime_MAX.
 
    Use _PyTime_GetSystemClockWithInfo() to check for failure. */
@@ -201,7 +207,7 @@ PyAPI_FUNC(int) _PyTime_GetSystemClockWithInfo(
    results of consecutive calls is valid.
 
    If the internal clock fails, silently ignore the error and return 0.
-   On integer overflow, silently ignore the overflow and truncated the clock to
+   On integer overflow, silently ignore the overflow and clamp the clock to
    _PyTime_MIN or _PyTime_MAX.
 
    Use _PyTime_GetMonotonicClockWithInfo() to check for failure. */
@@ -232,7 +238,7 @@ PyAPI_FUNC(int) _PyTime_gmtime(time_t t, struct tm *tm);
    measure a short duration.
 
    If the internal clock fails, silently ignore the error and return 0.
-   On integer overflow, silently ignore the overflow and truncated the clock to
+   On integer overflow, silently ignore the overflow and clamp the clock to
    _PyTime_MIN or _PyTime_MAX.
 
    Use _PyTime_GetPerfCounterWithInfo() to check for failure. */