Issue #23485: Add _PyTime_FromMillisecondsObject() function

Include/pytime.h

@@ -69,12 +69,18 @@ PyAPI_FUNC(int) _PyTime_ObjectToTimespec(
 /* Create a timestamp from a number of nanoseconds (C long). */
 PyAPI_FUNC(_PyTime_t) _PyTime_FromNanoseconds(PY_LONG_LONG ns);
 
-/* Convert a Python float or int to a timetamp.
+/* Convert a number of seconds (Python float or int) to a timetamp.
    Raise an exception and return -1 on error, return 0 on success. */
 PyAPI_FUNC(int) _PyTime_FromSecondsObject(_PyTime_t *t,
     PyObject *obj,
     _PyTime_round_t round);
 
+/* Convert a number of milliseconds (Python float or int, 10^-3) to a timetamp.
+   Raise an exception and return -1 on error, return 0 on success. */
+PyAPI_FUNC(int) _PyTime_FromMillisecondsObject(_PyTime_t *t,
+    PyObject *obj,
+    _PyTime_round_t round);
+
 /* Convert a timestamp to a number of seconds as a C double. */
 PyAPI_FUNC(double) _PyTime_AsSecondsDouble(_PyTime_t t);
 

Python/pytime.c

@@ -203,8 +203,9 @@ _PyTime_FromTimeval(_PyTime_t *tp, struct timeval *tv, int raise)
 }
 #endif
 
-int
-_PyTime_FromSecondsObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round)
+static int
+_PyTime_FromObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round,
+                   long to_nanoseconds)
 {
     if (PyFloat_Check(obj)) {
         /* volatile avoids unsafe optimization on float enabled by gcc -O3 */
@@ -212,7 +213,7 @@ _PyTime_FromSecondsObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round)
 
         /* convert to a number of nanoseconds */
         d = PyFloat_AsDouble(obj);
-        d *= 1e9;
+        d *= to_nanoseconds;
 
         if (round == _PyTime_ROUND_CEILING)
             d = ceil(d);
@@ -242,8 +243,8 @@ _PyTime_FromSecondsObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round)
                 _PyTime_overflow();
             return -1;
         }
-        *t = sec * SEC_TO_NS;
-        if (*t / SEC_TO_NS != sec) {
+        *t = sec * to_nanoseconds;
+        if (*t / to_nanoseconds != sec) {
             _PyTime_overflow();
             return -1;
         }
@@ -251,6 +252,18 @@ _PyTime_FromSecondsObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round)
     }
 }
 
+int
+_PyTime_FromSecondsObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round)
+{
+    return _PyTime_FromObject(t, obj, round, SEC_TO_NS);
+}
+
+int
+_PyTime_FromMillisecondsObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round)
+{
+    return _PyTime_FromObject(t, obj, round, MS_TO_NS);
+}
+
 double
 _PyTime_AsSecondsDouble(_PyTime_t t)
 {