1 files changed, 189 insertions, 118 deletions

diff --git a/Python/pytime.c b/Python/pytime.c
index 77db204489..9d0b0fafe1 100644
--- a/Python/pytime.c
+++ b/Python/pytime.c
@@ -7,6 +7,11 @@
 #include <mach/mach_time.h>   /* mach_absolute_time(), mach_timebase_info() */
 #endif
 
+#define _PyTime_check_mul_overflow(a, b) \
+    (assert(b > 0), \
+     (_PyTime_t)(a) < _PyTime_MIN / (_PyTime_t)(b) \
+     || _PyTime_MAX / (_PyTime_t)(b) < (_PyTime_t)(a))
+
 /* To millisecond (10^-3) */
 #define SEC_TO_MS 1000
 
@@ -60,50 +65,83 @@ _PyLong_FromTime_t(time_t t)
 #endif
 }
 
+/* Round to nearest with ties going to nearest even integer
+   (_PyTime_ROUND_HALF_EVEN) */
+static double
+_PyTime_RoundHalfEven(double x)
+{
+    double rounded = round(x);
+    if (fabs(x-rounded) == 0.5)
+        /* halfway case: round to even */
+        rounded = 2.0*round(x/2.0);
+    return rounded;
+}
+
+static double
+_PyTime_Round(double x, _PyTime_round_t round)
+{
+    /* volatile avoids optimization changing how numbers are rounded */
+    volatile double d;
+
+    d = x;
+    if (round == _PyTime_ROUND_HALF_EVEN)
+        d = _PyTime_RoundHalfEven(d);
+    else if (round == _PyTime_ROUND_CEILING)
+        d = ceil(d);
+    else
+        d = floor(d);
+    return d;
+}
+
 static int
-_PyTime_ObjectToDenominator(PyObject *obj, time_t *sec, long *numerator,
+_PyTime_DoubleToDenominator(double d, time_t *sec, long *numerator,
                             double denominator, _PyTime_round_t round)
 {
-    assert(denominator <= LONG_MAX);
-    if (PyFloat_Check(obj)) {
-        double d, intpart, err;
-        /* volatile avoids unsafe optimization on float enabled by gcc -O3 */
-        volatile double floatpart;
+    double intpart, err;
+    /* volatile avoids optimization changing how numbers are rounded */
+    volatile double floatpart;
 
-        d = PyFloat_AsDouble(obj);
-        floatpart = modf(d, &intpart);
-        if (floatpart < 0) {
-            floatpart = 1.0 + floatpart;
-            intpart -= 1.0;
-        }
+    floatpart = modf(d, &intpart);
 
-        floatpart *= denominator;
-        if (round == _PyTime_ROUND_CEILING) {
-            floatpart = ceil(floatpart);
-            if (floatpart >= denominator) {
-                floatpart = 0.0;
-                intpart += 1.0;
-            }
-        }
-        else {
-            floatpart = floor(floatpart);
-        }
+    floatpart *= denominator;
+    floatpart = _PyTime_Round(floatpart, round);
+    if (floatpart >= denominator) {
+        floatpart -= denominator;
+        intpart += 1.0;
+    }
+    else if (floatpart < 0) {
+        floatpart += denominator;
+        intpart -= 1.0;
+    }
+    assert(0.0 <= floatpart && floatpart < denominator);
 
-        *sec = (time_t)intpart;
-        err = intpart - (double)*sec;
-        if (err <= -1.0 || err >= 1.0) {
-            error_time_t_overflow();
-            return -1;
-        }
+    *sec = (time_t)intpart;
+    *numerator = (long)floatpart;
 
-        *numerator = (long)floatpart;
-        return 0;
+    err = intpart - (double)*sec;
+    if (err <= -1.0 || err >= 1.0) {
+        error_time_t_overflow();
+        return -1;
+    }
+    return 0;
+}
+
+static int
+_PyTime_ObjectToDenominator(PyObject *obj, time_t *sec, long *numerator,
+                            double denominator, _PyTime_round_t round)
+{
+    assert(denominator <= (double)LONG_MAX);
+
+    if (PyFloat_Check(obj)) {
+        double d = PyFloat_AsDouble(obj);
+        return _PyTime_DoubleToDenominator(d, sec, numerator,
+                                           denominator, round);
     }
     else {
         *sec = _PyLong_AsTime_t(obj);
+        *numerator = 0;
         if (*sec == (time_t)-1 && PyErr_Occurred())
             return -1;
-        *numerator = 0;
         return 0;
     }
 }
@@ -112,13 +150,12 @@ int
 _PyTime_ObjectToTime_t(PyObject *obj, time_t *sec, _PyTime_round_t round)
 {
     if (PyFloat_Check(obj)) {
-        double d, intpart, err;
+        double intpart, err;
+        /* volatile avoids optimization changing how numbers are rounded */
+        volatile double d;
 
         d = PyFloat_AsDouble(obj);
-        if (round == _PyTime_ROUND_CEILING)
-            d = ceil(d);
-        else
-            d = floor(d);
+        d = _PyTime_Round(d, round);
         (void)modf(d, &intpart);
 
         *sec = (time_t)intpart;
@@ -141,14 +178,20 @@ int
 _PyTime_ObjectToTimespec(PyObject *obj, time_t *sec, long *nsec,
                          _PyTime_round_t round)
 {
-    return _PyTime_ObjectToDenominator(obj, sec, nsec, 1e9, round);
+    int res;
+    res = _PyTime_ObjectToDenominator(obj, sec, nsec, 1e9, round);
+    assert(0 <= *nsec && *nsec < SEC_TO_NS);
+    return res;
 }
 
 int
 _PyTime_ObjectToTimeval(PyObject *obj, time_t *sec, long *usec,
                         _PyTime_round_t round)
 {
-    return _PyTime_ObjectToDenominator(obj, sec, usec, 1e6, round);
+    int res;
+    res = _PyTime_ObjectToDenominator(obj, sec, usec, 1e6, round);
+    assert(0 <= *usec && *usec < SEC_TO_US);
+    return res;
 }
 
 static void
@@ -162,12 +205,13 @@ _PyTime_t
 _PyTime_FromSeconds(int seconds)
 {
     _PyTime_t t;
+    t = (_PyTime_t)seconds;
     /* ensure that integer overflow cannot happen, int type should have 32
        bits, whereas _PyTime_t type has at least 64 bits (SEC_TO_MS takes 30
        bits). */
-    assert((seconds >= 0 && seconds <= _PyTime_MAX / SEC_TO_NS)
-           || (seconds < 0 && seconds >= _PyTime_MIN / SEC_TO_NS));
-    t = (_PyTime_t)seconds * SEC_TO_NS;
+    assert((t >= 0 && t <= _PyTime_MAX / SEC_TO_NS)
+           || (t < 0 && t >= _PyTime_MIN / SEC_TO_NS));
+    t *= SEC_TO_NS;
     return t;
 }
 
@@ -187,12 +231,15 @@ _PyTime_FromTimespec(_PyTime_t *tp, struct timespec *ts, int raise)
     _PyTime_t t;
     int res = 0;
 
-    t = (_PyTime_t)ts->tv_sec * SEC_TO_NS;
-    if (t / SEC_TO_NS != ts->tv_sec) {
+    assert(sizeof(ts->tv_sec) <= sizeof(_PyTime_t));
+    t = (_PyTime_t)ts->tv_sec;
+
+    if (_PyTime_check_mul_overflow(t, SEC_TO_NS)) {
         if (raise)
             _PyTime_overflow();
         res = -1;
     }
+    t = t * SEC_TO_NS;
 
     t += ts->tv_nsec;
 
@@ -206,12 +253,15 @@ _PyTime_FromTimeval(_PyTime_t *tp, struct timeval *tv, int raise)
     _PyTime_t t;
     int res = 0;
 
-    t = (_PyTime_t)tv->tv_sec * SEC_TO_NS;
-    if (t / SEC_TO_NS != tv->tv_sec) {
+    assert(sizeof(tv->tv_sec) <= sizeof(_PyTime_t));
+    t = (_PyTime_t)tv->tv_sec;
+
+    if (_PyTime_check_mul_overflow(t, SEC_TO_NS)) {
         if (raise)
             _PyTime_overflow();
         res = -1;
     }
+    t = t * SEC_TO_NS;
 
     t += (_PyTime_t)tv->tv_usec * US_TO_NS;
 
@@ -221,50 +271,59 @@ _PyTime_FromTimeval(_PyTime_t *tp, struct timeval *tv, int raise)
 #endif
 
 static int
+_PyTime_FromFloatObject(_PyTime_t *t, double value, _PyTime_round_t round,
+                        long unit_to_ns)
+{
+    double err;
+    /* volatile avoids optimization changing how numbers are rounded */
+    volatile double d;
+
+    /* convert to a number of nanoseconds */
+    d = value;
+    d *= (double)unit_to_ns;
+    d = _PyTime_Round(d, round);
+
+    *t = (_PyTime_t)d;
+    err = d - (double)*t;
+    if (fabs(err) >= 1.0) {
+        _PyTime_overflow();
+        return -1;
+    }
+    return 0;
+}
+
+static int
 _PyTime_FromObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round,
-                   long to_nanoseconds)
+                   long unit_to_ns)
 {
     if (PyFloat_Check(obj)) {
-        /* volatile avoids unsafe optimization on float enabled by gcc -O3 */
-        volatile double d, err;
-
-        /* convert to a number of nanoseconds */
+        double d;
         d = PyFloat_AsDouble(obj);
-        d *= to_nanoseconds;
-
-        if (round == _PyTime_ROUND_CEILING)
-            d = ceil(d);
-        else
-            d = floor(d);
-
-        *t = (_PyTime_t)d;
-        err = d - (double)*t;
-        if (fabs(err) >= 1.0) {
-            _PyTime_overflow();
-            return -1;
-        }
-        return 0;
+        return _PyTime_FromFloatObject(t, d, round, unit_to_ns);
     }
     else {
 #ifdef HAVE_LONG_LONG
         PY_LONG_LONG sec;
-        sec = PyLong_AsLongLong(obj);
         assert(sizeof(PY_LONG_LONG) <= sizeof(_PyTime_t));
+
+        sec = PyLong_AsLongLong(obj);
 #else
         long sec;
-        sec = PyLong_AsLong(obj);
         assert(sizeof(PY_LONG_LONG) <= sizeof(_PyTime_t));
+
+        sec = PyLong_AsLong(obj);
 #endif
         if (sec == -1 && PyErr_Occurred()) {
             if (PyErr_ExceptionMatches(PyExc_OverflowError))
                 _PyTime_overflow();
             return -1;
         }
-        *t = sec * to_nanoseconds;
-        if (*t / to_nanoseconds != sec) {
+
+        if (_PyTime_check_mul_overflow(sec, unit_to_ns)) {
             _PyTime_overflow();
             return -1;
         }
+        *t = sec * unit_to_ns;
         return 0;
     }
 }
@@ -284,12 +343,21 @@ _PyTime_FromMillisecondsObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t roun
 double
 _PyTime_AsSecondsDouble(_PyTime_t t)
 {
-    _PyTime_t sec, ns;
-    /* Divide using integers to avoid rounding issues on the integer part.
-       1e-9 cannot be stored exactly in IEEE 64-bit. */
-    sec = t / SEC_TO_NS;
-    ns = t % SEC_TO_NS;
-    return (double)sec + (double)ns * 1e-9;
+    /* volatile avoids optimization changing how numbers are rounded */
+    volatile double d;
+
+    if (t % SEC_TO_NS == 0) {
+        _PyTime_t secs;
+        /* Divide using integers to avoid rounding issues on the integer part.
+           1e-9 cannot be stored exactly in IEEE 64-bit. */
+        secs = t / SEC_TO_NS;
+        d = (double)secs;
+    }
+    else {
+        d = (double)t;
+        d /= 1e9;
+    }
+    return d;
 }
 
 PyObject *
@@ -305,17 +373,35 @@ _PyTime_AsNanosecondsObject(_PyTime_t t)
 }
 
 static _PyTime_t
-_PyTime_Divide(_PyTime_t t, _PyTime_t k, _PyTime_round_t round)
+_PyTime_Divide(const _PyTime_t t, const _PyTime_t k,
+               const _PyTime_round_t round)
 {
     assert(k > 1);
-    if (round == _PyTime_ROUND_CEILING) {
+    if (round == _PyTime_ROUND_HALF_EVEN) {
+        _PyTime_t x, r, abs_r;
+        x = t / k;
+        r = t % k;
+        abs_r = Py_ABS(r);
+        if (abs_r > k / 2 || (abs_r == k / 2 && (Py_ABS(x) & 1))) {
+            if (t >= 0)
+                x++;
+            else
+                x--;
+        }
+        return x;
+    }
+    else if (round == _PyTime_ROUND_CEILING) {
         if (t >= 0)
             return (t + k - 1) / k;
         else
+            return t / k;
+    }
+    else {
+        if (t >= 0)
+            return t / k;
+        else
             return (t - (k - 1)) / k;
     }
-    else
-        return t / k;
 }
 
 _PyTime_t
@@ -336,51 +422,34 @@ _PyTime_AsTimeval_impl(_PyTime_t t, struct timeval *tv, _PyTime_round_t round,
 {
     _PyTime_t secs, ns;
     int res = 0;
+    int usec;
 
     secs = t / SEC_TO_NS;
     ns = t % SEC_TO_NS;
-    if (ns < 0) {
-        ns += SEC_TO_NS;
-        secs -= 1;
-    }
 
 #ifdef MS_WINDOWS
-    /* On Windows, timeval.tv_sec is a long (32 bit),
-       whereas time_t can be 64-bit. */
-    assert(sizeof(tv->tv_sec) == sizeof(long));
-#if SIZEOF_TIME_T > SIZEOF_LONG
-    if (secs > LONG_MAX) {
-        secs = LONG_MAX;
-        res = -1;
-    }
-    else if (secs < LONG_MIN) {
-        secs = LONG_MIN;
-        res = -1;
-    }
-#endif
     tv->tv_sec = (long)secs;
 #else
-    /* On OpenBSD 5.4, timeval.tv_sec is a long.
-       Example: long is 64-bit, whereas time_t is 32-bit. */
     tv->tv_sec = secs;
+#endif
     if ((_PyTime_t)tv->tv_sec != secs)
         res = -1;
-#endif
-
-    if (round == _PyTime_ROUND_CEILING)
-        tv->tv_usec = (int)((ns + US_TO_NS - 1) / US_TO_NS);
-    else
-        tv->tv_usec = (int)(ns / US_TO_NS);
 
-    if (tv->tv_usec >= SEC_TO_US) {
-        tv->tv_usec -= SEC_TO_US;
+    usec = (int)_PyTime_Divide(ns, US_TO_NS, round);
+    if (usec < 0) {
+        usec += SEC_TO_US;
+        tv->tv_sec -= 1;
+    }
+    else if (usec >= SEC_TO_US) {
+        usec -= SEC_TO_US;
         tv->tv_sec += 1;
     }
 
-    if (res && raise)
-        _PyTime_overflow();
+    assert(0 <= usec && usec < SEC_TO_US);
+    tv->tv_usec = usec;
 
-    assert(0 <= tv->tv_usec && tv->tv_usec <= 999999);
+    if (res && raise)
+        error_time_t_overflow();
     return res;
 }
 
@@ -409,13 +478,13 @@ _PyTime_AsTimespec(_PyTime_t t, struct timespec *ts)
         secs -= 1;
     }
     ts->tv_sec = (time_t)secs;
+    assert(0 <= nsec && nsec < SEC_TO_NS);
+    ts->tv_nsec = nsec;
+
     if ((_PyTime_t)ts->tv_sec != secs) {
-        _PyTime_overflow();
+        error_time_t_overflow();
         return -1;
     }
-    ts->tv_nsec = nsec;
-
-    assert(0 <= ts->tv_nsec && ts->tv_nsec <= 999999999);
     return 0;
 }
 #endif
@@ -529,19 +598,20 @@ _PyTime_GetSystemClockWithInfo(_PyTime_t *t, _Py_clock_info_t *info)
     return pygettimeofday_new(t, info, 1);
 }
 
-
 static int
 pymonotonic(_PyTime_t *tp, _Py_clock_info_t *info, int raise)
 {
 #if defined(MS_WINDOWS)
-    ULONGLONG result;
+    ULONGLONG ticks;
+    _PyTime_t t;
 
     assert(info == NULL || raise);
 
-    result = GetTickCount64();
+    ticks = GetTickCount64();
+    assert(sizeof(ticks) <= sizeof(_PyTime_t));
+    t = (_PyTime_t)ticks;
 
-    *tp = result * MS_TO_NS;
-    if (*tp / MS_TO_NS != result) {
+    if (_PyTime_check_mul_overflow(t, MS_TO_NS)) {
         if (raise) {
             _PyTime_overflow();
             return -1;
@@ -549,6 +619,7 @@ pymonotonic(_PyTime_t *tp, _Py_clock_info_t *info, int raise)
         /* Hello, time traveler! */
         assert(0);
     }
+    *tp = t * MS_TO_NS;
 
     if (info) {
         DWORD timeAdjustment, timeIncrement;