pytime: add _PyTime_check_mul_overflow() macro to avoid undefined behaviour
Overflow test in test_FromSecondsObject() fails on FreeBSD 10.0 buildbot which uses clang. clang implements more aggressive optimization which gives different result than GCC on undefined behaviours. Check if a multiplication will overflow, instead of checking if a multiplicatin had overflowed, to avoid undefined behaviour. Add also debug information if the test on overflow fails.
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@ -781,7 +781,8 @@ class CPyTimeTestCase:
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overflow_values = convert_values(ns_timestamps)
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for time_rnd, _ in ROUNDING_MODES :
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for value in overflow_values:
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with self.assertRaises(OverflowError):
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debug_info = {'value': value, 'rounding': time_rnd}
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with self.assertRaises(OverflowError, msg=debug_info):
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pytime_converter(value, time_rnd)
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def check_int_rounding(self, pytime_converter, expected_func,
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@ -7,6 +7,11 @@
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#include <mach/mach_time.h> /* mach_absolute_time(), mach_timebase_info() */
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#endif
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#define _PyTime_check_mul_overflow(a, b) \
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(assert(b > 0), \
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(_PyTime_t)(a) < _PyTime_MIN / (_PyTime_t)(b) \
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|| _PyTime_MAX / (_PyTime_t)(b) < (_PyTime_t)(a))
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/* To millisecond (10^-3) */
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#define SEC_TO_MS 1000
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@ -226,12 +231,15 @@ _PyTime_FromTimespec(_PyTime_t *tp, struct timespec *ts, int raise)
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_PyTime_t t;
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int res = 0;
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t = (_PyTime_t)ts->tv_sec * SEC_TO_NS;
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if (t / SEC_TO_NS != ts->tv_sec) {
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assert(sizeof(ts->tv_sec) <= sizeof(_PyTime_t));
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t = (_PyTime_t)ts->tv_sec;
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if (_PyTime_check_mul_overflow(t, SEC_TO_NS)) {
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if (raise)
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_PyTime_overflow();
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res = -1;
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}
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t = t * SEC_TO_NS;
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t += ts->tv_nsec;
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@ -245,12 +253,15 @@ _PyTime_FromTimeval(_PyTime_t *tp, struct timeval *tv, int raise)
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_PyTime_t t;
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int res = 0;
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t = (_PyTime_t)tv->tv_sec * SEC_TO_NS;
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if (t / SEC_TO_NS != tv->tv_sec) {
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assert(sizeof(ts->tv_sec) <= sizeof(_PyTime_t));
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t = (_PyTime_t)tv->tv_sec;
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if (_PyTime_check_mul_overflow(t, SEC_TO_NS)) {
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if (raise)
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_PyTime_overflow();
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res = -1;
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}
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t = t * SEC_TO_NS;
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t += (_PyTime_t)tv->tv_usec * US_TO_NS;
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@ -308,11 +319,11 @@ _PyTime_FromObject(_PyTime_t *t, PyObject *obj, _PyTime_round_t round,
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return -1;
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}
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*t = sec * unit_to_ns;
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if (*t / unit_to_ns != sec) {
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if (_PyTime_check_mul_overflow(sec, unit_to_ns)) {
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_PyTime_overflow();
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return -1;
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}
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*t = sec * unit_to_ns;
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return 0;
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}
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}
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@ -587,19 +598,20 @@ _PyTime_GetSystemClockWithInfo(_PyTime_t *t, _Py_clock_info_t *info)
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return pygettimeofday_new(t, info, 1);
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}
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static int
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pymonotonic(_PyTime_t *tp, _Py_clock_info_t *info, int raise)
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{
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#if defined(MS_WINDOWS)
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ULONGLONG result;
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ULONGLONG ticks;
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_PyTime_t t;
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assert(info == NULL || raise);
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result = GetTickCount64();
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ticks = GetTickCount64();
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assert(sizeof(result) <= sizeof(_PyTime_t));
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t = (_PyTime_t)ticks;
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*tp = result * MS_TO_NS;
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if (*tp / MS_TO_NS != result) {
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if (_PyTime_check_mul_overflow(t, MS_TO_NS)) {
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if (raise) {
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_PyTime_overflow();
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return -1;
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@ -607,6 +619,7 @@ pymonotonic(_PyTime_t *tp, _Py_clock_info_t *info, int raise)
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/* Hello, time traveler! */
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assert(0);
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}
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*tp = t * MS_TO_NS;
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if (info) {
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DWORD timeAdjustment, timeIncrement;
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