cpython/Python/pytime.c
Victor Stinner bd273c1ec3 Issue #14180: Fix an invalid rounding when compiler optimization are enabled
Use volatile keyword to disable localy unsafe float optimizations.
2012-03-13 19:12:23 +01:00

178 lines
4.5 KiB
C

#include "Python.h"
#ifdef MS_WINDOWS
#include <windows.h>
#endif
#if defined(__APPLE__) && defined(HAVE_GETTIMEOFDAY) && defined(HAVE_FTIME)
/*
* _PyTime_gettimeofday falls back to ftime when getttimeofday fails because the latter
* might fail on some platforms. This fallback is unwanted on MacOSX because
* that makes it impossible to use a binary build on OSX 10.4 on earlier
* releases of the OS. Therefore claim we don't support ftime.
*/
# undef HAVE_FTIME
#endif
#if defined(HAVE_FTIME) && !defined(MS_WINDOWS)
#include <sys/timeb.h>
extern int ftime(struct timeb *);
#endif
void
_PyTime_gettimeofday(_PyTime_timeval *tp)
{
#ifdef MS_WINDOWS
FILETIME system_time;
ULARGE_INTEGER large;
ULONGLONG microseconds;
GetSystemTimeAsFileTime(&system_time);
large.u.LowPart = system_time.dwLowDateTime;
large.u.HighPart = system_time.dwHighDateTime;
/* 11,644,473,600,000,000: number of microseconds between
the 1st january 1601 and the 1st january 1970 (369 years + 89 leap
days). */
microseconds = large.QuadPart / 10 - 11644473600000000;
tp->tv_sec = microseconds / 1000000;
tp->tv_usec = microseconds % 1000000;
#else
/* There are three ways to get the time:
(1) gettimeofday() -- resolution in microseconds
(2) ftime() -- resolution in milliseconds
(3) time() -- resolution in seconds
In all cases the return value in a timeval struct.
Since on some systems (e.g. SCO ODT 3.0) gettimeofday() may
fail, so we fall back on ftime() or time().
Note: clock resolution does not imply clock accuracy! */
#ifdef HAVE_GETTIMEOFDAY
#ifdef GETTIMEOFDAY_NO_TZ
if (gettimeofday(tp) == 0)
return;
#else /* !GETTIMEOFDAY_NO_TZ */
if (gettimeofday(tp, (struct timezone *)NULL) == 0)
return;
#endif /* !GETTIMEOFDAY_NO_TZ */
#endif /* !HAVE_GETTIMEOFDAY */
#if defined(HAVE_FTIME)
{
struct timeb t;
ftime(&t);
tp->tv_sec = t.time;
tp->tv_usec = t.millitm * 1000;
}
#else /* !HAVE_FTIME */
tp->tv_sec = time(NULL);
tp->tv_usec = 0;
#endif /* !HAVE_FTIME */
#endif /* MS_WINDOWS */
}
static void
error_time_t_overflow(void)
{
PyErr_SetString(PyExc_OverflowError,
"timestamp out of range for platform time_t");
}
static time_t
_PyLong_AsTime_t(PyObject *obj)
{
#if defined(HAVE_LONG_LONG) && SIZEOF_TIME_T == SIZEOF_LONG_LONG
PY_LONG_LONG val;
val = PyLong_AsLongLong(obj);
#else
long val;
assert(sizeof(time_t) <= sizeof(long));
val = PyLong_AsLong(obj);
#endif
if (val == -1 && PyErr_Occurred()) {
if (PyErr_ExceptionMatches(PyExc_OverflowError))
error_time_t_overflow();
return -1;
}
return (time_t)val;
}
static int
_PyTime_ObjectToDenominator(PyObject *obj, time_t *sec, long *numerator,
double denominator)
{
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;
d = PyFloat_AsDouble(obj);
floatpart = modf(d, &intpart);
if (floatpart < 0) {
floatpart = 1.0 + floatpart;
intpart -= 1.0;
}
*sec = (time_t)intpart;
err = intpart - (double)*sec;
if (err <= -1.0 || err >= 1.0) {
error_time_t_overflow();
return -1;
}
floatpart *= denominator;
*numerator = (long)floatpart;
return 0;
}
else {
*sec = _PyLong_AsTime_t(obj);
if (*sec == (time_t)-1 && PyErr_Occurred())
return -1;
*numerator = 0;
return 0;
}
}
int
_PyTime_ObjectToTime_t(PyObject *obj, time_t *sec)
{
if (PyFloat_Check(obj)) {
double d, intpart, err;
d = PyFloat_AsDouble(obj);
(void)modf(d, &intpart);
*sec = (time_t)intpart;
err = intpart - (double)*sec;
if (err <= -1.0 || err >= 1.0) {
error_time_t_overflow();
return -1;
}
return 0;
}
else {
*sec = _PyLong_AsTime_t(obj);
if (*sec == (time_t)-1 && PyErr_Occurred())
return -1;
return 0;
}
}
int
_PyTime_ObjectToTimespec(PyObject *obj, time_t *sec, long *nsec)
{
return _PyTime_ObjectToDenominator(obj, sec, nsec, 1e9);
}
int
_PyTime_ObjectToTimeval(PyObject *obj, time_t *sec, long *usec)
{
return _PyTime_ObjectToDenominator(obj, sec, usec, 1e6);
}
void
_PyTime_Init()
{
/* Do nothing. Needed to force linking. */
}