Python/pytime.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

static void
pygettimeofday(_PyTime_timeval *tp, _Py_clock_info_t *info)
{
#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;
    if (info) {
        DWORD timeAdjustment, timeIncrement;
        BOOL isTimeAdjustmentDisabled;

        info->implementation = "GetSystemTimeAsFileTime()";
        info->monotonic = 0;
        (void) GetSystemTimeAdjustment(&timeAdjustment, &timeIncrement,
                                       &isTimeAdjustmentDisabled);
        info->resolution = timeIncrement * 1e-7;
        info->adjustable = 1;
    }
#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
    int err;
#ifdef GETTIMEOFDAY_NO_TZ
    err = gettimeofday(tp);
#else
    err = gettimeofday(tp, (struct timezone *)NULL);
#endif
    if (err == 0) {
        if (info) {
            info->implementation = "gettimeofday()";
            info->resolution = 1e-6;
            info->monotonic = 0;
            info->adjustable = 1;
        }
        return;
    }
#endif   /* HAVE_GETTIMEOFDAY */

#if defined(HAVE_FTIME)
    {
        struct timeb t;
        ftime(&t);
        tp->tv_sec = t.time;
        tp->tv_usec = t.millitm * 1000;
        if (info) {
            info->implementation = "ftime()";
            info->resolution = 1e-3;
            info->monotonic = 0;
            info->adjustable = 1;
        }
    }
#else /* !HAVE_FTIME */
    tp->tv_sec = time(NULL);
    tp->tv_usec = 0;
    if (info) {
        info->implementation = "time()";
        info->resolution = 1.0;
        info->monotonic = 0;
        info->adjustable = 1;
    }
#endif /* !HAVE_FTIME */

#endif /* MS_WINDOWS */
}

void
_PyTime_gettimeofday(_PyTime_timeval *tp)
{
    pygettimeofday(tp, NULL);
}

void
_PyTime_gettimeofday_info(_PyTime_timeval *tp, _Py_clock_info_t *info)
{
    pygettimeofday(tp, info);
}

static void
error_time_t_overflow(void)
{
    PyErr_SetString(PyExc_OverflowError,
                    "timestamp out of range for platform time_t");
}

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;
}

PyObject *
_PyLong_FromTime_t(time_t t)
{
#if defined(HAVE_LONG_LONG) && SIZEOF_TIME_T == SIZEOF_LONG_LONG
    return PyLong_FromLongLong((PY_LONG_LONG)t);
#else
    assert(sizeof(time_t) <= sizeof(long));
    return PyLong_FromLong((long)t);
#endif
}

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. */
}