localtime.cpp File Reference

#include <corecrt_internal_time.h>

Include dependency graph for localtime.cpp:

Go to the source code of this file.

Functions
template<typename TimeType >
static errno_t __cdecl	common_localtime_s (tm *const ptm, TimeType const *const ptime) throw ()
errno_t __cdecl	_localtime32_s (tm *const ptm, __time32_t const *const ptime)
errno_t __cdecl	_localtime64_s (tm *const ptm, __time64_t const *const ptime)
template<typename TimeType >
	_Success_ (return !=0) static tm *__cdecl common_localtime(TimeType const *const ptime) throw ()
tm *__cdecl	_localtime32 (__time32_t const *const ptime)
tm *__cdecl	_localtime64 (__time64_t const *const ptime)

Function Documentation

_localtime32()

tm *__cdecl _localtime32

(

__time32_t const *const

ptime

)

Definition at line 203 of file localtime.cpp.

{
    return common_localtime(ptime);
}

_localtime32_s()

errno_t __cdecl _localtime32_s	(	tm *const	ptm,
		__time32_t const *const	ptime
	)

Definition at line 165 of file localtime.cpp.

{
    return common_localtime_s(ptm, ptime);
}

_localtime64()

tm *__cdecl _localtime64

(

__time64_t const *const

ptime

)

Definition at line 208 of file localtime.cpp.

{
    return common_localtime(ptime);
}

Referenced by localtime().

_localtime64_s()

errno_t __cdecl _localtime64_s	(	tm *const	ptm,
		__time64_t const *const	ptime
	)

Definition at line 173 of file localtime.cpp.

{
    return common_localtime_s(ptm, ptime);
}

_Success_()

template<typename TimeType >

_Success_	(	return !	= 0	)	const
throw	(
	)

Definition at line 187 of file localtime.cpp.

{
    typedef __crt_time_time_t_traits<TimeType> time_traits;
 
    tm* const ptm = __getgmtimebuf();
    if (ptm == nullptr)
        return nullptr;
 
    errno_t const status = time_traits::localtime_s(ptm, ptime);
    if (status != 0)
        return nullptr;
 
    return ptm;
}

common_localtime_s()

template<typename TimeType >

static errno_t __cdecl common_localtime_s ( tm *const  ptm, TimeType const *const  ptime  ) throw ( )

static

Definition at line 33 of file localtime.cpp.

{
    typedef __crt_time_time_t_traits<TimeType> time_traits;
 
    _VALIDATE_RETURN_ERRCODE(ptm != nullptr, EINVAL);
    memset(ptm, 0xff, sizeof(tm));
 
    _VALIDATE_RETURN_ERRCODE(ptime != nullptr, EINVAL);
 
    // Check for illegal time_t value:
    _VALIDATE_RETURN_ERRCODE_NOEXC(*ptime >= 0,                       EINVAL);
    _VALIDATE_RETURN_ERRCODE_NOEXC(*ptime <= time_traits::max_time_t, EINVAL);
 
    __tzset();
 
    int  daylight = 0;
    long dstbias  = 0;
    long timezone = 0;
    _ERRCHECK(_get_daylight(&daylight));
    _ERRCHECK(_get_dstbias (&dstbias ));
    _ERRCHECK(_get_timezone(&timezone));
 
    if (*ptime > 3 * _DAY_SEC && *ptime < time_traits::max_time_t - 3 * _DAY_SEC)
    {
        // The date does not fall within the first three or last three representable
        // days; therefore, there is no possibility of overflowing or underflowing
        // the time_t representation as we compensate for time zone and daylight
        // savings time.
        TimeType ltime = *ptime - timezone;
 
        errno_t status0 = time_traits::gmtime_s(ptm, &ltime);
        if (status0 != 0)
            return status0;
 
        // Check and adjust for daylight savings time:
        if (daylight && _isindst(ptm))
        {
            ltime -= dstbias;
            
            errno_t const status1 = time_traits::gmtime_s(ptm, &ltime);
            if (status1 != 0)
                return status1;
 
            ptm->tm_isdst = 1;
        }
    }
    else
    {
        // The date falls within the first three or last three representable days;
        // therefore, it is possible that the time_t representation would overflow
        // or underflow while compensating for time zone and daylight savings time.
        // Therefore, we make the time zone and daylight savings time adjustments
        // directly in the tm structure.
        errno_t const status0 = time_traits::gmtime_s(ptm, ptime);
        if (status0 != 0)
            return status0;
 
        TimeType ltime = static_cast<TimeType>(ptm->tm_sec);
 
        // First, adjust for the time zone:
        if (daylight && _isindst(ptm))
        {
            ltime -= (timezone + dstbias);
            ptm->tm_isdst = 1;
        }
        else
        {
            ltime -= timezone;
        }
 
        ptm->tm_sec = static_cast<int>(ltime % 60);
        if (ptm->tm_sec < 0)
        {
            ptm->tm_sec += 60;
            ltime -= 60;
        }
 
        ltime = static_cast<TimeType>(ptm->tm_min) + ltime / 60;
        ptm->tm_min = static_cast<int>(ltime % 60);
        if (ptm->tm_min < 0)
        {
            ptm->tm_min += 60;
            ltime -= 60;
        }
 
        ltime = static_cast<TimeType>(ptm->tm_hour) + ltime / 60;
        ptm->tm_hour = static_cast<int>(ltime % 24);
        if (ptm->tm_hour < 0)
        {
            ptm->tm_hour += 24;
            ltime -=24;
        }
 
        ltime /= 24;
 
        if (ltime > 0)
        {
            // There is no possibility of overflowing the tm_day and tm_yday
            // members because the date can be no later than January 19.
            ptm->tm_wday = (ptm->tm_wday + static_cast<int>(ltime)) % 7;
            ptm->tm_mday += static_cast<int>(ltime);
            ptm->tm_yday += static_cast<int>(ltime);
        }
        else if (ltime < 0)
        {
            // It is possible to underflow the tm_mday and tm_yday fields.  If
            // this happens, then the adjusted date must lie in December 1969:
            ptm->tm_wday = (ptm->tm_wday + 7 + static_cast<int>(ltime)) % 7;
            ptm->tm_mday += static_cast<int>(ltime);
            if (ptm->tm_mday <= 0)
            {
                ptm->tm_mday += 31;
 
                // Per assumption #4 above, the time zone can cause the date to
                // underflow the epoch by more than a day.
                ptm->tm_yday = ptm->tm_yday + static_cast<int>(ltime) + 365;
                ptm->tm_mon = 11;
                ptm->tm_year--;
            }
            else
            {
                ptm->tm_yday += static_cast<int>(ltime);
            }
        }
    }
 
    return 0;
}

Referenced by _localtime32_s(), and _localtime64_s().