reactos/sdk/lib/ucrt/time/ftime.cpp
2025-01-16 14:18:53 +02:00

105 lines
2.8 KiB
C++

//
// ftime.cpp
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// The ftime() family of functions, which return the system date and time in a
// time structure.
//
#include <corecrt_internal_time.h>
#include <sys/timeb.h>
#include <sys/types.h>
// Cache for the minutes count for with DST status was last assessed
// CRT_REFACTOR TODO Check synchronization of access to this global variable.
static __time64_t elapsed_minutes_cache = 0;
// Three values of dstflag_cache
#define DAYLIGHT_TIME 1
#define STANDARD_TIME 0
#define UNKNOWN_TIME -1
// Cache for the last determined DST status:
static int dstflag_cache = UNKNOWN_TIME;
// Returns the system time in a structure; returns zero on success; returns an
// error code on failure.
template <typename TimeType, typename TimeBType>
static errno_t __cdecl common_ftime_s(TimeBType* const tp) throw()
{
_VALIDATE_RETURN_ERRCODE(tp != nullptr, EINVAL)
__tzset();
long timezone = 0;
_ERRCHECK(_get_timezone(&timezone));
tp->timezone = static_cast<short>(timezone / 60);
__crt_filetime_union system_time;
__acrt_GetSystemTimePreciseAsFileTime(&system_time._filetime);
// Obtain the current Daylight Savings Time status. Note that the status is
// cached and only updated once per minute, if necessary.
TimeType const current_minutes_value = static_cast<TimeType>(system_time._scalar / 600000000ll);
if (static_cast<__time64_t>(current_minutes_value) != elapsed_minutes_cache)
{
TIME_ZONE_INFORMATION tz_info;
DWORD const tz_state = GetTimeZoneInformation(&tz_info);
if (tz_state == 0xFFFFFFFF)
{
dstflag_cache = UNKNOWN_TIME;
}
else
{
// Must be very careful when determining whether or not Daylight
// Savings Time is in effect:
if (tz_state == TIME_ZONE_ID_DAYLIGHT &&
tz_info.DaylightDate.wMonth != 0 &&
tz_info.DaylightBias != 0)
{
dstflag_cache = DAYLIGHT_TIME;
}
else
{
// Assume Standard Time:
dstflag_cache = STANDARD_TIME;
}
}
elapsed_minutes_cache = current_minutes_value;
}
tp->dstflag = static_cast<short>(dstflag_cache);
tp->millitm = static_cast<unsigned short>((system_time._scalar / 10000ll) % 1000ll);
tp->time = static_cast<TimeType>((system_time._scalar - _EPOCH_BIAS) / 10000000ll);
return 0;
}
extern "C" errno_t __cdecl _ftime32_s(__timeb32* const tp)
{
return common_ftime_s<__time32_t>(tp);
}
extern "C" void __cdecl _ftime32(__timeb32* const tp)
{
_ftime32_s(tp);
}
extern "C" errno_t __cdecl _ftime64_s(__timeb64* const tp)
{
return common_ftime_s<__time64_t>(tp);
}
extern "C" void __cdecl _ftime64(__timeb64* const tp)
{
_ftime64_s(tp);
}