Fix timezone caching issues (#1499)

pkg/headers/kernel32/kernel32.go

@@ -0,0 +1,52 @@
+package kernel32
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+var (
+	kernel32 = syscall.NewLazyDLL("kernel32.dll")
+
+	procGetDynamicTimeZoneInformationSys = kernel32.NewProc("GetDynamicTimeZoneInformation")
+)
+
+// SYSTEMTIME contains a date and time.
+// 📑 https://docs.microsoft.com/en-us/windows/win32/api/minwinbase/ns-minwinbase-systemtime
+type SYSTEMTIME struct {
+	WYear         uint16
+	WMonth        uint16
+	WDayOfWeek    uint16
+	WDay          uint16
+	WHour         uint16
+	WMinute       uint16
+	WSecond       uint16
+	WMilliseconds uint16
+}
+
+// DynamicTimezoneInformation contains the current dynamic daylight time settings.
+// 📑 https://docs.microsoft.com/en-us/windows/win32/api/timezoneapi/ns-timezoneapi-dynamic_time_zone_information
+type DynamicTimezoneInformation struct {
+	Bias                        int32
+	standardName                [32]uint16
+	StandardDate                SYSTEMTIME
+	StandardBias                int32
+	DaylightName                [32]uint16
+	DaylightDate                SYSTEMTIME
+	DaylightBias                int32
+	TimeZoneKeyName             [128]uint16
+	DynamicDaylightTimeDisabled uint8 // BOOLEAN
+}
+
+// GetDynamicTimeZoneInformation retrieves the current dynamic daylight time settings.
+// 📑 https://docs.microsoft.com/en-us/windows/win32/api/timezoneapi/nf-timezoneapi-getdynamictimezoneinformation
+func GetDynamicTimeZoneInformation() (DynamicTimezoneInformation, error) {
+	var tzi DynamicTimezoneInformation
+
+	r0, _, err := syscall.SyscallN(procGetDynamicTimeZoneInformationSys.Addr(), uintptr(unsafe.Pointer(&tzi)))
+	if uint32(r0) == 0xffffffff {
+		return tzi, err
+	}
+
+	return tzi, nil
+}