[SOLVED] Does the windows FILETIME structure include leap seconds?

Does the windows FILETIME structure include leap seconds?

The FILETIME structure counts from January 1 1601 (presumably the start of that day) according to the Microsoft documentation, but does this include leap seconds?

Solution

The question shouldn't be if FILETIME includes leap seconds.

It should be:

Do the people, functions, and libraries, who interpret a FILETIME (i.e. FileTimeToSystemTime) include leap seconds when counting the duration?

The simple answer is "no". FileTimeToSystemTime returns seconds as 0..59.

The simpler answer is: "of course not, how could it?".

My Windows 2000 machine doesn't know that there were 2 leap seconds added in the decade since it was released. Any interpretation it makes of a FILETIME is wrong.

Finally, rather than relying on logic, we can determine by direct experimental observation, the answer to the posters question:

var
    systemTime: TSystemTime;
    fileTime: TFileTime;
begin
    //Construct a system-time for the 12/31/2008 11:59:59 pm
    ZeroMemory(@systemTime, SizeOf(systemTime));
    systemtime.wYear := 2008;
    systemTime.wMonth := 12;
    systemTime.wDay := 31;
    systemTime.wHour := 23;
    systemtime.wMinute := 59;
    systemtime.wSecond := 59;

    //Convert it to a file time
    SystemTimeToFileTime(systemTime, {var}fileTime);

    //There was a leap second 12/31/2008 11:59:60 pm
    //Add one second to our filetime to reach the leap second
    filetime.dwLowDateTime := fileTime.dwLowDateTime+10000000; //10,000,000 * 100ns = 1s

    //Convert the filetime, sitting on a leap second, to a displayable system time
    FileTimeToSystemTime(fileTime, {var}systemTime);

    //And now print the system time
    ShowMessage(DateTimeToStr(SystemTimeToDateTime(systemTime)));

Adding one second to

12/31/2008 11:59:59pm

gives

1/1/2009 12:00:00am

rather than

1/1/2009 11:59:60pm

Q.E.D.

Original poster might not like it, but god intentionally rigged it so that a year is not evenly divisible by a day. He did it just to screw up programmers.