[How To Convert a UNIX time_t to a Win32 FILETIME or SYSTEMTIME][kb]:

> Under Win32 platforms, file times are maintained primarily in the form of
> a 64-bit FILETIME structure, which represents the number of 100-nanosecond
> intervals since January 1, 1601 UTC (coordinate universal time).

***UPDATED* New version with fixes by Tim Williams for preserving microseconds. See [here for details][updated].**

It just so happens that [Microsoft Active Directory][msad] uses the same 64-bit value to store some time values. For example [the `accountExpires` attribute][expires] is in this format. Linked below is a module for Python with utility functions for converting between [Python’s datetime instances][datetime] and Microsoft’s FILETIME values.

Very handy if you enjoy querying Active Directory for login accounts that are due to expire. And who wouldn’t enjoy that? On a Monday.

[Download filetimes.py module for converting between FILETIME and `datetime` objects.][filetimes] This code is released under a 2-clause BSD license.

Example usage:

>>> from filetimes import filetime_to_dt, dt_to_filetime, utc
>>> filetime_to_dt(116444736000000000)
datetime.datetime(1970, 1, 1, 0, 0)
>>> filetime_to_dt(128930364000000000)
datetime.datetime(2009, 7, 25, 23, 0)
>>> “%.0f” % dt_to_filetime(datetime(2009, 7, 25, 23, 0))
‘128930364000000000’
>>> dt_to_filetime(datetime(1970, 1, 1, 0, 0, tzinfo=utc))
116444736000000000L
>>> dt_to_filetime(datetime(1970, 1, 1, 0, 0))
116444736000000000L

I even remembered to write tests for once!

[kb]: http://support.microsoft.com/kb/167296
[msad]: http://www.microsoft.com/windowsserver2008/en/us/active-directory.aspx
[datetime]: http://docs.python.org/library/datetime.html
[expires]: http://msdn.microsoft.com/en-us/library/ms675098(VS.85).aspx
[filetimes]: /b/wp-content/filetimes.py
[updated]: http://reliablybroken.com/b/2011/09/free-software-ftw-updated-filetimes-py/