python convert filetime to datetime for dates before 1970

Question

I need to convert filetime to datetime. I am using this code filetime.py, from here as mentioned in this thread Datetime to filetime (Python).

In the code

EPOCH_AS_FILETIME = 116444736000000000  # January 1, 1970 as MS file time
HUNDREDS_OF_NANOSECONDS = 10000000

def filetime_to_dt(ft):
    """Converts a Microsoft filetime number to a Python datetime. The new datetime object is time zone-naive but is equivalent to tzinfo=utc.

    >>> filetime_to_dt(116444736000000000)
    datetime.datetime(1970, 1, 1, 0, 0)
    """
    # Get seconds and remainder in terms of Unix epoch
    (s, ns100) = divmod(ft - EPOCH_AS_FILETIME, HUNDREDS_OF_NANOSECONDS)
    # Convert to datetime object
    dt = datetime.utcfromtimestamp(s)
    # Add remainder in as microseconds. Python 3.2 requires an integer
    dt = dt.replace(microsecond=(ns100 // 10))
    return dt

datetime.utcfromtimestamp does not take negative value on windows system, so I can't convert filetime before Jan 1st 1970. But I can convert dates before 1970 on Mac using the exact same code (reason here). Is there any workaround for windows?

So all you mean is that you want to convert some epoch time in normal date time right? — harshil9968, Aug 10 '16 at 16:17

score 3 · Accepted Answer · answered Aug 10 '16 at 18:11

By adding a timedelta to a reference date you can use any date formula you'd like. timedelta is allowed to be positive or negative.

def filetime_to_dt(ft):
    us = (ft - EPOCH_AS_FILETIME) // 10
    return datetime(1970, 1, 1) + timedelta(microseconds = us)

score 1 · Answer 2 · edited Aug 10 '16 at 16:33

1

According to docs, you have to use:

dt = datetime.fromtimestamp(s, datetime.timezone.utc)

instead of:

dt = datetime.utcfromtimestamp(s)

edited Aug 10 '16 at 16:33

Łukasz Rogalski

22,092
8
59
93

answered Aug 10 '16 at 16:24

Aaron

10,133
1
24
40

sorry, I am using `import datetime datetime.timezone.utc` give the error "AttributeError: 'module' object has no attribute 'timezone' ". Why is that? – Echo Aug 10 '16 at 17:32
@Echo: Maybe you are not using Python 3? – BlackJack Aug 24 '16 at 12:05
I am using Python 2 – Echo Aug 24 '16 at 20:08

score 0 · Answer 3 · answered Jul 20 '20 at 01:27

first you need to convert it to a recognizable filetime format like this:

>>> dwLowDateTime = 0x0F7297A80
>>> dwHighDateTime = 0x1C3F10F << 32
>>> ft = (dwLowDateTime & 0xFFFFFFFF) | dwHighDateTime
127210265370000000

and then use this script, it converts filetime to datetime and vice versa https://gist.github.com/Mostafa-Hamdy-Elgiar/9714475f1b3bc224ea063af81566d873

>>> filetime_to_dt(ft)
2004-02-12 02:28:57

score 0 · Answer 4 · answered Sep 04 '20 at 18:49

Use timedeltas to add/subtract/divide between time frames:

FILE_TIME_EPOCH = datetime.datetime(1601, 1, 1)
FILE_TIME_MICROSECOND = 10 # FILETIME counts 100 nanoseconds intervals = 0.1 microseconds, so 10 of those are 1 microsecond

def convert_from_file_time(file_time):
    microseconds_since_file_time_epoch = file_time // FILE_TIME_MICROSECOND
    return FILE_TIME_EPOCH + datetime.timedelta(microseconds=microseconds_since_file_time_epoch)

And the other side of this is:

def convert_to_file_time(date_time):
    microseconds_since_file_time_epoch = (date_time - FILE_TIME_EPOCH) // datetime.timedelta(microseconds=1)
    return microseconds_since_file_time_epoch * FILE_TIME_MICROSECOND

python convert filetime to datetime for dates before 1970

4 Answers4