I'm pulling a cookie expiration date from Google Chrome. From what it looks like, Chrome is storing cookie expirations with a timestamp that uses 1601-01-01 00:00:00 UTC as the epoch. My current implementation is as follows:
stamp = int(result[3]) date = datetime.datetime.fromtimestamp(stamp / 10000000.0) print date.year However, this is producing the wrong date (off by about a year). What am I doing wrong here?
Another option, getting tzinfo from the standard library since Python 3.2 (for older Python versions you can get if from pytz):
>>> import pytz >>> from datetime import datetime, timedelta, timezone >>> epoch = datetime(1601, 1, 1, tzinfo=timezone.utc) >>> cookie_microseconds_since_epoch = 13022344559000000 >>> cookie_datetime = epoch + timedelta(microseconds=cookie_microseconds_since_epoch) >>> str(cookie_datetime) '2013-08-29 13:55:59+00:00' I assume that the difference to your expected value is the timezones offset.
Update:
As @J.F.Sebastian correctly points out, if you are using implicit UTC naive datetime objects, tzinfo is redundant and the above can be simplified to:
>>> from datetime import datetime, timedelta >>> epoch = datetime(1601, 1, 1) >>> cookie_microseconds_since_epoch = 13022344559000000 >>> cookie_datetime = epoch + timedelta(microseconds=cookie_microseconds_since_epoch) >>> str(cookie_datetime) '2013-08-30 13:55:59' I'm not sure what data you're starting with but here is an example starting from an integer timestamp. Assumes the pytz module is present (which I recommend highly).
>>> import datetime, pytz >>> x = datetime.datetime.fromtimestamp(0) >>> x = x.replace(tzinfo=pytz.UTC) >>> str(x) '1970-01-01 00:00:00+00:00' >>> d = datetime.timedelta(365 * (1970 - 1601)) >>> str(x - d) '1601-03-31 00:00:00+00:00' >>> d = datetime.timedelta(365 * (1970 - 1601) + 31 + 28 + 31 - 1) >>> str(x - d) '1601-01-01 00:00:00+00:00' >>> str(d) '134774 days, 0:00:00' So there you have it. Conversion between a Jan 1 1601 epoch and a Jan 1 1970 epoch is 134774 days.
Why that number of days? Leap years! We added a certain number of days, not years. (In fact, adding years is not directly supported in timedelta objects.)