etc/Windows/py-kms/filetimes.py

   1 # Copyright (c) 2009, David Buxton <david@gasmark6.com>
   2 # All rights reserved.
   3 #
   4 # Redistribution and use in source and binary forms, with or without
   5 # modification, are permitted provided that the following conditions are
   6 # met:
   7 #
   8 #     * Redistributions of source code must retain the above copyright
   9 # notice, this list of conditions and the following disclaimer.
  10 #     * Redistributions in binary form must reproduce the above copyright
  11 # notice, this list of conditions and the following disclaimer in the
  12 # documentation and/or other materials provided with the distribution.
  13 #
  14 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
  15 # IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  16 # TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  17 # PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  18 # HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  19 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
  20 # TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  21 # PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  22 # LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  23 # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  24 # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25 """Tools to convert between Python datetime instances and Microsoft times.
  26 """
  27 from datetime import datetime, timedelta, tzinfo
  28 from calendar import timegm
  29
  30
  31 # http://support.microsoft.com/kb/167296
  32 # How To Convert a UNIX time_t to a Win32 FILETIME or SYSTEMTIME
  33 EPOCH_AS_FILETIME = 116444736000000000  # January 1, 1970 as MS file time
  34 HUNDREDS_OF_NANOSECONDS = 10000000
  35
  36
  37 ZERO = timedelta(0)
  38 HOUR = timedelta(hours=1)
  39
  40
  41 class UTC(tzinfo):
  42         """UTC"""
  43         def utcoffset(self, dt):
  44                 return ZERO
  45
  46         def tzname(self, dt):
  47                 return "UTC"
  48
  49         def dst(self, dt):
  50                 return ZERO
  51
  52
  53 utc = UTC()
  54
  55
  56 def dt_to_filetime(dt):
  57         """Converts a datetime to Microsoft filetime format. If the object is
  58         time zone-naive, it is forced to UTC before conversion.
  59
  60         >>> "%.0f" % dt_to_filetime(datetime(2009, 7, 25, 23, 0))
  61         '128930364000000000'
  62
  63         >>> "%.0f" % dt_to_filetime(datetime(1970, 1, 1, 0, 0, tzinfo=utc))
  64         '116444736000000000'
  65
  66         >>> "%.0f" % dt_to_filetime(datetime(1970, 1, 1, 0, 0))
  67         '116444736000000000'
  68
  69         >>> dt_to_filetime(datetime(2009, 7, 25, 23, 0, 0, 100))
  70         128930364000001000
  71         """
  72         if (dt.tzinfo is None) or (dt.tzinfo.utcoffset(dt) is None):
  73                 dt = dt.replace(tzinfo=utc)
  74         ft = EPOCH_AS_FILETIME + (timegm(dt.timetuple()) * HUNDREDS_OF_NANOSECONDS)
  75         return ft + (dt.microsecond * 10)
  76
  77
  78 def filetime_to_dt(ft):
  79         """Converts a Microsoft filetime number to a Python datetime. The new
  80         datetime object is time zone-naive but is equivalent to tzinfo=utc.
  81
  82         >>> filetime_to_dt(116444736000000000)
  83         datetime.datetime(1970, 1, 1, 0, 0)
  84
  85         >>> filetime_to_dt(128930364000000000)
  86         datetime.datetime(2009, 7, 25, 23, 0)
  87
  88         >>> filetime_to_dt(128930364000001000)
  89         datetime.datetime(2009, 7, 25, 23, 0, 0, 100)
  90         """
  91         # Get seconds and remainder in terms of Unix epoch
  92         (s, ns100) = divmod(ft - EPOCH_AS_FILETIME, HUNDREDS_OF_NANOSECONDS)
  93         # Convert to datetime object
  94         dt = datetime.utcfromtimestamp(s)
  95         # Add remainder in as microseconds. Python 3.2 requires an integer
  96         dt = dt.replace(microsecond=(ns100 // 10))
  97         return dt
  98
  99
 100 if __name__ == "__main__":
 101         import doctest
 102
 103         doctest.testmod()
 104