370 lines
13 KiB
Python
370 lines
13 KiB
Python
# -*- coding: utf-8 -*-
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"""
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This module provides an interface to the native time zone data on Windows,
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including :py:class:`datetime.tzinfo` implementations.
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Attempting to import this module on a non-Windows platform will raise an
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:py:obj:`ImportError`.
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"""
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# This code was originally contributed by Jeffrey Harris.
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import datetime
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import struct
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from six.moves import winreg
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from six import text_type
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try:
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import ctypes
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from ctypes import wintypes
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except ValueError:
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# ValueError is raised on non-Windows systems for some horrible reason.
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raise ImportError("Running tzwin on non-Windows system")
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from ._common import tzrangebase
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__all__ = ["tzwin", "tzwinlocal", "tzres"]
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ONEWEEK = datetime.timedelta(7)
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TZKEYNAMENT = r"SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones"
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TZKEYNAME9X = r"SOFTWARE\Microsoft\Windows\CurrentVersion\Time Zones"
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TZLOCALKEYNAME = r"SYSTEM\CurrentControlSet\Control\TimeZoneInformation"
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def _settzkeyname():
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handle = winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE)
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try:
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winreg.OpenKey(handle, TZKEYNAMENT).Close()
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TZKEYNAME = TZKEYNAMENT
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except WindowsError:
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TZKEYNAME = TZKEYNAME9X
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handle.Close()
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return TZKEYNAME
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TZKEYNAME = _settzkeyname()
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class tzres(object):
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"""
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Class for accessing ``tzres.dll``, which contains timezone name related
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resources.
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.. versionadded:: 2.5.0
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"""
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p_wchar = ctypes.POINTER(wintypes.WCHAR) # Pointer to a wide char
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def __init__(self, tzres_loc='tzres.dll'):
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# Load the user32 DLL so we can load strings from tzres
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user32 = ctypes.WinDLL('user32')
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# Specify the LoadStringW function
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user32.LoadStringW.argtypes = (wintypes.HINSTANCE,
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wintypes.UINT,
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wintypes.LPWSTR,
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ctypes.c_int)
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self.LoadStringW = user32.LoadStringW
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self._tzres = ctypes.WinDLL(tzres_loc)
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self.tzres_loc = tzres_loc
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def load_name(self, offset):
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"""
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Load a timezone name from a DLL offset (integer).
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>>> from dateutil.tzwin import tzres
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>>> tzr = tzres()
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>>> print(tzr.load_name(112))
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'Eastern Standard Time'
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:param offset:
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A positive integer value referring to a string from the tzres dll.
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.. note::
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Offsets found in the registry are generally of the form
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``@tzres.dll,-114``. The offset in this case is 114, not -114.
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"""
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resource = self.p_wchar()
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lpBuffer = ctypes.cast(ctypes.byref(resource), wintypes.LPWSTR)
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nchar = self.LoadStringW(self._tzres._handle, offset, lpBuffer, 0)
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return resource[:nchar]
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def name_from_string(self, tzname_str):
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"""
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Parse strings as returned from the Windows registry into the time zone
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name as defined in the registry.
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>>> from dateutil.tzwin import tzres
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>>> tzr = tzres()
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>>> print(tzr.name_from_string('@tzres.dll,-251'))
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'Dateline Daylight Time'
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>>> print(tzr.name_from_string('Eastern Standard Time'))
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'Eastern Standard Time'
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:param tzname_str:
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A timezone name string as returned from a Windows registry key.
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:return:
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Returns the localized timezone string from tzres.dll if the string
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is of the form `@tzres.dll,-offset`, else returns the input string.
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"""
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if not tzname_str.startswith('@'):
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return tzname_str
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name_splt = tzname_str.split(',-')
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try:
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offset = int(name_splt[1])
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except:
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raise ValueError("Malformed timezone string.")
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return self.load_name(offset)
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class tzwinbase(tzrangebase):
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"""tzinfo class based on win32's timezones available in the registry."""
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def __init__(self):
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raise NotImplementedError('tzwinbase is an abstract base class')
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def __eq__(self, other):
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# Compare on all relevant dimensions, including name.
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if not isinstance(other, tzwinbase):
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return NotImplemented
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return (self._std_offset == other._std_offset and
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self._dst_offset == other._dst_offset and
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self._stddayofweek == other._stddayofweek and
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self._dstdayofweek == other._dstdayofweek and
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self._stdweeknumber == other._stdweeknumber and
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self._dstweeknumber == other._dstweeknumber and
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self._stdhour == other._stdhour and
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self._dsthour == other._dsthour and
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self._stdminute == other._stdminute and
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self._dstminute == other._dstminute and
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self._std_abbr == other._std_abbr and
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self._dst_abbr == other._dst_abbr)
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@staticmethod
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def list():
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"""Return a list of all time zones known to the system."""
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with winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE) as handle:
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with winreg.OpenKey(handle, TZKEYNAME) as tzkey:
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result = [winreg.EnumKey(tzkey, i)
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for i in range(winreg.QueryInfoKey(tzkey)[0])]
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return result
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def display(self):
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"""
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Return the display name of the time zone.
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"""
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return self._display
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def transitions(self, year):
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"""
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For a given year, get the DST on and off transition times, expressed
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always on the standard time side. For zones with no transitions, this
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function returns ``None``.
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:param year:
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The year whose transitions you would like to query.
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:return:
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Returns a :class:`tuple` of :class:`datetime.datetime` objects,
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``(dston, dstoff)`` for zones with an annual DST transition, or
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``None`` for fixed offset zones.
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"""
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if not self.hasdst:
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return None
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dston = picknthweekday(year, self._dstmonth, self._dstdayofweek,
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self._dsthour, self._dstminute,
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self._dstweeknumber)
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dstoff = picknthweekday(year, self._stdmonth, self._stddayofweek,
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self._stdhour, self._stdminute,
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self._stdweeknumber)
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# Ambiguous dates default to the STD side
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dstoff -= self._dst_base_offset
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return dston, dstoff
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def _get_hasdst(self):
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return self._dstmonth != 0
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@property
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def _dst_base_offset(self):
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return self._dst_base_offset_
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class tzwin(tzwinbase):
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"""
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Time zone object created from the zone info in the Windows registry
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These are similar to :py:class:`dateutil.tz.tzrange` objects in that
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the time zone data is provided in the format of a single offset rule
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for either 0 or 2 time zone transitions per year.
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:param: name
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The name of a Windows time zone key, e.g. "Eastern Standard Time".
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The full list of keys can be retrieved with :func:`tzwin.list`.
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"""
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def __init__(self, name):
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self._name = name
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with winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE) as handle:
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tzkeyname = text_type("{kn}\\{name}").format(kn=TZKEYNAME, name=name)
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with winreg.OpenKey(handle, tzkeyname) as tzkey:
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keydict = valuestodict(tzkey)
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self._std_abbr = keydict["Std"]
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self._dst_abbr = keydict["Dlt"]
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self._display = keydict["Display"]
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# See http://ww_winreg.jsiinc.com/SUBA/tip0300/rh0398.htm
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tup = struct.unpack("=3l16h", keydict["TZI"])
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stdoffset = -tup[0]-tup[1] # Bias + StandardBias * -1
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dstoffset = stdoffset-tup[2] # + DaylightBias * -1
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self._std_offset = datetime.timedelta(minutes=stdoffset)
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self._dst_offset = datetime.timedelta(minutes=dstoffset)
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# for the meaning see the win32 TIME_ZONE_INFORMATION structure docs
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# http://msdn.microsoft.com/en-us/library/windows/desktop/ms725481(v=vs.85).aspx
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(self._stdmonth,
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self._stddayofweek, # Sunday = 0
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self._stdweeknumber, # Last = 5
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self._stdhour,
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self._stdminute) = tup[4:9]
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(self._dstmonth,
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self._dstdayofweek, # Sunday = 0
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self._dstweeknumber, # Last = 5
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self._dsthour,
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self._dstminute) = tup[12:17]
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self._dst_base_offset_ = self._dst_offset - self._std_offset
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self.hasdst = self._get_hasdst()
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def __repr__(self):
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return "tzwin(%s)" % repr(self._name)
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def __reduce__(self):
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return (self.__class__, (self._name,))
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class tzwinlocal(tzwinbase):
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"""
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Class representing the local time zone information in the Windows registry
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While :class:`dateutil.tz.tzlocal` makes system calls (via the :mod:`time`
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module) to retrieve time zone information, ``tzwinlocal`` retrieves the
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rules directly from the Windows registry and creates an object like
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:class:`dateutil.tz.tzwin`.
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Because Windows does not have an equivalent of :func:`time.tzset`, on
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Windows, :class:`dateutil.tz.tzlocal` instances will always reflect the
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time zone settings *at the time that the process was started*, meaning
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changes to the machine's time zone settings during the run of a program
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on Windows will **not** be reflected by :class:`dateutil.tz.tzlocal`.
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Because ``tzwinlocal`` reads the registry directly, it is unaffected by
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this issue.
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"""
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def __init__(self):
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with winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE) as handle:
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with winreg.OpenKey(handle, TZLOCALKEYNAME) as tzlocalkey:
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keydict = valuestodict(tzlocalkey)
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self._std_abbr = keydict["StandardName"]
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self._dst_abbr = keydict["DaylightName"]
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try:
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tzkeyname = text_type('{kn}\\{sn}').format(kn=TZKEYNAME,
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sn=self._std_abbr)
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with winreg.OpenKey(handle, tzkeyname) as tzkey:
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_keydict = valuestodict(tzkey)
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self._display = _keydict["Display"]
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except OSError:
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self._display = None
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stdoffset = -keydict["Bias"]-keydict["StandardBias"]
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dstoffset = stdoffset-keydict["DaylightBias"]
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self._std_offset = datetime.timedelta(minutes=stdoffset)
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self._dst_offset = datetime.timedelta(minutes=dstoffset)
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# For reasons unclear, in this particular key, the day of week has been
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# moved to the END of the SYSTEMTIME structure.
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tup = struct.unpack("=8h", keydict["StandardStart"])
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(self._stdmonth,
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self._stdweeknumber, # Last = 5
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self._stdhour,
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self._stdminute) = tup[1:5]
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self._stddayofweek = tup[7]
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tup = struct.unpack("=8h", keydict["DaylightStart"])
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(self._dstmonth,
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self._dstweeknumber, # Last = 5
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self._dsthour,
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self._dstminute) = tup[1:5]
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self._dstdayofweek = tup[7]
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self._dst_base_offset_ = self._dst_offset - self._std_offset
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self.hasdst = self._get_hasdst()
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def __repr__(self):
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return "tzwinlocal()"
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def __str__(self):
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# str will return the standard name, not the daylight name.
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return "tzwinlocal(%s)" % repr(self._std_abbr)
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def __reduce__(self):
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return (self.__class__, ())
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def picknthweekday(year, month, dayofweek, hour, minute, whichweek):
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""" dayofweek == 0 means Sunday, whichweek 5 means last instance """
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first = datetime.datetime(year, month, 1, hour, minute)
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# This will work if dayofweek is ISO weekday (1-7) or Microsoft-style (0-6),
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# Because 7 % 7 = 0
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weekdayone = first.replace(day=((dayofweek - first.isoweekday()) % 7) + 1)
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wd = weekdayone + ((whichweek - 1) * ONEWEEK)
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if (wd.month != month):
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wd -= ONEWEEK
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return wd
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def valuestodict(key):
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"""Convert a registry key's values to a dictionary."""
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dout = {}
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size = winreg.QueryInfoKey(key)[1]
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tz_res = None
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for i in range(size):
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key_name, value, dtype = winreg.EnumValue(key, i)
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if dtype == winreg.REG_DWORD or dtype == winreg.REG_DWORD_LITTLE_ENDIAN:
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# If it's a DWORD (32-bit integer), it's stored as unsigned - convert
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# that to a proper signed integer
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if value & (1 << 31):
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value = value - (1 << 32)
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elif dtype == winreg.REG_SZ:
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# If it's a reference to the tzres DLL, load the actual string
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if value.startswith('@tzres'):
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tz_res = tz_res or tzres()
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value = tz_res.name_from_string(value)
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value = value.rstrip('\x00') # Remove trailing nulls
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dout[key_name] = value
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return dout
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