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