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import logging
from datetime import datetime
try:
import _winreg as winreg
except ImportError:
import winreg
import zoneinfo
from tzlocal import utils
from tzlocal.windows_tz import win_tz
_cache_tz = None
_cache_tz_name = None
log = logging.getLogger("tzlocal")
def valuestodict(key):
"""Convert a registry key's values to a dictionary."""
result = {}
size = winreg.QueryInfoKey(key)[1]
for i in range(size):
data = winreg.EnumValue(key, i)
result[data[0]] = data[1]
return result
def _get_dst_info(tz):
# Find the offset for when it doesn't have DST:
dst_offset = std_offset = None
has_dst = False
year = datetime.now().year
for dt in (datetime(year, 1, 1), datetime(year, 6, 1)):
if tz.dst(dt).total_seconds() == 0.0:
# OK, no DST during winter, get this offset
std_offset = tz.utcoffset(dt).total_seconds()
else:
has_dst = True
return has_dst, std_offset, dst_offset
def _get_localzone_name():
# Windows is special. It has unique time zone names (in several
# meanings of the word) available, but unfortunately, they can be
# translated to the language of the operating system, so we need to
# do a backwards lookup, by going through all time zones and see which
# one matches.
tzenv = utils._tz_name_from_env()
if tzenv:
return tzenv
log.debug("Looking up time zone info from registry")
handle = winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE)
TZLOCALKEYNAME = r"SYSTEM\CurrentControlSet\Control\TimeZoneInformation"
localtz = winreg.OpenKey(handle, TZLOCALKEYNAME)
keyvalues = valuestodict(localtz)
localtz.Close()
if "TimeZoneKeyName" in keyvalues:
# Windows 7 and later
# For some reason this returns a string with loads of NUL bytes at
# least on some systems. I don't know if this is a bug somewhere, I
# just work around it.
tzkeyname = keyvalues["TimeZoneKeyName"].split("\x00", 1)[0]
else:
# Don't support XP any longer
raise LookupError("Can not find Windows timezone configuration")
timezone = win_tz.get(tzkeyname)
if timezone is None:
# Nope, that didn't work. Try adding "Standard Time",
# it seems to work a lot of times:
timezone = win_tz.get(tzkeyname + " Standard Time")
# Return what we have.
if timezone is None:
raise zoneinfo.ZoneInfoNotFoundError(tzkeyname)
if keyvalues.get("DynamicDaylightTimeDisabled", 0) == 1:
# DST is disabled, so don't return the timezone name,
# instead return Etc/GMT+offset
tz = zoneinfo.ZoneInfo(timezone)
has_dst, std_offset, dst_offset = _get_dst_info(tz)
if not has_dst:
# The DST is turned off in the windows configuration,
# but this timezone doesn't have DST so it doesn't matter
return timezone
if std_offset is None:
raise zoneinfo.ZoneInfoNotFoundError(
f"{tzkeyname} claims to not have a non-DST time!?"
)
if std_offset % 3600:
# I can't convert this to an hourly offset
raise zoneinfo.ZoneInfoNotFoundError(
f"tzlocal can't support disabling DST in the {timezone} zone."
)
# This has whole hours as offset, return it as Etc/GMT
return f"Etc/GMT{-std_offset//3600:+.0f}"
return timezone
def get_localzone_name() -> str:
"""Get the zoneinfo timezone name that matches the Windows-configured timezone."""
global _cache_tz_name
if _cache_tz_name is None:
_cache_tz_name = _get_localzone_name()
return _cache_tz_name
def get_localzone() -> zoneinfo.ZoneInfo:
"""Returns the zoneinfo-based tzinfo object that matches the Windows-configured timezone."""
global _cache_tz
if _cache_tz is None:
_cache_tz = zoneinfo.ZoneInfo(get_localzone_name())
if not utils._tz_name_from_env():
# If the timezone does NOT come from a TZ environment variable,
# verify that it's correct. If it's from the environment,
# we accept it, this is so you can run tests with different timezones.
utils.assert_tz_offset(_cache_tz, error=False)
return _cache_tz
def reload_localzone() -> zoneinfo.ZoneInfo:
"""Reload the cached localzone. You need to call this if the timezone has changed."""
global _cache_tz
global _cache_tz_name
_cache_tz_name = _get_localzone_name()
_cache_tz = zoneinfo.ZoneInfo(_cache_tz_name)
utils.assert_tz_offset(_cache_tz, error=False)
return _cache_tz
|
