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129 lines
4.0 KiB
129 lines
4.0 KiB
# -*- coding: utf-8 -*-
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import os
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import time
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import datetime
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import calendar
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import pytz_deprecation_shim as pds
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try:
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import zoneinfo # pragma: no cover
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except ImportError:
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from backports import zoneinfo # pragma: no cover
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from tzlocal import windows_tz
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class ZoneInfoNotFoundError(pds.UnknownTimeZoneError, zoneinfo.ZoneInfoNotFoundError):
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"""An exception derived from both pytz and zoneinfo
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This exception will be trappable both by pytz expecting clients and
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zoneinfo expecting clients.
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"""
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def get_system_offset():
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"""Get system's timezone offset using built-in library time.
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For the Timezone constants (altzone, daylight, timezone, and tzname), the
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value is determined by the timezone rules in effect at module load time or
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the last time tzset() is called and may be incorrect for times in the past.
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To keep compatibility with Windows, we're always importing time module here.
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"""
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localtime = calendar.timegm(time.localtime())
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gmtime = calendar.timegm(time.gmtime())
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offset = gmtime - localtime
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# We could get the localtime and gmtime on either side of a second switch
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# so we check that the difference is less than one minute, because nobody
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# has that small DST differences.
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if abs(offset - time.altzone) < 60:
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return -time.altzone # pragma: no cover
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else:
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return -time.timezone # pragma: no cover
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def get_tz_offset(tz):
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"""Get timezone's offset using built-in function datetime.utcoffset()."""
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return int(datetime.datetime.now(tz).utcoffset().total_seconds())
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def assert_tz_offset(tz):
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"""Assert that system's timezone offset equals to the timezone offset found.
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If they don't match, we probably have a misconfiguration, for example, an
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incorrect timezone set in /etc/timezone file in systemd distributions."""
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tz_offset = get_tz_offset(tz)
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system_offset = get_system_offset()
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if tz_offset != system_offset:
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msg = (
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"Timezone offset does not match system offset: {} != {}. "
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"Please, check your config files."
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).format(tz_offset, system_offset)
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raise ValueError(msg)
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def _tz_name_from_env(tzenv=None):
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if tzenv is None:
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tzenv = os.environ.get("TZ")
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if not tzenv:
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return None
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if tzenv[0] == ":":
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tzenv = tzenv[1:]
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if tzenv in windows_tz.tz_win:
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# Yup, it's a timezone
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return tzenv
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if os.path.isabs(tzenv) and os.path.exists(tzenv):
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# It's a file specification, expand it, if possible
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parts = os.path.realpath(tzenv).split(os.sep)
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# Is it a zone info zone?
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possible_tz = "/".join(parts[-2:])
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if possible_tz in windows_tz.tz_win:
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# Yup, it is
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return possible_tz
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# Maybe it's a short one, like UTC?
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if parts[-1] in windows_tz.tz_win:
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# Indeed
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return parts[-1]
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def _tz_from_env(tzenv=None):
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if tzenv is None:
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tzenv = os.environ.get("TZ")
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if not tzenv:
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return None
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# Some weird format that exists:
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if tzenv[0] == ":":
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tzenv = tzenv[1:]
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# TZ specifies a file
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if os.path.isabs(tzenv) and os.path.exists(tzenv):
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# Try to see if we can figure out the name
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tzname = _tz_name_from_env(tzenv)
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if not tzname:
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# Nope, not a standard timezone name, just take the filename
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tzname = tzenv.split(os.sep)[-1]
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with open(tzenv, "rb") as tzfile:
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zone = zoneinfo.ZoneInfo.from_file(tzfile, key=tzname)
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return pds.wrap_zone(zone)
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# TZ must specify a zoneinfo zone.
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try:
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tz = pds.timezone(tzenv)
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# That worked, so we return this:
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return tz
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except pds.UnknownTimeZoneError:
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# Nope, it's something like "PST4DST" etc, we can't handle that.
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raise ZoneInfoNotFoundError(
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"tzlocal() does not support non-zoneinfo timezones like %s. \n"
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"Please use a timezone in the form of Continent/City"
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) from None
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