113 lines
3.3 KiB
Python
113 lines
3.3 KiB
Python
import logging
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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 warnings
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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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log = logging.getLogger("tzlocal")
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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, error=True):
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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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If error is True, this method will raise a ValueError, otherwise it will
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emit a warning.
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"""
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tz_offset = get_tz_offset(tz)
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system_offset = calendar.timegm(time.localtime()) - calendar.timegm(time.gmtime())
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# No one has timezone offsets less than a minute, so this should be close enough:
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if abs(tz_offset - system_offset) > 60:
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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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if error:
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raise ValueError(msg)
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warnings.warn(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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log.debug(f"Found a TZ environment: {tzenv}")
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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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log.debug("TZ does not contain a time zone name")
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return None
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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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return zoneinfo.ZoneInfo.from_file(tzfile, key=tzname)
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# TZ must specify a zoneinfo zone.
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try:
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tz = zoneinfo.ZoneInfo(tzenv)
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# That worked, so we return this:
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return tz
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except zoneinfo.ZoneInfoNotFoundError:
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# Nope, it's something like "PST4DST" etc, we can't handle that.
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raise zoneinfo.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" % tzenv
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) from None
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