bazarr/libs/tzlocal/utils.py

112 lines
3.3 KiB
Python

import calendar
import datetime
import logging
import os
import time
import warnings
try:
import zoneinfo # pragma: no cover
except ImportError:
from backports import zoneinfo # pragma: no cover
from tzlocal import windows_tz
log = logging.getLogger("tzlocal")
def get_tz_offset(tz):
"""Get timezone's offset using built-in function datetime.utcoffset()."""
return int(datetime.datetime.now(tz).utcoffset().total_seconds())
def assert_tz_offset(tz, error=True):
"""Assert that system's timezone offset equals to the timezone offset found.
If they don't match, we probably have a misconfiguration, for example, an
incorrect timezone set in /etc/timezone file in systemd distributions.
If error is True, this method will raise a ValueError, otherwise it will
emit a warning.
"""
tz_offset = get_tz_offset(tz)
system_offset = calendar.timegm(time.localtime()) - calendar.timegm(time.gmtime())
# No one has timezone offsets less than a minute, so this should be close enough:
if abs(tz_offset - system_offset) > 60:
msg = (
f"Timezone offset does not match system offset: {tz_offset} != {system_offset}. "
"Please, check your config files."
)
if error:
raise ValueError(msg)
warnings.warn(msg)
def _tz_name_from_env(tzenv=None):
if tzenv is None:
tzenv = os.environ.get("TZ")
if not tzenv:
return None
log.debug(f"Found a TZ environment: {tzenv}")
if tzenv[0] == ":":
tzenv = tzenv[1:]
if tzenv in windows_tz.tz_win:
# Yup, it's a timezone
return tzenv
if os.path.isabs(tzenv) and os.path.exists(tzenv):
# It's a file specification, expand it, if possible
parts = os.path.realpath(tzenv).split(os.sep)
# Is it a zone info zone?
possible_tz = "/".join(parts[-2:])
if possible_tz in windows_tz.tz_win:
# Yup, it is
return possible_tz
# Maybe it's a short one, like UTC?
if parts[-1] in windows_tz.tz_win:
# Indeed
return parts[-1]
log.debug("TZ does not contain a time zone name")
return None
def _tz_from_env(tzenv=None):
if tzenv is None:
tzenv = os.environ.get("TZ")
if not tzenv:
return None
# Some weird format that exists:
if tzenv[0] == ":":
tzenv = tzenv[1:]
# TZ specifies a file
if os.path.isabs(tzenv) and os.path.exists(tzenv):
# Try to see if we can figure out the name
tzname = _tz_name_from_env(tzenv)
if not tzname:
# Nope, not a standard timezone name, just take the filename
tzname = tzenv.split(os.sep)[-1]
with open(tzenv, "rb") as tzfile:
return zoneinfo.ZoneInfo.from_file(tzfile, key=tzname)
# TZ must specify a zoneinfo zone.
try:
tz = zoneinfo.ZoneInfo(tzenv)
# That worked, so we return this:
return tz
except zoneinfo.ZoneInfoNotFoundError:
# Nope, it's something like "PST4DST" etc, we can't handle that.
raise zoneinfo.ZoneInfoNotFoundError(
f"tzlocal() does not support non-zoneinfo timezones like {tzenv}. \n"
"Please use a timezone in the form of Continent/City"
) from None