py-kms/py2-kms/timezones.py

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2018-02-28 23:25:00 +01:00
#!/usr/bin/env python
# Copyright 2009 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
#
# Disable the invalid name warning as we are inheriting from a standard library
# object.
# pylint: disable-msg=C6409,W0212
"""
Stripped down version of `python-datetime-tz`
that only contains the "find local timezone" bits.
"""
import datetime
import os.path
import time
import warnings
import pytz
# Need to patch pytz.utc to have a _utcoffset so you can normalize/localize
# using it.
pytz.utc._utcoffset = datetime.timedelta()
timedelta = datetime.timedelta
def _tzinfome(tzinfo):
"""Gets a tzinfo object from a string.
Args:
tzinfo: A string (or string like) object, or a datetime.tzinfo object.
Returns:
An datetime.tzinfo object.
Raises:
UnknownTimeZoneError: If the timezone given can't be decoded.
"""
if not isinstance(tzinfo, datetime.tzinfo):
try:
tzinfo = pytz.timezone(tzinfo)
except AttributeError:
raise pytz.UnknownTimeZoneError("Unknown timezone!")
return tzinfo
# Our "local" timezone
_localtz = None
def localtz():
"""Get the local timezone.
Returns:
The localtime timezone as a tzinfo object.
"""
# pylint: disable-msg=W0603
global _localtz
if _localtz is None:
_localtz = detect_timezone()
return _localtz
def detect_timezone():
"""Try and detect the timezone that Python is currently running in.
We have a bunch of different methods for trying to figure this out (listed in
order they are attempted).
* Try and find /etc/timezone file (with timezone name).
* Try and find /etc/localtime file (with timezone data).
* Try and match a TZ to the current dst/offset/shortname.
Returns:
The detected local timezone as a tzinfo object
Raises:
pytz.UnknownTimeZoneError: If it was unable to detect a timezone.
"""
tz = _detect_timezone_etc_timezone()
if tz is not None:
return tz
tz = _detect_timezone_etc_localtime()
if tz is not None:
return tz
# Next we try and use a similiar method to what PHP does.
# We first try to search on time.tzname, time.timezone, time.daylight to
# match a pytz zone.
warnings.warn("Had to fall back to worst detection method (the 'PHP' "
"method).")
tz = _detect_timezone_php()
if tz is not None:
return tz
raise pytz.UnknownTimeZoneError("Unable to detect your timezone!")
def _detect_timezone_etc_timezone():
if os.path.exists("/etc/timezone"):
try:
tz = file("/etc/timezone").read().strip()
try:
return pytz.timezone(tz)
except (IOError, pytz.UnknownTimeZoneError), ei:
warnings.warn("Your /etc/timezone file references a timezone (%r) that"
" is not valid (%r)." % (tz, ei))
# Problem reading the /etc/timezone file
except IOError, eo:
warnings.warn("Could not access your /etc/timezone file: %s" % eo)
def _detect_timezone_etc_localtime():
matches = []
if os.path.exists("/etc/localtime"):
localtime = pytz.tzfile.build_tzinfo("/etc/localtime",
file("/etc/localtime"))
# See if we can find a "Human Name" for this..
for tzname in pytz.all_timezones:
tz = _tzinfome(tzname)
if dir(tz) != dir(localtime):
continue
for attrib in dir(tz):
# Ignore functions and specials
if callable(getattr(tz, attrib)) or attrib.startswith("__"):
continue
# This will always be different
if attrib == "zone" or attrib == "_tzinfos":
continue
if getattr(tz, attrib) != getattr(localtime, attrib):
break
# We get here iff break didn't happen, i.e. no meaningful attributes
# differ between tz and localtime
else:
matches.append(tzname)
#if len(matches) == 1:
# return _tzinfome(matches[0])
#else:
# # Warn the person about this!
# warning = "Could not get a human name for your timezone: "
# if len(matches) > 1:
# warning += ("We detected multiple matches for your /etc/localtime. "
# "(Matches where %s)" % matches)
# else:
# warning += "We detected no matches for your /etc/localtime."
# warnings.warn(warning)
#
# return localtime
if len(matches) > 0:
return _tzinfome(matches[0])
def _detect_timezone_php():
tomatch = (time.tzname[0], time.timezone, time.daylight)
now = datetime.datetime.now()
matches = []
for tzname in pytz.all_timezones:
try:
tz = pytz.timezone(tzname)
except IOError:
continue
try:
indst = tz.localize(now).timetuple()[-1]
if tomatch == (tz._tzname, -tz._utcoffset.seconds, indst):
matches.append(tzname)
# pylint: disable-msg=W0704
except AttributeError:
pass
if len(matches) > 1:
warnings.warn("We detected multiple matches for the timezone, choosing "
"the first %s. (Matches where %s)" % (matches[0], matches))
return pytz.timezone(matches[0])