From 59c1cb619a959c4d354db21817fb689fe25d9cd7 Mon Sep 17 00:00:00 2001
From: Christopher Whelan <topherwhelan@gmail.com>
Date: Mon, 7 Jan 2019 15:48:44 -0800
Subject: [PATCH] PERF: leverage tzlocal package to provide 2000x speedup for
 dateutil.tz.tzlocal operations

---
 LICENSES/TZLOCAL_LICENSE               |  19 +
 asv_bench/benchmarks/timeseries.py     |   6 +-
 pandas/_libs/src/__init__.py           |   0
 pandas/_libs/src/tzlocal/__init__.py   |   5 +
 pandas/_libs/src/tzlocal/unix.py       | 164 ++++++
 pandas/_libs/src/tzlocal/utils.py      |  38 ++
 pandas/_libs/src/tzlocal/win32.py      | 104 ++++
 pandas/_libs/src/tzlocal/windows_tz.py | 690 +++++++++++++++++++++++++
 pandas/_libs/tslib.pyx                 |  18 +-
 pandas/_libs/tslibs/conversion.pyx     |  44 +-
 pandas/_libs/tslibs/offsets.pyx        |   2 +-
 pandas/_libs/tslibs/period.pyx         |   6 +-
 pandas/_libs/tslibs/resolution.pyx     |   5 +-
 pandas/_libs/tslibs/timezones.pxd      |   3 +
 pandas/_libs/tslibs/timezones.pyx      |  22 +
 pandas/tests/tslibs/test_timezones.py  |  21 +
 16 files changed, 1136 insertions(+), 11 deletions(-)
 create mode 100644 LICENSES/TZLOCAL_LICENSE
 create mode 100644 pandas/_libs/src/__init__.py
 create mode 100644 pandas/_libs/src/tzlocal/__init__.py
 create mode 100644 pandas/_libs/src/tzlocal/unix.py
 create mode 100644 pandas/_libs/src/tzlocal/utils.py
 create mode 100644 pandas/_libs/src/tzlocal/win32.py
 create mode 100644 pandas/_libs/src/tzlocal/windows_tz.py

diff --git a/LICENSES/TZLOCAL_LICENSE b/LICENSES/TZLOCAL_LICENSE
new file mode 100644
index 0000000000000..9be1d2fe595ad
--- /dev/null
+++ b/LICENSES/TZLOCAL_LICENSE
@@ -0,0 +1,19 @@
+Copyright 2011-2017 Lennart Regebro
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/asv_bench/benchmarks/timeseries.py b/asv_bench/benchmarks/timeseries.py
index 6efd720d1acdd..46138a42f9cf3 100644
--- a/asv_bench/benchmarks/timeseries.py
+++ b/asv_bench/benchmarks/timeseries.py
@@ -62,7 +62,8 @@ def time_to_pydatetime(self, index_type):
 
 class TzLocalize(object):
 
-    params = [None, 'US/Eastern', 'UTC', dateutil.tz.tzutc()]
+    params = [None, 'US/Eastern', 'UTC', dateutil.tz.tzutc(),
+              dateutil.tz.tzlocal()]
     param_names = 'tz'
 
     def setup(self, tz):
@@ -394,7 +395,8 @@ def time_dup_string_tzoffset_dates(self, cache):
 
 class DatetimeAccessor(object):
 
-    params = [None, 'US/Eastern', 'UTC', dateutil.tz.tzutc()]
+    params = [None, 'US/Eastern', 'UTC', dateutil.tz.tzutc(),
+              dateutil.tz.tzlocal()]
     param_names = 'tz'
 
     def setup(self, tz):
diff --git a/pandas/_libs/src/__init__.py b/pandas/_libs/src/__init__.py
new file mode 100644
index 0000000000000..e69de29bb2d1d
diff --git a/pandas/_libs/src/tzlocal/__init__.py b/pandas/_libs/src/tzlocal/__init__.py
new file mode 100644
index 0000000000000..2f5337bebcfbd
--- /dev/null
+++ b/pandas/_libs/src/tzlocal/__init__.py
@@ -0,0 +1,5 @@
+import sys
+if sys.platform == 'win32':
+    from pandas._libs.src.tzlocal.win32 import get_localzone, reload_localzone
+else:
+    from pandas._libs.src.tzlocal.unix import get_localzone, reload_localzone
diff --git a/pandas/_libs/src/tzlocal/unix.py b/pandas/_libs/src/tzlocal/unix.py
new file mode 100644
index 0000000000000..1f8f357ef68de
--- /dev/null
+++ b/pandas/_libs/src/tzlocal/unix.py
@@ -0,0 +1,164 @@
+import os
+import pytz
+import re
+
+from pandas._libs.src.tzlocal import utils
+
+_cache_tz = None
+
+
+def _tz_from_env(tzenv):
+    if tzenv[0] == ':':
+        tzenv = tzenv[1:]
+
+    # TZ specifies a file
+    if os.path.exists(tzenv):
+        with open(tzenv, 'rb') as tzfile:
+            return pytz.tzfile.build_tzinfo('local', tzfile)
+
+    # TZ specifies a zoneinfo zone.
+    try:
+        tz = pytz.timezone(tzenv)
+        # That worked, so we return this:
+        return tz
+    except pytz.UnknownTimeZoneError:
+        raise pytz.UnknownTimeZoneError(
+            "tzlocal() does not support non-zoneinfo timezones like %s. \n"
+            "Please use a timezone in the form of Continent/City")
+
+
+def _try_tz_from_env():
+    tzenv = os.environ.get('TZ')
+    if tzenv:
+        try:
+            return _tz_from_env(tzenv)
+        except pytz.UnknownTimeZoneError:
+            pass
+
+
+def _get_localzone(_root='/'):
+    """Tries to find the local timezone configuration.
+
+    This method prefers finding the timezone name and passing that to pytz,
+    over passing in the localtime file, as in the later case the zoneinfo
+    name is unknown.
+
+    The parameter _root makes the function look for files like /etc/localtime
+    beneath the _root directory. This is primarily used by the tests.
+    In normal usage you call the function without parameters."""
+
+    tzenv = _try_tz_from_env()
+    if tzenv:
+        return tzenv
+
+    # Now look for distribution specific configuration files
+    # that contain the timezone name.
+    for configfile in ('etc/timezone', 'var/db/zoneinfo'):
+        tzpath = os.path.join(_root, configfile)
+        try:
+            with open(tzpath, 'rb') as tzfile:
+                data = tzfile.read()
+
+                # Issue #3 was that /etc/timezone was a zoneinfo file.
+                # That's a misconfiguration, but we need to handle it gracefully:
+                if data[:5] == b'TZif2':
+                    continue
+
+                etctz = data.strip().decode()
+                if not etctz:
+                    # Empty file, skip
+                    continue
+                for etctz in data.decode().splitlines():
+                    # Get rid of host definitions and comments:
+                    if ' ' in etctz:
+                        etctz, dummy = etctz.split(' ', 1)
+                    if '#' in etctz:
+                        etctz, dummy = etctz.split('#', 1)
+                    if not etctz:
+                        continue
+                    return pytz.timezone(etctz.replace(' ', '_'))
+        except IOError:
+            # File doesn't exist or is a directory
+            continue
+
+    # CentOS has a ZONE setting in /etc/sysconfig/clock,
+    # OpenSUSE has a TIMEZONE setting in /etc/sysconfig/clock and
+    # Gentoo has a TIMEZONE setting in /etc/conf.d/clock
+    # We look through these files for a timezone:
+
+    zone_re = re.compile(r'\s*ZONE\s*=\s*\"')
+    timezone_re = re.compile(r'\s*TIMEZONE\s*=\s*\"')
+    end_re = re.compile('\"')
+
+    for filename in ('etc/sysconfig/clock', 'etc/conf.d/clock'):
+        tzpath = os.path.join(_root, filename)
+        try:
+            with open(tzpath, 'rt') as tzfile:
+                data = tzfile.readlines()
+
+            for line in data:
+                # Look for the ZONE= setting.
+                match = zone_re.match(line)
+                if match is None:
+                    # No ZONE= setting. Look for the TIMEZONE= setting.
+                    match = timezone_re.match(line)
+                if match is not None:
+                    # Some setting existed
+                    line = line[match.end():]
+                    etctz = line[:end_re.search(line).start()]
+
+                    # We found a timezone
+                    return pytz.timezone(etctz.replace(' ', '_'))
+        except IOError:
+            # File doesn't exist or is a directory
+            continue
+
+    # systemd distributions use symlinks that include the zone name,
+    # see manpage of localtime(5) and timedatectl(1)
+    tzpath = os.path.join(_root, 'etc/localtime')
+    if os.path.exists(tzpath) and os.path.islink(tzpath):
+        tzpath = os.path.realpath(tzpath)
+        start = tzpath.find("/")+1
+        while start is not 0:
+            tzpath = tzpath[start:]
+            try:
+                return pytz.timezone(tzpath)
+            except pytz.UnknownTimeZoneError:
+                pass
+            start = tzpath.find("/")+1
+
+    # Are we under Termux on Android? It's not officially supported, because
+    # there is no reasonable way to run tests for this, but let's make an effort.
+    if os.path.exists('/system/bin/getprop'):
+        import subprocess
+        androidtz = subprocess.check_output(['getprop', 'persist.sys.timezone'])
+        return pytz.timezone(androidtz.strip().decode())
+
+    # No explicit setting existed. Use localtime
+    for filename in ('etc/localtime', 'usr/local/etc/localtime'):
+        tzpath = os.path.join(_root, filename)
+
+        if not os.path.exists(tzpath):
+            continue
+        with open(tzpath, 'rb') as tzfile:
+            return pytz.tzfile.build_tzinfo('local', tzfile)
+
+    raise pytz.UnknownTimeZoneError('Can not find any timezone configuration')
+
+
+def get_localzone():
+    """Get the computers configured local timezone, if any."""
+    global _cache_tz
+    if _cache_tz is None:
+        _cache_tz = _get_localzone()
+
+    utils.assert_tz_offset(_cache_tz)
+    return _cache_tz
+
+
+def reload_localzone():
+    """Reload the cached localzone. You need to call this if the timezone has changed."""
+    global _cache_tz
+    _cache_tz = _get_localzone()
+    utils.assert_tz_offset(_cache_tz)
+    return _cache_tz
diff --git a/pandas/_libs/src/tzlocal/utils.py b/pandas/_libs/src/tzlocal/utils.py
new file mode 100644
index 0000000000000..bd9d663e88e7c
--- /dev/null
+++ b/pandas/_libs/src/tzlocal/utils.py
@@ -0,0 +1,38 @@
+# -*- coding: utf-8 -*-
+import datetime
+
+
+def get_system_offset():
+    """Get system's timezone offset using built-in library time.
+
+    For the Timezone constants (altzone, daylight, timezone, and tzname), the
+    value is determined by the timezone rules in effect at module load time or
+    the last time tzset() is called and may be incorrect for times in the past.
+
+    To keep compatibility with Windows, we're always importing time module here.
+    """
+    import time
+    if time.daylight and time.localtime().tm_isdst > 0:
+        return -time.altzone
+    else:
+        return -time.timezone
+
+
+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):
+    """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."""
+    tz_offset = get_tz_offset(tz)
+    system_offset = get_system_offset()
+    if tz_offset != system_offset:
+        msg = ('Timezone offset does not match system offset: {0} != {1}. '
+               'Please, check your config files.').format(
+                   tz_offset, system_offset
+               )
+        raise ValueError(msg)
diff --git a/pandas/_libs/src/tzlocal/win32.py b/pandas/_libs/src/tzlocal/win32.py
new file mode 100644
index 0000000000000..eaa32e88536dc
--- /dev/null
+++ b/pandas/_libs/src/tzlocal/win32.py
@@ -0,0 +1,104 @@
+try:
+    import _winreg as winreg
+except ImportError:
+    import winreg
+
+import pytz
+
+from pandas._libs.src.tzlocal.windows_tz import win_tz
+from pandas._libs.src.tzlocal import utils
+
+_cache_tz = None
+
+
+def valuestodict(key):
+    """Convert a registry key's values to a dictionary."""
+    dict = {}
+    size = winreg.QueryInfoKey(key)[1]
+    for i in range(size):
+        data = winreg.EnumValue(key, i)
+        dict[data[0]] = data[1]
+    return dict
+
+
+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.
+    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 Vista?)
+
+        # 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:
+        # Windows 2000 or XP
+
+        # This is the localized name:
+        tzwin = keyvalues['StandardName']
+
+        # Open the list of timezones to look up the real name:
+        TZKEYNAME = r"SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones"
+        tzkey = winreg.OpenKey(handle, TZKEYNAME)
+
+        # Now, match this value to Time Zone information
+        tzkeyname = None
+        for i in range(winreg.QueryInfoKey(tzkey)[0]):
+            subkey = winreg.EnumKey(tzkey, i)
+            sub = winreg.OpenKey(tzkey, subkey)
+            data = valuestodict(sub)
+            sub.Close()
+            try:
+                if data['Std'] == tzwin:
+                    tzkeyname = subkey
+                    break
+            except KeyError:
+                # This timezone didn't have proper configuration.
+                # Ignore it.
+                pass
+
+        tzkey.Close()
+        handle.Close()
+
+    if tzkeyname is None:
+        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 pytz.UnknownTimeZoneError('Can not find timezone ' + tzkeyname)
+
+    return timezone
+
+
+def get_localzone():
+    """Returns the zoneinfo-based tzinfo object that matches the Windows-configured timezone."""
+    global _cache_tz
+    if _cache_tz is None:
+        _cache_tz = pytz.timezone(get_localzone_name())
+
+    utils.assert_tz_offset(_cache_tz)
+    return _cache_tz
+
+
+def reload_localzone():
+    """Reload the cached localzone. You need to call this if the timezone has changed."""
+    global _cache_tz
+    _cache_tz = pytz.timezone(get_localzone_name())
+    utils.assert_tz_offset(_cache_tz)
+    return _cache_tz
diff --git a/pandas/_libs/src/tzlocal/windows_tz.py b/pandas/_libs/src/tzlocal/windows_tz.py
new file mode 100644
index 0000000000000..123980b80bf08
--- /dev/null
+++ b/pandas/_libs/src/tzlocal/windows_tz.py
@@ -0,0 +1,690 @@
+# This file is autogenerated by the update_windows_mapping.py script
+# Do not edit.
+win_tz = {'AUS Central Standard Time': 'Australia/Darwin',
+ 'AUS Eastern Standard Time': 'Australia/Sydney',
+ 'Afghanistan Standard Time': 'Asia/Kabul',
+ 'Alaskan Standard Time': 'America/Anchorage',
+ 'Aleutian Standard Time': 'America/Adak',
+ 'Altai Standard Time': 'Asia/Barnaul',
+ 'Arab Standard Time': 'Asia/Riyadh',
+ 'Arabian Standard Time': 'Asia/Dubai',
+ 'Arabic Standard Time': 'Asia/Baghdad',
+ 'Argentina Standard Time': 'America/Buenos_Aires',
+ 'Astrakhan Standard Time': 'Europe/Astrakhan',
+ 'Atlantic Standard Time': 'America/Halifax',
+ 'Aus Central W. Standard Time': 'Australia/Eucla',
+ 'Azerbaijan Standard Time': 'Asia/Baku',
+ 'Azores Standard Time': 'Atlantic/Azores',
+ 'Bahia Standard Time': 'America/Bahia',
+ 'Bangladesh Standard Time': 'Asia/Dhaka',
+ 'Belarus Standard Time': 'Europe/Minsk',
+ 'Bougainville Standard Time': 'Pacific/Bougainville',
+ 'Canada Central Standard Time': 'America/Regina',
+ 'Cape Verde Standard Time': 'Atlantic/Cape_Verde',
+ 'Caucasus Standard Time': 'Asia/Yerevan',
+ 'Cen. Australia Standard Time': 'Australia/Adelaide',
+ 'Central America Standard Time': 'America/Guatemala',
+ 'Central Asia Standard Time': 'Asia/Almaty',
+ 'Central Brazilian Standard Time': 'America/Cuiaba',
+ 'Central Europe Standard Time': 'Europe/Budapest',
+ 'Central European Standard Time': 'Europe/Warsaw',
+ 'Central Pacific Standard Time': 'Pacific/Guadalcanal',
+ 'Central Standard Time': 'America/Chicago',
+ 'Central Standard Time (Mexico)': 'America/Mexico_City',
+ 'Chatham Islands Standard Time': 'Pacific/Chatham',
+ 'China Standard Time': 'Asia/Shanghai',
+ 'Cuba Standard Time': 'America/Havana',
+ 'Dateline Standard Time': 'Etc/GMT+12',
+ 'E. Africa Standard Time': 'Africa/Nairobi',
+ 'E. Australia Standard Time': 'Australia/Brisbane',
+ 'E. Europe Standard Time': 'Europe/Chisinau',
+ 'E. South America Standard Time': 'America/Sao_Paulo',
+ 'Easter Island Standard Time': 'Pacific/Easter',
+ 'Eastern Standard Time': 'America/New_York',
+ 'Eastern Standard Time (Mexico)': 'America/Cancun',
+ 'Egypt Standard Time': 'Africa/Cairo',
+ 'Ekaterinburg Standard Time': 'Asia/Yekaterinburg',
+ 'FLE Standard Time': 'Europe/Kiev',
+ 'Fiji Standard Time': 'Pacific/Fiji',
+ 'GMT Standard Time': 'Europe/London',
+ 'GTB Standard Time': 'Europe/Bucharest',
+ 'Georgian Standard Time': 'Asia/Tbilisi',
+ 'Greenland Standard Time': 'America/Godthab',
+ 'Greenwich Standard Time': 'Atlantic/Reykjavik',
+ 'Haiti Standard Time': 'America/Port-au-Prince',
+ 'Hawaiian Standard Time': 'Pacific/Honolulu',
+ 'India Standard Time': 'Asia/Calcutta',
+ 'Iran Standard Time': 'Asia/Tehran',
+ 'Israel Standard Time': 'Asia/Jerusalem',
+ 'Jordan Standard Time': 'Asia/Amman',
+ 'Kaliningrad Standard Time': 'Europe/Kaliningrad',
+ 'Korea Standard Time': 'Asia/Seoul',
+ 'Libya Standard Time': 'Africa/Tripoli',
+ 'Line Islands Standard Time': 'Pacific/Kiritimati',
+ 'Lord Howe Standard Time': 'Australia/Lord_Howe',
+ 'Magadan Standard Time': 'Asia/Magadan',
+ 'Magallanes Standard Time': 'America/Punta_Arenas',
+ 'Marquesas Standard Time': 'Pacific/Marquesas',
+ 'Mauritius Standard Time': 'Indian/Mauritius',
+ 'Middle East Standard Time': 'Asia/Beirut',
+ 'Montevideo Standard Time': 'America/Montevideo',
+ 'Morocco Standard Time': 'Africa/Casablanca',
+ 'Mountain Standard Time': 'America/Denver',
+ 'Mountain Standard Time (Mexico)': 'America/Chihuahua',
+ 'Myanmar Standard Time': 'Asia/Rangoon',
+ 'N. Central Asia Standard Time': 'Asia/Novosibirsk',
+ 'Namibia Standard Time': 'Africa/Windhoek',
+ 'Nepal Standard Time': 'Asia/Katmandu',
+ 'New Zealand Standard Time': 'Pacific/Auckland',
+ 'Newfoundland Standard Time': 'America/St_Johns',
+ 'Norfolk Standard Time': 'Pacific/Norfolk',
+ 'North Asia East Standard Time': 'Asia/Irkutsk',
+ 'North Asia Standard Time': 'Asia/Krasnoyarsk',
+ 'North Korea Standard Time': 'Asia/Pyongyang',
+ 'Omsk Standard Time': 'Asia/Omsk',
+ 'Pacific SA Standard Time': 'America/Santiago',
+ 'Pacific Standard Time': 'America/Los_Angeles',
+ 'Pacific Standard Time (Mexico)': 'America/Tijuana',
+ 'Pakistan Standard Time': 'Asia/Karachi',
+ 'Paraguay Standard Time': 'America/Asuncion',
+ 'Romance Standard Time': 'Europe/Paris',
+ 'Russia Time Zone 10': 'Asia/Srednekolymsk',
+ 'Russia Time Zone 11': 'Asia/Kamchatka',
+ 'Russia Time Zone 3': 'Europe/Samara',
+ 'Russian Standard Time': 'Europe/Moscow',
+ 'SA Eastern Standard Time': 'America/Cayenne',
+ 'SA Pacific Standard Time': 'America/Bogota',
+ 'SA Western Standard Time': 'America/La_Paz',
+ 'SE Asia Standard Time': 'Asia/Bangkok',
+ 'Saint Pierre Standard Time': 'America/Miquelon',
+ 'Sakhalin Standard Time': 'Asia/Sakhalin',
+ 'Samoa Standard Time': 'Pacific/Apia',
+ 'Saratov Standard Time': 'Europe/Saratov',
+ 'Singapore Standard Time': 'Asia/Singapore',
+ 'South Africa Standard Time': 'Africa/Johannesburg',
+ 'Sri Lanka Standard Time': 'Asia/Colombo',
+ 'Syria Standard Time': 'Asia/Damascus',
+ 'Taipei Standard Time': 'Asia/Taipei',
+ 'Tasmania Standard Time': 'Australia/Hobart',
+ 'Tocantins Standard Time': 'America/Araguaina',
+ 'Tokyo Standard Time': 'Asia/Tokyo',
+ 'Tomsk Standard Time': 'Asia/Tomsk',
+ 'Tonga Standard Time': 'Pacific/Tongatapu',
+ 'Transbaikal Standard Time': 'Asia/Chita',
+ 'Turkey Standard Time': 'Europe/Istanbul',
+ 'Turks And Caicos Standard Time': 'America/Grand_Turk',
+ 'US Eastern Standard Time': 'America/Indianapolis',
+ 'US Mountain Standard Time': 'America/Phoenix',
+ 'UTC': 'Etc/GMT',
+ 'UTC+12': 'Etc/GMT-12',
+ 'UTC+13': 'Etc/GMT-13',
+ 'UTC-02': 'Etc/GMT+2',
+ 'UTC-08': 'Etc/GMT+8',
+ 'UTC-09': 'Etc/GMT+9',
+ 'UTC-11': 'Etc/GMT+11',
+ 'Ulaanbaatar Standard Time': 'Asia/Ulaanbaatar',
+ 'Venezuela Standard Time': 'America/Caracas',
+ 'Vladivostok Standard Time': 'Asia/Vladivostok',
+ 'W. Australia Standard Time': 'Australia/Perth',
+ 'W. Central Africa Standard Time': 'Africa/Lagos',
+ 'W. Europe Standard Time': 'Europe/Berlin',
+ 'W. Mongolia Standard Time': 'Asia/Hovd',
+ 'West Asia Standard Time': 'Asia/Tashkent',
+ 'West Bank Standard Time': 'Asia/Hebron',
+ 'West Pacific Standard Time': 'Pacific/Port_Moresby',
+ 'Yakutsk Standard Time': 'Asia/Yakutsk'}
+
+# Old name for the win_tz variable:
+tz_names = win_tz
+
+tz_win = {'Africa/Abidjan': 'Greenwich Standard Time',
+ 'Africa/Accra': 'Greenwich Standard Time',
+ 'Africa/Addis_Ababa': 'E. Africa Standard Time',
+ 'Africa/Algiers': 'W. Central Africa Standard Time',
+ 'Africa/Asmera': 'E. Africa Standard Time',
+ 'Africa/Bamako': 'Greenwich Standard Time',
+ 'Africa/Bangui': 'W. Central Africa Standard Time',
+ 'Africa/Banjul': 'Greenwich Standard Time',
+ 'Africa/Bissau': 'Greenwich Standard Time',
+ 'Africa/Blantyre': 'South Africa Standard Time',
+ 'Africa/Brazzaville': 'W. Central Africa Standard Time',
+ 'Africa/Bujumbura': 'South Africa Standard Time',
+ 'Africa/Cairo': 'Egypt Standard Time',
+ 'Africa/Casablanca': 'Morocco Standard Time',
+ 'Africa/Ceuta': 'Romance Standard Time',
+ 'Africa/Conakry': 'Greenwich Standard Time',
+ 'Africa/Dakar': 'Greenwich Standard Time',
+ 'Africa/Dar_es_Salaam': 'E. Africa Standard Time',
+ 'Africa/Djibouti': 'E. Africa Standard Time',
+ 'Africa/Douala': 'W. Central Africa Standard Time',
+ 'Africa/El_Aaiun': 'Morocco Standard Time',
+ 'Africa/Freetown': 'Greenwich Standard Time',
+ 'Africa/Gaborone': 'South Africa Standard Time',
+ 'Africa/Harare': 'South Africa Standard Time',
+ 'Africa/Johannesburg': 'South Africa Standard Time',
+ 'Africa/Juba': 'E. Africa Standard Time',
+ 'Africa/Kampala': 'E. Africa Standard Time',
+ 'Africa/Khartoum': 'E. Africa Standard Time',
+ 'Africa/Kigali': 'South Africa Standard Time',
+ 'Africa/Kinshasa': 'W. Central Africa Standard Time',
+ 'Africa/Lagos': 'W. Central Africa Standard Time',
+ 'Africa/Libreville': 'W. Central Africa Standard Time',
+ 'Africa/Lome': 'Greenwich Standard Time',
+ 'Africa/Luanda': 'W. Central Africa Standard Time',
+ 'Africa/Lubumbashi': 'South Africa Standard Time',
+ 'Africa/Lusaka': 'South Africa Standard Time',
+ 'Africa/Malabo': 'W. Central Africa Standard Time',
+ 'Africa/Maputo': 'South Africa Standard Time',
+ 'Africa/Maseru': 'South Africa Standard Time',
+ 'Africa/Mbabane': 'South Africa Standard Time',
+ 'Africa/Mogadishu': 'E. Africa Standard Time',
+ 'Africa/Monrovia': 'Greenwich Standard Time',
+ 'Africa/Nairobi': 'E. Africa Standard Time',
+ 'Africa/Ndjamena': 'W. Central Africa Standard Time',
+ 'Africa/Niamey': 'W. Central Africa Standard Time',
+ 'Africa/Nouakchott': 'Greenwich Standard Time',
+ 'Africa/Ouagadougou': 'Greenwich Standard Time',
+ 'Africa/Porto-Novo': 'W. Central Africa Standard Time',
+ 'Africa/Sao_Tome': 'Greenwich Standard Time',
+ 'Africa/Timbuktu': 'Greenwich Standard Time',
+ 'Africa/Tripoli': 'Libya Standard Time',
+ 'Africa/Tunis': 'W. Central Africa Standard Time',
+ 'Africa/Windhoek': 'Namibia Standard Time',
+ 'America/Adak': 'Aleutian Standard Time',
+ 'America/Anchorage': 'Alaskan Standard Time',
+ 'America/Anguilla': 'SA Western Standard Time',
+ 'America/Antigua': 'SA Western Standard Time',
+ 'America/Araguaina': 'Tocantins Standard Time',
+ 'America/Argentina/La_Rioja': 'Argentina Standard Time',
+ 'America/Argentina/Rio_Gallegos': 'Argentina Standard Time',
+ 'America/Argentina/Salta': 'Argentina Standard Time',
+ 'America/Argentina/San_Juan': 'Argentina Standard Time',
+ 'America/Argentina/San_Luis': 'Argentina Standard Time',
+ 'America/Argentina/Tucuman': 'Argentina Standard Time',
+ 'America/Argentina/Ushuaia': 'Argentina Standard Time',
+ 'America/Aruba': 'SA Western Standard Time',
+ 'America/Asuncion': 'Paraguay Standard Time',
+ 'America/Atka': 'Aleutian Standard Time',
+ 'America/Bahia': 'Bahia Standard Time',
+ 'America/Bahia_Banderas': 'Central Standard Time (Mexico)',
+ 'America/Barbados': 'SA Western Standard Time',
+ 'America/Belem': 'SA Eastern Standard Time',
+ 'America/Belize': 'Central America Standard Time',
+ 'America/Blanc-Sablon': 'SA Western Standard Time',
+ 'America/Boa_Vista': 'SA Western Standard Time',
+ 'America/Bogota': 'SA Pacific Standard Time',
+ 'America/Boise': 'Mountain Standard Time',
+ 'America/Buenos_Aires': 'Argentina Standard Time',
+ 'America/Cambridge_Bay': 'Mountain Standard Time',
+ 'America/Campo_Grande': 'Central Brazilian Standard Time',
+ 'America/Cancun': 'Eastern Standard Time (Mexico)',
+ 'America/Caracas': 'Venezuela Standard Time',
+ 'America/Catamarca': 'Argentina Standard Time',
+ 'America/Cayenne': 'SA Eastern Standard Time',
+ 'America/Cayman': 'SA Pacific Standard Time',
+ 'America/Chicago': 'Central Standard Time',
+ 'America/Chihuahua': 'Mountain Standard Time (Mexico)',
+ 'America/Coral_Harbour': 'SA Pacific Standard Time',
+ 'America/Cordoba': 'Argentina Standard Time',
+ 'America/Costa_Rica': 'Central America Standard Time',
+ 'America/Creston': 'US Mountain Standard Time',
+ 'America/Cuiaba': 'Central Brazilian Standard Time',
+ 'America/Curacao': 'SA Western Standard Time',
+ 'America/Danmarkshavn': 'UTC',
+ 'America/Dawson': 'Pacific Standard Time',
+ 'America/Dawson_Creek': 'US Mountain Standard Time',
+ 'America/Denver': 'Mountain Standard Time',
+ 'America/Detroit': 'Eastern Standard Time',
+ 'America/Dominica': 'SA Western Standard Time',
+ 'America/Edmonton': 'Mountain Standard Time',
+ 'America/Eirunepe': 'SA Pacific Standard Time',
+ 'America/El_Salvador': 'Central America Standard Time',
+ 'America/Ensenada': 'Pacific Standard Time (Mexico)',
+ 'America/Fort_Nelson': 'US Mountain Standard Time',
+ 'America/Fortaleza': 'SA Eastern Standard Time',
+ 'America/Glace_Bay': 'Atlantic Standard Time',
+ 'America/Godthab': 'Greenland Standard Time',
+ 'America/Goose_Bay': 'Atlantic Standard Time',
+ 'America/Grand_Turk': 'Turks And Caicos Standard Time',
+ 'America/Grenada': 'SA Western Standard Time',
+ 'America/Guadeloupe': 'SA Western Standard Time',
+ 'America/Guatemala': 'Central America Standard Time',
+ 'America/Guayaquil': 'SA Pacific Standard Time',
+ 'America/Guyana': 'SA Western Standard Time',
+ 'America/Halifax': 'Atlantic Standard Time',
+ 'America/Havana': 'Cuba Standard Time',
+ 'America/Hermosillo': 'US Mountain Standard Time',
+ 'America/Indiana/Knox': 'Central Standard Time',
+ 'America/Indiana/Marengo': 'US Eastern Standard Time',
+ 'America/Indiana/Petersburg': 'Eastern Standard Time',
+ 'America/Indiana/Tell_City': 'Central Standard Time',
+ 'America/Indiana/Vevay': 'US Eastern Standard Time',
+ 'America/Indiana/Vincennes': 'Eastern Standard Time',
+ 'America/Indiana/Winamac': 'Eastern Standard Time',
+ 'America/Indianapolis': 'US Eastern Standard Time',
+ 'America/Inuvik': 'Mountain Standard Time',
+ 'America/Iqaluit': 'Eastern Standard Time',
+ 'America/Jamaica': 'SA Pacific Standard Time',
+ 'America/Jujuy': 'Argentina Standard Time',
+ 'America/Juneau': 'Alaskan Standard Time',
+ 'America/Kentucky/Monticello': 'Eastern Standard Time',
+ 'America/Knox_IN': 'Central Standard Time',
+ 'America/Kralendijk': 'SA Western Standard Time',
+ 'America/La_Paz': 'SA Western Standard Time',
+ 'America/Lima': 'SA Pacific Standard Time',
+ 'America/Los_Angeles': 'Pacific Standard Time',
+ 'America/Louisville': 'Eastern Standard Time',
+ 'America/Lower_Princes': 'SA Western Standard Time',
+ 'America/Maceio': 'SA Eastern Standard Time',
+ 'America/Managua': 'Central America Standard Time',
+ 'America/Manaus': 'SA Western Standard Time',
+ 'America/Marigot': 'SA Western Standard Time',
+ 'America/Martinique': 'SA Western Standard Time',
+ 'America/Matamoros': 'Central Standard Time',
+ 'America/Mazatlan': 'Mountain Standard Time (Mexico)',
+ 'America/Mendoza': 'Argentina Standard Time',
+ 'America/Menominee': 'Central Standard Time',
+ 'America/Merida': 'Central Standard Time (Mexico)',
+ 'America/Metlakatla': 'Alaskan Standard Time',
+ 'America/Mexico_City': 'Central Standard Time (Mexico)',
+ 'America/Miquelon': 'Saint Pierre Standard Time',
+ 'America/Moncton': 'Atlantic Standard Time',
+ 'America/Monterrey': 'Central Standard Time (Mexico)',
+ 'America/Montevideo': 'Montevideo Standard Time',
+ 'America/Montreal': 'Eastern Standard Time',
+ 'America/Montserrat': 'SA Western Standard Time',
+ 'America/Nassau': 'Eastern Standard Time',
+ 'America/New_York': 'Eastern Standard Time',
+ 'America/Nipigon': 'Eastern Standard Time',
+ 'America/Nome': 'Alaskan Standard Time',
+ 'America/Noronha': 'UTC-02',
+ 'America/North_Dakota/Beulah': 'Central Standard Time',
+ 'America/North_Dakota/Center': 'Central Standard Time',
+ 'America/North_Dakota/New_Salem': 'Central Standard Time',
+ 'America/Ojinaga': 'Mountain Standard Time',
+ 'America/Panama': 'SA Pacific Standard Time',
+ 'America/Pangnirtung': 'Eastern Standard Time',
+ 'America/Paramaribo': 'SA Eastern Standard Time',
+ 'America/Phoenix': 'US Mountain Standard Time',
+ 'America/Port-au-Prince': 'Haiti Standard Time',
+ 'America/Port_of_Spain': 'SA Western Standard Time',
+ 'America/Porto_Acre': 'SA Pacific Standard Time',
+ 'America/Porto_Velho': 'SA Western Standard Time',
+ 'America/Puerto_Rico': 'SA Western Standard Time',
+ 'America/Punta_Arenas': 'Magallanes Standard Time',
+ 'America/Rainy_River': 'Central Standard Time',
+ 'America/Rankin_Inlet': 'Central Standard Time',
+ 'America/Recife': 'SA Eastern Standard Time',
+ 'America/Regina': 'Canada Central Standard Time',
+ 'America/Resolute': 'Central Standard Time',
+ 'America/Rio_Branco': 'SA Pacific Standard Time',
+ 'America/Santa_Isabel': 'Pacific Standard Time (Mexico)',
+ 'America/Santarem': 'SA Eastern Standard Time',
+ 'America/Santiago': 'Pacific SA Standard Time',
+ 'America/Santo_Domingo': 'SA Western Standard Time',
+ 'America/Sao_Paulo': 'E. South America Standard Time',
+ 'America/Scoresbysund': 'Azores Standard Time',
+ 'America/Shiprock': 'Mountain Standard Time',
+ 'America/Sitka': 'Alaskan Standard Time',
+ 'America/St_Barthelemy': 'SA Western Standard Time',
+ 'America/St_Johns': 'Newfoundland Standard Time',
+ 'America/St_Kitts': 'SA Western Standard Time',
+ 'America/St_Lucia': 'SA Western Standard Time',
+ 'America/St_Thomas': 'SA Western Standard Time',
+ 'America/St_Vincent': 'SA Western Standard Time',
+ 'America/Swift_Current': 'Canada Central Standard Time',
+ 'America/Tegucigalpa': 'Central America Standard Time',
+ 'America/Thule': 'Atlantic Standard Time',
+ 'America/Thunder_Bay': 'Eastern Standard Time',
+ 'America/Tijuana': 'Pacific Standard Time (Mexico)',
+ 'America/Toronto': 'Eastern Standard Time',
+ 'America/Tortola': 'SA Western Standard Time',
+ 'America/Vancouver': 'Pacific Standard Time',
+ 'America/Virgin': 'SA Western Standard Time',
+ 'America/Whitehorse': 'Pacific Standard Time',
+ 'America/Winnipeg': 'Central Standard Time',
+ 'America/Yakutat': 'Alaskan Standard Time',
+ 'America/Yellowknife': 'Mountain Standard Time',
+ 'Antarctica/Casey': 'Central Pacific Standard Time',
+ 'Antarctica/Davis': 'SE Asia Standard Time',
+ 'Antarctica/DumontDUrville': 'West Pacific Standard Time',
+ 'Antarctica/Macquarie': 'Central Pacific Standard Time',
+ 'Antarctica/Mawson': 'West Asia Standard Time',
+ 'Antarctica/McMurdo': 'New Zealand Standard Time',
+ 'Antarctica/Palmer': 'Magallanes Standard Time',
+ 'Antarctica/Rothera': 'SA Eastern Standard Time',
+ 'Antarctica/South_Pole': 'New Zealand Standard Time',
+ 'Antarctica/Syowa': 'E. Africa Standard Time',
+ 'Antarctica/Vostok': 'Central Asia Standard Time',
+ 'Arctic/Longyearbyen': 'W. Europe Standard Time',
+ 'Asia/Aden': 'Arab Standard Time',
+ 'Asia/Almaty': 'Central Asia Standard Time',
+ 'Asia/Amman': 'Jordan Standard Time',
+ 'Asia/Anadyr': 'Russia Time Zone 11',
+ 'Asia/Aqtau': 'West Asia Standard Time',
+ 'Asia/Aqtobe': 'West Asia Standard Time',
+ 'Asia/Ashgabat': 'West Asia Standard Time',
+ 'Asia/Ashkhabad': 'West Asia Standard Time',
+ 'Asia/Atyrau': 'West Asia Standard Time',
+ 'Asia/Baghdad': 'Arabic Standard Time',
+ 'Asia/Bahrain': 'Arab Standard Time',
+ 'Asia/Baku': 'Azerbaijan Standard Time',
+ 'Asia/Bangkok': 'SE Asia Standard Time',
+ 'Asia/Barnaul': 'Altai Standard Time',
+ 'Asia/Beirut': 'Middle East Standard Time',
+ 'Asia/Bishkek': 'Central Asia Standard Time',
+ 'Asia/Brunei': 'Singapore Standard Time',
+ 'Asia/Calcutta': 'India Standard Time',
+ 'Asia/Chita': 'Transbaikal Standard Time',
+ 'Asia/Choibalsan': 'Ulaanbaatar Standard Time',
+ 'Asia/Chongqing': 'China Standard Time',
+ 'Asia/Chungking': 'China Standard Time',
+ 'Asia/Colombo': 'Sri Lanka Standard Time',
+ 'Asia/Dacca': 'Bangladesh Standard Time',
+ 'Asia/Damascus': 'Syria Standard Time',
+ 'Asia/Dhaka': 'Bangladesh Standard Time',
+ 'Asia/Dili': 'Tokyo Standard Time',
+ 'Asia/Dubai': 'Arabian Standard Time',
+ 'Asia/Dushanbe': 'West Asia Standard Time',
+ 'Asia/Famagusta': 'Turkey Standard Time',
+ 'Asia/Gaza': 'West Bank Standard Time',
+ 'Asia/Harbin': 'China Standard Time',
+ 'Asia/Hebron': 'West Bank Standard Time',
+ 'Asia/Hong_Kong': 'China Standard Time',
+ 'Asia/Hovd': 'W. Mongolia Standard Time',
+ 'Asia/Irkutsk': 'North Asia East Standard Time',
+ 'Asia/Jakarta': 'SE Asia Standard Time',
+ 'Asia/Jayapura': 'Tokyo Standard Time',
+ 'Asia/Jerusalem': 'Israel Standard Time',
+ 'Asia/Kabul': 'Afghanistan Standard Time',
+ 'Asia/Kamchatka': 'Russia Time Zone 11',
+ 'Asia/Karachi': 'Pakistan Standard Time',
+ 'Asia/Kashgar': 'Central Asia Standard Time',
+ 'Asia/Katmandu': 'Nepal Standard Time',
+ 'Asia/Khandyga': 'Yakutsk Standard Time',
+ 'Asia/Krasnoyarsk': 'North Asia Standard Time',
+ 'Asia/Kuala_Lumpur': 'Singapore Standard Time',
+ 'Asia/Kuching': 'Singapore Standard Time',
+ 'Asia/Kuwait': 'Arab Standard Time',
+ 'Asia/Macao': 'China Standard Time',
+ 'Asia/Macau': 'China Standard Time',
+ 'Asia/Magadan': 'Magadan Standard Time',
+ 'Asia/Makassar': 'Singapore Standard Time',
+ 'Asia/Manila': 'Singapore Standard Time',
+ 'Asia/Muscat': 'Arabian Standard Time',
+ 'Asia/Nicosia': 'GTB Standard Time',
+ 'Asia/Novokuznetsk': 'North Asia Standard Time',
+ 'Asia/Novosibirsk': 'N. Central Asia Standard Time',
+ 'Asia/Omsk': 'Omsk Standard Time',
+ 'Asia/Oral': 'West Asia Standard Time',
+ 'Asia/Phnom_Penh': 'SE Asia Standard Time',
+ 'Asia/Pontianak': 'SE Asia Standard Time',
+ 'Asia/Pyongyang': 'North Korea Standard Time',
+ 'Asia/Qatar': 'Arab Standard Time',
+ 'Asia/Qyzylorda': 'Central Asia Standard Time',
+ 'Asia/Rangoon': 'Myanmar Standard Time',
+ 'Asia/Riyadh': 'Arab Standard Time',
+ 'Asia/Saigon': 'SE Asia Standard Time',
+ 'Asia/Sakhalin': 'Sakhalin Standard Time',
+ 'Asia/Samarkand': 'West Asia Standard Time',
+ 'Asia/Seoul': 'Korea Standard Time',
+ 'Asia/Shanghai': 'China Standard Time',
+ 'Asia/Singapore': 'Singapore Standard Time',
+ 'Asia/Srednekolymsk': 'Russia Time Zone 10',
+ 'Asia/Taipei': 'Taipei Standard Time',
+ 'Asia/Tashkent': 'West Asia Standard Time',
+ 'Asia/Tbilisi': 'Georgian Standard Time',
+ 'Asia/Tehran': 'Iran Standard Time',
+ 'Asia/Tel_Aviv': 'Israel Standard Time',
+ 'Asia/Thimbu': 'Bangladesh Standard Time',
+ 'Asia/Thimphu': 'Bangladesh Standard Time',
+ 'Asia/Tokyo': 'Tokyo Standard Time',
+ 'Asia/Tomsk': 'Tomsk Standard Time',
+ 'Asia/Ujung_Pandang': 'Singapore Standard Time',
+ 'Asia/Ulaanbaatar': 'Ulaanbaatar Standard Time',
+ 'Asia/Ulan_Bator': 'Ulaanbaatar Standard Time',
+ 'Asia/Urumqi': 'Central Asia Standard Time',
+ 'Asia/Ust-Nera': 'Vladivostok Standard Time',
+ 'Asia/Vientiane': 'SE Asia Standard Time',
+ 'Asia/Vladivostok': 'Vladivostok Standard Time',
+ 'Asia/Yakutsk': 'Yakutsk Standard Time',
+ 'Asia/Yekaterinburg': 'Ekaterinburg Standard Time',
+ 'Asia/Yerevan': 'Caucasus Standard Time',
+ 'Atlantic/Azores': 'Azores Standard Time',
+ 'Atlantic/Bermuda': 'Atlantic Standard Time',
+ 'Atlantic/Canary': 'GMT Standard Time',
+ 'Atlantic/Cape_Verde': 'Cape Verde Standard Time',
+ 'Atlantic/Faeroe': 'GMT Standard Time',
+ 'Atlantic/Jan_Mayen': 'W. Europe Standard Time',
+ 'Atlantic/Madeira': 'GMT Standard Time',
+ 'Atlantic/Reykjavik': 'Greenwich Standard Time',
+ 'Atlantic/South_Georgia': 'UTC-02',
+ 'Atlantic/St_Helena': 'Greenwich Standard Time',
+ 'Atlantic/Stanley': 'SA Eastern Standard Time',
+ 'Australia/ACT': 'AUS Eastern Standard Time',
+ 'Australia/Adelaide': 'Cen. Australia Standard Time',
+ 'Australia/Brisbane': 'E. Australia Standard Time',
+ 'Australia/Broken_Hill': 'Cen. Australia Standard Time',
+ 'Australia/Canberra': 'AUS Eastern Standard Time',
+ 'Australia/Currie': 'Tasmania Standard Time',
+ 'Australia/Darwin': 'AUS Central Standard Time',
+ 'Australia/Eucla': 'Aus Central W. Standard Time',
+ 'Australia/Hobart': 'Tasmania Standard Time',
+ 'Australia/LHI': 'Lord Howe Standard Time',
+ 'Australia/Lindeman': 'E. Australia Standard Time',
+ 'Australia/Lord_Howe': 'Lord Howe Standard Time',
+ 'Australia/Melbourne': 'AUS Eastern Standard Time',
+ 'Australia/NSW': 'AUS Eastern Standard Time',
+ 'Australia/North': 'AUS Central Standard Time',
+ 'Australia/Perth': 'W. Australia Standard Time',
+ 'Australia/Queensland': 'E. Australia Standard Time',
+ 'Australia/South': 'Cen. Australia Standard Time',
+ 'Australia/Sydney': 'AUS Eastern Standard Time',
+ 'Australia/Tasmania': 'Tasmania Standard Time',
+ 'Australia/Victoria': 'AUS Eastern Standard Time',
+ 'Australia/West': 'W. Australia Standard Time',
+ 'Australia/Yancowinna': 'Cen. Australia Standard Time',
+ 'Brazil/Acre': 'SA Pacific Standard Time',
+ 'Brazil/DeNoronha': 'UTC-02',
+ 'Brazil/East': 'E. South America Standard Time',
+ 'Brazil/West': 'SA Western Standard Time',
+ 'CST6CDT': 'Central Standard Time',
+ 'Canada/Atlantic': 'Atlantic Standard Time',
+ 'Canada/Central': 'Central Standard Time',
+ 'Canada/Eastern': 'Eastern Standard Time',
+ 'Canada/Mountain': 'Mountain Standard Time',
+ 'Canada/Newfoundland': 'Newfoundland Standard Time',
+ 'Canada/Pacific': 'Pacific Standard Time',
+ 'Canada/Saskatchewan': 'Canada Central Standard Time',
+ 'Canada/Yukon': 'Pacific Standard Time',
+ 'Chile/Continental': 'Pacific SA Standard Time',
+ 'Chile/EasterIsland': 'Easter Island Standard Time',
+ 'Cuba': 'Cuba Standard Time',
+ 'EST5EDT': 'Eastern Standard Time',
+ 'Egypt': 'Egypt Standard Time',
+ 'Eire': 'GMT Standard Time',
+ 'Etc/GMT': 'UTC',
+ 'Etc/GMT+1': 'Cape Verde Standard Time',
+ 'Etc/GMT+10': 'Hawaiian Standard Time',
+ 'Etc/GMT+11': 'UTC-11',
+ 'Etc/GMT+12': 'Dateline Standard Time',
+ 'Etc/GMT+2': 'UTC-02',
+ 'Etc/GMT+3': 'SA Eastern Standard Time',
+ 'Etc/GMT+4': 'SA Western Standard Time',
+ 'Etc/GMT+5': 'SA Pacific Standard Time',
+ 'Etc/GMT+6': 'Central America Standard Time',
+ 'Etc/GMT+7': 'US Mountain Standard Time',
+ 'Etc/GMT+8': 'UTC-08',
+ 'Etc/GMT+9': 'UTC-09',
+ 'Etc/GMT-1': 'W. Central Africa Standard Time',
+ 'Etc/GMT-10': 'West Pacific Standard Time',
+ 'Etc/GMT-11': 'Central Pacific Standard Time',
+ 'Etc/GMT-12': 'UTC+12',
+ 'Etc/GMT-13': 'UTC+13',
+ 'Etc/GMT-14': 'Line Islands Standard Time',
+ 'Etc/GMT-2': 'South Africa Standard Time',
+ 'Etc/GMT-3': 'E. Africa Standard Time',
+ 'Etc/GMT-4': 'Arabian Standard Time',
+ 'Etc/GMT-5': 'West Asia Standard Time',
+ 'Etc/GMT-6': 'Central Asia Standard Time',
+ 'Etc/GMT-7': 'SE Asia Standard Time',
+ 'Etc/GMT-8': 'Singapore Standard Time',
+ 'Etc/GMT-9': 'Tokyo Standard Time',
+ 'Etc/UTC': 'UTC',
+ 'Europe/Amsterdam': 'W. Europe Standard Time',
+ 'Europe/Andorra': 'W. Europe Standard Time',
+ 'Europe/Astrakhan': 'Astrakhan Standard Time',
+ 'Europe/Athens': 'GTB Standard Time',
+ 'Europe/Belfast': 'GMT Standard Time',
+ 'Europe/Belgrade': 'Central Europe Standard Time',
+ 'Europe/Berlin': 'W. Europe Standard Time',
+ 'Europe/Bratislava': 'Central Europe Standard Time',
+ 'Europe/Brussels': 'Romance Standard Time',
+ 'Europe/Bucharest': 'GTB Standard Time',
+ 'Europe/Budapest': 'Central Europe Standard Time',
+ 'Europe/Busingen': 'W. Europe Standard Time',
+ 'Europe/Chisinau': 'E. Europe Standard Time',
+ 'Europe/Copenhagen': 'Romance Standard Time',
+ 'Europe/Dublin': 'GMT Standard Time',
+ 'Europe/Gibraltar': 'W. Europe Standard Time',
+ 'Europe/Guernsey': 'GMT Standard Time',
+ 'Europe/Helsinki': 'FLE Standard Time',
+ 'Europe/Isle_of_Man': 'GMT Standard Time',
+ 'Europe/Istanbul': 'Turkey Standard Time',
+ 'Europe/Jersey': 'GMT Standard Time',
+ 'Europe/Kaliningrad': 'Kaliningrad Standard Time',
+ 'Europe/Kiev': 'FLE Standard Time',
+ 'Europe/Kirov': 'Russian Standard Time',
+ 'Europe/Lisbon': 'GMT Standard Time',
+ 'Europe/Ljubljana': 'Central Europe Standard Time',
+ 'Europe/London': 'GMT Standard Time',
+ 'Europe/Luxembourg': 'W. Europe Standard Time',
+ 'Europe/Madrid': 'Romance Standard Time',
+ 'Europe/Malta': 'W. Europe Standard Time',
+ 'Europe/Mariehamn': 'FLE Standard Time',
+ 'Europe/Minsk': 'Belarus Standard Time',
+ 'Europe/Monaco': 'W. Europe Standard Time',
+ 'Europe/Moscow': 'Russian Standard Time',
+ 'Europe/Oslo': 'W. Europe Standard Time',
+ 'Europe/Paris': 'Romance Standard Time',
+ 'Europe/Podgorica': 'Central Europe Standard Time',
+ 'Europe/Prague': 'Central Europe Standard Time',
+ 'Europe/Riga': 'FLE Standard Time',
+ 'Europe/Rome': 'W. Europe Standard Time',
+ 'Europe/Samara': 'Russia Time Zone 3',
+ 'Europe/San_Marino': 'W. Europe Standard Time',
+ 'Europe/Sarajevo': 'Central European Standard Time',
+ 'Europe/Saratov': 'Saratov Standard Time',
+ 'Europe/Simferopol': 'Russian Standard Time',
+ 'Europe/Skopje': 'Central European Standard Time',
+ 'Europe/Sofia': 'FLE Standard Time',
+ 'Europe/Stockholm': 'W. Europe Standard Time',
+ 'Europe/Tallinn': 'FLE Standard Time',
+ 'Europe/Tirane': 'Central Europe Standard Time',
+ 'Europe/Tiraspol': 'E. Europe Standard Time',
+ 'Europe/Ulyanovsk': 'Astrakhan Standard Time',
+ 'Europe/Uzhgorod': 'FLE Standard Time',
+ 'Europe/Vaduz': 'W. Europe Standard Time',
+ 'Europe/Vatican': 'W. Europe Standard Time',
+ 'Europe/Vienna': 'W. Europe Standard Time',
+ 'Europe/Vilnius': 'FLE Standard Time',
+ 'Europe/Volgograd': 'Russian Standard Time',
+ 'Europe/Warsaw': 'Central European Standard Time',
+ 'Europe/Zagreb': 'Central European Standard Time',
+ 'Europe/Zaporozhye': 'FLE Standard Time',
+ 'Europe/Zurich': 'W. Europe Standard Time',
+ 'GB': 'GMT Standard Time',
+ 'GB-Eire': 'GMT Standard Time',
+ 'GMT+0': 'UTC',
+ 'GMT-0': 'UTC',
+ 'GMT0': 'UTC',
+ 'Greenwich': 'UTC',
+ 'Hongkong': 'China Standard Time',
+ 'Iceland': 'Greenwich Standard Time',
+ 'Indian/Antananarivo': 'E. Africa Standard Time',
+ 'Indian/Chagos': 'Central Asia Standard Time',
+ 'Indian/Christmas': 'SE Asia Standard Time',
+ 'Indian/Cocos': 'Myanmar Standard Time',
+ 'Indian/Comoro': 'E. Africa Standard Time',
+ 'Indian/Kerguelen': 'West Asia Standard Time',
+ 'Indian/Mahe': 'Mauritius Standard Time',
+ 'Indian/Maldives': 'West Asia Standard Time',
+ 'Indian/Mauritius': 'Mauritius Standard Time',
+ 'Indian/Mayotte': 'E. Africa Standard Time',
+ 'Indian/Reunion': 'Mauritius Standard Time',
+ 'Iran': 'Iran Standard Time',
+ 'Israel': 'Israel Standard Time',
+ 'Jamaica': 'SA Pacific Standard Time',
+ 'Japan': 'Tokyo Standard Time',
+ 'Kwajalein': 'UTC+12',
+ 'Libya': 'Libya Standard Time',
+ 'MST7MDT': 'Mountain Standard Time',
+ 'Mexico/BajaNorte': 'Pacific Standard Time (Mexico)',
+ 'Mexico/BajaSur': 'Mountain Standard Time (Mexico)',
+ 'Mexico/General': 'Central Standard Time (Mexico)',
+ 'NZ': 'New Zealand Standard Time',
+ 'NZ-CHAT': 'Chatham Islands Standard Time',
+ 'Navajo': 'Mountain Standard Time',
+ 'PRC': 'China Standard Time',
+ 'PST8PDT': 'Pacific Standard Time',
+ 'Pacific/Apia': 'Samoa Standard Time',
+ 'Pacific/Auckland': 'New Zealand Standard Time',
+ 'Pacific/Bougainville': 'Bougainville Standard Time',
+ 'Pacific/Chatham': 'Chatham Islands Standard Time',
+ 'Pacific/Easter': 'Easter Island Standard Time',
+ 'Pacific/Efate': 'Central Pacific Standard Time',
+ 'Pacific/Enderbury': 'UTC+13',
+ 'Pacific/Fakaofo': 'UTC+13',
+ 'Pacific/Fiji': 'Fiji Standard Time',
+ 'Pacific/Funafuti': 'UTC+12',
+ 'Pacific/Galapagos': 'Central America Standard Time',
+ 'Pacific/Gambier': 'UTC-09',
+ 'Pacific/Guadalcanal': 'Central Pacific Standard Time',
+ 'Pacific/Guam': 'West Pacific Standard Time',
+ 'Pacific/Honolulu': 'Hawaiian Standard Time',
+ 'Pacific/Johnston': 'Hawaiian Standard Time',
+ 'Pacific/Kiritimati': 'Line Islands Standard Time',
+ 'Pacific/Kosrae': 'Central Pacific Standard Time',
+ 'Pacific/Kwajalein': 'UTC+12',
+ 'Pacific/Majuro': 'UTC+12',
+ 'Pacific/Marquesas': 'Marquesas Standard Time',
+ 'Pacific/Midway': 'UTC-11',
+ 'Pacific/Nauru': 'UTC+12',
+ 'Pacific/Niue': 'UTC-11',
+ 'Pacific/Norfolk': 'Norfolk Standard Time',
+ 'Pacific/Noumea': 'Central Pacific Standard Time',
+ 'Pacific/Pago_Pago': 'UTC-11',
+ 'Pacific/Palau': 'Tokyo Standard Time',
+ 'Pacific/Pitcairn': 'UTC-08',
+ 'Pacific/Ponape': 'Central Pacific Standard Time',
+ 'Pacific/Port_Moresby': 'West Pacific Standard Time',
+ 'Pacific/Rarotonga': 'Hawaiian Standard Time',
+ 'Pacific/Saipan': 'West Pacific Standard Time',
+ 'Pacific/Samoa': 'UTC-11',
+ 'Pacific/Tahiti': 'Hawaiian Standard Time',
+ 'Pacific/Tarawa': 'UTC+12',
+ 'Pacific/Tongatapu': 'Tonga Standard Time',
+ 'Pacific/Truk': 'West Pacific Standard Time',
+ 'Pacific/Wake': 'UTC+12',
+ 'Pacific/Wallis': 'UTC+12',
+ 'Poland': 'Central European Standard Time',
+ 'Portugal': 'GMT Standard Time',
+ 'ROC': 'Taipei Standard Time',
+ 'ROK': 'Korea Standard Time',
+ 'Singapore': 'Singapore Standard Time',
+ 'Turkey': 'Turkey Standard Time',
+ 'US/Alaska': 'Alaskan Standard Time',
+ 'US/Aleutian': 'Aleutian Standard Time',
+ 'US/Arizona': 'US Mountain Standard Time',
+ 'US/Central': 'Central Standard Time',
+ 'US/Eastern': 'Eastern Standard Time',
+ 'US/Hawaii': 'Hawaiian Standard Time',
+ 'US/Indiana-Starke': 'Central Standard Time',
+ 'US/Michigan': 'Eastern Standard Time',
+ 'US/Mountain': 'Mountain Standard Time',
+ 'US/Pacific': 'Pacific Standard Time',
+ 'US/Samoa': 'UTC-11',
+ 'UTC': 'UTC',
+ 'Universal': 'UTC',
+ 'W-SU': 'Russian Standard Time',
+ 'Zulu': 'UTC'}
diff --git a/pandas/_libs/tslib.pyx b/pandas/_libs/tslib.pyx
index f932e236b5218..9e06852cfd79e 100644
--- a/pandas/_libs/tslib.pyx
+++ b/pandas/_libs/tslib.pyx
@@ -28,7 +28,8 @@ from pandas._libs.tslibs.np_datetime import OutOfBoundsDatetime
 from pandas._libs.tslibs.parsing import parse_datetime_string
 
 from pandas._libs.tslibs.timedeltas cimport cast_from_unit
-from pandas._libs.tslibs.timezones cimport is_utc, is_tzlocal, get_dst_info
+from pandas._libs.tslibs.timezones cimport (is_utc, is_tzlocal, get_dst_info,
+    get_tzlocal_tz)
 from pandas._libs.tslibs.timezones import UTC
 from pandas._libs.tslibs.conversion cimport (
     tz_convert_single, _TSObject, convert_datetime_to_tsobject,
@@ -101,7 +102,8 @@ def ints_to_pydatetime(int64_t[:] arr, object tz=None, object freq=None,
         int64_t[:] deltas
         Py_ssize_t pos
         npy_datetimestruct dts
-        object dt, new_tz
+        object dt, new_tz, orig_tz
+        bint tz_changed
         str typ
         int64_t value, delta, local_value
         ndarray[object] result = np.empty(n, dtype=object)
@@ -124,6 +126,15 @@ def ints_to_pydatetime(int64_t[:] arr, object tz=None, object freq=None,
         raise ValueError("box must be one of 'datetime', 'date', 'time' or"
                          " 'timestamp'")
 
+    orig_tz = tz
+    tz_changed = False
+
+    if is_tzlocal(tz):
+        new_tz = get_tzlocal_tz(tz)
+        if new_tz != tz:
+            tz_changed = True
+            tz = new_tz
+
     if is_utc(tz) or tz is None:
         for i in range(n):
             value = arr[i]
@@ -184,7 +195,8 @@ def ints_to_pydatetime(int64_t[:] arr, object tz=None, object freq=None,
                     new_tz = tz._tzinfos[tz._transition_info[pos]]
 
                     dt64_to_dtstruct(value + deltas[pos], &dts)
-                    result[i] = func_create(value, dts, new_tz, freq)
+                    tz_to_use = orig_tz if tz_changed else new_tz
+                    result[i] = func_create(value, dts, tz_to_use, freq)
 
     return result
 
diff --git a/pandas/_libs/tslibs/conversion.pyx b/pandas/_libs/tslibs/conversion.pyx
index 1c0adaaa288a9..bfb39f80992f3 100644
--- a/pandas/_libs/tslibs/conversion.pyx
+++ b/pandas/_libs/tslibs/conversion.pyx
@@ -33,7 +33,7 @@ from pandas._libs.tslibs.timedeltas cimport (cast_from_unit,
                                              delta_to_nanoseconds)
 from pandas._libs.tslibs.timezones cimport (
     is_utc, is_tzlocal, is_fixed_offset, get_utcoffset, get_dst_info,
-    get_timezone, maybe_get_tz, tz_compare)
+    get_timezone, maybe_get_tz, tz_compare, get_tzlocal_tz)
 from pandas._libs.tslibs.timezones import UTC
 from pandas._libs.tslibs.parsing import parse_datetime_string
 
@@ -541,9 +541,19 @@ cdef inline void localize_tso(_TSObject obj, tzinfo tz):
         int64_t local_val
         Py_ssize_t pos
         str typ
+        bint tz_changed
 
     assert obj.tzinfo is None
 
+    orig_tz = tz
+    tz_changed = False
+
+    if is_tzlocal(tz):
+        new_tz = get_tzlocal_tz(tz)
+        if new_tz != tz:
+            tz_changed = True
+            tz = new_tz
+
     if is_utc(tz):
         pass
     elif obj.value == NPY_NAT:
@@ -574,7 +584,12 @@ cdef inline void localize_tso(_TSObject obj, tzinfo tz):
             # so this branch will never be reached.
             pass
 
-    obj.tzinfo = tz
+    if tz_changed:
+        # We want to return tzlocal() if provided it, even if we map it
+        # to a real tz for performance reasons
+        obj.tzinfo = orig_tz
+    else:
+        obj.tzinfo = tz
 
 
 cdef inline datetime _localize_pydatetime(datetime dt, tzinfo tz):
@@ -652,6 +667,9 @@ cdef inline int64_t[:] _tz_convert_dst(int64_t[:] values, tzinfo tz,
         bint tz_is_local
 
     tz_is_local = is_tzlocal(tz)
+    if tz_is_local:
+        tz = get_tzlocal_tz(tz)
+        tz_is_local = is_tzlocal(tz)
 
     if not tz_is_local:
         # get_dst_info cannot extract offsets from tzlocal because its
@@ -763,6 +781,11 @@ cpdef int64_t tz_convert_single(int64_t val, object tz1, object tz2):
     if val == NPY_NAT:
         return val
 
+    if is_tzlocal(tz1):
+        tz1 = get_tzlocal_tz(tz1)
+    if is_tzlocal(tz2):
+        tz2 = get_tzlocal_tz(tz2)
+
     # Convert to UTC
     if is_tzlocal(tz1):
         utc_date = _tz_convert_tzlocal_utc(val, tz1, to_utc=True)
@@ -807,10 +830,16 @@ cdef inline int64_t[:] _tz_convert_one_way(int64_t[:] vals, object tz,
         int64_t[:] converted, result
         Py_ssize_t i, n = len(vals)
         int64_t val
+        bint tz_is_local
+
+    tz_is_local = is_tzlocal(tz)
+    if tz_is_local:
+        tz = get_tzlocal_tz(tz)
+        tz_is_local = is_tzlocal(tz)
 
     if not is_utc(get_timezone(tz)):
         converted = np.empty(n, dtype=np.int64)
-        if is_tzlocal(tz):
+        if tz_is_local:
             for i in range(n):
                 val = vals[i]
                 if val == NPY_NAT:
@@ -915,6 +944,9 @@ def tz_localize_to_utc(ndarray[int64_t] vals, object tz, object ambiguous=None,
 
     result = np.empty(n, dtype=np.int64)
 
+    if is_tzlocal(tz):
+        tz = get_tzlocal_tz(tz)
+
     if is_tzlocal(tz):
         for i in range(n):
             v = vals[i]
@@ -1222,6 +1254,9 @@ cdef int64_t[:] _normalize_local(int64_t[:] stamps, tzinfo tz):
         npy_datetimestruct dts
         int64_t delta, local_val
 
+    if is_tzlocal(tz):
+        tz = get_tzlocal_tz(tz)
+
     if is_tzlocal(tz):
         for i in range(n):
             if stamps[i] == NPY_NAT:
@@ -1301,6 +1336,9 @@ def is_date_array_normalized(int64_t[:] stamps, object tz=None):
         int64_t local_val, delta
         str typ
 
+    if is_tzlocal(tz):
+        tz = get_tzlocal_tz(tz)
+
     if tz is None or is_utc(tz):
         for i in range(n):
             dt64_to_dtstruct(stamps[i], &dts)
diff --git a/pandas/_libs/tslibs/offsets.pyx b/pandas/_libs/tslibs/offsets.pyx
index e28462f7103b9..fc9a8e26fe3d7 100644
--- a/pandas/_libs/tslibs/offsets.pyx
+++ b/pandas/_libs/tslibs/offsets.pyx
@@ -17,7 +17,7 @@ cimport numpy as cnp
 from numpy cimport int64_t
 cnp.import_array()
 
-
+cimport pandas._libs.tslibs
 from pandas._libs.tslibs cimport util
 from pandas._libs.tslibs.util cimport is_string_object, is_integer_object
 
diff --git a/pandas/_libs/tslibs/period.pyx b/pandas/_libs/tslibs/period.pyx
index e38e9a1ca5df6..ef7c003fa9032 100644
--- a/pandas/_libs/tslibs/period.pyx
+++ b/pandas/_libs/tslibs/period.pyx
@@ -32,7 +32,8 @@ cimport pandas._libs.tslibs.util as util
 from pandas._libs.tslibs.util cimport is_period_object, is_string_object
 
 from pandas._libs.tslibs.timestamps import Timestamp
-from pandas._libs.tslibs.timezones cimport is_utc, is_tzlocal, get_dst_info
+from pandas._libs.tslibs.timezones cimport (is_utc, is_tzlocal, get_dst_info,
+    get_tzlocal_tz)
 from pandas._libs.tslibs.timedeltas import Timedelta
 from pandas._libs.tslibs.timedeltas cimport delta_to_nanoseconds
 
@@ -1506,6 +1507,9 @@ cdef int64_t[:] localize_dt64arr_to_period(int64_t[:] stamps,
         npy_datetimestruct dts
         int64_t local_val
 
+    if is_tzlocal(tz):
+        tz = get_tzlocal_tz(tz)
+
     if is_utc(tz) or tz is None:
         with nogil:
             for i in range(n):
diff --git a/pandas/_libs/tslibs/resolution.pyx b/pandas/_libs/tslibs/resolution.pyx
index 13a4f5ba48557..4decb2b21ce6f 100644
--- a/pandas/_libs/tslibs/resolution.pyx
+++ b/pandas/_libs/tslibs/resolution.pyx
@@ -9,7 +9,7 @@ from pandas._libs.tslibs.np_datetime cimport (
     npy_datetimestruct, dt64_to_dtstruct)
 from pandas._libs.tslibs.frequencies cimport get_freq_code
 from pandas._libs.tslibs.timezones cimport (
-    is_utc, is_tzlocal, maybe_get_tz, get_dst_info)
+    is_utc, is_tzlocal, maybe_get_tz, get_dst_info, get_tzlocal_tz)
 from pandas._libs.tslibs.conversion cimport tz_convert_utc_to_tzlocal
 from pandas._libs.tslibs.ccalendar cimport get_days_in_month
 
@@ -50,6 +50,9 @@ cdef _reso_local(int64_t[:] stamps, object tz):
         npy_datetimestruct dts
         int64_t local_val, delta
 
+    if is_tzlocal(tz):
+        tz = get_tzlocal_tz(tz)
+
     if is_utc(tz) or tz is None:
         for i in range(n):
             if stamps[i] == NPY_NAT:
diff --git a/pandas/_libs/tslibs/timezones.pxd b/pandas/_libs/tslibs/timezones.pxd
index 50c4a41f97a82..c7902452ade70 100644
--- a/pandas/_libs/tslibs/timezones.pxd
+++ b/pandas/_libs/tslibs/timezones.pxd
@@ -3,6 +3,9 @@
 cpdef bint is_utc(object tz)
 cdef bint is_tzlocal(object tz)
 
+cpdef object get_tzlocal_tz(object tz)
+cpdef _set_tzlocal_tz(object tz)
+
 cdef bint treat_tz_as_pytz(object tz)
 cdef bint treat_tz_as_dateutil(object tz)
 
diff --git a/pandas/_libs/tslibs/timezones.pyx b/pandas/_libs/tslibs/timezones.pyx
index 43a35d77dd127..5031481d3cd34 100644
--- a/pandas/_libs/tslibs/timezones.pyx
+++ b/pandas/_libs/tslibs/timezones.pyx
@@ -12,12 +12,15 @@ from pytz.tzinfo import BaseTzInfo as _pytz_BaseTzInfo
 import pytz
 UTC = pytz.utc
 
+tzlocal_tz = None
 
 import numpy as np
 cimport numpy as cnp
 from numpy cimport int64_t
 cnp.import_array()
 
+import pandas._libs.src.tzlocal as tzlocal_package
+
 # ----------------------------------------------------------------------
 from pandas._libs.tslibs.util cimport (
     is_string_object, is_integer_object, get_nat)
@@ -34,6 +37,25 @@ cdef inline bint is_tzlocal(object tz):
     return isinstance(tz, _dateutil_tzlocal)
 
 
+cpdef object get_tzlocal_tz(object tz):
+    global tzlocal_tz
+    if tzlocal_tz is None:
+        local_tz = tzlocal_package.get_localzone()
+        tzlocal_tz = local_tz.zone
+
+    try:
+        return pytz.timezone(tzlocal_tz)
+    except pytz.exceptions.UnknownTimeZoneError:
+        tzlocal_tz = None
+
+    return tz
+
+
+cpdef _set_tzlocal_tz(object tz_str):
+    global tzlocal_tz
+    tzlocal_tz = str(tz_str)
+
+
 cdef inline bint treat_tz_as_pytz(object tz):
     return (hasattr(tz, '_utc_transition_times') and
             hasattr(tz, '_transition_info'))
diff --git a/pandas/tests/tslibs/test_timezones.py b/pandas/tests/tslibs/test_timezones.py
index 0255865dbdf71..4f4678ef39d29 100644
--- a/pandas/tests/tslibs/test_timezones.py
+++ b/pandas/tests/tslibs/test_timezones.py
@@ -49,6 +49,27 @@ def test_tzlocal_offset():
     assert ts.value + offset == Timestamp("2011-01-01").value
 
 
+def test_tzlocal_package():
+    orig_tzlocal_tz = timezones.get_tzlocal_tz(None)
+    # Check that we fall back to non-tzlocal code path if user has an invalid
+    # system tz set
+    timezones._set_tzlocal_tz('foo/bar')
+    ts = Timestamp("2011-01-01", tz=dateutil.tz.tzlocal())
+    assert ts.tz == dateutil.tz.tzlocal()
+
+    utc = pytz.utc
+    for tz in pytz.all_timezones:
+        # Check that all pytz timezones work
+        ts_tz = Timestamp("2011-01-01", tz=tz)
+        timezones._set_tzlocal_tz(tz)
+        ts_local = Timestamp("2011-01-01", tz=dateutil.tz.tzlocal())
+
+        assert ts_tz.astimezone(utc) == ts_local.astimezone(utc)
+        assert ts_local.tz == dateutil.tz.tzlocal()
+
+    timezones._set_tzlocal_tz(orig_tzlocal_tz.zone)
+
+
 @pytest.fixture(params=[
     (pytz.timezone("US/Eastern"), lambda tz, x: tz.localize(x)),
     (dateutil.tz.gettz("US/Eastern"), lambda tz, x: x.replace(tzinfo=tz))