etc/Windows/py-kms/timezones.py

   1 #!/usr/bin/python
   2 #
   3 # Copyright 2009 Google Inc.
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #      http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16 #
  17 #
  18 # Disable the invalid name warning as we are inheriting from a standard library
  19 # object.
  20 # pylint: disable-msg=C6409,W0212
  21
  22 """
  23 Stripped down version of `python-datetime-tz` that only contains the "find local
  24 timezone" bits.
  25 """
  26
  27 import datetime
  28 import os.path
  29 import time
  30 import warnings
  31 import pytz
  32
  33
  34 # Need to patch pytz.utc to have a _utcoffset so you can normalize/localize
  35 # using it.
  36 pytz.utc._utcoffset = datetime.timedelta()
  37
  38
  39 timedelta = datetime.timedelta
  40
  41
  42 def _tzinfome(tzinfo):
  43   """Gets a tzinfo object from a string.
  44
  45   Args:
  46     tzinfo: A string (or string like) object, or a datetime.tzinfo object.
  47
  48   Returns:
  49     An datetime.tzinfo object.
  50
  51   Raises:
  52     UnknownTimeZoneError: If the timezone given can't be decoded.
  53   """
  54   if not isinstance(tzinfo, datetime.tzinfo):
  55     try:
  56       tzinfo = pytz.timezone(tzinfo)
  57     except AttributeError:
  58       raise pytz.UnknownTimeZoneError("Unknown timezone!")
  59   return tzinfo
  60
  61
  62 # Our "local" timezone
  63 _localtz = None
  64
  65
  66 def localtz():
  67   """Get the local timezone.
  68
  69   Returns:
  70     The localtime timezone as a tzinfo object.
  71   """
  72   # pylint: disable-msg=W0603
  73   global _localtz
  74   if _localtz is None:
  75     _localtz = detect_timezone()
  76   return _localtz
  77
  78
  79 def detect_timezone():
  80   """Try and detect the timezone that Python is currently running in.
  81
  82   We have a bunch of different methods for trying to figure this out (listed in
  83   order they are attempted).
  84     * Try and find /etc/timezone file (with timezone name).
  85     * Try and find /etc/localtime file (with timezone data).
  86     * Try and match a TZ to the current dst/offset/shortname.
  87
  88   Returns:
  89     The detected local timezone as a tzinfo object
  90
  91   Raises:
  92     pytz.UnknownTimeZoneError: If it was unable to detect a timezone.
  93   """
  94
  95   tz = _detect_timezone_etc_timezone()
  96   if tz is not None:
  97     return tz
  98
  99   tz = _detect_timezone_etc_localtime()
 100   if tz is not None:
 101     return tz
 102
 103   # Next we try and use a similiar method to what PHP does.
 104   # We first try to search on time.tzname, time.timezone, time.daylight to
 105   # match a pytz zone.
 106   warnings.warn("Had to fall back to worst detection method (the 'PHP' "
 107                 "method).")
 108
 109   tz = _detect_timezone_php()
 110   if tz is not None:
 111     return tz
 112
 113   raise pytz.UnknownTimeZoneError("Unable to detect your timezone!")
 114
 115 def _detect_timezone_etc_timezone():
 116   if os.path.exists("/etc/timezone"):
 117     try:
 118       tz = file("/etc/timezone").read().strip()
 119       try:
 120         return pytz.timezone(tz)
 121       except (IOError, pytz.UnknownTimeZoneError), ei:
 122         warnings.warn("Your /etc/timezone file references a timezone (%r) that"
 123                       " is not valid (%r)." % (tz, ei))
 124
 125     # Problem reading the /etc/timezone file
 126     except IOError, eo:
 127       warnings.warn("Could not access your /etc/timezone file: %s" % eo)
 128
 129
 130 def _detect_timezone_etc_localtime():
 131   matches = []
 132   if os.path.exists("/etc/localtime"):
 133     localtime = pytz.tzfile.build_tzinfo("/etc/localtime",
 134                                          file("/etc/localtime"))
 135
 136     # See if we can find a "Human Name" for this..
 137     for tzname in pytz.all_timezones:
 138       tz = _tzinfome(tzname)
 139
 140       if dir(tz) != dir(localtime):
 141         continue
 142
 143       for attrib in dir(tz):
 144         # Ignore functions and specials
 145         if callable(getattr(tz, attrib)) or attrib.startswith("__"):
 146           continue
 147
 148         # This will always be different
 149         if attrib == "zone" or attrib == "_tzinfos":
 150           continue
 151
 152         if getattr(tz, attrib) != getattr(localtime, attrib):
 153           break
 154
 155       # We get here iff break didn't happen, i.e. no meaningful attributes
 156       # differ between tz and localtime
 157       else:
 158         matches.append(tzname)
 159
 160     #if len(matches) == 1:
 161     #  return _tzinfome(matches[0])
 162     #else:
 163     #  # Warn the person about this!
 164     #  warning = "Could not get a human name for your timezone: "
 165     #  if len(matches) > 1:
 166     #    warning += ("We detected multiple matches for your /etc/localtime. "
 167     #                "(Matches where %s)" % matches)
 168     #  else:
 169     #    warning += "We detected no matches for your /etc/localtime."
 170     #  warnings.warn(warning)
 171     #
 172     #  return localtime
 173     if len(matches) > 0:
 174         return _tzinfome(matches[0])
 175
 176
 177 def _detect_timezone_php():
 178   tomatch = (time.tzname[0], time.timezone, time.daylight)
 179   now = datetime.datetime.now()
 180
 181   matches = []
 182   for tzname in pytz.all_timezones:
 183     try:
 184       tz = pytz.timezone(tzname)
 185     except IOError:
 186       continue
 187
 188     try:
 189       indst = tz.localize(now).timetuple()[-1]
 190
 191       if tomatch == (tz._tzname, -tz._utcoffset.seconds, indst):
 192         matches.append(tzname)
 193
 194     # pylint: disable-msg=W0704
 195     except AttributeError:
 196       pass
 197
 198   if len(matches) > 1:
 199     warnings.warn("We detected multiple matches for the timezone, choosing "
 200                   "the first %s. (Matches where %s)" % (matches[0], matches))
 201     return pytz.timezone(matches[0])
 202