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82 lines
2.7 KiB
Python
82 lines
2.7 KiB
Python
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import sys
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import os
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import struct
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from array import array
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from collections import namedtuple
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from datetime import datetime, timedelta
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ttinfo = namedtuple('ttinfo', ['tt_gmtoff', 'tt_isdst', 'tt_abbrind'])
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class TZInfo:
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def __init__(self, transitions, type_indices, ttis, abbrs):
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self.transitions = transitions
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self.type_indices = type_indices
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self.ttis = ttis
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self.abbrs = abbrs
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@classmethod
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def fromfile(cls, fileobj):
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if fileobj.read(4).decode() != "TZif":
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raise ValueError("not a zoneinfo file")
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fileobj.seek(20)
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header = fileobj.read(24)
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tzh = (tzh_ttisgmtcnt, tzh_ttisstdcnt, tzh_leapcnt,
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tzh_timecnt, tzh_typecnt, tzh_charcnt) = struct.unpack(">6l", header)
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transitions = array('i')
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transitions.fromfile(fileobj, tzh_timecnt)
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if sys.byteorder != 'big':
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transitions.byteswap()
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type_indices = array('B')
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type_indices.fromfile(fileobj, tzh_timecnt)
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ttis = []
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for i in range(tzh_typecnt):
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ttis.append(ttinfo._make(struct.unpack(">lbb", fileobj.read(6))))
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abbrs = fileobj.read(tzh_charcnt)
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self = cls(transitions, type_indices, ttis, abbrs)
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self.tzh = tzh
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return self
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def dump(self, stream, start=None, end=None):
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for j, (trans, i) in enumerate(zip(self.transitions, self.type_indices)):
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utc = datetime.utcfromtimestamp(trans)
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tti = self.ttis[i]
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lmt = datetime.utcfromtimestamp(trans + tti.tt_gmtoff)
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abbrind = tti.tt_abbrind
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abbr = self.abbrs[abbrind:self.abbrs.find(0, abbrind)].decode()
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if j > 0:
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prev_tti = self.ttis[self.type_indices[j - 1]]
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shift = " %+g" % ((tti.tt_gmtoff - prev_tti.tt_gmtoff) / 3600)
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else:
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shift = ''
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print("%s UTC = %s %-5s isdst=%d" % (utc, lmt, abbr, tti[1]) + shift, file=stream)
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@classmethod
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def zonelist(cls, zonedir='/usr/share/zoneinfo'):
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zones = []
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for root, _, files in os.walk(zonedir):
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for f in files:
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p = os.path.join(root, f)
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with open(p, 'rb') as o:
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magic = o.read(4)
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if magic == b'TZif':
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zones.append(p[len(zonedir) + 1:])
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return zones
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if __name__ == '__main__':
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if len(sys.argv) < 2:
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zones = TZInfo.zonelist()
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for z in zones:
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print(z)
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sys.exit()
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filepath = sys.argv[1]
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if not filepath.startswith('/'):
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filepath = os.path.join('/usr/share/zoneinfo', filepath)
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with open(filepath, 'rb') as fileobj:
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tzi = TZInfo.fromfile(fileobj)
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tzi.dump(sys.stdout)
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