| Alexander Belopolsky | 5d0c598 | 2016-07-22 18:47:04 -0400 | [diff] [blame] | 1 | import sys |
| 2 | import os |
| 3 | import struct |
| 4 | from array import array |
| 5 | from collections import namedtuple |
| 6 | from datetime import datetime, timedelta |
| 7 | |
| 8 | ttinfo = namedtuple('ttinfo', ['tt_gmtoff', 'tt_isdst', 'tt_abbrind']) |
| 9 | |
| 10 | class TZInfo: |
| 11 | def __init__(self, transitions, type_indices, ttis, abbrs): |
| 12 | self.transitions = transitions |
| 13 | self.type_indices = type_indices |
| 14 | self.ttis = ttis |
| 15 | self.abbrs = abbrs |
| 16 | |
| 17 | @classmethod |
| 18 | def fromfile(cls, fileobj): |
| 19 | if fileobj.read(4).decode() != "TZif": |
| 20 | raise ValueError("not a zoneinfo file") |
| 21 | fileobj.seek(20) |
| 22 | header = fileobj.read(24) |
| 23 | tzh = (tzh_ttisgmtcnt, tzh_ttisstdcnt, tzh_leapcnt, |
| 24 | tzh_timecnt, tzh_typecnt, tzh_charcnt) = struct.unpack(">6l", header) |
| 25 | transitions = array('i') |
| 26 | transitions.fromfile(fileobj, tzh_timecnt) |
| 27 | if sys.byteorder != 'big': |
| 28 | transitions.byteswap() |
| 29 | |
| 30 | type_indices = array('B') |
| 31 | type_indices.fromfile(fileobj, tzh_timecnt) |
| 32 | |
| 33 | ttis = [] |
| 34 | for i in range(tzh_typecnt): |
| 35 | ttis.append(ttinfo._make(struct.unpack(">lbb", fileobj.read(6)))) |
| 36 | |
| 37 | abbrs = fileobj.read(tzh_charcnt) |
| 38 | |
| 39 | self = cls(transitions, type_indices, ttis, abbrs) |
| 40 | self.tzh = tzh |
| 41 | |
| 42 | return self |
| 43 | |
| 44 | def dump(self, stream, start=None, end=None): |
| 45 | for j, (trans, i) in enumerate(zip(self.transitions, self.type_indices)): |
| 46 | utc = datetime.utcfromtimestamp(trans) |
| 47 | tti = self.ttis[i] |
| 48 | lmt = datetime.utcfromtimestamp(trans + tti.tt_gmtoff) |
| 49 | abbrind = tti.tt_abbrind |
| 50 | abbr = self.abbrs[abbrind:self.abbrs.find(0, abbrind)].decode() |
| 51 | if j > 0: |
| 52 | prev_tti = self.ttis[self.type_indices[j - 1]] |
| 53 | shift = " %+g" % ((tti.tt_gmtoff - prev_tti.tt_gmtoff) / 3600) |
| 54 | else: |
| 55 | shift = '' |
| 56 | print("%s UTC = %s %-5s isdst=%d" % (utc, lmt, abbr, tti[1]) + shift, file=stream) |
| 57 | |
| 58 | @classmethod |
| 59 | def zonelist(cls, zonedir='/usr/share/zoneinfo'): |
| 60 | zones = [] |
| 61 | for root, _, files in os.walk(zonedir): |
| 62 | for f in files: |
| 63 | p = os.path.join(root, f) |
| 64 | with open(p, 'rb') as o: |
| 65 | magic = o.read(4) |
| 66 | if magic == b'TZif': |
| 67 | zones.append(p[len(zonedir) + 1:]) |
| 68 | return zones |
| 69 | |
| 70 | if __name__ == '__main__': |
| 71 | if len(sys.argv) < 2: |
| 72 | zones = TZInfo.zonelist() |
| 73 | for z in zones: |
| 74 | print(z) |
| 75 | sys.exit() |
| 76 | filepath = sys.argv[1] |
| 77 | if not filepath.startswith('/'): |
| 78 | filepath = os.path.join('/usr/share/zoneinfo', filepath) |
| 79 | with open(filepath, 'rb') as fileobj: |
| 80 | tzi = TZInfo.fromfile(fileobj) |
| 81 | tzi.dump(sys.stdout) |