| // Copyright (c) 2014, the timezone project authors. Please see the AUTHORS |
| // file for details. All rights reserved. Use of this source code is governed |
| // by a BSD-style license that can be found in the LICENSE file. |
| |
| // ignore_for_file: non_constant_identifier_names |
| |
| import 'dart:collection'; |
| import 'dart:typed_data'; |
| |
| /// Time Zone information file magic header "TZif" |
| const int _ziMagic = 1415211366; |
| |
| /// tzfile header structure |
| class _Header { |
| /// Header size |
| static int size = 6 * 4; |
| |
| /// The number of UTC/local indicators stored in the file. |
| final int tzh_ttisgmtcnt; |
| |
| /// The number of standard/wall indicators stored in the file. |
| final int tzh_ttisstdcnt; |
| |
| /// The number of leap seconds for which data is stored in the file. |
| final int tzh_leapcnt; |
| |
| /// The number of "transition times" for which data is stored in the file. |
| final int tzh_timecnt; |
| |
| /// The number of "local time types" for which data is stored in the file |
| /// (must not be zero). |
| final int tzh_typecnt; |
| |
| /// The number of characters of "timezone abbreviation strings" stored in the |
| /// file. |
| final int tzh_charcnt; |
| |
| _Header( |
| this.tzh_ttisgmtcnt, |
| this.tzh_ttisstdcnt, |
| this.tzh_leapcnt, |
| this.tzh_timecnt, |
| this.tzh_typecnt, |
| this.tzh_charcnt, |
| ); |
| |
| int dataLength(int longSize) { |
| final leapBytes = tzh_leapcnt * (longSize + 4); |
| final timeBytes = tzh_timecnt * (longSize + 1); |
| final typeBytes = tzh_typecnt * 6; |
| |
| return tzh_ttisgmtcnt + |
| tzh_ttisstdcnt + |
| leapBytes + |
| timeBytes + |
| typeBytes + |
| tzh_charcnt; |
| } |
| |
| factory _Header.fromBytes(List<int> rawData) { |
| final data = rawData is Uint8List ? rawData : Uint8List.fromList(rawData); |
| final bdata = ByteData.sublistView(data); |
| |
| final tzh_ttisgmtcnt = bdata.getInt32(0); |
| final tzh_ttisstdcnt = bdata.getInt32(4); |
| final tzh_leapcnt = bdata.getInt32(8); |
| final tzh_timecnt = bdata.getInt32(12); |
| final tzh_typecnt = bdata.getInt32(16); |
| final tzh_charcnt = bdata.getInt32(20); |
| |
| return _Header( |
| tzh_ttisgmtcnt, |
| tzh_ttisstdcnt, |
| tzh_leapcnt, |
| tzh_timecnt, |
| tzh_typecnt, |
| tzh_charcnt, |
| ); |
| } |
| } |
| |
| /// Read NUL-terminated string |
| String _readByteString(Uint8List data, int offset) { |
| var i = offset; |
| for (; i < data.length; i++) { |
| final byte = data[i]; |
| if (byte >= 1 && byte < 0x80) continue; |
| if (byte == 0) break; |
| throw FormatException('Not ASCII', data, i); |
| } |
| return String.fromCharCodes(data, offset, i); |
| } |
| |
| /// This exception is thrown when Zone Info data is invalid. |
| class InvalidZoneInfoDataException implements Exception { |
| final String msg; |
| |
| InvalidZoneInfoDataException(this.msg); |
| |
| @override |
| String toString() => msg; |
| } |
| |
| /// TimeZone data |
| class TimeZone { |
| /// Offset in seconds east of UTC. |
| final int offset; |
| |
| /// DST time. |
| final bool isDst; |
| |
| /// Index to abbreviation. |
| final int abbreviationIndex; |
| |
| const TimeZone( |
| this.offset, { |
| required this.isDst, |
| required this.abbreviationIndex, |
| }); |
| } |
| |
| /// Location data |
| class Location { |
| /// [Location] name |
| final String name; |
| |
| /// Time in seconds when the transitioning is occured. |
| final List<int> transitionAt; |
| |
| /// Transition zone index. |
| final List<int> transitionZone; |
| |
| /// List of abbreviations. |
| final List<String> abbreviations; |
| |
| /// List of [TimeZone]s. |
| final List<TimeZone> zones; |
| |
| /// Time in seconds when the leap seconds should be applied. |
| final List<int> leapAt; |
| |
| /// Amount of leap seconds that should be applied. |
| final List<int> leapDiff; |
| |
| /// Whether transition times associated with local time types are specified as |
| /// standard time or wall time. |
| final List<int> isStd; |
| |
| /// Whether transition times associated with local time types are specified as |
| /// UTC or local time. |
| final List<int> isUtc; |
| |
| Location( |
| this.name, |
| this.transitionAt, |
| this.transitionZone, |
| this.abbreviations, |
| this.zones, |
| this.leapAt, |
| this.leapDiff, |
| this.isStd, |
| this.isUtc, |
| ); |
| |
| /// Deserialize [Location] from bytes |
| factory Location.fromBytes(String name, List<int> rawData) { |
| final data = rawData is Uint8List ? rawData : Uint8List.fromList(rawData); |
| |
| final bdata = ByteData.sublistView(data); |
| |
| final magic1 = bdata.getUint32(0); |
| if (magic1 != _ziMagic) { |
| throw InvalidZoneInfoDataException('Invalid magic header "$magic1"'); |
| } |
| final version1 = bdata.getUint8(4); |
| |
| var offset = 20; |
| |
| switch (version1) { |
| case 0: |
| final header = _Header.fromBytes( |
| Uint8List.sublistView(bdata, offset, _Header.size), |
| ); |
| |
| // calculating data offsets |
| final dataOffset = offset + _Header.size; |
| final transitionAtOffset = dataOffset; |
| final transitionZoneOffset = |
| transitionAtOffset + header.tzh_timecnt * 5; |
| final abbreviationsOffset = |
| transitionZoneOffset + header.tzh_typecnt * 6; |
| final leapOffset = abbreviationsOffset + header.tzh_charcnt; |
| final stdOrWctOffset = leapOffset + header.tzh_leapcnt * 8; |
| final utcOrGmtOffset = stdOrWctOffset + header.tzh_ttisstdcnt; |
| |
| // read transitions |
| final transitionAt = <int>[]; |
| final transitionZone = <int>[]; |
| |
| offset = transitionAtOffset; |
| |
| for (var i = 0; i < header.tzh_timecnt; i++) { |
| transitionAt.add(bdata.getInt32(offset)); |
| offset += 4; |
| } |
| |
| for (var i = 0; i < header.tzh_timecnt; i++) { |
| transitionZone.add(bdata.getUint8(offset)); |
| offset += 1; |
| } |
| |
| // function to read from abbreviation buffer |
| final abbreviationsData = Uint8List.sublistView( |
| data, |
| abbreviationsOffset, |
| abbreviationsOffset + header.tzh_charcnt, |
| ); |
| final abbreviations = <String>[]; |
| final abbreviationsCache = HashMap<int, int>(); |
| int readAbbreviation(int offset) { |
| var result = abbreviationsCache[offset]; |
| if (result == null) { |
| result = abbreviations.length; |
| abbreviationsCache[offset] = result; |
| abbreviations.add(_readByteString(abbreviationsData, offset)); |
| } |
| return result; |
| } |
| |
| // read zones |
| final zones = <TimeZone>[]; |
| offset = transitionZoneOffset; |
| |
| for (var i = 0; i < header.tzh_typecnt; i++) { |
| final tt_gmtoff = bdata.getInt32(offset); |
| final tt_isdst = bdata.getInt8(offset + 4); |
| final tt_abbrind = bdata.getUint8(offset + 5); |
| offset += 6; |
| |
| zones.add( |
| TimeZone( |
| tt_gmtoff, |
| isDst: tt_isdst == 1, |
| abbreviationIndex: readAbbreviation(tt_abbrind), |
| ), |
| ); |
| } |
| |
| // read leap seconds |
| final leapAt = <int>[]; |
| final leapDiff = <int>[]; |
| |
| offset = leapOffset; |
| for (var i = 0; i < header.tzh_leapcnt; i++) { |
| leapAt.add(bdata.getInt32(offset)); |
| leapDiff.add(bdata.getInt32(offset + 4)); |
| offset += 5; |
| } |
| |
| // read std flags |
| final isStd = <int>[]; |
| |
| offset = stdOrWctOffset; |
| for (var i = 0; i < header.tzh_ttisstdcnt; i++) { |
| isStd.add(bdata.getUint8(offset)); |
| offset += 1; |
| } |
| |
| // read utc flags |
| final isUtc = <int>[]; |
| |
| offset = utcOrGmtOffset; |
| for (var i = 0; i < header.tzh_ttisgmtcnt; i++) { |
| isUtc.add(bdata.getUint8(offset)); |
| offset += 1; |
| } |
| |
| return Location( |
| name, |
| transitionAt, |
| transitionZone, |
| abbreviations, |
| zones, |
| leapAt, |
| leapDiff, |
| isStd, |
| isUtc, |
| ); |
| |
| case 50: |
| case 51: |
| // skip old version header/data |
| final header1 = _Header.fromBytes( |
| Uint8List.sublistView(bdata, offset, offset + _Header.size), |
| ); |
| offset += _Header.size + header1.dataLength(4); |
| |
| final magic2 = bdata.getUint32(offset); |
| if (magic2 != _ziMagic) { |
| throw InvalidZoneInfoDataException( |
| 'Invalid second magic header "$magic2"', |
| ); |
| } |
| |
| final version2 = bdata.getUint8(offset + 4); |
| if (version2 != version1) { |
| throw InvalidZoneInfoDataException( |
| 'Second version "$version2" doesn\'t match first version ' |
| '"$version1"', |
| ); |
| } |
| |
| offset += 20; |
| |
| final header2 = _Header.fromBytes( |
| Uint8List.sublistView(bdata, offset, offset + _Header.size), |
| ); |
| |
| // calculating data offsets |
| final dataOffset = offset + _Header.size; |
| final transitionAtOffset = dataOffset; |
| final transitionZoneOffset = |
| transitionAtOffset + header2.tzh_timecnt * 9; |
| final abbreviationsOffset = |
| transitionZoneOffset + header2.tzh_typecnt * 6; |
| final leapOffset = abbreviationsOffset + header2.tzh_charcnt; |
| final stdOrWctOffset = leapOffset + header2.tzh_leapcnt * 12; |
| final utcOrGmtOffset = stdOrWctOffset + header2.tzh_ttisstdcnt; |
| |
| // read transitions |
| final transitionAt = <int>[]; |
| final transitionZone = <int>[]; |
| |
| offset = transitionAtOffset; |
| |
| for (var i = 0; i < header2.tzh_timecnt; i++) { |
| transitionAt.add(bdata.getInt64(offset)); |
| offset += 8; |
| } |
| |
| for (var i = 0; i < header2.tzh_timecnt; i++) { |
| transitionZone.add(bdata.getUint8(offset)); |
| offset += 1; |
| } |
| |
| // function to read from abbreviation buffer |
| final abbreviationsData = Uint8List.sublistView( |
| data, |
| abbreviationsOffset, |
| abbreviationsOffset + header2.tzh_charcnt, |
| ); |
| final abbreviations = <String>[]; |
| final abbreviationsCache = HashMap<int, int>(); |
| int readAbbreviation(int offset) { |
| var result = abbreviationsCache[offset]; |
| if (result == null) { |
| result = abbreviations.length; |
| abbreviationsCache[offset] = result; |
| abbreviations.add(_readByteString(abbreviationsData, offset)); |
| } |
| return result; |
| } |
| |
| // read transition info |
| final zones = <TimeZone>[]; |
| offset = transitionZoneOffset; |
| |
| for (var i = 0; i < header2.tzh_typecnt; i++) { |
| final tt_gmtoff = bdata.getInt32(offset); |
| final tt_isdst = bdata.getInt8(offset + 4); |
| final tt_abbrind = bdata.getUint8(offset + 5); |
| offset += 6; |
| |
| zones.add( |
| TimeZone( |
| tt_gmtoff, |
| isDst: tt_isdst == 1, |
| abbreviationIndex: readAbbreviation(tt_abbrind), |
| ), |
| ); |
| } |
| |
| // read leap seconds |
| final leapAt = <int>[]; |
| final leapDiff = <int>[]; |
| |
| offset = leapOffset; |
| for (var i = 0; i < header2.tzh_leapcnt; i++) { |
| leapAt.add(bdata.getInt64(offset)); |
| leapDiff.add(bdata.getInt32(offset + 8)); |
| offset += 9; |
| } |
| |
| // read std flags |
| final isStd = <int>[]; |
| |
| offset = stdOrWctOffset; |
| for (var i = 0; i < header2.tzh_ttisstdcnt; i++) { |
| isStd.add(bdata.getUint8(offset)); |
| offset += 1; |
| } |
| |
| // read utc flags |
| final isUtc = <int>[]; |
| |
| offset = utcOrGmtOffset; |
| for (var i = 0; i < header2.tzh_ttisgmtcnt; i++) { |
| isUtc.add(bdata.getUint8(offset)); |
| offset += 1; |
| } |
| |
| return Location( |
| name, |
| transitionAt, |
| transitionZone, |
| abbreviations, |
| zones, |
| leapAt, |
| leapDiff, |
| isStd, |
| isUtc, |
| ); |
| |
| default: |
| throw InvalidZoneInfoDataException('Unknown version: $version1'); |
| } |
| } |
| } |
