local tz_info_mt = require "luatz.tzinfo".tz_info_mt local tt_info_mt = require "luatz.tzinfo".tt_info_mt local read_int32be, read_int64be if string.unpack then -- Only available in Lua 5.3+ function read_int32be(fd) local data, err = fd:read(4) if data == nil then return nil, err end return string.unpack(">i4", data) end function read_int64be(fd) local data, err = fd:read(8) if data == nil then return nil, err end return string.unpack(">i8", data) end else function read_int32be(fd) local data, err = fd:read(4) if data == nil then return nil, err end local o1, o2, o3, o4 = data:byte(1, 4) local unsigned = o4 + o3*2^8 + o2*2^16 + o1*2^24 if unsigned >= 2^31 then return unsigned - 2^32 else return unsigned end end function read_int64be(fd) local data, err = fd:read(8) if data == nil then return nil, err end local o1, o2, o3, o4, o5, o6, o7, o8 = data:byte(1, 8) local unsigned = o8 + o7*2^8 + o6*2^16 + o5*2^24 + o4*2^32 + o3*2^40 + o2*2^48 + o1*2^56 if unsigned >= 2^63 then return unsigned - 2^64 else return unsigned end end end local function read_flags ( fd , n ) local data , err = fd:read ( n ) if data == nil then return nil , err end local res = { } for i=1, n do res[i] = data:byte(i,i) ~= 0 end return res end local fifteen_nulls = ("\0"):rep(15) local function read_tz ( fd ) assert ( fd:read(4) == "TZif" , "Invalid TZ file" ) local version = assert ( fd:read(1) ) if version == "\0" or version == "2" then local MIN_TIME = -2^32+1 assert ( assert ( fd:read(15) ) == fifteen_nulls , "Expected 15 nulls" ) -- The number of UTC/local indicators stored in the file. local tzh_ttisgmtcnt = assert ( read_int32be ( fd ) ) -- The number of standard/wall indicators stored in the file. local tzh_ttisstdcnt = assert ( read_int32be ( fd ) ) -- The number of leap seconds for which data is stored in the file. local tzh_leapcnt = assert ( read_int32be ( fd ) ) -- The number of "transition times" for which data is stored in the file. local tzh_timecnt = assert ( read_int32be ( fd ) ) -- The number of "local time types" for which data is stored in the file (must not be zero). local tzh_typecnt = assert ( read_int32be ( fd ) ) -- The number of characters of "timezone abbreviation strings" stored in the file. local tzh_charcnt = assert ( read_int32be ( fd ) ) local transition_times = { } for i=1, tzh_timecnt do transition_times [ i ] = assert ( read_int32be ( fd ) ) end local transition_time_ind = { assert ( fd:read ( tzh_timecnt ) ):byte ( 1 , -1 ) } local ttinfos = { } for i=1, tzh_typecnt do ttinfos [ i ] = { gmtoff = assert ( read_int32be ( fd ) ) ; isdst = assert ( fd:read ( 1 ) ) ~= "\0" ; abbrind = assert ( fd:read ( 1 ) ):byte ( ) ; } end local abbreviations = assert ( fd:read ( tzh_charcnt ) ) local leap_seconds = { } for i=1, tzh_leapcnt do leap_seconds [ i ] = { offset = assert ( read_int32be ( fd ) ) ; n = assert ( read_int32be ( fd ) ) ; } end local isstd = assert ( read_flags ( fd , tzh_ttisstdcnt ) ) local isgmt = assert ( read_flags ( fd , tzh_ttisgmtcnt ) ) local TZ if version == "2" or version == "3" then --[[ For version-2-format timezone files, the above header and data is followed by a second header and data, identical in format except that eight bytes are used for each transition time or leap-second time. ]] assert ( fd:read(5) == "TZif2" ) assert ( assert ( fd:read(15) ) == fifteen_nulls , "Expected 15 nulls" ) MIN_TIME = -2^64+1 -- The number of UTC/local indicators stored in the file. tzh_ttisgmtcnt = assert ( read_int32be ( fd ) ) -- The number of standard/wall indicators stored in the file. tzh_ttisstdcnt = assert ( read_int32be ( fd ) ) -- The number of leap seconds for which data is stored in the file. tzh_leapcnt = assert ( read_int32be ( fd ) ) -- The number of "transition times" for which data is stored in the file. tzh_timecnt = assert ( read_int32be ( fd ) ) -- The number of "local time types" for which data is stored in the file (must not be zero). tzh_typecnt = assert ( read_int32be ( fd ) ) -- The number of characters of "timezone abbreviation strings" stored in the file. tzh_charcnt = assert ( read_int32be ( fd ) ) transition_times = { } for i=1, tzh_timecnt do transition_times [ i ] = assert ( read_int64be ( fd ) ) end transition_time_ind = { assert ( fd:read ( tzh_timecnt ) ):byte ( 1 , -1 ) } ttinfos = { } for i=1, tzh_typecnt do ttinfos [ i ] = { gmtoff = assert ( read_int32be ( fd ) ) ; isdst = assert ( fd:read ( 1 ) ) ~= "\0" ; abbrind = assert ( fd:read ( 1 ) ):byte ( ) ; } end abbreviations = assert ( fd:read ( tzh_charcnt ) ) leap_seconds = { } for i=1, tzh_leapcnt do leap_seconds [ i ] = { offset = assert ( read_int64be ( fd ) ) ; n = assert ( read_int32be ( fd ) ) ; } end isstd = assert ( read_flags ( fd , tzh_ttisstdcnt ) ) isgmt = assert ( read_flags ( fd , tzh_ttisgmtcnt ) ) --[[ After the second header and data comes a newline-enclosed, POSIX-TZ-environment-variable-style string for use in handling instants after the last transition time stored in the file (with nothing between the newlines if there is no POSIX representation for such instants). ]] --[[ For version-3-format time zone files, the POSIX-TZ-style string may use two minor extensions to the POSIX TZ format, as described in newtzset (3). First, the hours part of its transition times may be signed and range from -167 through 167 instead of the POSIX-required unsigned values from 0 through 24. Second, DST is in effect all year if it starts January 1 at 00:00 and ends December 31 at 24:00 plus the difference between daylight saving and standard time. ]] assert ( assert ( fd:read ( 1 ) ) == "\n" , "Expected newline at end of version 2 header" ) TZ = assert ( fd:read ( "*l" ) ) if #TZ == 0 then TZ = nil end end for i=1, tzh_typecnt do local v = ttinfos [ i ] v.abbr = abbreviations:sub ( v.abbrind+1 , v.abbrind+3 ) v.isstd = isstd [ i ] or false v.isgmt = isgmt [ i ] or false setmetatable ( v , tt_info_mt ) end --[[ Use the first standard-time ttinfo structure in the file (or simply the first ttinfo structure in the absence of a standard-time structure) if either tzh_timecnt is zero or the time argument is less than the first transition time recorded in the file. ]] local first = 1 do for i=1, tzh_ttisstdcnt do if isstd[i] then first = i break end end end local res = { [0] = { transition_time = MIN_TIME ; info = ttinfos [ first ] ; } } for i=1, tzh_timecnt do res [ i ] = { transition_time = transition_times [ i ] ; info = ttinfos [ transition_time_ind [ i ]+1 ] ; } end return setmetatable ( res , tz_info_mt ) else error ( "Unsupported version" ) end end local function read_tzfile ( path ) local fd = assert ( io.open ( path , "rb" ) ) local tzinfo = read_tz ( fd ) fd:close ( ) return tzinfo end return { read_tz = read_tz ; read_tzfile = read_tzfile ; }