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doc/index.md: Fix internal link
[etc/awesome.git] / luatz / tzfile.lua
index 36fd8a765a775e12a67715ec63cc8f6215a3fc41..e57db6d8fa82dbcf719eaa2b135825a9e1930499 100644 (file)
@@ -1,38 +1,55 @@
 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
+
+-- luacheck: push std max
+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
 
-local 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
+       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 -- luacheck: pop
+       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
-end
 
-local 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 )
+       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
+               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 function read_flags(fd, n)
+       local data, err = fd:read(n)
+       if data == nil then return nil, err end
 
-       local res = { }
+       local res = {}
        for i=1, n do
                res[i] = data:byte(i,i) ~= 0
        end
@@ -40,139 +57,151 @@ local function read_flags ( fd , n )
 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 function read_tz(fd)
+       assert(fd:read(4) == "TZif", "Invalid TZ file")
+       local version = assert(fd:read(1))
+       if version == "\0" or version == "2" or version == "3" then
                local MIN_TIME = -2^32+1
 
-               assert ( assert ( fd:read(15) ) == fifteen_nulls , "Expected 15 nulls" )
+               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 ) )
+               local tzh_ttisgmtcnt = assert(read_int32be(fd))
 
                -- The number of standard/wall indicators stored in the file.
-               local tzh_ttisstdcnt = assert ( read_int32be ( fd ) )
+               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 ) )
+               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 ) )
+               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 ) )
+               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 tzh_charcnt = assert(read_int32be(fd))
 
-               local transition_times = { }
+               local transition_times = {}
                for i=1, tzh_timecnt do
-                       transition_times [ i ] = assert ( read_int32be ( fd ) )
+                       transition_times[i] = assert(read_int32be(fd))
                end
-               local transition_time_ind = { assert ( fd:read ( tzh_timecnt ) ):byte ( 1 , -1 ) }
+               local transition_time_ind = {assert(fd:read(tzh_timecnt)):byte(1, -1)}
 
-               local ttinfos = { }
+               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 ( ) ;
+                       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 abbreviations = assert(fd:read(tzh_charcnt))
 
-               local leap_seconds = { }
+               local leap_seconds = {} -- luacheck: ignore 241
                for i=1, tzh_leapcnt do
-                       leap_seconds [ i ] = {
-                               offset = assert ( read_int32be ( fd ) ) ;
-                               n = assert ( read_int32be ( fd ) ) ;
+                       leap_seconds[i] = {
+                               offset = assert(read_int32be(fd));
+                               n = assert(read_int32be(fd));
                        }
                end
 
-               local isstd = assert ( read_flags ( fd , tzh_ttisstdcnt ) )
+               local isstd = assert(read_flags(fd, tzh_ttisstdcnt))
 
-               local isgmt = assert ( read_flags ( fd , tzh_ttisgmtcnt ) )
+               local isgmt = assert(read_flags(fd, tzh_ttisgmtcnt))
 
                local TZ
 
-               if version == "2" then
+               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" )
+                       assert(fd:read(4) == "TZif")
+                       assert(fd:read(1) == version)
+                       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 ) )
+                       tzh_ttisgmtcnt = assert(read_int32be(fd))
 
                        -- The number of standard/wall indicators stored in the file.
-                       tzh_ttisstdcnt = assert ( read_int32be ( fd ) )
+                       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 ) )
+                       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 ) )
+                       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 ) )
+                       tzh_typecnt = assert(read_int32be(fd))
 
                        -- The number of characters of "timezone abbreviation strings" stored in the file.
-                       tzh_charcnt = assert ( read_int32be ( fd ) )
+                       tzh_charcnt = assert(read_int32be(fd))
 
-                       transition_times = { }
+                       transition_times = {}
                        for i=1, tzh_timecnt do
-                               transition_times [ i ] = assert ( read_int64be ( fd ) )
+                               transition_times[i] = assert(read_int64be(fd))
                        end
-                       transition_time_ind = { assert ( fd:read ( tzh_timecnt ) ):byte ( 1 , -1 ) }
+                       transition_time_ind = {assert(fd:read(tzh_timecnt)):byte(1, -1)}
 
-                       ttinfos = { }
+                       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 ( ) ;
+                               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 ) )
+                       abbreviations = assert(fd:read(tzh_charcnt))
 
-                       leap_seconds = { }
+                       leap_seconds = {}
                        for i=1, tzh_leapcnt do
-                               leap_seconds [ i ] = {
-                                       offset = assert ( read_int64be ( fd ) ) ;
-                                       n = assert ( read_int32be ( fd ) ) ;
+                               leap_seconds[i] = {
+                                       offset = assert(read_int64be(fd));
+                                       n = assert(read_int32be(fd));
                                }
                        end
 
-                       isstd = assert ( read_flags ( fd , tzh_ttisstdcnt ) )
+                       isstd = assert(read_flags(fd, tzh_ttisstdcnt))
 
-                       isgmt = assert ( read_flags ( fd , tzh_ttisgmtcnt ) )
+                       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).
                        ]]
-                       assert ( assert ( fd:read ( 1 ) ) == "\n" , "Expected newline at end of version 2 header" )
 
-                       TZ = assert ( fd:read ( "*l" ) )
+                       --[[
+                       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 )
+                       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
 
                --[[
@@ -191,31 +220,32 @@ local function read_tz ( fd )
                end
 
                local res = {
+                       future = TZ;
                        [0] = {
-                               transition_time = MIN_TIME ;
-                               info = ttinfos [ first ] ;
+                               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 ] ;
+                       res[i] = {
+                               transition_time = transition_times[i];
+                               info = ttinfos[transition_time_ind[i]+1];
                        }
                end
-               return setmetatable ( res , tz_info_mt )
+               return setmetatable(res, tz_info_mt)
        else
-               error ( "Unsupported version" )
+               error("Unsupported version")
        end
 end
 
-local function read_tzfile ( path )
-       local fd = assert ( io.open ( path , "rb" ) )
-       local tzinfo = read_tz ( fd )
-       fd:close ( )
+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 ;
+       read_tz = read_tz;
+       read_tzfile = read_tzfile;
 }