luatz/tzfile: Use string.unpack when available (Lua 5.3+)

diff --git a/luatz/tzfile.lua b/luatz/tzfile.lua
index a3fa7941171e5c5d188481a7aa6b7dd9fe7e9e72..d4285c4b2b73bfdad4448dc2474f71d1897f021b 100644 (file)
--- a/luatz/tzfile.lua
+++ b/luatz/tzfile.lua
@@ -1,30 +1,45 @@
 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
 
-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 )
+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 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
+       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