Add vendored lua compat53 v0.14.4

1 files changed, 894 insertions, 0 deletions

diff --git a/src/compat53/module.lua b/src/compat53/module.lua
new file mode 100644
index 00000000..52b1dd63
--- /dev/null
+++ b/src/compat53/module.lua
@@ -0,0 +1,894 @@
+local _G, _VERSION = _G, _VERSION
+local lua_version = _VERSION:sub(-3)
+
+
+local M = _G
+
+if lua_version < "5.3" then
+
+   -- cache globals in upvalues
+   local error, ipairs, pairs, pcall, require, select, setmetatable, type =
+         error, ipairs, pairs, pcall, require, select, setmetatable, type
+   local debug, io, math, package, string, table =
+         debug, io, math, package, string, table
+   local io_lines = io.lines
+   local io_read = io.read
+   local io_open = io.open
+   local io_popen = io.popen
+   local io_tmpfile = io.tmpfile
+   local unpack = lua_version == "5.1" and unpack or table.unpack
+   local debug_setmetatable = type(debug) == "table" and debug.setmetatable
+
+   -- create module table
+   M = {}
+   local M_meta = {
+      __index = _G,
+      -- __newindex is set at the end
+   }
+   setmetatable(M, M_meta)
+
+   -- create subtables
+   M.io = setmetatable({}, { __index = io })
+   M.math = setmetatable({}, { __index = math })
+   M.string = setmetatable({}, { __index = string })
+   M.table = setmetatable({}, { __index = table })
+   M.utf8 = {}
+
+
+   -- select the most powerful getmetatable function available
+   local gmt = type(debug) == "table" and debug.getmetatable or
+               getmetatable or function() return false end
+
+   -- type checking functions
+   local checkinteger -- forward declararation
+
+   local function argcheck(cond, i, f, extra)
+      if not cond then
+         error("bad argument #"..i.." to '"..f.."' ("..extra..")", 0)
+      end
+   end
+
+
+   -- load utf8 library
+   local utf8_ok, utf8lib = pcall(require, "compat53.utf8")
+   if utf8_ok then
+      if lua_version == "5.1" then
+         utf8lib.charpattern = "[%z\1-\127\194-\244][\128-\191]*"
+      end
+      for k,v in pairs(utf8lib) do
+         M.utf8[k] = v
+      end
+      package.loaded["utf8"] = M.utf8
+   end
+
+
+   -- load table library
+   local table_ok, tablib = pcall(require, "compat53.table")
+   if table_ok then
+      for k,v in pairs(tablib) do
+         M.table[k] = v
+      end
+   end
+
+
+   -- load io functions
+   local io_ok, iolib = pcall(require, "compat53.io")
+   if io_ok then
+      for k,v in pairs(iolib) do
+         M.io[k] = v
+      end
+   end
+
+
+   -- load string packing functions
+   local str_ok, strlib = pcall(require, "compat53.string")
+   if str_ok then
+      for k,v in pairs(strlib) do
+         M.string[k] = v
+      end
+   end
+
+
+   -- try Roberto's struct module for string packing/unpacking if
+   -- compat53.string is unavailable
+   if not str_ok then
+      local struct_ok, struct = pcall(require, "struct")
+      if struct_ok then
+         M.string.pack = struct.pack
+         M.string.packsize = struct.size
+         M.string.unpack = struct.unpack
+      end
+   end
+
+
+   -- update math library
+   do
+      local maxint, minint = 1
+
+      while maxint+1 > maxint and 2*maxint > maxint do
+         maxint = maxint * 2
+      end
+      if 2*maxint <= maxint then
+         maxint = 2*maxint-1
+         minint = -maxint-1
+      else
+         maxint = maxint
+         minint = -maxint
+      end
+      M.math.maxinteger = maxint
+      M.math.mininteger = minint
+
+      function M.math.tointeger(n)
+         n = tonumber(n)
+         if type(n) == "number" and n <= maxint and n >= minint and n % 1 == 0 then
+            return n
+         end
+         return nil
+      end
+
+      function M.math.type(n)
+         if type(n) == "number" then
+            if n <= maxint and n >= minint and n % 1 == 0 then
+               return "integer"
+            else
+               return "float"
+            end
+         else
+            return nil
+         end
+      end
+
+      function checkinteger(x, i, f)
+         local t = type(x)
+         if t ~= "number" then
+            error("bad argument #"..i.." to '"..f..
+                  "' (number expected, got "..t..")", 0)
+         elseif x > maxint or x < minint or x % 1 ~= 0 then
+            error("bad argument #"..i.." to '"..f..
+                  "' (number has no integer representation)", 0)
+         else
+            return x
+         end
+      end
+
+      function M.math.ult(m, n)
+         m = checkinteger(m, "1", "math.ult")
+         n = checkinteger(n, "2", "math.ult")
+         if m >= 0 and n < 0 then
+            return true
+         elseif m < 0 and n >= 0 then
+            return false
+         else
+            return m < n
+         end
+      end
+   end
+
+
+   -- assert should allow non-string error objects
+   function M.assert(cond, ...)
+      if cond then
+         return cond, ...
+      elseif select('#', ...) > 0 then
+         error((...), 0)
+      else
+         error("assertion failed!", 0)
+      end
+   end
+
+
+   -- ipairs should respect __index metamethod
+   do
+      local function ipairs_iterator(st, var)
+         var = var + 1
+         local val = st[var]
+         if val ~= nil then
+            return var, st[var]
+         end
+      end
+      function M.ipairs(t)
+         if gmt(t) ~= nil then -- t has metatable
+            return ipairs_iterator, t, 0
+         else
+            return ipairs(t)
+         end
+      end
+   end
+
+
+   -- make '*' optional for io.read and io.lines
+   do
+      local function addasterisk(fmt)
+         if type(fmt) == "string" and fmt:sub(1, 1) ~= "*" then
+            return "*"..fmt
+         else
+            return fmt
+         end
+      end
+
+      function M.io.read(...)
+         local n = select('#', ...)
+         for i = 1, n do
+            local a = select(i, ...)
+            local b = addasterisk(a)
+            -- as an optimization we only allocate a table for the
+            -- modified format arguments when we have a '*' somewhere.
+            if a ~= b then
+               local args = { ... }
+               args[i] = b
+               for j = i+1, n do
+                  args[j] = addasterisk(args[j])
+               end
+               return io_read(unpack(args, 1, n))
+            end
+         end
+         return io_read(...)
+      end
+
+      -- PUC-Rio Lua 5.1 uses a different implementation for io.lines!
+      function M.io.lines(...)
+         local n = select('#', ...)
+         for i = 2, n do
+            local a = select(i, ...)
+            local b = addasterisk(a)
+            -- as an optimization we only allocate a table for the
+            -- modified format arguments when we have a '*' somewhere.
+            if a ~= b then
+               local args = { ... }
+               args[i] = b
+               for j = i+1, n do
+                  args[j] = addasterisk(args[j])
+               end
+               return io_lines(unpack(args, 1, n))
+            end
+         end
+         return io_lines(...)
+      end
+   end
+
+
+   -- update table library (if C module not available)
+   if not table_ok then
+      local table_concat = table.concat
+      local table_insert = table.insert
+      local table_remove = table.remove
+      local table_sort = table.sort
+
+      function M.table.concat(list, sep, i, j)
+         local mt = gmt(list)
+         if type(mt) == "table" and type(mt.__len) == "function" then
+            local src = list
+            list, i, j  = {}, i or 1, j or mt.__len(src)
+            for k = i, j do
+               list[k] = src[k]
+            end
+         end
+         return table_concat(list, sep, i, j)
+      end
+
+      function M.table.insert(list, ...)
+         local mt = gmt(list)
+         local has_mt = type(mt) == "table"
+         local has_len = has_mt and type(mt.__len) == "function"
+         if has_mt and (has_len or mt.__index or mt.__newindex) then
+            local e = (has_len and mt.__len(list) or #list)+1
+            local nargs, pos, value = select('#', ...), ...
+            if nargs == 1 then
+               pos, value = e, pos
+            elseif nargs == 2 then
+               pos = checkinteger(pos, "2", "table.insert")
+               argcheck(1 <= pos and pos <= e, "2", "table.insert",
+                        "position out of bounds" )
+            else
+               error("wrong number of arguments to 'insert'", 0)
+            end
+            for i = e-1, pos, -1 do
+               list[i+1] = list[i]
+            end
+            list[pos] = value
+         else
+            return table_insert(list, ...)
+         end
+      end
+
+      function M.table.move(a1, f, e, t, a2)
+         a2 = a2 or a1
+         f = checkinteger(f, "2", "table.move")
+         argcheck(f > 0, "2", "table.move",
+                  "initial position must be positive")
+         e = checkinteger(e, "3", "table.move")
+         t = checkinteger(t, "4", "table.move")
+         if e >= f then
+            local m, n, d = 0, e-f, 1
+            if t > f then m, n, d = n, m, -1 end
+            for i = m, n, d do
+               a2[t+i] = a1[f+i]
+            end
+         end
+         return a2
+      end
+
+      function M.table.remove(list, pos)
+         local mt = gmt(list)
+         local has_mt = type(mt) == "table"
+         local has_len = has_mt and type(mt.__len) == "function"
+         if has_mt and (has_len or mt.__index or mt.__newindex) then
+            local e = (has_len and mt.__len(list) or #list)
+            pos = pos ~= nil and checkinteger(pos, "2", "table.remove") or e
+            if pos ~= e then
+               argcheck(1 <= pos and pos <= e+1, "2", "table.remove",
+                        "position out of bounds" )
+            end
+            local result = list[pos]
+            while pos < e do
+               list[pos] = list[pos+1]
+               pos = pos + 1
+            end
+            list[pos] = nil
+            return result
+         else
+            return table_remove(list, pos)
+         end
+      end
+
+      do
+         local function pivot(list, cmp, a, b)
+            local m = b - a
+            if m > 2 then
+               local c = a + (m-m%2)/2
+               local x, y, z = list[a], list[b], list[c]
+               if not cmp(x, y) then
+                  x, y, a, b = y, x, b, a
+               end
+               if not cmp(y, z) then
+                  y, b = z, c
+               end
+               if not cmp(x, y) then
+                  y, b = x, a
+               end
+               return b, y
+            else
+               return b, list[b]
+            end
+         end
+
+         local function lt_cmp(a, b)
+            return a < b
+         end
+
+         local function qsort(list, cmp, b, e)
+            if b < e then
+               local i, j, k, val = b, e, pivot(list, cmp, b, e)
+               while i < j do
+                  while i < j and cmp(list[i], val) do
+                     i = i + 1
+                  end
+                  while i < j and not cmp(list[j], val) do
+                     j = j - 1
+                  end
+                  if i < j then
+                     list[i], list[j] = list[j], list[i]
+                     if i == k then k = j end -- update pivot position
+                     i, j = i+1, j-1
+                  end
+               end
+               if i ~= k and not cmp(list[i], val) then
+                  list[i], list[k] = val, list[i]
+                  k = i -- update pivot position
+               end
+               qsort(list, cmp, b, i == k and i-1 or i)
+               return qsort(list, cmp, i+1, e)
+            end
+         end
+
+         function M.table.sort(list, cmp)
+            local mt = gmt(list)
+            local has_mt = type(mt) == "table"
+            local has_len = has_mt and type(mt.__len) == "function"
+            if has_len then
+               cmp = cmp or lt_cmp
+               local len = mt.__len(list)
+               return qsort(list, cmp, 1, len)
+            else
+               return table_sort(list, cmp)
+            end
+         end
+      end
+
+      local function unpack_helper(list, i, j, ...)
+         if j < i then
+            return ...
+         else
+            return unpack_helper(list, i, j-1, list[j], ...)
+         end
+      end
+      function M.table.unpack(list, i, j)
+         local mt = gmt(list)
+         local has_mt = type(mt) == "table"
+         local has_len = has_mt and type(mt.__len) == "function"
+         if has_mt and (has_len or mt.__index) then
+            i, j = i or 1, j or (has_len and mt.__len(list)) or #list
+            return unpack_helper(list, i, j)
+         else
+            return unpack(list, i, j)
+         end
+      end
+   end -- update table library
+
+
+   -- bring Lua 5.1 (and LuaJIT) up to speed with Lua 5.2
+   if lua_version == "5.1" then
+      -- detect LuaJIT (including LUAJIT_ENABLE_LUA52COMPAT compilation flag)
+      local is_luajit = (string.dump(function() end) or ""):sub(1, 3) == "\027LJ"
+      local is_luajit52 = is_luajit and
+        #setmetatable({}, { __len = function() return 1 end }) == 1
+
+      -- cache globals in upvalues
+      local load, loadfile, loadstring, setfenv, xpcall =
+            load, loadfile, loadstring, setfenv, xpcall
+      local coroutine, os = coroutine, os
+      local coroutine_create = coroutine.create
+      local coroutine_resume = coroutine.resume
+      local coroutine_running = coroutine.running
+      local coroutine_status = coroutine.status
+      local coroutine_yield = coroutine.yield
+      local io_input = io.input
+      local io_open = io.open
+      local io_output = io.output
+      local io_write = io.write
+      local math_log = math.log
+      local os_execute = os.execute
+      local string_find = string.find
+      local string_format = string.format
+      local string_gmatch = string.gmatch
+      local string_gsub = string.gsub
+      local string_match = string.match
+      local string_rep = string.rep
+      local table_concat = table.concat
+
+      -- create subtables
+      M.coroutine = setmetatable({}, { __index = coroutine })
+      M.os = setmetatable({}, { __index = os })
+      M.package = setmetatable({}, { __index = package })
+
+      -- handle debug functions
+      if type(debug) == "table" then
+         local debug_setfenv = debug.setfenv
+         local debug_getfenv = debug.getfenv
+
+         M.debug = setmetatable({}, { __index = debug })
+
+         if not is_luajit52 then
+            function M.debug.setuservalue(obj, value)
+               if type(obj) ~= "userdata" then
+                  error("bad argument #1 to 'setuservalue' (userdata expected, got "..
+                        type(obj)..")", 2)
+               end
+               if value == nil then value = _G end
+               if type(value) ~= "table" then
+                  error("bad argument #2 to 'setuservalue' (table expected, got "..
+                        type(value)..")", 2)
+               end
+               return debug_setfenv(obj, value)
+            end
+
+            function M.debug.getuservalue(obj)
+               if type(obj) ~= "userdata" then
+                  return nil
+               else
+                  local v = debug_getfenv(obj)
+                  if v == _G or v == package then
+                     return nil
+                  end
+                  return v
+               end
+            end
+
+            function M.debug.setmetatable(value, tab)
+               debug_setmetatable(value, tab)
+               return value
+            end
+         end -- not luajit with compat52 enabled
+      end -- debug table available
+
+
+      if not is_luajit52 then
+         function M.pairs(t)
+            local mt = gmt(t)
+            if type(mt) == "table" and type(mt.__pairs) == "function" then
+               return mt.__pairs(t)
+            else
+               return pairs(t)
+            end
+         end
+      end
+
+
+      if not is_luajit then
+         local function check_mode(mode, prefix)
+            local has = { text = false, binary = false }
+            for i = 1,#mode do
+               local c = mode:sub(i, i)
+               if c == "t" then has.text = true end
+               if c == "b" then has.binary = true end
+            end
+            local t = prefix:sub(1, 1) == "\27" and "binary" or "text"
+            if not has[t] then
+               return "attempt to load a "..t.." chunk (mode is '"..mode.."')"
+            end
+         end
+
+         function M.load(ld, source, mode, env)
+            mode = mode or "bt"
+            local chunk, msg
+            if type( ld ) == "string" then
+               if mode ~= "bt" then
+                  local merr = check_mode(mode, ld)
+                  if merr then return nil, merr end
+               end
+               chunk, msg = loadstring(ld, source)
+            else
+               local ld_type = type(ld)
+               if ld_type ~= "function" then
+                  error("bad argument #1 to 'load' (function expected, got "..
+                        ld_type..")", 2)
+               end
+               if mode ~= "bt" then
+                  local checked, merr = false, nil
+                  local function checked_ld()
+                     if checked then
+                        return ld()
+                     else
+                        checked = true
+                        local v = ld()
+                        merr = check_mode(mode, v or "")
+                        if merr then return nil end
+                        return v
+                     end
+                  end
+                  chunk, msg = load(checked_ld, source)
+                  if merr then return nil, merr end
+               else
+                  chunk, msg = load(ld, source)
+               end
+            end
+            if not chunk then
+               return chunk, msg
+            end
+            if env ~= nil then
+               setfenv(chunk, env)
+            end
+            return chunk
+         end
+
+         M.loadstring = M.load
+
+         function M.loadfile(file, mode, env)
+            mode = mode or "bt"
+            if mode ~= "bt" then
+               local f = io_open(file, "rb")
+               if f then
+                  local prefix = f:read(1)
+                  f:close()
+                  if prefix then
+                     local merr = check_mode(mode, prefix)
+                     if merr then return nil, merr end
+                  end
+               end
+            end
+            local chunk, msg = loadfile(file)
+            if not chunk then
+               return chunk, msg
+            end
+            if env ~= nil then
+               setfenv(chunk, env)
+            end
+            return chunk
+         end
+      end -- not luajit
+
+
+      if not is_luajit52 then
+         function M.rawlen(v)
+            local t = type(v)
+            if t ~= "string" and t ~= "table" then
+               error("bad argument #1 to 'rawlen' (table or string expected)", 2)
+            end
+            return #v
+         end
+      end
+
+
+      if not is_luajit then
+         function M.xpcall(f, msgh, ...)
+            local args, n = { ... }, select('#', ...)
+            return xpcall(function() return f(unpack(args, 1, n)) end, msgh)
+         end
+      end
+
+
+      if not is_luajit52 then
+         function M.os.execute(cmd)
+            local code = os_execute(cmd)
+            -- Lua 5.1 does not report exit by signal.
+            if code == 0 then
+               return true, "exit", code
+            else
+               if package.config:sub(1, 1) == '/' then
+                  code = code/256 -- only correct on Linux!
+               end
+               return nil, "exit", code
+            end
+         end
+      end
+
+
+      if not table_ok and not is_luajit52 then
+         M.table.pack = function(...)
+            return { n = select('#', ...), ... }
+         end
+      end
+
+
+      local main_coroutine = coroutine_create(function() end)
+
+      function M.coroutine.create(func)
+         local success, result = pcall(coroutine_create, func)
+         if not success then
+            if type(func) ~= "function" then
+               error("bad argument #1 (function expected)", 0)
+             end
+            result = coroutine_create(function(...) return func(...) end)
+         end
+         return result
+      end
+
+      if not is_luajit52 then
+         function M.coroutine.running()
+            local co = coroutine_running()
+            if co then
+               return co, false
+            else
+               return main_coroutine, true
+            end
+         end
+      end
+
+      function M.coroutine.yield(...)
+         local co, flag = coroutine_running()
+         if co and not flag then
+            return coroutine_yield(...)
+         else
+            error("attempt to yield from outside a coroutine", 0)
+         end
+      end
+
+      if not is_luajit then
+         function M.coroutine.resume(co, ...)
+            if co == main_coroutine then
+               return false, "cannot resume non-suspended coroutine"
+            else
+               return coroutine_resume(co, ...)
+            end
+         end
+
+         function M.coroutine.status(co)
+            local notmain = coroutine_running()
+            if co == main_coroutine then
+               return notmain and "normal" or "running"
+            else
+               return coroutine_status(co)
+            end
+         end
+      end -- not luajit
+
+
+      if not is_luajit then
+         M.math.log = function(x, base)
+            if base ~= nil then
+               return math_log(x)/math_log(base)
+            else
+               return math_log(x)
+            end
+         end
+      end
+
+
+      if not is_luajit then
+         function M.package.searchpath(name, path, sep, rep)
+            sep = (sep or "."):gsub("(%p)", "%%%1")
+            rep = (rep or package.config:sub(1, 1)):gsub("(%%)", "%%%1")
+            local pname = name:gsub(sep, rep):gsub("(%%)", "%%%1")
+            local msg = {}
+            for subpath in path:gmatch("[^;]+") do
+               local fpath = subpath:gsub("%?", pname)
+               local f = io_open(fpath, "r")
+               if f then
+                  f:close()
+                  return fpath
+               end
+               msg[#msg+1] = "\n\tno file '" .. fpath .. "'"
+            end
+            return nil, table_concat(msg)
+         end
+      end
+
+
+      local function fix_pattern(pattern)
+         return (string_gsub(pattern, "%z", "%%z"))
+      end
+
+      function M.string.find(s, pattern, ...)
+         return string_find(s, fix_pattern(pattern), ...)
+      end
+
+      function M.string.gmatch(s, pattern)
+         return string_gmatch(s, fix_pattern(pattern))
+      end
+
+      function M.string.gsub(s, pattern, ...)
+         return string_gsub(s, fix_pattern(pattern), ...)
+      end
+
+      function M.string.match(s, pattern, ...)
+         return string_match(s, fix_pattern(pattern), ...)
+      end
+
+      if not is_luajit then
+         function M.string.rep(s, n, sep)
+            if sep ~= nil and sep ~= "" and n >= 2 then
+               return s .. string_rep(sep..s, n-1)
+            else
+               return string_rep(s, n)
+            end
+         end
+      end
+
+      if not is_luajit then
+         do
+            local addqt = {
+               ["\n"] = "\\\n",
+               ["\\"] = "\\\\",
+               ["\""] = "\\\""
+            }
+
+            local function addquoted(c, d)
+               return (addqt[c] or string_format(d~="" and "\\%03d" or "\\%d", c:byte()))..d
+            end
+
+            function M.string.format(fmt, ...)
+               local args, n = { ... }, select('#', ...)
+               local i = 0
+               local function adjust_fmt(lead, mods, kind)
+                  if #lead % 2 == 0 then
+                     i = i + 1
+                     if kind == "s" then
+                        args[i] = _G.tostring(args[i])
+                     elseif kind == "q" then
+                        args[i] = '"'..string_gsub(args[i], "([%z%c\\\"\n])(%d?)", addquoted)..'"'
+                        return lead.."%"..mods.."s"
+                     end
+                  end
+               end
+               fmt = string_gsub(fmt, "(%%*)%%([%d%.%-%+%# ]*)(%a)", adjust_fmt)
+               return string_format(fmt, unpack(args, 1, n))
+            end
+         end
+      end
+
+
+      function M.io.write(...)
+         local res, msg, errno = io_write(...)
+         if res then
+            return io_output()
+         else
+            return nil, msg, errno
+         end
+      end
+
+      if not is_luajit then
+         local function helper(st, var_1, ...)
+            if var_1 == nil then
+               if st.doclose then st.f:close() end
+               if (...) ~= nil then
+                  error((...), 2)
+               end
+            end
+            return var_1, ...
+         end
+
+         local function lines_iterator(st)
+            return helper(st, st.f:read(unpack(st, 1, st.n)))
+         end
+
+         function M.io.lines(fname, ...)
+            local doclose, file, msg
+            if fname ~= nil then
+               doclose, file, msg = true, io_open(fname, "r")
+               if not file then error(msg, 2) end
+            else
+               doclose, file = false, io_input()
+            end
+            local st = { f=file, doclose=doclose, n=select('#', ...), ... }
+            for i = 1, st.n do
+               local t = type(st[i])
+               if t == "string" then
+                  local fmt = st[i]:match("^%*?([aln])")
+                  if not fmt then
+                     error("bad argument #"..(i+1).." to 'for iterator' (invalid format)", 2)
+                  end
+                  st[i] = "*"..fmt
+               elseif t ~= "number" then
+                  error("bad argument #"..(i+1).." to 'for iterator' (invalid format)", 2)
+               end
+            end
+            return lines_iterator, st
+         end
+      end -- not luajit
+
+      if is_luajit then
+         local compat_file_meta = {}
+         local compat_file_meta_loaded = 0
+
+         local function load_compat_file_meta(file_meta)
+            -- fill compat_file_meta with original entries
+            for k, v in pairs(file_meta) do
+               compat_file_meta[k] = v
+            end
+            compat_file_meta.__index = {}
+            for k, v in pairs(file_meta.__index) do
+               compat_file_meta.__index[k] = v
+            end
+
+            compat_file_meta_loaded = 1
+
+            -- update it with compatibility functions
+            local file_mt_ok, file_mt = pcall(require, "compat53.file_mt")
+            if file_mt_ok then
+               file_mt.update_file_meta(compat_file_meta, is_luajit52)
+
+               compat_file_meta_loaded = 2
+            end
+         end
+
+         local function return_fd(fd, err, code)
+            if not fd then
+               return fd, err, code
+            end
+            if fd and debug_setmetatable then
+               if compat_file_meta_loaded == 0 then
+                  local file_meta = gmt(fd)
+                  load_compat_file_meta(file_meta)
+               end
+               if compat_file_meta_loaded == 2 then
+                  debug_setmetatable(fd, compat_file_meta)
+               end
+            end
+            return fd
+         end
+
+         function M.io.open(...)
+            return return_fd(io_open(...))
+         end
+
+         function M.io.popen(...)
+            return return_fd(io_popen(...))
+         end
+
+         function M.io.tmpfile(...)
+            return return_fd(io_tmpfile(...))
+         end
+      end
+
+   end -- lua 5.1
+
+   -- further write should be forwarded to _G
+   M_meta.__newindex = _G
+
+end -- lua < 5.3
+
+
+-- return module table
+return M
+
+-- vi: set expandtab softtabstop=3 shiftwidth=3 :