Detecting windows and service pack versions

get_win_ver.lua

local function exec(str)
  local f, err = io.popen(str .. " 2>&1", "r")
  if not f then return nil, err end
  local str, err = f:read("*all")
  f:close()
  if str then return str end
  return str, err
end

local WINVER = {
  {"6.2", "Windows 8"           },
  {"6.1", "Windows 7"           },
  {"6.0", "Windows Vista"       },
  {"5.2", "Windows Server 2003" },
  {"5.1", "Windows XP"          },
  {"5.0", "Windows 2000"        },
}

local function win_ver(...)
  local str, err = exec("ver")
  if not str then return nil, err end
  for _, t in ipairs(WINVER) do
    if str:find(t[1], 1, true) then
      return unpack(t)
    end
  end
  return ...
end

local function win_sp(...)
  local COMMANDS = {
    {[[Reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion" /v CSDversion]], "Service%s*Pack%s*(%d+)"},
    {[[Reg query "HKLM\Software\Microsoft\Windows NT\CurrentVersion" /v ServicePack]],"Service%s*Pack%s*(%d+)"},
  }

  for _, cmd in ipairs(COMMANDS) do
    local str, err = exec(cmd[1])
    if not str then return nil, err end
    local ver = str:match(cmd[2])
    if ver then return tonumber(ver) end
  end

  return ...
end

local function get_win_val(arr)
  local ver, err = win_ver('5.0')
  if not ver then return nil, err end
  local sp, err = win_sp(0)
  if not sp then return nil, err end
  for _, row in ipairs(arr) do
    local key, val = row[1], row[2]
    local kv, ks = key[1], key[2]
    if kv == ver then
      if not ks then return val end
      if sp >= ks then return val end
    end
  end
end

-- http://msdn.microsoft.com/en-us/library/windows/desktop/aa383745%28v=vs.85%29.aspx
local _WINNT_VER = {
  {{"6.2"   }, "0x0602"}, -- Win8
  {{"6.1"   }, "0x0601"}, -- Win7
  {{"6.0"   }, "0x0600"}, -- Vista, Win2k8
  {{"5.2", 1}, "0x0502"}, -- Win2k3 SP1
  {{"5.1", 2}, "0x0502"}, -- WinXP SP2
  {{"5.2"   }, "0x0501"}, -- Win2k3
  {{"5.1"   }, "0x0501"}, -- WinXP
  {{"5.0"   }, "0x0500"}, -- Win2k
}

-- http://msdn.microsoft.com/en-us/library/windows/desktop/aa383745%28v=vs.85%29.aspx
local NTDDI_VERSION = {
  {{"6.2",  }, "0x06010000"}, -- Win8
  {{"6.1",  }, "0x06010000"}, -- Win7
  {{"6.0", 1}, "0x06000100"}, -- Vista SP1, Win2k8 --???
  {{"6.0",  }, "0x06000000"}, -- Vista
  {{"5.2", 2}, "0x05020200"}, -- Win2k3 SP2
  {{"5.2", 1}, "0x05020100"}, -- Win2k3 SP1
  {{"5.2",  }, "0x05020000"}, -- Win2k3
  {{"5.1", 3}, "0x05010300"}, -- WinXP SP3
  {{"5.1", 2}, "0x05010200"}, -- WinXP SP2
  {{"5.1", 1}, "0x05010100"}, -- WinXP SP1
  {{"5.1",  }, "0x05010000"}, -- WinXP
  {{"5.0",  }, "0x05000000"}, -- Win2k -- ???
}

print(get_win_val(_WINNT_VER))
print(get_win_val(NTDDI_VERSION))