[Lua] Small set of some OS and filesystem utilities

utils.lua

-- Determines if this script is running on Windows
os.is_win = package.config:sub(1, 1) == "\\"

-- Return the path to the temp dir
function os.get_temp_dir()
  if os.is_win then
    -- Windows. Same as:
    --     os.getenv("TEMP")
    --     os.getenv("TMP")
    return os.getenv("UserProfile") .. "/AppData/Local/Temp"
  else
    -- Unix
    return os.getenv("TMPDIR") or "/tmp"
  end
end

-- Check if the given file exists
function io.exists(path)
  local ok, _, code = os.rename(path, path)

  if code == 13 then
    -- Permission denied, but it exists
    return true
  end

  return ok ~= nil
end

-- Check if the given path is a folder
function io.is_dir(path)
  if os.is_win then
    return io.exists(path .. "/")
  end

  return (io.open(path .. "/") == nil) and false or true
end

-- Returns the path to the user "home" dir
function os.get_home_dir( ... )
  if os.is_win then
    return os.getenv("UserProfile")
  else
    return os.getenv("HOME")
  end
end