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{-| Utilities for virtual clusters.

-}

{-

Copyright (C) 2014 Google Inc.

This program is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2 of the License, or

(at your option) any later version.

This program is distributed in the hope that it will be useful, but

WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301, USA.

-}

module Ganeti.VCluster

  ( makeVirtualPath

  ) where

import Control.Monad (liftM)

import Data.Set (member)

import System.Posix.Env (getEnv)

import System.FilePath.Posix

import Ganeti.ConstantUtils (unFrozenSet)

import Ganeti.Constants

getRootDirectory :: IO (Maybe FilePath)

getRootDirectory = fmap normalise `liftM` getEnv vClusterRootdirEnvname

-- | Pure computation of the virtual path from the original path

-- and the vcluster root

virtualPath :: FilePath -> FilePath -> FilePath

virtualPath fpath root =

  let relpath = makeRelative root fpath

  in if member fpath (unFrozenSet vClusterVpathWhitelist)

       then fpath

       else vClusterVirtPathPrefix </> relpath

-- | Given a path, make it a virtual one, if in a vcluster environment.

-- Otherwise, return unchanged.

makeVirtualPath :: FilePath -> IO FilePath

makeVirtualPath fpath = maybe fpath (virtualPath fpath) `liftM` getRootDirectory