Synnefo » snf-ganeti

import Control.Monad (liftM, unless)

import System.Posix.Files

import System.Posix.Types

-- | File stat identifier.

type FStat = (EpochTime, FileID, FileOffset)

-- | Null 'FStat' value.

nullFStat :: FStat

nullFStat = (-1, -1, -1)

-- | Computes the file cache data from a FileStatus structure.

buildFileStatus :: FileStatus -> FStat

buildFileStatus ofs =

    let modt = modificationTime ofs

        inum = fileID ofs

        fsize = fileSize ofs

    in (modt, inum, fsize)

-- | Wrapper over 'buildFileStatus'. This reads the data from the

-- filesystem and then builds our cache structure.

getFStat :: FilePath -> IO FStat

getFStat p = liftM buildFileStatus (getFileStatus p)

-- | Check if the file needs reloading

needsReload :: FStat -> FilePath -> IO (Maybe FStat)

needsReload oldstat path = do

  newstat <- getFStat path

  return $ if newstat /= oldstat

             then Just newstat

             else Nothing