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|
{- Caching a file's inode, size, and modification time to see when it's changed.
-
- Copyright 2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Utility.InodeCache where
import Common
import System.Posix.Types
data InodeCache = InodeCache FileID FileOffset EpochTime
deriving (Eq, Show)
showInodeCache :: InodeCache -> String
showInodeCache (InodeCache inode size mtime) = unwords
[ show inode
, show size
, show mtime
]
readInodeCache :: String -> Maybe InodeCache
readInodeCache s = case words s of
(inode:size:mtime:_) -> InodeCache
<$> readish inode
<*> readish size
<*> readish mtime
_ -> Nothing
-- for quickcheck
prop_read_show_inodecache :: InodeCache -> Bool
prop_read_show_inodecache c = readInodeCache (showInodeCache c) == Just c
genInodeCache :: FilePath -> IO (Maybe InodeCache)
genInodeCache f = catchDefaultIO Nothing $ toInodeCache <$> getFileStatus f
toInodeCache :: FileStatus -> Maybe InodeCache
toInodeCache s
| isRegularFile s = Just $ InodeCache
(fileID s)
(fileSize s)
(modificationTime s)
| otherwise = Nothing
{- Compares an inode cache with the current inode of file. -}
compareInodeCache :: FilePath -> Maybe InodeCache -> IO Bool
compareInodeCache file old = do
curr <- genInodeCache file
return $ isJust curr && curr == old
|
