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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)
{- Weak comparison of the inode caches, comparing the size and mtime, but
- not the actual inode. Useful when inodes have changed, perhaps
- due to some filesystems being remounted. -}
compareWeak :: InodeCache -> InodeCache -> Bool
compareWeak (InodeCache _ size1 mtime1) (InodeCache _ size2 mtime2) =
size1 == size2 && mtime1 == mtime2
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
|
