directory-1.3.3.0: System/Directory/Internal/Common.hs
module System.Directory.Internal.Common where
import Prelude ()
import System.Directory.Internal.Prelude
import System.FilePath ((</>), isPathSeparator, isRelative,
pathSeparator, splitDrive, takeDrive)
-- | A generator with side-effects.
newtype ListT m a = ListT { unListT :: m (Maybe (a, ListT m a)) }
emptyListT :: Applicative m => ListT m a
emptyListT = ListT (pure Nothing)
maybeToListT :: Applicative m => m (Maybe a) -> ListT m a
maybeToListT m = ListT (((\ x -> (x, emptyListT)) <$>) <$> m)
listToListT :: Applicative m => [a] -> ListT m a
listToListT [] = emptyListT
listToListT (x : xs) = ListT (pure (Just (x, listToListT xs)))
liftJoinListT :: Monad m => m (ListT m a) -> ListT m a
liftJoinListT m = ListT (m >>= unListT)
listTHead :: Functor m => ListT m a -> m (Maybe a)
listTHead (ListT m) = (fst <$>) <$> m
listTToList :: Monad m => ListT m a -> m [a]
listTToList (ListT m) = do
mx <- m
case mx of
Nothing -> return []
Just (x, m') -> do
xs <- listTToList m'
return (x : xs)
andM :: Monad m => m Bool -> m Bool -> m Bool
andM mx my = do
x <- mx
if x
then my
else return x
sequenceWithIOErrors_ :: [IO ()] -> IO ()
sequenceWithIOErrors_ actions = go (Right ()) actions
where
go :: Either IOError () -> [IO ()] -> IO ()
go (Left e) [] = ioError e
go (Right ()) [] = pure ()
go s (m : ms) = s `seq` do
r <- tryIOError m
go (thenEither s r) ms
-- equivalent to (*>) for Either, defined here to retain compatibility
-- with base prior to 4.3
thenEither :: Either b a -> Either b a -> Either b a
thenEither x@(Left _) _ = x
thenEither _ y = y
-- | Similar to 'try' but only catches a specify kind of 'IOError' as
-- specified by the predicate.
tryIOErrorType :: (IOError -> Bool) -> IO a -> IO (Either IOError a)
tryIOErrorType check action = do
result <- tryIOError action
case result of
Left err -> if check err then pure (Left err) else throwIO err
Right val -> pure (Right val)
-- | Attempt to perform the given action, silencing any IO exception thrown by
-- it.
ignoreIOExceptions :: IO () -> IO ()
ignoreIOExceptions io = io `catchIOError` (\_ -> pure ())
specializeErrorString :: String -> (IOError -> Bool) -> IO a -> IO a
specializeErrorString str errType action = do
mx <- tryIOErrorType errType action
case mx of
Left e -> throwIO (ioeSetErrorString e str)
Right x -> pure x
ioeAddLocation :: IOError -> String -> IOError
ioeAddLocation e loc = do
ioeSetLocation e newLoc
where
newLoc = loc <> if null oldLoc then "" else ":" <> oldLoc
oldLoc = ioeGetLocation e
data FileType = File
| SymbolicLink -- ^ POSIX: either file or directory link; Windows: file link
| Directory
| DirectoryLink -- ^ Windows only: directory link
deriving (Bounded, Enum, Eq, Ord, Read, Show)
-- | Check whether the given 'FileType' is considered a directory by the
-- operating system. This affects the choice of certain functions
-- e.g. `removeDirectory` vs `removeFile`.
fileTypeIsDirectory :: FileType -> Bool
fileTypeIsDirectory Directory = True
fileTypeIsDirectory DirectoryLink = True
fileTypeIsDirectory _ = False
-- | Return whether the given 'FileType' is a link.
fileTypeIsLink :: FileType -> Bool
fileTypeIsLink SymbolicLink = True
fileTypeIsLink DirectoryLink = True
fileTypeIsLink _ = False
data Permissions
= Permissions
{ readable :: Bool
, writable :: Bool
, executable :: Bool
, searchable :: Bool
} deriving (Eq, Ord, Read, Show)
-- | Convert a path into an absolute path. If the given path is relative, the
-- current directory is prepended. If the path is already absolute, the path
-- is returned unchanged. The function preserves the presence or absence of
-- the trailing path separator.
--
-- If the path is already absolute, the operation never fails. Otherwise, the
-- operation may fail with the same exceptions as 'getCurrentDirectory'.
--
-- (internal API)
prependCurrentDirectoryWith :: IO FilePath -> FilePath -> IO FilePath
prependCurrentDirectoryWith getCurrentDirectory path =
((`ioeAddLocation` "prependCurrentDirectory") .
(`ioeSetFileName` path)) `modifyIOError` do
if isRelative path -- avoid the call to `getCurrentDirectory` if we can
then do
cwd <- getCurrentDirectory
let curDrive = takeWhile (not . isPathSeparator) (takeDrive cwd)
let (drive, subpath) = splitDrive path
-- handle drive-relative paths (Windows only)
pure . (</> subpath) $
case drive of
_ : _ | (toUpper <$> drive) /= (toUpper <$> curDrive) ->
drive <> [pathSeparator]
_ -> cwd
else pure path
-- | Truncate the destination file and then copy the contents of the source
-- file to the destination file. If the destination file already exists, its
-- attributes shall remain unchanged. Otherwise, its attributes are reset to
-- the defaults.
copyFileContents :: FilePath -- ^ Source filename
-> FilePath -- ^ Destination filename
-> IO ()
copyFileContents fromFPath toFPath =
(`ioeAddLocation` "copyFileContents") `modifyIOError` do
withBinaryFile toFPath WriteMode $ \ hTo ->
copyFileToHandle fromFPath hTo
-- | Copy all data from a file to a handle.
copyFileToHandle :: FilePath -- ^ Source file
-> Handle -- ^ Destination handle
-> IO ()
copyFileToHandle fromFPath hTo =
(`ioeAddLocation` "copyFileToHandle") `modifyIOError` do
withBinaryFile fromFPath ReadMode $ \ hFrom ->
copyHandleData hFrom hTo
-- | Copy data from one handle to another until end of file.
copyHandleData :: Handle -- ^ Source handle
-> Handle -- ^ Destination handle
-> IO ()
copyHandleData hFrom hTo =
(`ioeAddLocation` "copyData") `modifyIOError` do
allocaBytes bufferSize go
where
bufferSize = 131072 -- 128 KiB, as coreutils `cp` uses as of May 2014 (see ioblksize.h)
go buffer = do
count <- hGetBuf hFrom buffer bufferSize
when (count > 0) $ do
hPutBuf hTo buffer count
go buffer
-- | Special directories for storing user-specific application data,
-- configuration, and cache files, as specified by the
-- <http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html XDG Base Directory Specification>.
--
-- Note: On Windows, 'XdgData' and 'XdgConfig' map to the same directory.
--
-- @since 1.2.3.0
data XdgDirectory
= XdgData
-- ^ For data files (e.g. images).
-- Defaults to @~\/.local\/share@ and can be
-- overridden by the @XDG_DATA_HOME@ environment variable.
-- On Windows, it is @%APPDATA%@
-- (e.g. @C:\/Users\//\<user\>/\/AppData\/Roaming@).
-- Can be considered as the user-specific equivalent of @\/usr\/share@.
| XdgConfig
-- ^ For configuration files.
-- Defaults to @~\/.config@ and can be
-- overridden by the @XDG_CONFIG_HOME@ environment variable.
-- On Windows, it is @%APPDATA%@
-- (e.g. @C:\/Users\//\<user\>/\/AppData\/Roaming@).
-- Can be considered as the user-specific equivalent of @\/etc@.
| XdgCache
-- ^ For non-essential files (e.g. cache).
-- Defaults to @~\/.cache@ and can be
-- overridden by the @XDG_CACHE_HOME@ environment variable.
-- On Windows, it is @%LOCALAPPDATA%@
-- (e.g. @C:\/Users\//\<user\>/\/AppData\/Local@).
-- Can be considered as the user-specific equivalent of @\/var\/cache@.
deriving (Bounded, Enum, Eq, Ord, Read, Show)
-- | Search paths for various application data, as specified by the
-- <http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html XDG Base Directory Specification>.
--
-- Note: On Windows, 'XdgDataDirs' and 'XdgConfigDirs' yield the same result.
--
-- @since 1.3.2.0
data XdgDirectoryList
= XdgDataDirs
-- ^ For data files (e.g. images).
-- Defaults to @/usr/local/share/@ and @/usr/share/@ and can be
-- overridden by the @XDG_DATA_DIRS@ environment variable.
-- On Windows, it is @%PROGRAMDATA%@ or @%ALLUSERSPROFILE%@
-- (e.g. @C:\/ProgramData@).
| XdgConfigDirs
-- ^ For configuration files.
-- Defaults to @/etc/xdg@ and can be
-- overridden by the @XDG_CONFIG_DIRS@ environment variable.
-- On Windows, it is @%PROGRAMDATA%@ or @%ALLUSERSPROFILE%@
-- (e.g. @C:\/ProgramData@).
deriving (Bounded, Enum, Eq, Ord, Read, Show)