made parentDir return a Maybe FilePath; removed most uses of it

parentDir is less safe than takeDirectory, especially when working
with relative FilePaths. It's really only useful in loops that
want to terminate at /

This commit was sponsored by Audric SCHILTKNECHT.

Build/DesktopFile.hs

@@ -22,6 +22,7 @@ import Assistant.Install.Menu
 import Control.Applicative
 import System.Directory
 import System.Environment
+import System.FilePath
 #ifndef mingw32_HOST_OS
 import System.Posix.User
 #endif
@@ -75,6 +76,6 @@ install command = do
 		( return ()
 		, do
 			programfile <- inDestDir =<< programFile
-			createDirectoryIfMissing True (parentDir programfile)
+			createDirectoryIfMissing True (takeDirectory programfile)
 			writeFile programfile command
 		)

Build/DistributionUpdate.hs

@@ -64,7 +64,7 @@ getbuild repodir (url, f) = do
 	let dest = repodir </> f
 	let tmp = dest ++ ".tmp"
 	nukeFile tmp
-	createDirectoryIfMissing True (parentDir dest)
+	createDirectoryIfMissing True (takeDirectory dest)
 	let oops s = do
 		nukeFile tmp
 		putStrLn $ "*** " ++ s

Build/EvilSplicer.hs

@@ -204,7 +204,7 @@ applySplices destdir imports splices@(first:_) = do
 	let f = splicedFile first
 	let dest = (destdir </> f)
 	lls <- map (++ "\n") . lines <$> readFileStrictAnyEncoding f
-	createDirectoryIfMissing True (parentDir dest)
+	createDirectoryIfMissing True (takeDirectory dest)
 	let newcontent = concat $ addimports $ expand lls splices
 	oldcontent <- catchMaybeIO $ readFileStrictAnyEncoding dest
 	when (oldcontent /= Just newcontent) $ do

Build/LinuxMkLibs.hs

@@ -47,7 +47,7 @@ mklibs top = do
 	writeFile (top </> "linker")
 		(Prelude.head $ filter ("ld-linux" `isInfixOf`) libs')
 	writeFile (top </> "gconvdir")
-		(parentDir $ Prelude.head $ filter ("/gconv/" `isInfixOf`) glibclibs)
+		(takeDirectory $ Prelude.head $ filter ("/gconv/" `isInfixOf`) glibclibs)
 	
 	mapM_ (installLinkerShim top) exes
 
@@ -75,7 +75,7 @@ installLinkerShim top exe = do
 symToHardLink :: FilePath -> IO ()
 symToHardLink f = whenM (isSymbolicLink <$> getSymbolicLinkStatus f) $ do
 	l <- readSymbolicLink f
-	let absl = absPathFrom (parentDir f) l
+	let absl = absPathFrom (takeDirectory f) l
 	nukeFile f
 	createLink absl f
 
@@ -84,7 +84,7 @@ installFile top f = do
 	createDirectoryIfMissing True destdir
 	void $ copyFileExternal CopyTimeStamps f destdir
   where
-	destdir = inTop top $ parentDir f
+	destdir = inTop top $ takeDirectory f
 
 checkExe :: FilePath -> IO Bool
 checkExe f

Build/OSXMkLibs.hs

@@ -50,7 +50,7 @@ installLibs appbase replacement_libs libmap = do
 		ifM (doesFileExist dest)
 			( return Nothing
 			, do
-				createDirectoryIfMissing True (parentDir dest)
+				createDirectoryIfMissing True (takeDirectory dest)
 				putStrLn $ "installing " ++ pathlib ++ " as " ++ shortlib
 				_ <- boolSystem "cp" [File pathlib, File dest]
 				_ <- boolSystem "chmod" [Param "644", File dest]