simplify and speed up Utility.FileSystemEncoding

This eliminates the distinction between decodeBS and decodeBS', encodeBS
and encodeBS', etc. The old implementation truncated at NUL, and the
primed versions had to do extra work to avoid that problem. The new
implementation does not truncate at NUL, and is also a lot faster.
(Benchmarked at 2x faster for decodeBS and 3x for encodeBS; more for the
primed versions.)

Note that filepath-bytestring 1.4.2.1.8 contains the same optimisation,
and upgrading to it will speed up to/fromRawFilePath.

AFAIK, nothing relied on the old behavior of truncating at NUL. Some
code used the faster versions in places where I was sure there would not
be a NUL. So this change is unlikely to break anything.

Also, moved s2w8 and w82s out of the module, as they do not involve
filesystem encoding really.

Sponsored-by: Shae Erisson on Patreon

Annex.hs

@@ -401,7 +401,7 @@ adjustGitRepo a = do
 addGitConfigOverride :: String -> Annex ()
 addGitConfigOverride v = do
 	adjustGitRepo $ \r ->
-		Git.Config.store (encodeBS' v) Git.Config.ConfigList $
+		Git.Config.store (encodeBS v) Git.Config.ConfigList $
 			r { Git.gitGlobalOpts = go (Git.gitGlobalOpts r) }
 	changeState $ \st -> st { gitconfigoverride = v : gitconfigoverride st }
   where

Annex/MetaData.hs

@@ -72,11 +72,11 @@ genMetaData key file status = do
  - only changes to add the date fields. -}
 dateMetaData :: UTCTime -> MetaData -> MetaData
 dateMetaData mtime old = modMeta old $
-	(SetMeta yearMetaField $ S.singleton $ toMetaValue $ encodeBS' $ show y)
+	(SetMeta yearMetaField $ S.singleton $ toMetaValue $ encodeBS $ show y)
 		`ComposeModMeta`
-	(SetMeta monthMetaField $ S.singleton $ toMetaValue $ encodeBS' $ show m)
+	(SetMeta monthMetaField $ S.singleton $ toMetaValue $ encodeBS $ show m)
 		`ComposeModMeta`
-	(SetMeta dayMetaField $ S.singleton $ toMetaValue $ encodeBS' $ show d)
+	(SetMeta dayMetaField $ S.singleton $ toMetaValue $ encodeBS $ show d)
   where
 	(y, m, d) = toGregorian $ utctDay mtime
 

Annex/UUID.hs

@@ -110,7 +110,7 @@ storeUUIDIn configfield = setConfig configfield . fromUUID
 {- Only sets the configkey in the Repo; does not change .git/config -}
 setUUID :: Git.Repo -> UUID -> IO Git.Repo
 setUUID r u = do
-	let s = encodeBS' $ show configkeyUUID ++ "=" ++ fromUUID u
+	let s = encodeBS $ show configkeyUUID ++ "=" ++ fromUUID u
 	Git.Config.store s Git.Config.ConfigList r
 
 -- Dummy uuid for the whole web. Do not alter.

Assistant/Threads/Merger.hs

@@ -118,6 +118,6 @@ isAnnexBranch f = n `isSuffixOf` f
 	n = '/' : Git.fromRef Annex.Branch.name
 
 fileToBranch :: FilePath -> Git.Ref
-fileToBranch f = Git.Ref $ encodeBS' $ "refs" </> base
+fileToBranch f = Git.Ref $ encodeBS $ "refs" </> base
   where
 	base = Prelude.last $ split "/refs/" f

Assistant/Threads/Watcher.hs

@@ -321,7 +321,7 @@ addLink :: FilePath -> LinkTarget -> Maybe Key -> Assistant (Maybe Change)
 addLink file link mk = do
 	debug ["add symlink", file]
 	liftAnnex $ do
-		v <- catObjectDetails $ Ref $ encodeBS' $ ':':file
+		v <- catObjectDetails $ Ref $ encodeBS $ ':':file
 		case v of
 			Just (currlink, sha, _type)
 				| L.fromStrict link == currlink ->

Assistant/WebApp/Configurators/Edit.hs

@@ -102,7 +102,7 @@ setRepoConfig uuid mremote oldc newc = do
 			 - there's not. Special remotes don't normally
 			 - have that, and don't use it. Temporarily add
 			 - it if it's missing. -}
-			let remotefetch = Git.ConfigKey $ encodeBS' $
+			let remotefetch = Git.ConfigKey $ encodeBS $
 				"remote." ++ T.unpack (repoName oldc) ++ ".fetch"
 			needfetch <- isNothing <$> fromRepo (Git.Config.getMaybe remotefetch)
 			when needfetch $

Backend/External.hs

@@ -239,7 +239,7 @@ newExternalState ebname hasext pid = do
 		warning msg
 
 externalBackendProgram :: ExternalBackendName -> String
-externalBackendProgram (ExternalBackendName bname) = "git-annex-backend-X" ++ decodeBS' bname
+externalBackendProgram (ExternalBackendName bname) = "git-annex-backend-X" ++ decodeBS bname
 
 -- Runs an action with an ExternalState, starting a new external backend
 -- process if necessary. It is returned to the pool once the action

Backend/Utilities.hs

@@ -28,10 +28,10 @@ import Data.Word
 genKeyName :: String -> S.ByteString
 genKeyName s
 	-- Avoid making keys longer than the length of a SHA256 checksum.
-	| bytelen > sha256len = encodeBS' $
+	| bytelen > sha256len = encodeBS $
 		truncateFilePath (sha256len - md5len - 1) s' ++ "-" ++ 
 			show (md5 bl)
-	| otherwise = encodeBS' s'
+	| otherwise = encodeBS s'
   where
 	s' = preSanitizeKeyName s
 	bl = encodeBL s

CmdLine/Option.hs

@@ -79,7 +79,7 @@ commonGlobalOptions =
 		-- Also set in git config so it will be passed on to any
 		-- git-annex child processes.
 		, setAnnexState $ Annex.addGitConfigOverride $
-			decodeBS' $ debugconfig <> "=" <> boolConfig' v
+			decodeBS $ debugconfig <> "=" <> boolConfig' v
 		]
 	
 	setdebugfilter v = mconcat
@@ -88,7 +88,7 @@ commonGlobalOptions =
 		-- Also set in git config so it will be passed on to any
 		-- git-annex child processes.
 		, setAnnexState $ Annex.addGitConfigOverride $ 
-			decodeBS' (debugfilterconfig <> "=") ++ v
+			decodeBS (debugfilterconfig <> "=") ++ v
 		]
 	
 	(ConfigKey debugconfig) = annexConfig "debug"

Command/Config.hs

@@ -55,23 +55,23 @@ optParser _ = setconfig <|> getconfig <|> unsetconfig
 
 seek :: Action -> CommandSeek
 seek (SetConfig ck@(ConfigKey name) val) = checkIsGlobalConfig ck $ commandAction $
-	startingUsualMessages (decodeBS' name) ai si $ do
+	startingUsualMessages (decodeBS name) ai si $ do
 		setGlobalConfig ck val
 		when (needLocalUpdate ck) $
 			setConfig ck (fromConfigValue val)
 		next $ return True
   where
 	ai = ActionItemOther (Just (fromConfigValue val))
-	si = SeekInput [decodeBS' name]
+	si = SeekInput [decodeBS name]
 seek (UnsetConfig ck@(ConfigKey name)) = checkIsGlobalConfig ck $ commandAction $
-	startingUsualMessages (decodeBS' name) ai si $ do
+	startingUsualMessages (decodeBS name) ai si $ do
 		unsetGlobalConfig ck
 		when (needLocalUpdate ck) $
 			unsetConfig ck
 		next $ return True
   where
 	ai = ActionItemOther (Just "unset")
-	si = SeekInput [decodeBS' name]
+	si = SeekInput [decodeBS name]
 seek (GetConfig ck) = checkIsGlobalConfig ck $ commandAction $
 	startingCustomOutput ai $ do
 		getGlobalConfig ck >>= \case

Command/DiffDriver.hs

@@ -89,7 +89,7 @@ fixupReq req@(Req {}) =
 	check rOldFile rOldMode (\r f -> r { rOldFile = f }) req
 		>>= check rNewFile rNewMode (\r f -> r { rNewFile = f })
   where
-	check getfile getmode setfile r = case readTreeItemType (encodeBS' (getmode r)) of
+	check getfile getmode setfile r = case readTreeItemType (encodeBS (getmode r)) of
 		Just TreeSymlink -> do
 			v <- getAnnexLinkTarget' f False
 			maybe (return r) repoint (parseLinkTargetOrPointer =<< v)

Command/FindRef.hs

@@ -22,6 +22,6 @@ seek o = Find.seek o'
   where
 	o' = o 
 		{ Find.keyOptions = Just $ WantBranchKeys $
-			map (Git.Ref . encodeBS') (Find.findThese o)
+			map (Git.Ref . encodeBS) (Find.findThese o)
 		, Find.findThese = []
 		}

Command/Fsck.hs

@@ -292,7 +292,7 @@ verifyLocationLog' key ai present u updatestatus = do
 			fix InfoMissing
 			warning $
 				"** Based on the location log, " ++
-				decodeBS' (actionItemDesc ai) ++
+				decodeBS (actionItemDesc ai) ++
 				"\n** was expected to be present, " ++
 				"but its content is missing."
 			return False
@@ -332,7 +332,7 @@ verifyRequiredContent key ai@(ActionItemAssociatedFile afile _) = case afile of
 				missingrequired <- Remote.prettyPrintUUIDs "missingrequired" missinglocs
 				warning $
 					"** Required content " ++
-					decodeBS' (actionItemDesc ai) ++
+					decodeBS (actionItemDesc ai) ++
 					" is missing from these repositories:\n" ++
 					missingrequired
 				return False
@@ -406,7 +406,7 @@ checkKeySizeOr bad key file ai = case fromKey keySize key of
 	badsize a b = do
 		msg <- bad key
 		warning $ concat
-			[ decodeBS' (actionItemDesc ai)
+			[ decodeBS (actionItemDesc ai)
 			, ": Bad file size ("
 			, compareSizes storageUnits True a b
 			, "); "
@@ -424,11 +424,11 @@ checkKeyUpgrade backend key ai (AssociatedFile (Just file)) =
 	case Types.Backend.canUpgradeKey backend of
 		Just a | a key -> do
 			warning $ concat
-				[ decodeBS' (actionItemDesc ai)
+				[ decodeBS (actionItemDesc ai)
 				, ": Can be upgraded to an improved key format. "
 				, "You can do so by running: git annex migrate --backend="
 				, decodeBS (formatKeyVariety (fromKey keyVariety key)) ++ " "
-				, decodeBS' file
+				, decodeBS file
 				]
 			return True
 		_ -> return True
@@ -475,7 +475,7 @@ checkBackendOr bad backend key file ai =
 			unless ok $ do
 				msg <- bad key
 				warning $ concat
-					[ decodeBS' (actionItemDesc ai)
+					[ decodeBS (actionItemDesc ai)
 					, ": Bad file content; "
 					, msg
 					]
@@ -503,7 +503,7 @@ checkInodeCache key content mic ai = case mic of
 					Nothing -> noop
 					Just ic' -> whenM (compareInodeCaches ic ic') $ do
 						warning $ concat
-							[ decodeBS' (actionItemDesc ai)
+							[ decodeBS (actionItemDesc ai)
 							, ": Stale or missing inode cache; updating."
 							]
 						Database.Keys.addInodeCaches key [ic]

Command/Import.hs

@@ -85,7 +85,7 @@ optParser desc = do
 			[bs] -> 
 				let (branch, subdir) = separate (== ':') bs
 				in RemoteImportOptions r
-					(Ref (encodeBS' branch))
+					(Ref (encodeBS branch))
 					(if null subdir then Nothing else Just subdir)
 					content
 					ic

Command/Info.hs

@@ -163,7 +163,7 @@ itemInfo o (si, p) = ifM (isdir p)
 
 noInfo :: String -> SeekInput -> Annex ()
 noInfo s si = do
-	showStart "info" (encodeBS' s) si
+	showStart "info" (encodeBS s) si
 	showNote $ "not a directory or an annexed file or a treeish or a remote or a uuid"
 	showEndFail
 
@@ -183,7 +183,7 @@ dirInfo o dir si = showCustom (unwords ["info", dir]) si $ do
 
 treeishInfo :: InfoOptions -> String -> SeekInput -> Annex ()
 treeishInfo o t si = do
-	mi <- getTreeStatInfo o (Git.Ref (encodeBS' t))
+	mi <- getTreeStatInfo o (Git.Ref (encodeBS t))
 	case mi of
 		Nothing -> noInfo t si
 		Just i -> showCustom (unwords ["info", t]) si $ do
@@ -313,8 +313,8 @@ showStat :: Stat -> StatState ()
 showStat s = maybe noop calc =<< s
   where
 	calc (desc, a) = do
-		(lift . showHeader . encodeBS') desc
-		lift . showRaw . encodeBS' =<< a
+		(lift . showHeader . encodeBS) desc
+		lift . showRaw . encodeBS =<< a
 
 repo_list :: TrustLevel -> Stat
 repo_list level = stat n $ nojson $ lift $ do

Command/Log.hs

@@ -230,7 +230,7 @@ getGitLog fs os = do
 		[ Param $ Git.fromRef Annex.Branch.fullname
 		, Param "--"
 		] ++ map Param fs
-	return (parseGitRawLog config (map decodeBL' ls), cleanup)
+	return (parseGitRawLog config (map decodeBL ls), cleanup)
 
 -- Parses chunked git log --raw output, which looks something like:
 --

Command/Merge.hs

@@ -39,7 +39,7 @@ seek o
 	| otherwise = do
 		prepMerge
 		forM_ (mergeBranches o) $
-			commandAction . mergeBranch o . Git.Ref . encodeBS'
+			commandAction . mergeBranch o . Git.Ref . encodeBS
 
 mergeAnnexBranch :: CommandStart
 mergeAnnexBranch = starting "merge" ai si $ do

Command/Uninit.hs

@@ -37,7 +37,7 @@ check = do
 	whenM ((/=) <$> liftIO (absPath top) <*> liftIO (absPath currdir)) $
 		giveup "can only run uninit from the top of the git repository"
   where
-	current_branch = Git.Ref . encodeBS' . Prelude.head . lines . decodeBS' <$> revhead
+	current_branch = Git.Ref . encodeBS . Prelude.head . lines . decodeBS <$> revhead
 	revhead = inRepo $ Git.Command.pipeReadStrict
 		[Param "rev-parse", Param "--abbrev-ref", Param "HEAD"]
 

Command/Vicfg.hs

@@ -311,7 +311,7 @@ parseCfg defcfg = go [] defcfg . lines
 				let m = M.insert u l (cfgScheduleMap cfg)
 				in Right $ cfg { cfgScheduleMap = m }
 		| setting == "config" =
-			let m = M.insert (ConfigKey (encodeBS' f)) (ConfigValue (encodeBS' val)) (cfgGlobalConfigs cfg)
+			let m = M.insert (ConfigKey (encodeBS f)) (ConfigValue (encodeBS val)) (cfgGlobalConfigs cfg)
 			in Right $ cfg { cfgGlobalConfigs = m }
 		| setting == "numcopies" = case readish val of
 			Nothing -> Left "parse error (expected an integer)"

Config.hs

@@ -39,7 +39,7 @@ setConfig :: ConfigKey -> String -> Annex ()
 setConfig (ConfigKey key) value = do
 	inRepo $ Git.Command.run
 		[ Param "config"
-		, Param (decodeBS' key)
+		, Param (decodeBS key)
 		, Param value
 		]
 	reloadConfig

Database/Types.hs

@@ -95,10 +95,10 @@ newtype SSha = SSha String
 	deriving (Eq, Show)
 
 toSSha :: Sha -> SSha
-toSSha (Ref s) = SSha (decodeBS' s)
+toSSha (Ref s) = SSha (decodeBS s)
 
 fromSSha :: SSha -> Ref
-fromSSha (SSha s) = Ref (encodeBS' s)
+fromSSha (SSha s) = Ref (encodeBS s)
 
 instance PersistField SSha where
 	toPersistValue (SSha b) = toPersistValue b

Git/Config.hs

@@ -170,7 +170,7 @@ parse s st
 
 {- Checks if a string from git config is a true/false value. -}
 isTrueFalse :: String -> Maybe Bool
-isTrueFalse = isTrueFalse' . ConfigValue . encodeBS'
+isTrueFalse = isTrueFalse' . ConfigValue . encodeBS
 
 isTrueFalse' :: ConfigValue -> Maybe Bool
 isTrueFalse' (ConfigValue s)
@@ -248,8 +248,8 @@ changeFile f (ConfigKey k) v = boolSystem "git"
 	[ Param "config"
 	, Param "--file"
 	, File f
-	, Param (decodeBS' k)
-	, Param (decodeBS' v)
+	, Param (decodeBS k)
+	, Param (decodeBS v)
 	]
 
 {- Unsets a git config setting, in both the git repo,
@@ -264,4 +264,4 @@ unset ck@(ConfigKey k) r = ifM (Git.Command.runBool ps r)
 	, return Nothing
 	)
   where
-	ps = [Param "config", Param "--unset-all", Param (decodeBS' k)]
+	ps = [Param "config", Param "--unset-all", Param (decodeBS k)]

Git/ConfigTypes.hs

@@ -31,7 +31,7 @@ getSharedRepository r =
 			"all" -> AllShared
 			"world" -> AllShared
 			"everybody" -> AllShared
-			_ -> maybe UnShared UmaskShared (readish (decodeBS' v))
+			_ -> maybe UnShared UmaskShared (readish (decodeBS v))
 		Just NoConfigValue -> UnShared
 		Nothing -> UnShared
 

Git/DiffTree.hs

@@ -114,7 +114,7 @@ parseDiffRaw l = go l
 	go (info:f:rest) = case A.parse (parserDiffRaw (L.toStrict f)) info of
 		A.Done _ r -> r : go rest
 		A.Fail _ _ err -> error $ "diff-tree parse error: " ++ err
-	go (s:[]) = error $ "diff-tree parse error near \"" ++ decodeBL' s ++ "\""
+	go (s:[]) = error $ "diff-tree parse error near \"" ++ decodeBL s ++ "\""
 
 -- :<srcmode> SP <dstmode> SP <srcsha> SP <dstsha> SP <status>
 --

Git/Fsck.hs

@@ -159,7 +159,7 @@ isMissing s r = either (const True) (const False) <$> tryIO dump
 		] r
 
 findShas :: [String] -> [Sha]
-findShas = catMaybes . map (extractSha . encodeBS') 
+findShas = catMaybes . map (extractSha . encodeBS) 
 	. concat . map words . filter wanted
   where
 	wanted l = not ("dangling " `isPrefixOf` l)

Git/GCrypt.hs

@@ -107,7 +107,7 @@ getParticiantList globalconfigrepo repo remotename = KeyIds $ parse $ firstJust
   where
 	defaultkey = "gcrypt.participants"
 	parse (Just (ConfigValue "simple")) = []
-	parse (Just (ConfigValue b)) = words (decodeBS' b)
+	parse (Just (ConfigValue b)) = words (decodeBS b)
 	parse (Just NoConfigValue) = []
 	parse Nothing = []
 
@@ -122,4 +122,4 @@ remoteSigningKey = remoteConfigKey "gcrypt-signingkey"
 
 remoteConfigKey :: S.ByteString -> RemoteName -> ConfigKey
 remoteConfigKey key remotename = ConfigKey $
-	"remote." <> encodeBS' remotename <> "." <> key
+	"remote." <> encodeBS remotename <> "." <> key

Git/LsFiles.hs

@@ -251,7 +251,7 @@ data Unmerged = Unmerged
 unmerged :: [RawFilePath] -> Repo -> IO ([Unmerged], IO Bool)
 unmerged l repo = guardSafeForLsFiles repo $ do
 	(fs, cleanup) <- pipeNullSplit params repo
-	return (reduceUnmerged [] $ catMaybes $ map (parseUnmerged . decodeBL') fs, cleanup)
+	return (reduceUnmerged [] $ catMaybes $ map (parseUnmerged . decodeBL) fs, cleanup)
   where
 	params = 
 		Param "ls-files" :
@@ -277,7 +277,7 @@ parseUnmerged s
 				then Nothing
 				else do
 					treeitemtype <- readTreeItemType (encodeBS rawtreeitemtype)
-					sha <- extractSha (encodeBS' rawsha)
+					sha <- extractSha (encodeBS rawsha)
 					return $ InternalUnmerged (stage == 2) (toRawFilePath file)
 						(Just treeitemtype) (Just sha)
 		_ -> Nothing

Git/LsTree.hs

@@ -149,7 +149,7 @@ parserLsTree long = case long of
  - generated, so any size information is not included. -}
 formatLsTree :: TreeItem -> S.ByteString
 formatLsTree ti = S.intercalate (S.singleton (fromIntegral (ord ' ')))
-	[ encodeBS' (showOct (mode ti) "")
+	[ encodeBS (showOct (mode ti) "")
 	, typeobj ti
 	, fromRef' (sha ti)
 	] <> (S.cons (fromIntegral (ord '\t')) (getTopFilePath (file ti)))

Git/Ref.hs

@@ -82,7 +82,7 @@ branchFileRef branch f = Ref $ fromRef' branch <> ":" <> toInternalGitPath f
 
 {- Converts a Ref to refer to the content of the Ref on a given date. -}
 dateRef :: Ref -> RefDate -> Ref
-dateRef r (RefDate d) = Ref $ fromRef' r <> "@" <> encodeBS' d
+dateRef r (RefDate d) = Ref $ fromRef' r <> "@" <> encodeBS d
 
 {- A Ref that can be used to refer to a file in the repository as it
  - appears in a given Ref. -}
@@ -177,7 +177,7 @@ tree (Ref ref) = extractSha <$$> pipeReadStrict
 	[ Param "rev-parse"
 	, Param "--verify"
 	, Param "--quiet"
-	, Param (decodeBS' ref')
+	, Param (decodeBS ref')
 	]
   where
 	ref' = if ":" `S.isInfixOf` ref

Git/Remote.hs

@@ -37,7 +37,7 @@ remoteKeyToRemoteName :: ConfigKey -> Maybe RemoteName
 remoteKeyToRemoteName (ConfigKey k)
 	| "remote." `S.isPrefixOf` k = 
 		let n = S.intercalate "." $ dropFromEnd 1 $ drop 1 $ S8.split '.' k
-		in if S.null n then Nothing else Just (decodeBS' n)
+		in if S.null n then Nothing else Just (decodeBS n)
 	| otherwise = Nothing
 
 {- Construct a legal git remote name out of an arbitrary input string.
@@ -90,7 +90,7 @@ parseRemoteLocation s repo = ret $ calcloc s
 		| null insteadofs = l
 		| otherwise = replacement ++ drop (S.length bestvalue) l
 	  where
-		replacement = decodeBS' $ S.drop (S.length prefix) $
+		replacement = decodeBS $ S.drop (S.length prefix) $
 			S.take (S.length bestkey - S.length suffix) bestkey
 		(bestkey, bestvalue) = 
 			case maximumBy longestvalue insteadofs of

Git/Repair.hs

@@ -252,7 +252,7 @@ getAllRefs r = getAllRefs' (fromRawFilePath (localGitDir r) </> "refs")
 getAllRefs' :: FilePath -> IO [Ref]
 getAllRefs' refdir = do
 	let topsegs = length (splitPath refdir) - 1
-	let toref = Ref . encodeBS' . joinPath . drop topsegs . splitPath
+	let toref = Ref . encodeBS . joinPath . drop topsegs . splitPath
 	map toref <$> dirContentsRecursive refdir
 
 explodePackedRefsFile :: Repo -> IO ()
@@ -279,8 +279,8 @@ packedRefsFile r = fromRawFilePath (localGitDir r) </> "packed-refs"
 parsePacked :: String -> Maybe (Sha, Ref)
 parsePacked l = case words l of
 	(sha:ref:[])
-		| isJust (extractSha (encodeBS' sha)) && Ref.legal True ref ->
-			Just (Ref (encodeBS' sha), Ref (encodeBS' ref))
+		| isJust (extractSha (encodeBS sha)) && Ref.legal True ref ->
+			Just (Ref (encodeBS sha), Ref (encodeBS ref))
 	_ -> Nothing
 
 {- git-branch -d cannot be used to remove a branch that is directly
@@ -350,8 +350,8 @@ verifyCommit missing goodcommits commit r
   where
 	parse l = case words l of
 		(commitsha:treesha:[]) -> (,)
-			<$> extractSha (encodeBS' commitsha)
-			<*> extractSha (encodeBS' treesha)
+			<$> extractSha (encodeBS commitsha)
+			<*> extractSha (encodeBS treesha)
 		_ -> Nothing
 	check [] = return True
 	check ((c, t):rest)
@@ -469,7 +469,7 @@ preRepair g = do
   where
 	headfile = localGitDir g P.</> "HEAD"
 	validhead s = "ref: refs/" `isPrefixOf` s
-		|| isJust (extractSha (encodeBS' s))
+		|| isJust (extractSha (encodeBS s))
 
 {- Put it all together. -}
 runRepair :: (Ref -> Bool) -> Bool -> Repo -> IO (Bool, [Branch])

Git/Types.hs

@@ -75,7 +75,7 @@ instance Default ConfigValue where
 	def = ConfigValue mempty
 
 fromConfigKey :: ConfigKey -> String
-fromConfigKey (ConfigKey s) = decodeBS' s
+fromConfigKey (ConfigKey s) = decodeBS s
 
 instance Show ConfigKey where
 	show = fromConfigKey
@@ -88,16 +88,16 @@ instance FromConfigValue S.ByteString where
 	fromConfigValue NoConfigValue = mempty
 
 instance FromConfigValue String where
-	fromConfigValue = decodeBS' . fromConfigValue
+	fromConfigValue = decodeBS . fromConfigValue
 
 instance Show ConfigValue where
 	show = fromConfigValue
 
 instance IsString ConfigKey where
-	fromString = ConfigKey . encodeBS'
+	fromString = ConfigKey . encodeBS
 
 instance IsString ConfigValue where
-	fromString = ConfigValue . encodeBS'
+	fromString = ConfigValue . encodeBS
 
 type RemoteName = String
 
@@ -106,7 +106,7 @@ newtype Ref = Ref S.ByteString
 	deriving (Eq, Ord, Read, Show)
 
 fromRef :: Ref -> String
-fromRef = decodeBS' . fromRef'
+fromRef = decodeBS . fromRef'
 
 fromRef' :: Ref -> S.ByteString
 fromRef' (Ref s) = s

Git/UpdateIndex.hs

@@ -80,14 +80,14 @@ lsTree (Ref x) repo streamer = do
 	mapM_ streamer s
 	void $ cleanup
   where
-	params = map Param ["ls-tree", "-z", "-r", "--full-tree", decodeBS' x]
+	params = map Param ["ls-tree", "-z", "-r", "--full-tree", decodeBS x]
 lsSubTree :: Ref -> FilePath -> Repo -> Streamer
 lsSubTree (Ref x) p repo streamer = do
 	(s, cleanup) <- pipeNullSplit params repo
 	mapM_ streamer s
 	void $ cleanup
   where
-	params = map Param ["ls-tree", "-z", "-r", "--full-tree", decodeBS' x, p]
+	params = map Param ["ls-tree", "-z", "-r", "--full-tree", decodeBS x, p]
 
 {- Generates a line suitable to be fed into update-index, to add
  - a given file with a given sha. -}

Key.hs

@@ -59,13 +59,13 @@ isChunkKey :: Key -> Bool
 isChunkKey k = isJust (fromKey keyChunkSize k) && isJust (fromKey keyChunkNum k)
 
 serializeKey :: Key -> String
-serializeKey = decodeBS' . serializeKey'
+serializeKey = decodeBS . serializeKey'
 
 serializeKey' :: Key -> S.ByteString
 serializeKey' = keySerialization
 
 deserializeKey :: String -> Maybe Key
-deserializeKey = deserializeKey' . encodeBS'
+deserializeKey = deserializeKey' . encodeBS
 
 deserializeKey' :: S.ByteString -> Maybe Key
 deserializeKey' = eitherToMaybe . A.parseOnly keyParser

Logs/FsckResults.hs

@@ -54,7 +54,7 @@ deserializeFsckResults = deserialize . lines
 	deserialize ("truncated":ls) = deserialize' ls True
 	deserialize ls = deserialize' ls False
 	deserialize' ls t =
-		let s = S.fromList $ map (Ref . encodeBS') ls
+		let s = S.fromList $ map (Ref . encodeBS) ls
 		in if S.null s then FsckFailed else FsckFoundMissing s t
 
 clearFsckResults :: UUID -> Annex ()

Logs/Transfer.hs

@@ -35,7 +35,7 @@ describeTransfer :: Transfer -> TransferInfo -> String
 describeTransfer t info = unwords
 	[ show $ transferDirection t
 	, show $ transferUUID t
-	, decodeBS' $ actionItemDesc $ ActionItemAssociatedFile
+	, decodeBS $ actionItemDesc $ ActionItemAssociatedFile
 		(associatedFile info)
 		(transferKey t)
 	, show $ bytesComplete info

Logs/View.hs

@@ -74,7 +74,7 @@ branchView view
 	| B.null name = Git.Ref branchViewPrefix
 	| otherwise = Git.Ref $ branchViewPrefix <> "/" <> name
   where
-	name = encodeBS' $
+	name = encodeBS $
 		intercalate ";" $ map branchcomp (viewComponents view)
 	branchcomp c
 		| viewVisible c = branchcomp' c

Messages.hs

@@ -72,18 +72,18 @@ import qualified Annex
 
 showStart :: String -> RawFilePath -> SeekInput -> Annex ()
 showStart command file si = outputMessage json $
-	encodeBS' command <> " " <> file <> " "
+	encodeBS command <> " " <> file <> " "
   where
 	json = JSON.start command (Just file) Nothing si
 
 showStartKey :: String -> Key -> ActionItem -> SeekInput -> Annex ()
 showStartKey command key ai si = outputMessage json $
-	encodeBS' command <> " " <> actionItemDesc ai <> " "
+	encodeBS command <> " " <> actionItemDesc ai <> " "
   where
 	json = JSON.start command (actionItemFile ai) (Just key) si
 
 showStartOther :: String -> Maybe String -> SeekInput -> Annex ()
-showStartOther command mdesc si = outputMessage json $ encodeBS' $
+showStartOther command mdesc si = outputMessage json $ encodeBS $
 	command ++ (maybe "" (" " ++) mdesc) ++ " "
   where
 	json = JSON.start command Nothing Nothing si
@@ -116,7 +116,7 @@ showEndMessage (StartNoMessage _) = const noop
 showEndMessage (CustomOutput _) = const noop
 
 showNote :: String -> Annex ()
-showNote s = outputMessage (JSON.note s) $ encodeBS' $ "(" ++ s ++ ") "
+showNote s = outputMessage (JSON.note s) $ encodeBS $ "(" ++ s ++ ") "
 
 showAction :: String -> Annex ()
 showAction s = showNote $ s ++ "..."
@@ -131,7 +131,7 @@ showSideAction m = Annex.getState Annex.output >>= go
 			Annex.changeState $ \s -> s { Annex.output = st' }
 		| sideActionBlock st == InBlock = return ()
 		| otherwise = go'
-	go' = outputMessage JSON.none $ encodeBS' $ "(" ++ m ++ "...)\n"
+	go' = outputMessage JSON.none $ encodeBS $ "(" ++ m ++ "...)\n"
 			
 showStoringStateAction :: Annex ()
 showStoringStateAction = showSideAction "recording state in git"
@@ -175,7 +175,7 @@ showOutput = unlessM commandProgressDisabled $
 	outputMessage JSON.none "\n"
 
 showLongNote :: String -> Annex ()
-showLongNote s = outputMessage (JSON.note s) (encodeBS' (formatLongNote s))
+showLongNote s = outputMessage (JSON.note s) (encodeBS (formatLongNote s))
 
 formatLongNote :: String -> String
 formatLongNote s = '\n' : indent s ++ "\n"
@@ -184,7 +184,7 @@ formatLongNote s = '\n' : indent s ++ "\n"
 -- to console, but json object containing the info is emitted immediately.
 showInfo :: String -> Annex ()
 showInfo s = outputMessage' outputJSON (JSON.info s) $
-	encodeBS' (formatLongNote s)
+	encodeBS (formatLongNote s)
 
 showEndOk :: Annex ()
 showEndOk = showEndResult True

P2P/Protocol.hs

@@ -172,7 +172,7 @@ instance Proto.Serializable Service where
 instance Proto.Serializable ProtoAssociatedFile where
 	serialize (ProtoAssociatedFile (AssociatedFile Nothing)) = ""
 	serialize (ProtoAssociatedFile (AssociatedFile (Just af))) = 
-		decodeBS' $ toInternalGitPath $ encodeBS' $ concatMap esc $ fromRawFilePath af
+		decodeBS $ toInternalGitPath $ encodeBS $ concatMap esc $ fromRawFilePath af
 	  where
 		esc '%' = "%%"
 		esc c 

Remote.hs

@@ -153,7 +153,7 @@ byName' n = go . filter matching <$> remoteList
 
 {- Finds the remote or remote group matching the name. -}
 byNameOrGroup :: RemoteName -> Annex [Remote]
-byNameOrGroup n = go =<< getConfigMaybe (ConfigKey ("remotes." <> encodeBS' n))
+byNameOrGroup n = go =<< getConfigMaybe (ConfigKey ("remotes." <> encodeBS n))
   where
 	go (Just l) = catMaybes
 		<$> mapM (byName . Just) (splitc ' ' (fromConfigValue l))

Remote/Adb.hs

@@ -307,7 +307,7 @@ listImportableContentsM serial adir = adbfind >>= \case
 	mk ('S':'T':'\t':l) =
 		let (stat, fn) = separate (== '\t') l
 		    sz = fromMaybe 0 (readish (takeWhile (/= ' ') stat))
-		    cid = ContentIdentifier (encodeBS' stat)
+		    cid = ContentIdentifier (encodeBS stat)
 		    loc = mkImportLocation $ toRawFilePath $ 
 		    	Posix.makeRelative (fromAndroidPath adir) fn
 		in Just (loc, (cid, sz))
@@ -440,7 +440,7 @@ getExportContentIdentifier serial adir loc = do
 	return $ case ls of
 		Just ["n"] -> Right Nothing
 		Just (('S':'T':'\t':stat):[]) -> Right $ Just $
-			ContentIdentifier (encodeBS' stat)
+			ContentIdentifier (encodeBS stat)
 		_ -> Left (ExitFailure 1)
   where
 	aloc = fromAndroidPath $ androidExportLocation adir loc

Remote/Borg.hs

@@ -149,7 +149,7 @@ borgLocal :: BorgRepo -> Bool
 borgLocal (BorgRepo r) = notElem ':' r
 
 borgArchive :: BorgRepo -> BorgArchiveName -> String
-borgArchive (BorgRepo r) n = r ++ "::" ++ decodeBS' n
+borgArchive (BorgRepo r) n = r ++ "::" ++ decodeBS n
 
 absBorgRepo :: BorgRepo -> IO BorgRepo
 absBorgRepo r@(BorgRepo p)

Remote/GCrypt.hs

@@ -311,7 +311,7 @@ setupRepo gcryptid r
 			, Param tmpconfig
 			]
 		liftIO $ do
-			void $ Git.Config.changeFile tmpconfig coreGCryptId (encodeBS' gcryptid)
+			void $ Git.Config.changeFile tmpconfig coreGCryptId (encodeBS gcryptid)
 			void $ Git.Config.changeFile tmpconfig denyNonFastForwards (Git.Config.boolConfig' False)
 		ok <- liftIO $ rsync $ opts ++
 			[ Param "--recursive"

Remote/GitLFS.hs

@@ -213,7 +213,7 @@ configKnownUrl r
 	set k v r' = do
 		let k' = remoteAnnexConfig r' k
 		setConfig k' v
-		return $ Git.Config.store' k' (Git.ConfigValue (encodeBS' v)) r'
+		return $ Git.Config.store' k' (Git.ConfigValue (encodeBS v)) r'
 
 data LFSHandle = LFSHandle
 	{ downloadEndpoint :: Maybe LFS.Endpoint

Remote/Helper/Special.hs

@@ -68,13 +68,13 @@ findSpecialRemotes s = do
 		(pure Git.Construct.fromUnknown)
 	match (ConfigKey k) _ =
 		"remote." `S.isPrefixOf` k 
-		&& (".annex-" <> encodeBS' s) `S.isSuffixOf` k
+		&& (".annex-" <> encodeBS s) `S.isSuffixOf` k
 
 {- Sets up configuration for a special remote in .git/config. -}
 gitConfigSpecialRemote :: UUID -> RemoteConfig -> [(String, String)] -> Annex ()
 gitConfigSpecialRemote u c cfgs = do
 	forM_ cfgs $ \(k, v) -> 
-		setConfig (remoteAnnexConfig c (encodeBS' k)) v
+		setConfig (remoteAnnexConfig c (encodeBS k)) v
 	storeUUIDIn (remoteAnnexConfig c "uuid") u
 
 -- RetrievalVerifiableKeysSecure unless overridden by git config.

Remote/Hook.hs

@@ -131,8 +131,8 @@ lookupHook hookname action = do
 				else return $ Just fallback
 		else return $ Just command
   where
-	hook = annexConfig $ encodeBS' $ hookname ++ "-" ++ action ++ "-hook"
-	hookfallback = annexConfig $ encodeBS' $ hookname ++ "-hook"
+	hook = annexConfig $ encodeBS $ hookname ++ "-" ++ action ++ "-hook"
+	hookfallback = annexConfig $ encodeBS $ hookname ++ "-hook"
 
 runHook :: HookName -> Action -> Key -> Maybe FilePath -> Annex ()
 runHook hook action k f = lookupHook hook action >>= \case

Test/Framework.hs

@@ -108,7 +108,7 @@ inmainrepo a = do
 
 with_ssh_origin :: (Assertion -> Assertion) -> (Assertion -> Assertion)
 with_ssh_origin cloner a = cloner $ do
-	let k = Git.Types.ConfigKey (encodeBS' config)
+	let k = Git.Types.ConfigKey (encodeBS config)
 	let v = Git.Types.ConfigValue (toRawFilePath "/dev/null")
 	origindir <- absPath . Git.Types.fromConfigValue
 		=<< annexeval (Config.getConfig k v)

Types/ActionItem.hs

@@ -65,7 +65,7 @@ actionItemDesc (ActionItemBranchFilePath bfp _) = descBranchFilePath bfp
 actionItemDesc (ActionItemFailedTransfer t i) = actionItemDesc $
 	ActionItemAssociatedFile (associatedFile i) (transferKey t)
 actionItemDesc (ActionItemTreeFile f) = f
-actionItemDesc (ActionItemOther s) = encodeBS' (fromMaybe "" s)
+actionItemDesc (ActionItemOther s) = encodeBS (fromMaybe "" s)
 actionItemDesc (OnlyActionOn _ ai) = actionItemDesc ai
 
 actionItemKey :: ActionItem -> Maybe Key

Types/GitConfig.hs

@@ -476,4 +476,4 @@ remoteAnnexConfigEnd key = "annex-" <> key
 {- A per-remote setting in git config. -}
 remoteConfig :: RemoteNameable r => r -> UnqualifiedConfigKey -> ConfigKey
 remoteConfig r key = ConfigKey $
-	"remote." <> encodeBS' (getRemoteName r) <> "." <> key
+	"remote." <> encodeBS (getRemoteName r) <> "." <> key

Types/UUID.hs

@@ -48,10 +48,10 @@ instance ToUUID B.ByteString where
 		| otherwise = UUID b
 
 instance FromUUID String where
-	fromUUID s = decodeBS' (fromUUID s)
+	fromUUID s = decodeBS (fromUUID s)
 
 instance ToUUID String where
-	toUUID s = toUUID (encodeBS' s)
+	toUUID s = toUUID (encodeBS s)
 
 instance FromUUID ConfigValue where
 	fromUUID s = (ConfigValue (fromUUID s))

Upgrade/V2.hs

@@ -93,7 +93,7 @@ logFiles dir = return . filter (".log" `isSuffixOf`)
 push :: Annex ()
 push = do
 	origin_master <- inRepo $ Git.Ref.exists $ 
-		Git.Ref $ encodeBS' "origin/master"
+		Git.Ref $ encodeBS "origin/master"
 	origin_gitannex <- Annex.Branch.hasOrigin
 	case (origin_master, origin_gitannex) of
 		(_, True) -> do

Upgrade/V5/Direct.hs

@@ -60,7 +60,7 @@ setIndirect = do
 fromDirectBranch :: Ref -> Ref
 fromDirectBranch directhead = case splitc '/' $ fromRef directhead of
 	("refs":"heads":"annex":"direct":rest) -> 
-		Ref $ encodeBS' $ "refs/heads/" ++ intercalate "/" rest
+		Ref $ encodeBS $ "refs/heads/" ++ intercalate "/" rest
 	_ -> directhead
 
 switchHEADBack :: Annex ()

Utility/Data.hs

@@ -1,6 +1,6 @@
 {- utilities for simple data types
  -
- - Copyright 2013 Joey Hess <id@joeyh.name>
+ - Copyright 2013-2021 Joey Hess <id@joeyh.name>
  -
  - License: BSD-2-clause
  -}
@@ -10,8 +10,12 @@
 module Utility.Data (
 	firstJust,
 	eitherToMaybe,
+	s2w8,
+	w82s,
 ) where
 
+import Data.Word
+
 {- First item in the list that is not Nothing. -}
 firstJust :: Eq a => [Maybe a] -> Maybe a
 firstJust ms = case dropWhile (== Nothing) ms of
@@ -20,3 +24,15 @@ firstJust ms = case dropWhile (== Nothing) ms of
 
 eitherToMaybe :: Either a b -> Maybe b
 eitherToMaybe = either (const Nothing) Just
+
+c2w8 :: Char -> Word8
+c2w8 = fromIntegral . fromEnum
+
+w82c :: Word8 -> Char
+w82c = toEnum . fromIntegral
+
+s2w8 :: String -> [Word8]
+s2w8 = map c2w8
+
+w82s :: [Word8] -> String
+w82s = map w82c

Utility/Debug.hs

@@ -34,7 +34,7 @@ newtype DebugSource = DebugSource S.ByteString
 	deriving (Eq, Show)
 
 instance IsString DebugSource where
-	fromString = DebugSource . encodeBS'
+	fromString = DebugSource . encodeBS
 
 -- | Selects whether to display a message from a source.
 data DebugSelector 
@@ -97,6 +97,6 @@ fastDebug (DebugSelector p) src msg
 
 formatDebugMessage :: DebugSource -> String -> IO S.ByteString
 formatDebugMessage (DebugSource src) msg = do
-	t <- encodeBS' . formatTime defaultTimeLocale "[%F %X%Q]"
+	t <- encodeBS . formatTime defaultTimeLocale "[%F %X%Q]"
 		<$> getZonedTime
 	return (t <> " (" <> src <> ") " <> encodeBS msg)

Utility/FileSystemEncoding.hs

@@ -1,6 +1,6 @@
 {- GHC File system encoding handling.
  -
- - Copyright 2012-2016 Joey Hess <id@joeyh.name>
+ - Copyright 2012-2021 Joey Hess <id@joeyh.name>
  -
  - License: BSD-2-clause
  -}
@@ -18,36 +18,22 @@ module Utility.FileSystemEncoding (
 	encodeBL,
 	decodeBS,
 	encodeBS,
-	decodeBL',
-	encodeBL',
-	decodeBS',
-	encodeBS',
 	truncateFilePath,
-	s2w8,
-	w82s,
-	c2w8,
-	w82c,
 ) where
 
 import qualified GHC.Foreign as GHC
 import qualified GHC.IO.Encoding as Encoding
-import Foreign.C
 import System.IO
 import System.IO.Unsafe
-import Data.Word
 import System.FilePath.ByteString (RawFilePath, encodeFilePath, decodeFilePath)
 import qualified Data.ByteString as S
 import qualified Data.ByteString.Lazy as L
+import Data.ByteString.Unsafe (unsafePackMallocCStringLen)
 #ifdef mingw32_HOST_OS
 import qualified Data.ByteString.UTF8 as S8
 import qualified Data.ByteString.Lazy.UTF8 as L8
-#else
-import Data.List
-import Utility.Split
 #endif
 
-import Utility.Exception
-
 {- Makes all subsequent Handles that are opened, as well as stdio Handles,
  - use the filesystem encoding, instead of the encoding of the current
  - locale.
@@ -80,32 +66,10 @@ fileEncoding h = hSetEncoding h =<< Encoding.getFileSystemEncoding
 fileEncoding h = hSetEncoding h Encoding.utf8
 #endif
 
-{- Encodes a FilePath into a String, applying the filesystem encoding.
- -
- - There are very few things it makes sense to do with such an encoded
- - string. It's not a legal filename; it should not be displayed.
- - So this function is not exported, but instead used by the few functions
- - that can usefully consume it.
- -
- - This use of unsafePerformIO is belived to be safe; GHC's interface
- - only allows doing this conversion with CStrings, and the CString buffer
- - is allocated, used, and deallocated within the call, with no side
- - effects.
- -
- - If the FilePath contains a value that is not legal in the filesystem
- - encoding, rather than thowing an exception, it will be returned as-is.
- -}
-{-# NOINLINE _encodeFilePath #-}
-_encodeFilePath :: FilePath -> String
-_encodeFilePath fp = unsafePerformIO $ do
-	enc <- Encoding.getFileSystemEncoding
-	GHC.withCString enc fp (GHC.peekCString Encoding.char8)
-		`catchNonAsync` (\_ -> return fp)
-
 {- Decodes a ByteString into a FilePath, applying the filesystem encoding. -}
 decodeBL :: L.ByteString -> FilePath
 #ifndef mingw32_HOST_OS
-decodeBL = encodeW8NUL . L.unpack
+decodeBL = decodeBS . L.toStrict
 #else
 {- On Windows, we assume that the ByteString is utf-8, since Windows
  - only uses unicode for filenames. -}
@@ -115,104 +79,45 @@ decodeBL = L8.toString
 {- Encodes a FilePath into a ByteString, applying the filesystem encoding. -}
 encodeBL :: FilePath -> L.ByteString
 #ifndef mingw32_HOST_OS
-encodeBL = L.pack . decodeW8NUL
+encodeBL = L.fromStrict . encodeBS
 #else
 encodeBL = L8.fromString
 #endif
 
 decodeBS :: S.ByteString -> FilePath
 #ifndef mingw32_HOST_OS
-decodeBS = encodeW8NUL . S.unpack
+-- This is a copy of code from System.FilePath.Internal.decodeFilePath.
+-- However, older versions of that library truncated at NUL, which this
+-- must not do, because it may end up used on something other than a unix
+-- filepath.
+{-# NOINLINE decodeBS #-}
+decodeBS b = unsafePerformIO $ do
+	enc <- Encoding.getFileSystemEncoding
+	S.useAsCStringLen b (GHC.peekCStringLen enc)
 #else
 decodeBS = S8.toString
 #endif
 
 encodeBS :: FilePath -> S.ByteString
 #ifndef mingw32_HOST_OS
-encodeBS = S.pack . decodeW8NUL
+-- This is a copy of code from System.FilePath.Internal.encodeFilePath.
+-- However, older versions of that library truncated at NUL, which this
+-- must not do, because it may end up used on something other than a unix
+-- filepath.
+{-# NOINLINE encodeBS #-}
+encodeBS f = unsafePerformIO $ do
+	enc <- Encoding.getFileSystemEncoding
+	GHC.newCStringLen enc f >>= unsafePackMallocCStringLen
 #else
 encodeBS = S8.fromString
 #endif
 
-{- Faster version that assumes the string does not contain NUL;
- - if it does it will be truncated before the NUL. -}
-decodeBS' :: S.ByteString -> FilePath
-#ifndef mingw32_HOST_OS
-decodeBS' = encodeW8 . S.unpack
-#else
-decodeBS' = S8.toString
-#endif
-
-encodeBS' :: FilePath -> S.ByteString
-#ifndef mingw32_HOST_OS
-encodeBS' = S.pack . decodeW8
-#else
-encodeBS' = S8.fromString
-#endif
-
-decodeBL' :: L.ByteString -> FilePath
-#ifndef mingw32_HOST_OS
-decodeBL' = encodeW8 . L.unpack
-#else
-decodeBL' = L8.toString
-#endif
-
-encodeBL' :: FilePath -> L.ByteString
-#ifndef mingw32_HOST_OS
-encodeBL' = L.pack . decodeW8
-#else
-encodeBL' = L8.fromString
-#endif
-
 fromRawFilePath :: RawFilePath -> FilePath
 fromRawFilePath = decodeFilePath
 
 toRawFilePath :: FilePath -> RawFilePath
 toRawFilePath = encodeFilePath
 
-#ifndef mingw32_HOST_OS
-{- Converts a [Word8] to a FilePath, encoding using the filesystem encoding.
- -
- - w82s produces a String, which may contain Chars that are invalid
- - unicode. From there, this is really a simple matter of applying the
- - file system encoding, only complicated by GHC's interface to doing so.
- -
- - Note that the encoding stops at any NUL in the input. FilePaths
- - cannot contain embedded NUL, but Haskell Strings may.
- -}
-{-# NOINLINE encodeW8 #-}
-encodeW8 :: [Word8] -> FilePath
-encodeW8 w8 = unsafePerformIO $ do
-	enc <- Encoding.getFileSystemEncoding
-	GHC.withCString Encoding.char8 (w82s w8) $ GHC.peekCString enc
-
-decodeW8 :: FilePath -> [Word8]
-decodeW8 = s2w8 . _encodeFilePath
-
-{- Like encodeW8 and decodeW8, but NULs are passed through unchanged. -}
-encodeW8NUL :: [Word8] -> FilePath
-encodeW8NUL = intercalate [nul] . map encodeW8 . splitc (c2w8 nul)
-  where
-	nul = '\NUL'
-
-decodeW8NUL :: FilePath -> [Word8]
-decodeW8NUL = intercalate [c2w8 nul] . map decodeW8 . splitc nul
-  where
-	nul = '\NUL'
-#endif
-
-c2w8 :: Char -> Word8
-c2w8 = fromIntegral . fromEnum
-
-w82c :: Word8 -> Char
-w82c = toEnum . fromIntegral
-
-s2w8 :: String -> [Word8]
-s2w8 = map c2w8
-
-w82s :: [Word8] -> String
-w82s = map w82c
-
 {- Truncates a FilePath to the given number of bytes (or less),
  - as represented on disk.
  -
@@ -224,8 +129,8 @@ truncateFilePath :: Int -> FilePath -> FilePath
 truncateFilePath n = go . reverse
   where
 	go f =
-		let bytes = decodeW8 f
-		in if length bytes <= n
+		let b = encodeBS f
+		in if S.length b <= n
 			then reverse f
 			else go (drop 1 f)
 #else