Merge posix-paths into hpath

.gitmodules

@@ -1,3 +0,0 @@
-[submodule "3rdparty/posix-paths"]
-	path = 3rdparty/posix-paths
-	url = https://github.com/hasufell/posix-paths.git

3rdparty/posix-paths

@@ -1 +0,0 @@
-Subproject commit 5338c03af0a6efeb3914123e9ff085387c3151f9

README.md

@@ -1,6 +1,7 @@
 # HPath
 
-Support for well-typed paths in Haskell.
+Support for well-typed paths in Haskell. Also provides ByteString based filepath
+manipulation.
 
 ## Motivation
 
@@ -14,9 +15,13 @@ The library that came closest to my needs was
 but the API turned out to be oddly complicated for my use case, so I
 decided to fork it.
 
+Similarly, [posix-paths](https://github.com/JohnLato/posix-paths)
+was exactly what I wanted for the low-level operations, but upstream seems dead,
+so it is forked as well and merged into this library.
+
 ## Differences to 'path'
 
-* doesn't attempt to fake IO-related types into the path, so whether a path points to a file or directory is up to your IO-code to decide... this should be a library that is used _with_ a proper IO File Type
+* doesn't attempt to fake IO-related information into the path, so whether a path points to a file or directory is up to your IO-code to decide...
 * trailing path separators will be preserved if they exist, no messing with that
 * uses safe ByteString for filepaths under the hood instead of unsafe String
 * fixes broken [dirname](https://github.com/chrisdone/path/issues/18)
@@ -27,3 +32,7 @@ decided to fork it.
 * allows `~/` as relative path, because on posix level `~` is just a regular filename that does _NOT_ point to `$HOME`
 * remove TH, it sucks
 
+## Differences to 'posix-paths'
+
+* `hasTrailingPathSeparator` behaves in the same way as `System.FilePath`
+* `dropTrailingPathSeparator` behaves in the same way as `System.FilePath`

benchmarks/Bench.hs

@@ -0,0 +1,90 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TupleSections #-}
+{-# LANGUAGE ViewPatterns #-}
+
+{-# OPTIONS_GHC -Wall #-}
+import Control.Applicative
+import Control.Monad
+import System.Directory
+import System.FilePath ((</>))
+import System.Posix.ByteString.FilePath
+import System.Posix.Directory.ByteString as PosixBS
+import System.Posix.Directory.Traversals
+import qualified System.Posix.FilePath as PosixBS
+import System.Posix.Files.ByteString
+
+import Control.Exception
+import qualified Data.ByteString.Char8 as BS
+
+import System.Environment (getArgs, withArgs)
+import System.IO.Error
+import System.IO.Unsafe
+import System.Process (system)
+import Criterion.Main
+
+
+-- | Based on code from 'Real World Haskell', at
+-- http://book.realworldhaskell.org/read/io-case-study-a-library-for-searching-the-filesystem.html#id620419
+listFilesRecursive :: FilePath -> IO [FilePath]
+listFilesRecursive topdir = do
+    names <- System.Directory.getDirectoryContents topdir
+    let properNames = filter (`notElem` [".", ".."]) names
+    paths <- forM properNames $ \name -> do
+        let path = topdir </> name
+        isDir <- doesDirectoryExist path
+        if isDir
+            then listFilesRecursive path
+            else return [path]
+    return (topdir : concat paths)
+
+----------------------------------------------------------
+
+getDirectoryContentsBS :: RawFilePath -> IO [RawFilePath]
+getDirectoryContentsBS path = 
+  modifyIOError ((`ioeSetFileName` (BS.unpack path)) .
+                 (`ioeSetLocation` "getDirectoryContentsBS")) $ do
+    bracket
+      (PosixBS.openDirStream path)
+      PosixBS.closeDirStream
+      loop
+ where
+  loop dirp = do
+     e <- PosixBS.readDirStream dirp
+     if BS.null e then return [] else do
+       es <- loop dirp
+       return (e:es)
+
+
+-- | similar to 'listFilesRecursive, but uses RawFilePaths
+listFilesRecursiveBS :: RawFilePath -> IO [RawFilePath]
+listFilesRecursiveBS topdir = do
+    names <- getDirectoryContentsBS topdir
+    let properNames = filter (`notElem` [".", ".."]) names
+    paths <- forM properNames $ \name -> unsafeInterleaveIO $ do
+        let path = PosixBS.combine topdir name
+        isDir <- isDirectory <$> getFileStatus path
+        if isDir
+            then listFilesRecursiveBS path
+            else return [path]
+    return (topdir : concat paths)
+----------------------------------------------------------
+
+
+benchTraverse :: RawFilePath -> IO ()
+benchTraverse = traverseDirectory (\() p -> BS.putStrLn p) ()
+
+main :: IO ()
+main = do
+  args <- getArgs
+  let (d,otherArgs) = case args of
+          []   -> ("/usr/local",[])
+          x:xs -> (x,xs)
+  withArgs otherArgs $ defaultMain
+    [ bench "traverse (FilePath)"      $ nfIO $ listFilesRecursive d >>= mapM_ putStrLn
+    , bench "traverse (RawFilePath)"   $ nfIO $ listFilesRecursiveBS (BS.pack d) >>= mapM_ BS.putStrLn
+    , bench "allDirectoryContents"     $ nfIO $ allDirectoryContents (BS.pack d) >>= mapM_ BS.putStrLn
+    , bench "allDirectoryContents'"    $ nfIO $ allDirectoryContents' (BS.pack d) >>= mapM_ BS.putStrLn
+    , bench "traverseDirectory"        $ nfIO $ benchTraverse (BS.pack d)
+    , bench "unix find"                $ nfIO $ void $ system ("find " ++ d)
+    ]

cbits/dirutils.c

@@ -0,0 +1,7 @@
+#include "dirutils.h"
+unsigned int
+    __posixdir_d_type(struct dirent* d)
+    {
+      return(d -> d_type);
+    }
+

cbits/dirutils.h

@@ -0,0 +1,13 @@
+#ifndef POSIXPATHS_CBITS_DIRUTILS_H
+#define POSIXPATHS_CBITS_DIRUTILS_H
+
+#include <stdlib.h>
+#include <dirent.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+extern unsigned int
+    __posixdir_d_type(struct dirent* d)
+    ;
+#endif

doctests-hpath.hs

@@ -2,12 +2,14 @@
 
 module Main where
 
+import Control.Applicative
+
 import Test.DocTest
 import Test.HUnit
 
 main =
     doctest
-      [ "-isrc"
+      ["-isrc"
       , "-XOverloadedStrings"
       , "src/HPath.hs"
       ]

doctests-posix.hs

@@ -0,0 +1,25 @@
+{-# LANGUAGE OverloadedStrings #-}
+
+module Main where
+
+import Control.Applicative
+import System.Posix.Directory.Traversals
+
+import Test.DocTest
+import Test.HUnit
+
+main = do
+    doctest
+      [ "-isrc"
+      , "-XOverloadedStrings"
+      , "System.Posix.FilePath"
+      ]
+    runTestTT unitTests
+
+
+unitTests :: Test
+unitTests = test
+    [ TestCase $ do
+        r <- (==) <$> allDirectoryContents "." <*> allDirectoryContents' "."
+        assertBool "allDirectoryContents == allDirectoryContents'" r
+    ]

hpath.cabal

@@ -9,34 +9,73 @@ maintainer:          Julian Ospald <hasufell@posteo.de>
 copyright:           2015–2016 FP Complete, Julian Ospald 2016
 category:            Filesystem
 build-type:          Simple
-cabal-version:       >=1.8
-extra-source-files:  README.md, CHANGELOG
+cabal-version:       >=1.14
+extra-source-files:  README.md
+                     CHANGELOG
+                     cbits/dirutils.h
+                     doctests.hs
+                     benchmarks/*.hs
 
 library
   hs-source-dirs:    src/
+  default-language:  Haskell2010
   ghc-options:       -Wall -O2
-  exposed-modules:   HPath, HPath.Internal
-  build-depends:     base >= 4 && <5
-                   , HUnit
-                   , bytestring
+  c-sources:         cbits/dirutils.c
+  exposed-modules:   HPath,
+                     HPath.Internal,
+                     System.Posix.Directory.Foreign,
+                     System.Posix.Directory.Traversals,
+                     System.Posix.FilePath
+  build-depends:     base >= 4.2 && <5
+                   , bytestring >= 0.9.2.0
                    , deepseq
                    , exceptions
                    , hspec
-                   , posix-paths
+                   , unix >= 2.5
                    , utf8-string
                    , word8
 
 
-test-suite doctests
+test-suite doctests-hpath
+  default-language:  Haskell2010
   type:              exitcode-stdio-1.0
   ghc-options:       -threaded
-  main-is:           doctests.hs
+  main-is:           doctests-hpath.hs
   build-depends:     base
                    , HUnit
-                   , bytestring
+                   , QuickCheck
                    , doctest >= 0.8
                    , hpath
-                   , posix-paths
+
+test-suite doctests-posix
+  default-language:  Haskell2010
+  type:              exitcode-stdio-1.0
+  ghc-options:       -threaded
+  main-is:           doctests-posix.hs
+  build-depends:     base,
+                     bytestring,
+                     unix,
+                     hpath,
+                     doctest >= 0.8,
+                     HUnit,
+                     QuickCheck
+
+benchmark bench.hs
+  default-language: Haskell2010
+  type: exitcode-stdio-1.0
+  hs-source-dirs: benchmarks
+  main-is:        Bench.hs
+
+  build-depends:
+      base,
+      hpath,
+      bytestring,
+      unix,
+      directory  >= 1.1 && < 1.3,
+      filepath   >= 1.2 && < 1.4,
+      process    >= 1.0 && < 1.3,
+      criterion  >= 0.6 && < 0.9
+  ghc-options: -O2
 
 source-repository head
   type:     git

src/System/Posix/Directory/Foreign.hsc

@@ -0,0 +1,55 @@
+module System.Posix.Directory.Foreign where
+
+import Data.Bits
+import Data.List (foldl')
+import Foreign.C.Types
+
+#include <limits.h>
+#include <stdlib.h>
+#include <dirent.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+newtype DirType = DirType Int deriving (Eq, Show)
+data Flags = Flags Int | UnsupportedFlag String deriving (Eq, Show)
+
+unFlags :: Flags -> Int
+unFlags (Flags i) = i
+unFlags (UnsupportedFlag name) = error (name ++ " is not supported on this platform")
+
+-- |Returns @True@ if posix-paths was compiled with support for the provided
+-- flag. (As of this writing, the only flag for which this check may be
+-- necessary is 'oCloexec'; all other flags will always yield @True@.)
+isSupported :: Flags -> Bool
+isSupported (Flags _) = True
+isSupported _ = False
+
+-- |@O_CLOEXEC@ is not supported on every POSIX platform. Use
+-- @'isSupported' oCloexec@ to determine if support for @O_CLOEXEC@ was
+-- compiled into your version of posix-paths. (If not, using @oCloexec@ will
+-- throw an exception.)
+oCloexec :: Flags
+#ifdef O_CLOEXEC
+oCloexec = Flags #{const O_CLOEXEC}
+#else
+{-# WARNING oCloexec
+    "This version of posix-paths was compiled without @O_CLOEXEC@ support." #-}
+oCloexec = UnsupportedFlag "O_CLOEXEC"
+#endif
+
+
+
+-- If these enum declarations occur earlier in the file, haddock
+-- gets royally confused about the above doc comments.
+-- Probably http://trac.haskell.org/haddock/ticket/138
+
+#{enum DirType, DirType, DT_BLK, DT_CHR, DT_DIR, DT_FIFO, DT_LNK, DT_REG, DT_SOCK, DT_UNKNOWN}
+
+#{enum Flags, Flags, O_APPEND, O_ASYNC, O_CREAT, O_DIRECTORY, O_EXCL, O_NOCTTY, O_NOFOLLOW, O_NONBLOCK, O_RDONLY, O_WRONLY, O_RDWR, O_SYNC, O_TRUNC}
+
+pathMax :: Int
+pathMax = #{const PATH_MAX}
+
+unionFlags :: [Flags] -> CInt
+unionFlags = fromIntegral . foldl' ((. unFlags) . (.|.)) 0

src/System/Posix/Directory/Traversals.hs

@@ -0,0 +1,269 @@
+{-# LANGUAGE ForeignFunctionInterface #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TupleSections #-}
+{-# LANGUAGE ViewPatterns #-}
+
+{-# OPTIONS_GHC -Wall #-}
+module System.Posix.Directory.Traversals (
+
+  getDirectoryContents
+, getDirectoryContents'
+
+, allDirectoryContents
+, allDirectoryContents'
+, traverseDirectory
+
+-- lower-level stuff
+, readDirEnt
+, packDirStream
+, unpackDirStream
+, openFd
+
+, realpath
+) where
+
+import Control.Applicative
+import Control.Monad
+import System.Posix.FilePath ((</>))
+import System.Posix.Directory.Foreign
+
+import qualified System.Posix as Posix
+import System.IO.Error
+import Control.Exception
+import qualified Data.ByteString.Char8 as BS
+import System.Posix.ByteString.FilePath
+import System.Posix.Directory.ByteString as PosixBS
+import System.Posix.Files.ByteString
+
+import System.IO.Unsafe
+import Unsafe.Coerce (unsafeCoerce)
+import Foreign.C.Error
+import Foreign.C.String
+import Foreign.C.Types
+import Foreign.Marshal.Alloc (alloca,allocaBytes)
+import Foreign.Ptr
+import Foreign.Storable
+
+
+
+
+----------------------------------------------------------
+
+-- | Get all files from a directory and its subdirectories.
+--
+-- Upon entering a directory, 'allDirectoryContents' will get all entries
+-- strictly.  However the returned list is lazy in that directories will only
+-- be accessed on demand.
+allDirectoryContents :: RawFilePath -> IO [RawFilePath]
+allDirectoryContents topdir = do
+    namesAndTypes <- getDirectoryContents topdir
+    let properNames = filter ((`notElem` [".", ".."]) . snd) namesAndTypes
+    paths <- forM properNames $ \(typ,name) -> unsafeInterleaveIO $ do
+        let path = topdir </> name
+        case () of
+            () | typ == dtDir -> allDirectoryContents path
+               | typ == dtUnknown -> do
+                    isDir <- isDirectory <$> getFileStatus path
+                    if isDir
+                        then allDirectoryContents path
+                        else return [path]
+               | otherwise -> return [path]
+    return (topdir : concat paths)
+
+-- | Get all files from a directory and its subdirectories strictly.
+allDirectoryContents' :: RawFilePath -> IO [RawFilePath]
+allDirectoryContents' = fmap reverse . traverseDirectory (\acc fp -> return (fp:acc)) []
+-- this uses traverseDirectory because it's more efficient than forcing the
+-- lazy version.
+
+-- | Recursively apply the 'action' to the parent directory and all
+-- files/subdirectories.
+--
+-- This function allows for memory-efficient traversals.
+traverseDirectory :: (s -> RawFilePath -> IO s) -> s -> RawFilePath -> IO s
+traverseDirectory act s0 topdir = toploop
+  where
+    toploop = do
+        isDir <- isDirectory <$> getFileStatus topdir
+        s' <- act s0 topdir
+        if isDir then actOnDirContents topdir s' loop
+                 else return s'
+    loop typ path acc = do
+        isDir <- case () of
+            () | typ == dtDir     -> return True
+               | typ == dtUnknown -> isDirectory <$> getFileStatus path
+               | otherwise        -> return False
+        if isDir
+          then act acc path >>= \acc' -> actOnDirContents path acc' loop
+          else act acc path
+
+actOnDirContents :: RawFilePath
+                 -> b
+                 -> (DirType -> RawFilePath -> b -> IO b)
+                 -> IO b
+actOnDirContents pathRelToTop b f =
+  modifyIOError ((`ioeSetFileName` (BS.unpack pathRelToTop)) .
+                 (`ioeSetLocation` "findBSTypRel")) $ do
+    bracket
+      (openDirStream pathRelToTop)
+      (Posix.closeDirStream)
+      (\dirp -> loop dirp b)
+ where
+  loop dirp b' = do
+    (typ,e) <- readDirEnt dirp
+    if (e == "")
+      then return b'
+      else do
+          if (e == "." || e == "..")
+              then loop dirp b'
+              else f typ (pathRelToTop </> e) b' >>= loop dirp
+
+
+----------------------------------------------------------
+-- dodgy stuff
+
+type CDir = ()
+type CDirent = ()
+
+-- Posix doesn't export DirStream, so to re-use that type we need to use
+-- unsafeCoerce.  It's just a newtype, so this is a legitimate usage.
+-- ugly trick.
+unpackDirStream :: DirStream -> Ptr CDir
+unpackDirStream = unsafeCoerce
+
+packDirStream :: Ptr CDir -> DirStream
+packDirStream = unsafeCoerce
+
+-- the __hscore_* functions are defined in the unix package.  We can import them and let
+-- the linker figure it out.
+foreign import ccall unsafe "__hscore_readdir"
+  c_readdir  :: Ptr CDir -> Ptr (Ptr CDirent) -> IO CInt
+
+foreign import ccall unsafe "__hscore_free_dirent"
+  c_freeDirEnt  :: Ptr CDirent -> IO ()
+
+foreign import ccall unsafe "__hscore_d_name"
+  c_name :: Ptr CDirent -> IO CString
+
+foreign import ccall unsafe "__posixdir_d_type"
+  c_type :: Ptr CDirent -> IO DirType
+
+foreign import ccall "realpath"
+  c_realpath :: CString -> CString -> IO CString
+
+foreign import ccall unsafe "fdopendir"
+  c_fdopendir :: Posix.Fd -> IO (Ptr ())
+
+foreign import ccall unsafe "open"
+   c_open :: CString -> CInt -> Posix.CMode -> IO CInt
+
+----------------------------------------------------------
+-- less dodgy but still lower-level
+
+
+readDirEnt :: DirStream -> IO (DirType, RawFilePath)
+readDirEnt (unpackDirStream -> dirp) =
+  alloca $ \ptr_dEnt  -> loop ptr_dEnt
+ where
+  loop ptr_dEnt = do
+    resetErrno
+    r <- c_readdir dirp ptr_dEnt
+    if (r == 0)
+       then do
+         dEnt <- peek ptr_dEnt
+         if (dEnt == nullPtr)
+            then return (dtUnknown,BS.empty)
+            else do
+                 dName <- c_name dEnt >>= peekFilePath
+                 dType <- c_type dEnt
+                 c_freeDirEnt dEnt
+                 return (dType, dName)
+       else do
+         errno <- getErrno
+         if (errno == eINTR)
+            then loop ptr_dEnt
+            else do
+                 let (Errno eo) = errno
+                 if (eo == 0)
+                    then return (dtUnknown,BS.empty)
+                    else throwErrno "readDirEnt"
+
+
+getDirectoryContents :: RawFilePath -> IO [(DirType, RawFilePath)]
+getDirectoryContents path =
+  modifyIOError ((`ioeSetFileName` (BS.unpack path)) .
+                 (`ioeSetLocation` "System.Posix.Directory.Traversals.getDirectoryContents")) $ do
+    bracket
+      (PosixBS.openDirStream path)
+      PosixBS.closeDirStream
+      loop
+ where
+  loop dirp = do
+     t@(_typ,e) <- readDirEnt dirp
+     if BS.null e then return [] else do
+       es <- loop dirp
+       return (t:es)
+
+
+fdOpendir :: Posix.Fd -> IO DirStream
+fdOpendir fd =
+    packDirStream <$> throwErrnoIfNull "fdOpendir" (c_fdopendir fd)
+
+
+getDirectoryContents' :: Posix.Fd -> IO [(DirType, RawFilePath)]
+getDirectoryContents' fd =
+    bracket
+      (fdOpendir fd)
+      PosixBS.closeDirStream
+      loop
+ where
+  loop dirp = do
+     t@(_typ,e) <- readDirEnt dirp
+     if BS.null e then return [] else do
+       es <- loop dirp
+       return (t:es)
+
+
+open_  :: CString
+       -> Posix.OpenMode
+       -> [Flags]
+       -> Maybe Posix.FileMode
+       -> IO Posix.Fd
+open_ str how optional_flags maybe_mode = do
+    fd <- c_open str all_flags mode_w
+    return (Posix.Fd fd)
+  where
+    all_flags  = unionFlags $ optional_flags ++ [open_mode] ++ creat
+
+
+    (creat, mode_w) = case maybe_mode of
+                        Nothing -> ([],0)
+                        Just x  -> ([oCreat], x)
+
+    open_mode = case how of
+                   Posix.ReadOnly  -> oRdonly
+                   Posix.WriteOnly -> oWronly
+                   Posix.ReadWrite -> oRdwr
+
+
+-- |Open and optionally create this file.  See 'System.Posix.Files'
+-- for information on how to use the 'FileMode' type.
+openFd :: RawFilePath
+       -> Posix.OpenMode
+       -> [Flags]
+       -> Maybe Posix.FileMode
+       -> IO Posix.Fd
+openFd name how optional_flags maybe_mode =
+   withFilePath name $ \str ->
+     throwErrnoPathIfMinus1Retry "openFd" name $
+       open_ str how optional_flags maybe_mode
+
+
+-- | return the canonicalized absolute pathname
+--
+-- like canonicalizePath, but uses realpath(3)
+realpath :: RawFilePath -> IO RawFilePath
+realpath inp = do
+    allocaBytes pathMax $ \tmp -> do
+        void $ BS.useAsCString inp $ \cstr -> throwErrnoIfNull "realpath" $ c_realpath cstr tmp
+        BS.packCString tmp

src/System/Posix/FilePath.hs

@@ -0,0 +1,535 @@
+{-# LANGUAGE TupleSections #-}
+
+{-# OPTIONS_GHC -Wall #-}
+
+-- | The equivalent of "System.FilePath" on raw (byte string) file paths.
+--
+-- Not all functions of "System.FilePath" are implemented yet. Feel free to contribute!
+module System.Posix.FilePath (
+
+  pathSeparator
+, isPathSeparator
+, searchPathSeparator
+, isSearchPathSeparator
+, extSeparator
+, isExtSeparator
+
+, splitExtension
+, takeExtension
+, replaceExtension
+, dropExtension
+, addExtension
+, hasExtension
+, (<.>)
+, splitExtensions
+, dropExtensions
+, takeExtensions
+
+, splitFileName
+, takeFileName
+, replaceFileName
+, dropFileName
+, takeBaseName
+, replaceBaseName
+, takeDirectory
+, replaceDirectory
+, combine
+, (</>)
+, splitPath
+, joinPath
+, normalise
+, splitDirectories
+
+, hasTrailingPathSeparator
+, addTrailingPathSeparator
+, dropTrailingPathSeparator
+
+, isRelative
+, isAbsolute
+, isValid
+, equalFilePath
+
+, module System.Posix.ByteString.FilePath
+) where
+
+import           Data.ByteString (ByteString)
+import qualified Data.ByteString as BS
+import           System.Posix.ByteString.FilePath
+
+import           Data.Maybe (isJust)
+import           Data.Word8
+
+import           Control.Arrow (second)
+
+-- $setup
+-- >>> import Data.Char
+-- >>> import Test.QuickCheck
+-- >>> import Control.Applicative
+-- >>> import qualified Data.ByteString as BS
+-- >>> import Data.ByteString (ByteString)
+-- >>> instance Arbitrary ByteString where arbitrary = BS.pack <$> arbitrary
+-- >>> instance CoArbitrary ByteString where coarbitrary = coarbitrary . BS.unpack
+--
+-- >>> let _chr :: Word8 -> Char; _chr = chr . fromIntegral
+
+
+-- | Path separator character
+pathSeparator :: Word8
+pathSeparator = _slash
+
+-- | Check if a character is the path separator
+--
+-- prop> \n ->  (_chr n == '/') == isPathSeparator n
+isPathSeparator :: Word8 -> Bool
+isPathSeparator = (== pathSeparator)
+
+-- | Search path separator
+searchPathSeparator :: Word8
+searchPathSeparator = _colon
+
+-- | Check if a character is the search path separator
+--
+-- prop> \n -> (_chr n == ':') == isSearchPathSeparator n
+isSearchPathSeparator :: Word8 -> Bool
+isSearchPathSeparator = (== searchPathSeparator)
+
+-- | File extension separator
+extSeparator :: Word8
+extSeparator = _period
+
+-- | Check if a character is the file extension separator
+--
+-- prop> \n -> (_chr n == '.') == isExtSeparator n
+isExtSeparator :: Word8 -> Bool
+isExtSeparator = (== extSeparator)
+
+------------------------
+-- extension stuff
+
+-- | Split a 'RawFilePath' into a path+filename and extension
+--
+-- >>> splitExtension "file.exe"
+-- ("file",".exe")
+-- >>> splitExtension "file"
+-- ("file","")
+-- >>> splitExtension "/path/file.tar.gz"
+-- ("/path/file.tar",".gz")
+--
+-- prop> \path -> uncurry (BS.append) (splitExtension path) == path
+splitExtension :: RawFilePath -> (RawFilePath, ByteString)
+splitExtension x = if BS.null basename
+    then (x,BS.empty)
+    else (BS.append path (BS.init basename),BS.cons extSeparator fileExt)
+  where
+    (path,file) = splitFileNameRaw x
+    (basename,fileExt) = BS.breakEnd isExtSeparator file
+
+-- | Get the final extension from a 'RawFilePath'
+--
+-- >>> takeExtension "file.exe"
+-- ".exe"
+-- >>> takeExtension "file"
+-- ""
+-- >>> takeExtension "/path/file.tar.gz"
+-- ".gz"
+takeExtension :: RawFilePath -> ByteString
+takeExtension = snd . splitExtension
+
+-- | Change a file's extension
+--
+-- prop> \path -> let ext = takeExtension path in replaceExtension path ext == path
+replaceExtension :: RawFilePath -> ByteString -> RawFilePath
+replaceExtension path ext = dropExtension path <.> ext
+
+-- | Drop the final extension from a 'RawFilePath'
+--
+-- >>> dropExtension "file.exe"
+-- "file"
+-- >>> dropExtension "file"
+-- "file"
+-- >>> dropExtension "/path/file.tar.gz"
+-- "/path/file.tar"
+dropExtension :: RawFilePath -> RawFilePath
+dropExtension = fst . splitExtension
+
+-- | Add an extension to a 'RawFilePath'
+--
+-- >>> addExtension "file" ".exe"
+-- "file.exe"
+-- >>> addExtension "file.tar" ".gz"
+-- "file.tar.gz"
+-- >>> addExtension "/path/" ".ext"
+-- "/path/.ext"
+addExtension :: RawFilePath -> ByteString -> RawFilePath
+addExtension file ext
+    | BS.null ext = file
+    | isExtSeparator (BS.head ext) = BS.append file ext
+    | otherwise = BS.intercalate (BS.singleton extSeparator) [file, ext]
+
+
+-- | Operator version of 'addExtension'
+(<.>) :: RawFilePath -> ByteString -> RawFilePath
+(<.>) = addExtension
+
+-- | Check if a 'RawFilePath' has an extension
+--
+-- >>> hasExtension "file"
+-- False
+-- >>> hasExtension "file.tar"
+-- True
+-- >>> hasExtension "/path.part1/"
+-- False
+hasExtension :: RawFilePath -> Bool
+hasExtension = isJust . BS.elemIndex extSeparator . takeFileName
+
+-- | Split a 'RawFilePath' on the first extension
+--
+-- >>> splitExtensions "/path/file.tar.gz"
+-- ("/path/file",".tar.gz")
+--
+-- prop> \path -> uncurry addExtension (splitExtensions path) == path
+splitExtensions :: RawFilePath -> (RawFilePath, ByteString)
+splitExtensions x = if BS.null basename
+    then (path,fileExt)
+    else (BS.append path basename,fileExt)
+  where
+    (path,file) = splitFileNameRaw x
+    (basename,fileExt) = BS.break isExtSeparator file
+
+-- | Remove all extensions from a 'RawFilePath'
+--
+-- >>> dropExtensions "/path/file.tar.gz"
+-- "/path/file"
+dropExtensions :: RawFilePath -> RawFilePath
+dropExtensions = fst . splitExtensions
+
+-- | Take all extensions from a 'RawFilePath'
+--
+-- >>> takeExtensions "/path/file.tar.gz"
+-- ".tar.gz"
+takeExtensions :: RawFilePath -> ByteString
+takeExtensions = snd . splitExtensions
+
+------------------------
+-- more stuff
+
+-- | Split a 'RawFilePath' into (path,file).  'combine' is the inverse
+--
+-- >>> splitFileName "path/file.txt"
+-- ("path/","file.txt")
+-- >>> splitFileName "path/"
+-- ("path/","")
+-- >>> splitFileName "file.txt"
+-- ("./","file.txt")
+--
+-- prop> \path -> uncurry combine (splitFileName path) == path || fst (splitFileName path) == "./"
+splitFileName :: RawFilePath -> (RawFilePath, RawFilePath)
+splitFileName x = if BS.null path
+    then (dotSlash, file)
+    else (path,file)
+  where
+    (path,file) = splitFileNameRaw x
+    dotSlash = _period `BS.cons` (BS.singleton pathSeparator)
+
+
+-- | Get the file name
+--
+-- >>> takeFileName "path/file.txt"
+-- "file.txt"
+-- >>> takeFileName "path/"
+-- ""
+takeFileName :: RawFilePath -> RawFilePath
+takeFileName = snd . splitFileName
+
+-- | Change the file name
+--
+-- prop> \path -> replaceFileName path (takeFileName path) == path
+replaceFileName :: RawFilePath -> ByteString -> RawFilePath
+replaceFileName x y = fst (splitFileNameRaw x) </> y
+
+-- | Drop the file name
+--
+-- >>> dropFileName "path/file.txt"
+-- "path/"
+-- >>> dropFileName "file.txt"
+-- "./"
+dropFileName :: RawFilePath -> RawFilePath
+dropFileName = fst . splitFileName
+
+-- | Get the file name, without a trailing extension
+--
+-- >>> takeBaseName "path/file.tar.gz"
+-- "file.tar"
+-- >>> takeBaseName ""
+-- ""
+takeBaseName :: RawFilePath -> ByteString
+takeBaseName = dropExtension . takeFileName
+
+-- | Change the base name
+--
+-- >>> replaceBaseName "path/file.tar.gz" "bob"
+-- "path/bob.gz"
+--
+-- prop> \path -> replaceBaseName path (takeBaseName path) == path
+replaceBaseName :: RawFilePath -> ByteString -> RawFilePath
+replaceBaseName path name = combineRaw dir (name <.> ext)
+  where
+    (dir,file) = splitFileNameRaw path
+    ext = takeExtension file
+
+-- | Get the directory, moving up one level if it's already a directory
+--
+-- >>> takeDirectory "path/file.txt"
+-- "path"
+-- >>> takeDirectory "file"
+-- "."
+-- >>> takeDirectory "/path/to/"
+-- "/path/to"
+-- >>> takeDirectory "/path/to"
+-- "/path"
+takeDirectory :: RawFilePath -> RawFilePath
+takeDirectory x = case () of
+    () | x == BS.singleton pathSeparator -> x
+       | BS.null res && not (BS.null file) -> file
+       | otherwise -> res
+  where
+    res = fst $ BS.spanEnd isPathSeparator file
+    file = dropFileName x
+
+-- | Change the directory component of a 'RawFilePath'
+--
+-- prop> \path -> replaceDirectory path (takeDirectory path) `equalFilePath` path || takeDirectory path == "."
+replaceDirectory :: RawFilePath -> ByteString -> RawFilePath
+replaceDirectory file dir = combineRaw dir (takeFileName file)
+
+-- | Join two paths together
+--
+-- >>> combine "/" "file"
+-- "/file"
+-- >>> combine "/path/to" "file"
+-- "/path/to/file"
+-- >>> combine "file" "/absolute/path"
+-- "/absolute/path"
+combine :: RawFilePath -> RawFilePath -> RawFilePath
+combine a b | not (BS.null b) && isPathSeparator (BS.head b) = b
+            | otherwise = combineRaw a b
+
+-- | Operator version of combine
+(</>) :: RawFilePath -> RawFilePath -> RawFilePath
+(</>) = combine
+
+-- | Split a path into a list of components:
+--
+-- >>> splitPath "/path/to/file.txt"
+-- ["/","path/","to/","file.txt"]
+--
+-- prop> \path -> BS.concat (splitPath path) == path
+splitPath :: RawFilePath -> [RawFilePath]
+splitPath = splitter
+  where
+    splitter x
+      | BS.null x = []
+      | otherwise = case BS.elemIndex pathSeparator x of
+            Nothing -> [x]
+            Just ix -> case BS.findIndex (not . isPathSeparator) $ BS.drop (ix+1) x of
+                          Nothing -> [x]
+                          Just runlen -> uncurry (:) . second splitter $ BS.splitAt (ix+1+runlen) x
+
+-- | Like 'splitPath', but without trailing slashes
+--
+-- >>> splitDirectories "/path/to/file.txt"
+-- ["/","path","to","file.txt"]
+-- >>> splitDirectories ""
+-- []
+splitDirectories :: RawFilePath -> [RawFilePath]
+splitDirectories x
+    | BS.null x = []
+    | isPathSeparator (BS.head x) = let (root,rest) = BS.splitAt 1 x
+                                    in root : splitter rest
+    | otherwise = splitter x
+  where
+    splitter = filter (not . BS.null) . BS.split pathSeparator
+
+-- | Join a split path back together
+--
+-- prop> \path -> joinPath (splitPath path) == path
+--
+-- >>> joinPath ["path","to","file.txt"]
+-- "path/to/file.txt"
+joinPath :: [RawFilePath] -> RawFilePath
+joinPath = foldr (</>) BS.empty
+
+
+-- |Normalise a file.
+--
+-- >>> normalise "/file/\\test////"
+-- "/file/\\test/"
+-- >>> normalise "/file/./test"
+-- "/file/test"
+-- >>> normalise "/test/file/../bob/fred/"
+-- "/test/file/../bob/fred/"
+-- >>> normalise "../bob/fred/"
+-- "../bob/fred/"
+-- >>> normalise "./bob/fred/"
+-- "bob/fred/"
+-- >>> normalise "./bob////.fred/./...///./..///#."
+-- "bob/.fred/.../../#."
+-- >>> normalise "."
+-- "."
+-- >>> normalise "./"
+-- "./"
+-- >>> normalise "./."
+-- "./"
+-- >>> normalise "/./"
+-- "/"
+-- >>> normalise "/"
+-- "/"
+-- >>> normalise "bob/fred/."
+-- "bob/fred/"
+-- >>> normalise "//home"
+-- "/home"
+normalise :: RawFilePath -> RawFilePath
+normalise filepath =
+  result `BS.append`
+  (if addPathSeparator
+       then BS.singleton pathSeparator
+       else BS.empty)
+  where
+    result = let n = f filepath
+             in if BS.null n
+                then BS.singleton _period
+                else n
+    addPathSeparator = isDirPath filepath &&
+      not (hasTrailingPathSeparator result)
+    isDirPath xs = hasTrailingPathSeparator xs
+        || not (BS.null xs) && BS.last xs == _period
+           && hasTrailingPathSeparator (BS.init xs)
+    f = joinPath . dropDots . propSep . splitDirectories
+    propSep :: [ByteString] -> [ByteString]
+    propSep (x:xs)
+      | BS.all (== pathSeparator) x = BS.singleton pathSeparator : xs
+      | otherwise                   = x : xs
+    propSep [] = []
+    dropDots :: [ByteString] -> [ByteString]
+    dropDots = filter (BS.singleton _period /=)
+
+
+------------------------
+-- trailing path separators
+
+-- | Check if the last character of a 'RawFilePath' is '/'.
+--
+-- >>> hasTrailingPathSeparator "/path/"
+-- True
+-- >>> hasTrailingPathSeparator "/"
+-- True
+-- >>> hasTrailingPathSeparator "/path"
+-- False
+hasTrailingPathSeparator :: RawFilePath -> Bool
+hasTrailingPathSeparator x
+  | BS.null x = False
+  | otherwise = isPathSeparator $ BS.last x
+
+-- | Add a trailing path separator.
+--
+-- >>> addTrailingPathSeparator "/path"
+-- "/path/"
+-- >>> addTrailingPathSeparator "/path/"
+-- "/path/"
+-- >>> addTrailingPathSeparator "/"
+-- "/"
+addTrailingPathSeparator :: RawFilePath -> RawFilePath
+addTrailingPathSeparator x = if hasTrailingPathSeparator x
+    then x
+    else x `BS.snoc` pathSeparator
+
+-- | Remove a trailing path separator
+--
+-- >>> dropTrailingPathSeparator "/path/"
+-- "/path"
+-- >>> dropTrailingPathSeparator "/path////"
+-- "/path"
+-- >>> dropTrailingPathSeparator "/"
+-- "/"
+-- >>> dropTrailingPathSeparator "//"
+-- "/"
+dropTrailingPathSeparator :: RawFilePath -> RawFilePath
+dropTrailingPathSeparator x
+  | x == BS.singleton pathSeparator = x
+  | otherwise = if hasTrailingPathSeparator x
+                  then dropTrailingPathSeparator $ BS.init x
+                  else x
+
+------------------------
+-- Filename/system stuff
+
+-- | Check if a path is absolute
+--
+-- >>> isAbsolute "/path"
+-- True
+-- >>> isAbsolute "path"
+-- False
+-- >>> isAbsolute ""
+-- False
+isAbsolute :: RawFilePath -> Bool
+isAbsolute x
+    | BS.length x > 0 = isPathSeparator (BS.head x)
+    | otherwise = False
+
+-- | Check if a path is relative
+--
+-- prop> \path -> isRelative path /= isAbsolute path
+isRelative :: RawFilePath -> Bool
+isRelative = not . isAbsolute
+
+-- | Is a FilePath valid, i.e. could you create a file like it?
+--
+-- >>> isValid ""
+-- False
+-- >>> isValid "\0"
+-- False
+-- >>> isValid "/random_ path:*"
+-- True
+isValid :: RawFilePath -> Bool
+isValid filepath
+  | BS.null filepath        = False
+  | _nul `BS.elem` filepath = False
+  | otherwise               = True
+
+-- |Equality of two filepaths. The filepaths are normalised
+-- and trailing path separators are dropped.
+--
+-- >>> equalFilePath "foo" "foo"
+-- True
+-- >>> equalFilePath "foo" "foo/"
+-- True
+-- >>> equalFilePath "foo" "./foo"
+-- True
+-- >>> equalFilePath "foo" "/foo"
+-- False
+-- >>> equalFilePath "foo" "FOO"
+-- False
+-- >>> equalFilePath "foo" "../foo"
+-- False
+--
+-- prop> \p -> equalFilePath p p
+equalFilePath :: RawFilePath -> RawFilePath -> Bool
+equalFilePath p1 p2 = f p1 == f p2
+  where
+    f x = dropTrailingPathSeparator $ normalise x
+
+------------------------
+-- internal stuff
+
+-- Just split the input FileName without adding/normalizing or changing
+-- anything.
+splitFileNameRaw :: RawFilePath -> (RawFilePath, RawFilePath)
+splitFileNameRaw x = BS.breakEnd isPathSeparator x
+
+-- | Combine two paths, assuming rhs is NOT absolute.
+combineRaw :: RawFilePath -> RawFilePath -> RawFilePath
+combineRaw a b | BS.null a = b
+                  | BS.null b = a
+                  | isPathSeparator (BS.last a) = BS.append a b
+                  | otherwise = BS.intercalate (BS.singleton pathSeparator) [a, b]
+