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1+{-# LANGUAGE TemplateHaskell #-}
3+{-# LANGUAGE OverloadedStrings #-}
4+-- | This module uses template Haskell. Following is a simplified explanation of usage for those unfamiliar with calling Template Haskell functions.
6+-- The function @embedFile@ in this modules embeds a file into the executable
7+-- that you can use it at runtime. A file is represented as a @ByteString@.
8+-- However, as you can see below, the type signature indicates a value of type
9+-- @Q Exp@ will be returned. In order to convert this into a @ByteString@, you
10+-- must use Template Haskell syntax, e.g.:
12+-- > $(embedFile "myfile.txt")
14+-- This expression will have type @ByteString@. Be certain to enable the
15+-- TemplateHaskell language extension, usually by adding the following to the
16+-- top of your module:
18+-- > {-# LANGUAGE TemplateHaskell #-}
20+ ( -- * Embed at compile time
27+ -- * Embed as a IsString
29+ , embedOneStringFileOf
30+ -- * Inject into an executable
32+#if MIN_VERSION_template_haskell(2,5,0)
40+ -- * Relative path manipulation
41+ , makeRelativeToProject
42+ , makeRelativeToLocationPredicate
49+import Language.Haskell.TH.Syntax
50+ ( Exp (AppE, ListE, LitE, TupE, SigE, VarE)
54+ , qLocation, loc_filename
55+#if MIN_VERSION_template_haskell(2,7,0)
56+ , Quasi(qAddDependentFile)
59+#if MIN_VERSION_template_haskell(2,16,0)
60+import Language.Haskell.TH ( mkBytes, bytesPrimL )
61+import qualified Data.ByteString.Internal as B
63+import System.Directory (doesDirectoryExist, doesFileExist,
64+ getDirectoryContents, canonicalizePath)
65+import Control.Exception (throw, tryJust, ErrorCall(..))
66+import Control.Monad (filterM, guard)
67+import qualified Data.ByteString as B
68+import qualified Data.ByteString.Char8 as B8
69+import Control.Arrow ((&&&), second)
70+import Control.Applicative ((<$>))
71+import Data.ByteString.Unsafe (unsafePackAddressLen)
72+import System.IO.Error (isDoesNotExistError)
73+import System.IO.Unsafe (unsafePerformIO)
74+import System.FilePath ((</>), takeDirectory, takeExtension)
75+import Data.String (fromString)
77+import Data.List (sortBy)
78+import Data.Ord (comparing)
80+-- | Embed a single file in your source code.
82+-- > import qualified Data.ByteString
84+-- > myFile :: Data.ByteString.ByteString
85+-- > myFile = $(embedFile "dirName/fileName")
86+embedFile :: FilePath -> Q Exp
88+#if MIN_VERSION_template_haskell(2,7,0)
89+ qAddDependentFile fp >>
91+ (runIO $ B.readFile fp) >>= bsToExp
93+-- | Maybe embed a single file in your source code depending on whether or not file exists.
95+-- Warning: When a build is compiled with the file missing, a recompile when the file exists might not trigger an embed of the file.
96+-- You might try to fix this by doing a clean build.
98+-- > import qualified Data.ByteString
100+-- > maybeMyFile :: Maybe Data.ByteString.ByteString
101+-- > maybeMyFile = $(embedFileIfExists "dirName/fileName")
104+embedFileIfExists :: FilePath -> Q Exp
105+embedFileIfExists fp = do
106+ mbs <- runIO maybeFile
108+ Nothing -> [| Nothing |]
110+#if MIN_VERSION_template_haskell(2,7,0)
111+ qAddDependentFile fp
113+ [| Just $(bsToExp bs) |]
115+ maybeFile :: IO (Maybe B.ByteString)
117+ either (const Nothing) Just <$>
118+ tryJust (guard . isDoesNotExistError) (B.readFile fp)
120+-- | Embed a single existing file in your source code
121+-- out of list a list of paths supplied.
123+-- > import qualified Data.ByteString
125+-- > myFile :: Data.ByteString.ByteString
126+-- > myFile = $(embedOneFileOf [ "dirName/fileName", "src/dirName/fileName" ])
127+embedOneFileOf :: [FilePath] -> Q Exp
129+ (runIO $ readExistingFile ps) >>= \ ( path, content ) -> do
130+#if MIN_VERSION_template_haskell(2,7,0)
131+ qAddDependentFile path
135+ readExistingFile :: [FilePath] -> IO ( FilePath, B.ByteString )
136+ readExistingFile xs = do
137+ ys <- filterM doesFileExist xs
139+ (p:_) -> B.readFile p >>= \ c -> return ( p, c )
140+ _ -> throw $ ErrorCall "Cannot find file to embed as resource"
142+-- | Embed a directory recursively in your source code.
144+-- > import qualified Data.ByteString
146+-- > myDir :: [(FilePath, Data.ByteString.ByteString)]
147+-- > myDir = $(embedDir "dirName")
148+embedDir :: FilePath -> Q Exp
150+ typ <- [t| [(FilePath, B.ByteString)] |]
151+ e <- ListE <$> ((runIO $ fileList fp) >>= mapM (pairToExp fp))
154+-- | Embed a directory listing recursively in your source code.
156+-- > myFiles :: [FilePath]
157+-- > myFiles = $(embedDirListing "dirName")
160+embedDirListing :: FilePath -> Q Exp
161+embedDirListing fp = do
162+ typ <- [t| [FilePath] |]
163+ e <- ListE <$> ((runIO $ fmap fst <$> fileList fp) >>= mapM strToExp)
166+-- | Get a directory tree in the IO monad.
168+-- This is the workhorse of 'embedDir'
169+getDir :: FilePath -> IO [(FilePath, B.ByteString)]
172+pairToExp :: FilePath -> (FilePath, B.ByteString) -> Q Exp
173+pairToExp _root (path, bs) = do
174+#if MIN_VERSION_template_haskell(2,7,0)
175+ qAddDependentFile $ _root ++ '/' : path
179+#if MIN_VERSION_template_haskell(2,16,0)
182+ [LitE $ StringL path, exp']
184+bsToExp :: B.ByteString -> Q Exp
185+#if MIN_VERSION_template_haskell(2, 5, 0)
187+ return $ VarE 'unsafePerformIO
188+ `AppE` (VarE 'unsafePackAddressLen
189+ `AppE` LitE (IntegerL $ fromIntegral $ B8.length bs)
190+#if MIN_VERSION_template_haskell(2, 16, 0)
191+ `AppE` LitE (bytesPrimL (
192+ let B.PS ptr off sz = bs
193+ in mkBytes ptr (fromIntegral off) (fromIntegral sz))))
194+#elif MIN_VERSION_template_haskell(2, 8, 0)
195+ `AppE` LitE (StringPrimL $ B.unpack bs))
197+ `AppE` LitE (StringPrimL $ B8.unpack bs))
201+ helper <- [| stringToBs |]
202+ let chars = B8.unpack bs
203+ return $! AppE helper $! LitE $! StringL chars
206+stringToBs :: String -> B.ByteString
209+-- | Embed a single file in your source code.
211+-- > import Data.String
213+-- > myFile :: IsString a => a
214+-- > myFile = $(embedStringFile "dirName/fileName")
217+embedStringFile :: FilePath -> Q Exp
219+#if MIN_VERSION_template_haskell(2,7,0)
220+ qAddDependentFile fp >>
222+ (runIO $ P.readFile fp) >>= strToExp
224+-- | Embed a single existing string file in your source code
225+-- out of list a list of paths supplied.
228+embedOneStringFileOf :: [FilePath] -> Q Exp
229+embedOneStringFileOf ps =
230+ (runIO $ readExistingFile ps) >>= \ ( path, content ) -> do
231+#if MIN_VERSION_template_haskell(2,7,0)
232+ qAddDependentFile path
236+ readExistingFile :: [FilePath] -> IO ( FilePath, String )
237+ readExistingFile xs = do
238+ ys <- filterM doesFileExist xs
240+ (p:_) -> P.readFile p >>= \ c -> return ( p, c )
241+ _ -> throw $ ErrorCall "Cannot find file to embed as resource"
243+strToExp :: String -> Q Exp
244+#if MIN_VERSION_template_haskell(2, 5, 0)
246+ return $ VarE 'fromString
247+ `AppE` LitE (StringL s)
250+ helper <- [| fromString |]
251+ return $! AppE helper $! LitE $! StringL s
254+notHidden :: FilePath -> Bool
255+notHidden ('.':_) = False
258+fileList :: FilePath -> IO [(FilePath, B.ByteString)]
259+fileList top = fileList' top ""
261+fileList' :: FilePath -> FilePath -> IO [(FilePath, B.ByteString)]
262+fileList' realTop top = do
263+ allContents <- filter notHidden <$> getDirectoryContents (realTop </> top)
264+ let all' = map ((top </>) &&& (\x -> realTop </> top </> x)) allContents
265+ files <- filterM (doesFileExist . snd) all' >>=
266+ mapM (liftPair2 . second B.readFile)
267+ dirs <- filterM (doesDirectoryExist . snd) all' >>=
268+ mapM (fileList' realTop . fst)
269+ return $ sortBy (comparing fst) $ concat $ files : dirs
271+liftPair2 :: Monad m => (a, m b) -> m (a, b)
272+liftPair2 (a, b) = b >>= \b' -> return (a, b')
274+magic :: B.ByteString -> B.ByteString
275+magic x = B8.concat ["fe", x]
280+getInner :: B.ByteString -> B.ByteString
282+ let (sizeBS, rest) = B.splitAt sizeLen b
283+ in case reads $ B8.unpack sizeBS of
284+ (i, _):_ -> B.take i rest
285+ [] -> error "Data.FileEmbed (getInner): Your dummy space has been corrupted."
287+padSize :: Int -> String
290+ in replicate (sizeLen - length s) '0' ++ s
292+#if MIN_VERSION_template_haskell(2,5,0)
293+-- | Allocate the given number of bytes in the generate executable. That space
294+-- can be filled up with the 'inject' and 'injectFile' functions.
295+dummySpace :: Int -> Q Exp
296+dummySpace = dummySpaceWith "MS"
298+-- | Like 'dummySpace', but takes a postfix for the magic string. In
299+-- order for this to work, the same postfix must be used by 'inject' /
300+-- 'injectFile'. This allows an executable to have multiple
301+-- 'ByteString's injected into it, without encountering collisions.
304+dummySpaceWith :: B.ByteString -> Int -> Q Exp
305+dummySpaceWith postfix space = do
306+ let size = padSize space
307+ magic' = magic postfix
308+ start = B8.unpack magic' ++ size
309+ magicLen = B8.length magic'
310+ len = magicLen + sizeLen + space
311+ chars = LitE $ StringPrimL $
312+#if MIN_VERSION_template_haskell(2,6,0)
313+ map (toEnum . fromEnum) $
315+ start ++ replicate space '0'
316+ [| getInner (B.drop magicLen (unsafePerformIO (unsafePackAddressLen len $(return chars)))) |]
319+-- | Inject some raw data inside a @ByteString@ containing empty, dummy space
320+-- (allocated with @dummySpace@). Typically, the original @ByteString@ is an
321+-- executable read from the filesystem.
322+inject :: B.ByteString -- ^ bs to inject
323+ -> B.ByteString -- ^ original BS containing dummy
324+ -> Maybe B.ByteString -- ^ new BS, or Nothing if there is insufficient dummy space
325+inject = injectWith "MS"
327+-- | Like 'inject', but takes a postfix for the magic string.
330+injectWith :: B.ByteString -- ^ postfix of magic string
331+ -> B.ByteString -- ^ bs to inject
332+ -> B.ByteString -- ^ original BS containing dummy
333+ -> Maybe B.ByteString -- ^ new BS, or Nothing if there is insufficient dummy space
334+injectWith postfix toInj orig =
337+ else Just $ B.concat [before, magic', B8.pack $ padSize toInjL, toInj, B8.pack $ replicate (size - toInjL) '0', after]
339+ magic' = magic postfix
340+ toInjL = B.length toInj
341+ (before, rest) = B.breakSubstring magic' orig
342+ (sizeBS, rest') = B.splitAt sizeLen $ B.drop (B8.length magic') rest
343+ size = case reads $ B8.unpack sizeBS of
345+ [] -> error $ "Data.FileEmbed (inject): Your dummy space has been corrupted. Size is: " ++ show sizeBS
346+ after = B.drop size rest'
348+-- | Same as 'inject', but instead of performing the injecting in memory, read
349+-- the contents from the filesystem and write back to a different file on the
351+injectFile :: B.ByteString -- ^ bs to inject
352+ -> FilePath -- ^ template file
353+ -> FilePath -- ^ output file
355+injectFile = injectFileWith "MS"
357+-- | Like 'injectFile', but takes a postfix for the magic string.
360+injectFileWith :: B.ByteString -- ^ postfix of magic string
361+ -> B.ByteString -- ^ bs to inject
362+ -> FilePath -- ^ template file
363+ -> FilePath -- ^ output file
365+injectFileWith postfix inj srcFP dstFP = do
366+ src <- B.readFile srcFP
367+ case injectWith postfix inj src of
368+ Nothing -> error "Insufficient dummy space"
369+ Just dst -> B.writeFile dstFP dst
373+The inject system allows arbitrary content to be embedded inside a Haskell
374+executable, post compilation. Typically, file-embed allows you to read some
375+contents from the file system at compile time and embed them inside your
376+executable. Consider a case, instead, where you would want to embed these
377+contents after compilation. Two real-world examples are:
379+* You would like to embed a hash of the executable itself, for sanity checking in a network protocol. (Obviously the hash will change after you embed the hash.)
381+* You want to create a self-contained web server that has a set of content, but will need to update the content on machines that do not have access to GHC.
383+The typical workflow use:
385+* Use 'dummySpace' or 'dummySpaceWith' to create some empty space in your executable
387+* Use 'injectFile' or 'injectFileWith' from a separate utility to modify that executable to have the updated content.
389+The reason for the @With@-variant of the functions is for cases where you wish
390+to inject multiple different kinds of content, and therefore need control over
391+the magic key. If you know for certain that there will only be one dummy space
392+available, you can use the non-@With@ variants.
396+-- | Take a relative file path and attach it to the root of the current
399+-- The idea here is that, when building with Stack, the build will always be
400+-- executed with a current working directory of the root of the project (where
401+-- your .cabal file is located). However, if you load up multiple projects with
402+-- @stack ghci@, the working directory may be something else entirely.
404+-- This function looks at the source location of the Haskell file calling it,
405+-- finds the first parent directory with a .cabal file, and uses that as the
406+-- root directory for fixing the relative path.
408+-- @$(makeRelativeToProject "data/foo.txt" >>= embedFile)@
411+makeRelativeToProject :: FilePath -> Q FilePath
412+makeRelativeToProject = makeRelativeToLocationPredicate $ (==) ".cabal" . takeExtension
414+-- | Take a predicate to infer the project root and a relative file path, the given file path is then attached to the inferred project root
416+-- This function looks at the source location of the Haskell file calling it,
417+-- finds the first parent directory with a file matching the given predicate, and uses that as the
418+-- root directory for fixing the relative path.
420+-- @$(makeRelativeToLocationPredicate ((==) ".cabal" . takeExtension) "data/foo.txt" >>= embedFile)@
423+makeRelativeToLocationPredicate :: (FilePath -> Bool) -> FilePath -> Q FilePath
424+makeRelativeToLocationPredicate isTargetFile rel = do
427+ srcFP <- canonicalizePath $ loc_filename loc
428+ mdir <- findProjectDir srcFP
430+ Nothing -> error $ "Could not find .cabal file for path: " ++ srcFP
431+ Just dir -> return $ dir </> rel
433+ findProjectDir x = do
434+ let dir = takeDirectory x
438+ contents <- getDirectoryContents dir
439+ if any isTargetFile contents
440+ then return (Just dir)
441+ else findProjectDir dir