57 lines
2.1 KiB
Haskell
57 lines
2.1 KiB
Haskell
{- GHC File system encoding handling.
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-
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- Copyright 2012 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Utility.FileSystemEncoding where
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import qualified GHC.Foreign as GHC
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import qualified GHC.IO.Encoding as Encoding
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import Foreign.C
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import System.IO
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import System.IO.Unsafe
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import qualified Data.Hash.MD5 as MD5
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import Data.Word
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import Data.Bits.Utils
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{- Sets a Handle to use the filesystem encoding. This causes data
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- written or read from it to be encoded/decoded the same
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- as ghc 7.4 does to filenames etc. This special encoding
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- allows "arbitrary undecodable bytes to be round-tripped through it". -}
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fileEncoding :: Handle -> IO ()
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fileEncoding h = hSetEncoding h =<< Encoding.getFileSystemEncoding
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{- Marshal a Haskell FilePath into a NUL terminated C string using temporary
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- storage. The FilePath is encoded using the filesystem encoding,
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- reversing the decoding that should have been done when the FilePath
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- was obtained. -}
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withFilePath :: FilePath -> (CString -> IO a) -> IO a
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withFilePath fp f = Encoding.getFileSystemEncoding
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>>= \enc -> GHC.withCString enc fp f
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{- Encodes a FilePath into a Md5.Str, applying the filesystem encoding.
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-
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- This use of unsafePerformIO is belived to be safe; GHC's interface
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- only allows doing this conversion with CStrings, and the CString buffer
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- is allocated, used, and deallocated within the call, with no side
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- effects.
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-}
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{-# NOINLINE encodeFilePath #-}
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encodeFilePath :: FilePath -> MD5.Str
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encodeFilePath fp = MD5.Str $ unsafePerformIO $ do
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enc <- Encoding.getFileSystemEncoding
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GHC.withCString enc fp $ GHC.peekCString Encoding.char8
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{- Converts a [Word8] to a FilePath, encoding using the filesystem encoding.
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-
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- w82c produces a String, which may contain Chars that are invalid
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- unicode. From there, this is really a simple matter of applying the
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- file system encoding, only complicated by GHC's interface to doing so.
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-}
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{-# NOINLINE encodeW8 #-}
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encodeW8 :: [Word8] -> FilePath
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encodeW8 w8 = unsafePerformIO $ do
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enc <- Encoding.getFileSystemEncoding
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GHC.withCString Encoding.char8 (w82s w8) $ GHC.peekCString enc
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