{-# LANGUAGE Trustworthy #-} {-# LANGUAGE CPP, NoImplicitPrelude #-} {-# OPTIONS_GHC -funbox-strict-fields #-} ----------------------------------------------------------------------------- -- | -- Module : GHC.IO.Encoding -- Copyright : (c) The University of Glasgow, 2008-2009 -- License : see libraries/base/LICENSE -- -- Maintainer : [email protected] -- Stability : internal -- Portability : non-portable -- -- Text codecs for I/O -- ----------------------------------------------------------------------------- module GHC.IO.Encoding ( BufferCodec(..), TextEncoding(..), TextEncoder, TextDecoder, CodingProgress(..), latin1, latin1_encode, latin1_decode, utf8, utf8_bom, utf16, utf16le, utf16be, utf32, utf32le, utf32be, initLocaleEncoding, getLocaleEncoding, getFileSystemEncoding, getForeignEncoding, setLocaleEncoding, setFileSystemEncoding, setForeignEncoding, char8, mkTextEncoding, ) where import GHC.Base import GHC.IO.Exception import GHC.IO.Buffer import GHC.IO.Encoding.Failure import GHC.IO.Encoding.Types #if !defined(mingw32_HOST_OS) import qualified GHC.IO.Encoding.Iconv as Iconv #else import qualified GHC.IO.Encoding.CodePage as CodePage import Text.Read (reads) #endif import qualified GHC.IO.Encoding.Latin1 as Latin1 import qualified GHC.IO.Encoding.UTF8 as UTF8 import qualified GHC.IO.Encoding.UTF16 as UTF16 import qualified GHC.IO.Encoding.UTF32 as UTF32 import GHC.List import GHC.Word import Data.IORef import Data.Char (toUpper) import System.IO.Unsafe (unsafePerformIO) -- ----------------------------------------------------------------------------- -- | The Latin1 (ISO8859-1) encoding. This encoding maps bytes -- directly to the first 256 Unicode code points, and is thus not a -- complete Unicode encoding. An attempt to write a character greater than -- '\255' to a 'Handle' using the 'latin1' encoding will result in an error. latin1 :: TextEncoding latin1 = Latin1.latin1_checked -- | The UTF-8 Unicode encoding utf8 :: TextEncoding utf8 = UTF8.utf8 -- | The UTF-8 Unicode encoding, with a byte-order-mark (BOM; the byte -- sequence 0xEF 0xBB 0xBF). This encoding behaves like 'utf8', -- except that on input, the BOM sequence is ignored at the beginning -- of the stream, and on output, the BOM sequence is prepended. -- -- The byte-order-mark is strictly unnecessary in UTF-8, but is -- sometimes used to identify the encoding of a file. -- utf8_bom :: TextEncoding utf8_bom = UTF8.utf8_bom -- | The UTF-16 Unicode encoding (a byte-order-mark should be used to -- indicate endianness). utf16 :: TextEncoding utf16 = UTF16.utf16 -- | The UTF-16 Unicode encoding (litte-endian) utf16le :: TextEncoding utf16le = UTF16.utf16le -- | The UTF-16 Unicode encoding (big-endian) utf16be :: TextEncoding utf16be = UTF16.utf16be -- | The UTF-32 Unicode encoding (a byte-order-mark should be used to -- indicate endianness). utf32 :: TextEncoding utf32 = UTF32.utf32 -- | The UTF-32 Unicode encoding (litte-endian) utf32le :: TextEncoding utf32le = UTF32.utf32le -- | The UTF-32 Unicode encoding (big-endian) utf32be :: TextEncoding utf32be = UTF32.utf32be -- | The Unicode encoding of the current locale -- -- @since 4.5.0.0 getLocaleEncoding :: IO TextEncoding -- | The Unicode encoding of the current locale, but allowing arbitrary -- undecodable bytes to be round-tripped through it. -- -- This 'TextEncoding' is used to decode and encode command line arguments -- and environment variables on non-Windows platforms. -- -- On Windows, this encoding *should not* be used if possible because -- the use of code pages is deprecated: Strings should be retrieved -- via the "wide" W-family of UTF-16 APIs instead -- -- @since 4.5.0.0 getFileSystemEncoding :: IO TextEncoding -- | The Unicode encoding of the current locale, but where undecodable -- bytes are replaced with their closest visual match. Used for -- the 'CString' marshalling functions in "Foreign.C.String" -- -- @since 4.5.0.0 getForeignEncoding :: IO TextEncoding -- | @since 4.5.0.0 setLocaleEncoding, setFileSystemEncoding, setForeignEncoding :: TextEncoding -> IO () (getLocaleEncoding, setLocaleEncoding) = mkGlobal initLocaleEncoding (getFileSystemEncoding, setFileSystemEncoding) = mkGlobal initFileSystemEncoding (getForeignEncoding, setForeignEncoding) = mkGlobal initForeignEncoding mkGlobal :: a -> (IO a, a -> IO ()) mkGlobal x = unsafePerformIO $ do x_ref <- newIORef x return (readIORef x_ref, writeIORef x_ref) -- | @since 4.5.0.0 initLocaleEncoding, initFileSystemEncoding, initForeignEncoding :: TextEncoding #if !defined(mingw32_HOST_OS) -- It is rather important that we don't just call Iconv.mkIconvEncoding here -- because some iconvs (in particular GNU iconv) will brokenly UTF-8 encode -- lone surrogates without complaint. -- -- By going through our Haskell implementations of those encodings, we are -- guaranteed to catch such errors. -- -- FIXME: this is not a complete solution because if the locale encoding is one -- which we don't have a Haskell-side decoder for, iconv might still ignore the -- lone surrogate in the input. initLocaleEncoding = unsafePerformIO $ mkTextEncoding' ErrorOnCodingFailure Iconv.localeEncodingName initFileSystemEncoding = unsafePerformIO $ mkTextEncoding' RoundtripFailure Iconv.localeEncodingName initForeignEncoding = unsafePerformIO $ mkTextEncoding' IgnoreCodingFailure Iconv.localeEncodingName #else initLocaleEncoding = CodePage.localeEncoding initFileSystemEncoding = CodePage.mkLocaleEncoding RoundtripFailure initForeignEncoding = CodePage.mkLocaleEncoding IgnoreCodingFailure #endif -- | An encoding in which Unicode code points are translated to bytes -- by taking the code point modulo 256. When decoding, bytes are -- translated directly into the equivalent code point. -- -- This encoding never fails in either direction. However, encoding -- discards information, so encode followed by decode is not the -- identity. -- -- @since 4.4.0.0 char8 :: TextEncoding char8 = Latin1.latin1 -- | Look up the named Unicode encoding. May fail with -- -- * 'isDoesNotExistError' if the encoding is unknown -- -- The set of known encodings is system-dependent, but includes at least: -- -- * @UTF-8@ -- -- * @UTF-16@, @UTF-16BE@, @UTF-16LE@ -- -- * @UTF-32@, @UTF-32BE@, @UTF-32LE@ -- -- There is additional notation (borrowed from GNU iconv) for specifying -- how illegal characters are handled: -- -- * a suffix of @\/\/IGNORE@, e.g. @UTF-8\/\/IGNORE@, will cause -- all illegal sequences on input to be ignored, and on output -- will drop all code points that have no representation in the -- target encoding. -- -- * a suffix of @\/\/TRANSLIT@ will choose a replacement character -- for illegal sequences or code points. -- -- * a suffix of @\/\/ROUNDTRIP@ will use a PEP383-style escape mechanism -- to represent any invalid bytes in the input as Unicode codepoints (specifically, -- as lone surrogates, which are normally invalid in UTF-32). -- Upon output, these special codepoints are detected and turned back into the -- corresponding original byte. -- -- In theory, this mechanism allows arbitrary data to be roundtripped via -- a 'String' with no loss of data. In practice, there are two limitations -- to be aware of: -- -- 1. This only stands a chance of working for an encoding which is an ASCII -- superset, as for security reasons we refuse to escape any bytes smaller -- than 128. Many encodings of interest are ASCII supersets (in particular, -- you can assume that the locale encoding is an ASCII superset) but many -- (such as UTF-16) are not. -- -- 2. If the underlying encoding is not itself roundtrippable, this mechanism -- can fail. Roundtrippable encodings are those which have an injective mapping -- into Unicode. Almost all encodings meet this criteria, but some do not. Notably, -- Shift-JIS (CP932) and Big5 contain several different encodings of the same -- Unicode codepoint. -- -- On Windows, you can access supported code pages with the prefix -- @CP@; for example, @\"CP1250\"@. -- mkTextEncoding :: String -> IO TextEncoding mkTextEncoding e = case mb_coding_failure_mode of Nothing -> unknownEncodingErr e Just cfm -> mkTextEncoding' cfm enc where (enc, suffix) = span (/= '/') e mb_coding_failure_mode = case suffix of "" -> Just ErrorOnCodingFailure "//IGNORE" -> Just IgnoreCodingFailure "//TRANSLIT" -> Just TransliterateCodingFailure "//ROUNDTRIP" -> Just RoundtripFailure _ -> Nothing mkTextEncoding' :: CodingFailureMode -> String -> IO TextEncoding mkTextEncoding' cfm enc = case [toUpper c | c <- enc, c /= '-'] of -- UTF-8 and friends we can handle ourselves "UTF8" -> return $ UTF8.mkUTF8 cfm "UTF16" -> return $ UTF16.mkUTF16 cfm "UTF16LE" -> return $ UTF16.mkUTF16le cfm "UTF16BE" -> return $ UTF16.mkUTF16be cfm "UTF32" -> return $ UTF32.mkUTF32 cfm "UTF32LE" -> return $ UTF32.mkUTF32le cfm "UTF32BE" -> return $ UTF32.mkUTF32be cfm -- ISO8859-1 we can handle ourselves as well "ISO88591" -> return $ Latin1.mkLatin1 cfm #if defined(mingw32_HOST_OS) 'C':'P':n | [(cp,"")] <- reads n -> return $ CodePage.mkCodePageEncoding cfm cp _ -> unknownEncodingErr (enc ++ codingFailureModeSuffix cfm) #else -- Otherwise, handle other encoding needs via iconv. -- Unfortunately there is no good way to determine whether iconv is actually -- functional without telling it to do something. _ -> do res <- Iconv.mkIconvEncoding cfm enc let isAscii = any (== enc) ansiEncNames case res of Just e -> return e -- At this point we know that we can't count on iconv to work -- (see, for instance, Trac #10298). However, we still want to do -- what we can to work with what we have. For instance, ASCII is -- easy. We match on ASCII encodings directly using several -- possible aliases (specified by RFC 1345 & Co) and for this use -- the 'ascii' encoding Nothing | isAscii -> return (Latin1.mkAscii cfm) | otherwise -> unknownEncodingErr (enc ++ codingFailureModeSuffix cfm) where ansiEncNames = -- ASCII aliases [ "ANSI_X3.4-1968", "iso-ir-6", "ANSI_X3.4-1986", "ISO_646.irv:1991" , "US-ASCII", "us", "IBM367", "cp367", "csASCII", "ASCII", "ISO646-US" ] #endif latin1_encode :: CharBuffer -> Buffer Word8 -> IO (CharBuffer, Buffer Word8) latin1_encode input output = fmap (\(_why,input',output') -> (input',output')) $ Latin1.latin1_encode input output -- unchecked, used for char8 --latin1_encode = unsafePerformIO $ do mkTextEncoder Iconv.latin1 >>= return.encode latin1_decode :: Buffer Word8 -> CharBuffer -> IO (Buffer Word8, CharBuffer) latin1_decode input output = fmap (\(_why,input',output') -> (input',output')) $ Latin1.latin1_decode input output --latin1_decode = unsafePerformIO $ do mkTextDecoder Iconv.latin1 >>= return.encode unknownEncodingErr :: String -> IO a unknownEncodingErr e = ioException (IOError Nothing NoSuchThing "mkTextEncoding" ("unknown encoding:" ++ e) Nothing Nothing)