{-# 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  :  libraries@haskell.org
-- 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,
        argvEncoding
    ) 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 'System.IO.Handle' using the 'latin1' encoding will result in an
-- error.
latin1  :: TextEncoding
latin1 :: TextEncoding
latin1 = TextEncoding
Latin1.latin1_checked

-- | The UTF-8 Unicode encoding
utf8  :: TextEncoding
utf8 :: TextEncoding
utf8 = TextEncoding
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 :: TextEncoding
utf8_bom = TextEncoding
UTF8.utf8_bom

-- | The UTF-16 Unicode encoding (a byte-order-mark should be used to
-- indicate endianness).
utf16  :: TextEncoding
utf16 :: TextEncoding
utf16 = TextEncoding
UTF16.utf16

-- | The UTF-16 Unicode encoding (little-endian)
utf16le  :: TextEncoding
utf16le :: TextEncoding
utf16le = TextEncoding
UTF16.utf16le

-- | The UTF-16 Unicode encoding (big-endian)
utf16be  :: TextEncoding
utf16be :: TextEncoding
utf16be = TextEncoding
UTF16.utf16be

-- | The UTF-32 Unicode encoding (a byte-order-mark should be used to
-- indicate endianness).
utf32  :: TextEncoding
utf32 :: TextEncoding
utf32 = TextEncoding
UTF32.utf32

-- | The UTF-32 Unicode encoding (little-endian)
utf32le  :: TextEncoding
utf32le :: TextEncoding
utf32le = TextEncoding
UTF32.utf32le

-- | The UTF-32 Unicode encoding (big-endian)
utf32be  :: TextEncoding
utf32be :: TextEncoding
utf32be = TextEncoding
UTF32.utf32be

-- | The Unicode encoding of the current locale
--
-- @since 4.5.0.0
getLocaleEncoding :: IO TextEncoding
{-# NOINLINE getLocaleEncoding #-}

-- | 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
{-# NOINLINE getFileSystemEncoding #-}

-- | The Unicode encoding of the current locale, but where undecodable
-- bytes are replaced with their closest visual match. Used for
-- the 'Foreign.C.String.CString' marshalling functions in "Foreign.C.String"
--
-- @since 4.5.0.0
getForeignEncoding :: IO TextEncoding
{-# NOINLINE getForeignEncoding #-}

-- | Set locale encoding for your program. The locale affects
-- how 'Char's are encoded and decoded when serialized to bytes: e. g.,
-- when you read or write files ('System.IO.readFile'', 'System.IO.writeFile')
-- or use standard input/output ('System.IO.getLine', 'System.IO.putStrLn').
-- For instance, if your program prints non-ASCII characters, it is prudent to execute
--
-- > setLocaleEncoding utf8
--
-- This is necessary, but not enough on Windows, where console is
-- a stateful device, which needs to be configured using
-- @System.Win32.Console.setConsoleOutputCP@ and restored back afterwards.
-- These intricacies are covered by
-- <https://hackage.haskell.org/package/code-page code-page> package,
-- which offers a crossplatform @System.IO.CodePage.withCodePage@ bracket.
--
-- Wrong locale encoding typically causes error messages like
-- "invalid argument (cannot decode byte sequence starting from ...)"
-- or "invalid argument (cannot encode character ...)".
--
-- @since 4.5.0.0
setLocaleEncoding :: TextEncoding -> IO ()
{-# NOINLINE setLocaleEncoding #-}

-- | @since 4.5.0.0
setFileSystemEncoding :: TextEncoding -> IO ()
{-# NOINLINE setFileSystemEncoding #-}

-- | @since 4.5.0.0
setForeignEncoding :: TextEncoding -> IO ()
{-# NOINLINE setForeignEncoding #-}

(IO TextEncoding
getLocaleEncoding, TextEncoding -> IO ()
setLocaleEncoding)         = forall a. a -> (IO a, a -> IO ())
mkGlobal TextEncoding
initLocaleEncoding
(IO TextEncoding
getFileSystemEncoding, TextEncoding -> IO ()
setFileSystemEncoding) = forall a. a -> (IO a, a -> IO ())
mkGlobal TextEncoding
initFileSystemEncoding
(IO TextEncoding
getForeignEncoding, TextEncoding -> IO ()
setForeignEncoding)       = forall a. a -> (IO a, a -> IO ())
mkGlobal TextEncoding
initForeignEncoding

mkGlobal :: a -> (IO a, a -> IO ())
mkGlobal :: forall a. a -> (IO a, a -> IO ())
mkGlobal a
x = forall a. IO a -> a
unsafePerformIO forall a b. (a -> b) -> a -> b
$ do
    IORef a
x_ref <- forall a. a -> IO (IORef a)
newIORef a
x
    forall (m :: * -> *) a. Monad m => a -> m a
return (forall a. IORef a -> IO a
readIORef IORef a
x_ref, forall a. IORef a -> a -> IO ()
writeIORef IORef a
x_ref)
{-# NOINLINE mkGlobal #-}

-- | @since 4.5.0.0
initLocaleEncoding, initFileSystemEncoding, initForeignEncoding :: TextEncoding
{-# NOINLINE initLocaleEncoding #-}
-- N.B. initLocaleEncoding is exported for use in System.IO.localeEncoding.
-- NOINLINE ensures that this result is shared.

#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 :: TextEncoding
initLocaleEncoding     = forall a. IO a -> a
unsafePerformIO forall a b. (a -> b) -> a -> b
$ CodingFailureMode -> String -> IO TextEncoding
mkTextEncoding' CodingFailureMode
ErrorOnCodingFailure String
Iconv.localeEncodingName
initFileSystemEncoding :: TextEncoding
initFileSystemEncoding = forall a. IO a -> a
unsafePerformIO forall a b. (a -> b) -> a -> b
$ CodingFailureMode -> String -> IO TextEncoding
mkTextEncoding' CodingFailureMode
RoundtripFailure     String
Iconv.localeEncodingName
initForeignEncoding :: TextEncoding
initForeignEncoding    = forall a. IO a -> a
unsafePerformIO forall a b. (a -> b) -> a -> b
$ CodingFailureMode -> String -> IO TextEncoding
mkTextEncoding' CodingFailureMode
IgnoreCodingFailure  String
Iconv.localeEncodingName
#else
initLocaleEncoding     = CodePage.localeEncoding
initFileSystemEncoding = CodePage.mkLocaleEncoding RoundtripFailure
initForeignEncoding    = CodePage.mkLocaleEncoding IgnoreCodingFailure
#endif

-- See Note [Windows Unicode Arguments] in rts/RtsFlags.c
-- On Windows we assume hs_init argv is in utf8 encoding.

-- | Internal encoding of argv
argvEncoding :: IO TextEncoding
#if defined(mingw32_HOST_OS)
argvEncoding = return utf8
#else
argvEncoding :: IO TextEncoding
argvEncoding = IO TextEncoding
getFileSystemEncoding
#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 :: TextEncoding
char8 = TextEncoding
Latin1.latin1

-- | Look up the named Unicode encoding.  May fail with
--
--  * 'System.IO.Error.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 :: String -> IO TextEncoding
mkTextEncoding String
e = case Maybe CodingFailureMode
mb_coding_failure_mode of
    Maybe CodingFailureMode
Nothing -> forall a. String -> IO a
unknownEncodingErr String
e
    Just CodingFailureMode
cfm -> CodingFailureMode -> String -> IO TextEncoding
mkTextEncoding' CodingFailureMode
cfm String
enc
  where
    (String
enc, String
suffix) = forall a. (a -> Bool) -> [a] -> ([a], [a])
span (forall a. Eq a => a -> a -> Bool
/= Char
'/') String
e
    mb_coding_failure_mode :: Maybe CodingFailureMode
mb_coding_failure_mode = case String
suffix of
        String
""            -> forall a. a -> Maybe a
Just CodingFailureMode
ErrorOnCodingFailure
        String
"//IGNORE"    -> forall a. a -> Maybe a
Just CodingFailureMode
IgnoreCodingFailure
        String
"//TRANSLIT"  -> forall a. a -> Maybe a
Just CodingFailureMode
TransliterateCodingFailure
        String
"//ROUNDTRIP" -> forall a. a -> Maybe a
Just CodingFailureMode
RoundtripFailure
        String
_             -> forall a. Maybe a
Nothing

mkTextEncoding' :: CodingFailureMode -> String -> IO TextEncoding
mkTextEncoding' :: CodingFailureMode -> String -> IO TextEncoding
mkTextEncoding' CodingFailureMode
cfm String
enc =
  case [Char -> Char
toUpper Char
c | Char
c <- String
enc, Char
c forall a. Eq a => a -> a -> Bool
/= Char
'-'] of
  -- UTF-8 and friends we can handle ourselves
    String
"UTF8"    -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ CodingFailureMode -> TextEncoding
UTF8.mkUTF8 CodingFailureMode
cfm
    String
"UTF16"   -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ CodingFailureMode -> TextEncoding
UTF16.mkUTF16 CodingFailureMode
cfm
    String
"UTF16LE" -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ CodingFailureMode -> TextEncoding
UTF16.mkUTF16le CodingFailureMode
cfm
    String
"UTF16BE" -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ CodingFailureMode -> TextEncoding
UTF16.mkUTF16be CodingFailureMode
cfm
    String
"UTF32"   -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ CodingFailureMode -> TextEncoding
UTF32.mkUTF32 CodingFailureMode
cfm
    String
"UTF32LE" -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ CodingFailureMode -> TextEncoding
UTF32.mkUTF32le CodingFailureMode
cfm
    String
"UTF32BE" -> forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ CodingFailureMode -> TextEncoding
UTF32.mkUTF32be CodingFailureMode
cfm
    -- On AIX, we want to avoid iconv, because it is either
    -- a) totally broken, or b) non-reentrant, or c) actually works.
    -- Detecting b) is difficult as you'd have to trigger the reentrancy
    -- corruption.
    -- Therefore, on AIX, we handle the popular ASCII and latin1 encodings
    -- ourselves. For consistency, we do the same on other platforms.
    -- We use `mkLatin1_checked` instead of `mkLatin1`, since the latter
    -- completely ignores the CodingFailureMode (TEST=encoding005).
    String
_ | Bool
isAscii -> forall (m :: * -> *) a. Monad m => a -> m a
return (CodingFailureMode -> TextEncoding
Latin1.mkAscii CodingFailureMode
cfm)
    String
_ | Bool
isLatin1 -> forall (m :: * -> *) a. Monad m => a -> m a
return (CodingFailureMode -> TextEncoding
Latin1.mkLatin1_checked CodingFailureMode
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.
    String
_ -> do Maybe TextEncoding
res <- CodingFailureMode -> String -> IO (Maybe TextEncoding)
Iconv.mkIconvEncoding CodingFailureMode
cfm String
enc
            case Maybe TextEncoding
res of
              Just TextEncoding
e -> forall (m :: * -> *) a. Monad m => a -> m a
return TextEncoding
e
              Maybe TextEncoding
Nothing -> forall a. String -> IO a
unknownEncodingErr (String
enc forall a. [a] -> [a] -> [a]
++ CodingFailureMode -> String
codingFailureModeSuffix CodingFailureMode
cfm)
#endif
  where
    isAscii :: Bool
isAscii = String
enc forall a. Eq a => a -> [a] -> Bool
`elem` [String]
asciiEncNames
    isLatin1 :: Bool
isLatin1 = String
enc forall a. Eq a => a -> [a] -> Bool
`elem` [String]
latin1EncNames
    asciiEncNames :: [String]
asciiEncNames = -- ASCII aliases specified by RFC 1345 and RFC 3808.
      [ String
"ANSI_X3.4-1968", String
"iso-ir-6", String
"ANSI_X3.4-1986", String
"ISO_646.irv:1991"
      , String
"US-ASCII", String
"us", String
"IBM367", String
"cp367", String
"csASCII", String
"ASCII", String
"ISO646-US"
      ]
    latin1EncNames :: [String]
latin1EncNames = -- latin1 aliases specified by RFC 1345 and RFC 3808.
      [ String
"ISO_8859-1:1987", String
"iso-ir-100", String
"ISO_8859-1", String
"ISO-8859-1", String
"latin1",
        String
"l1", String
"IBM819", String
"CP819", String
"csISOLatin1"
      ]


latin1_encode :: CharBuffer -> Buffer Word8 -> IO (CharBuffer, Buffer Word8)
latin1_encode :: CharBuffer -> Buffer Word8 -> IO (CharBuffer, Buffer Word8)
latin1_encode CharBuffer
input Buffer Word8
output = forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (\(CodingProgress
_why,CharBuffer
input',Buffer Word8
output') -> (CharBuffer
input',Buffer Word8
output')) forall a b. (a -> b) -> a -> b
$ EncodeBuffer
Latin1.latin1_encode CharBuffer
input Buffer Word8
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 :: Buffer Word8 -> CharBuffer -> IO (Buffer Word8, CharBuffer)
latin1_decode Buffer Word8
input CharBuffer
output = forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap (\(CodingProgress
_why,Buffer Word8
input',CharBuffer
output') -> (Buffer Word8
input',CharBuffer
output')) forall a b. (a -> b) -> a -> b
$ DecodeBuffer
Latin1.latin1_decode Buffer Word8
input CharBuffer
output
--latin1_decode = unsafePerformIO $ do mkTextDecoder Iconv.latin1 >>= return.encode

unknownEncodingErr :: String -> IO a
unknownEncodingErr :: forall a. String -> IO a
unknownEncodingErr String
e = forall a. IOException -> IO a
ioException (Maybe Handle
-> IOErrorType
-> String
-> String
-> Maybe CInt
-> Maybe String
-> IOException
IOError forall a. Maybe a
Nothing IOErrorType
NoSuchThing String
"mkTextEncoding"
                                            (String
"unknown encoding:" forall a. [a] -> [a] -> [a]
++ String
e)  forall a. Maybe a
Nothing forall a. Maybe a
Nothing)