X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=System%2FIO.hs;h=93166b94edc21cb44c6c4c790b1393e09b274f14;hb=a2bcd1899dea9b266b7c795e391f658985deda2e;hp=bc1d254c9528d9ee151bca74f471e0c574dafa0d;hpb=8fae8163976b1d4b3db7d259b067fa4d5fdcc907;p=ghc-base.git diff --git a/System/IO.hs b/System/IO.hs index bc1d254..93166b9 100644 --- a/System/IO.hs +++ b/System/IO.hs @@ -1,4 +1,4 @@ -{-# OPTIONS -fno-implicit-prelude #-} +{-# OPTIONS_GHC -XNoImplicitPrelude #-} ----------------------------------------------------------------------------- -- | -- Module : System.IO @@ -6,7 +6,7 @@ -- License : BSD-style (see the file libraries/base/LICENSE) -- -- Maintainer : libraries@haskell.org --- Stability : provisional +-- Stability : stable -- Portability : portable -- -- The standard IO library. @@ -14,102 +14,176 @@ ----------------------------------------------------------------------------- module System.IO ( - Handle, -- abstract, instance of: Eq, Show. - HandlePosn(..), -- abstract, instance of: Eq, Show. + -- * The IO monad + IO, -- instance MonadFix + fixIO, -- :: (a -> IO a) -> IO a + + -- * Files and handles + + FilePath, -- :: String + + Handle, -- abstract, instance of: Eq, Show. + + -- ** Standard handles + + -- | Three handles are allocated during program initialisation, + -- and are initially open. + + stdin, stdout, stderr, -- :: Handle + + -- * Opening and closing files + + -- ** Opening files + + withFile, + openFile, -- :: FilePath -> IOMode -> IO Handle IOMode(ReadMode,WriteMode,AppendMode,ReadWriteMode), + + -- ** Closing files + + hClose, -- :: Handle -> IO () + + -- ** Special cases + + -- | These functions are also exported by the "Prelude". + + readFile, -- :: FilePath -> IO String + writeFile, -- :: FilePath -> String -> IO () + appendFile, -- :: FilePath -> String -> IO () + + -- ** File locking + + -- $locking + + -- * Operations on handles + + -- ** Determining and changing the size of a file + + hFileSize, -- :: Handle -> IO Integer +#ifdef __GLASGOW_HASKELL__ + hSetFileSize, -- :: Handle -> Integer -> IO () +#endif + + -- ** Detecting the end of input + + hIsEOF, -- :: Handle -> IO Bool + isEOF, -- :: IO Bool + + -- ** Buffering operations + BufferMode(NoBuffering,LineBuffering,BlockBuffering), - SeekMode(AbsoluteSeek,RelativeSeek,SeekFromEnd), + hSetBuffering, -- :: Handle -> BufferMode -> IO () + hGetBuffering, -- :: Handle -> IO BufferMode + hFlush, -- :: Handle -> IO () - stdin, stdout, stderr, -- :: Handle + -- ** Repositioning handles + + hGetPosn, -- :: Handle -> IO HandlePosn + hSetPosn, -- :: HandlePosn -> IO () + HandlePosn, -- abstract, instance of: Eq, Show. - openFile, -- :: FilePath -> IOMode -> IO Handle - openBinaryFile, -- :: FilePath -> IOMode -> IO Handle - hClose, -- :: Handle -> IO () - hFileSize, -- :: Handle -> IO Integer - hIsEOF, -- :: Handle -> IO Bool - isEOF, -- :: IO Bool - - hSetBuffering, -- :: Handle -> BufferMode -> IO () - hGetBuffering, -- :: Handle -> IO BufferMode -#ifndef __HUGS__ - hSetBinaryMode, -- :: Handle -> Bool -> IO () -#endif - hFlush, -- :: Handle -> IO () - hGetPosn, -- :: Handle -> IO HandlePosn - hSetPosn, -- :: HandlePosn -> IO () - hSeek, -- :: Handle -> SeekMode -> Integer -> IO () + hSeek, -- :: Handle -> SeekMode -> Integer -> IO () + SeekMode(AbsoluteSeek,RelativeSeek,SeekFromEnd), #if !defined(__NHC__) - hTell, -- :: Handle -> IO Integer -#endif - hWaitForInput, -- :: Handle -> Int -> IO Bool - hReady, -- :: Handle -> IO Bool - hGetChar, -- :: Handle -> IO Char - hGetLine, -- :: Handle -> IO [Char] - hLookAhead, -- :: Handle -> IO Char - hGetContents, -- :: Handle -> IO [Char] - hPutChar, -- :: Handle -> Char -> IO () - hPutStr, -- :: Handle -> [Char] -> IO () - hPutStrLn, -- :: Handle -> [Char] -> IO () - hPrint, -- :: Show a => Handle -> a -> IO () + hTell, -- :: Handle -> IO Integer +#endif + + -- ** Handle properties + hIsOpen, hIsClosed, -- :: Handle -> IO Bool hIsReadable, hIsWritable, -- :: Handle -> IO Bool hIsSeekable, -- :: Handle -> IO Bool - isAlreadyExistsError, isDoesNotExistError, -- :: IOError -> Bool - isAlreadyInUseError, isFullError, - isEOFError, isIllegalOperation, - isPermissionError, isUserError, - - ioeGetErrorString, -- :: IOError -> String - ioeGetHandle, -- :: IOError -> Maybe Handle - ioeGetFileName, -- :: IOError -> Maybe FilePath - - try, -- :: IO a -> IO (Either IOError a) - - -- re-exports of Prelude names - IO, -- instance MonadFix - FilePath, -- :: String - IOError, - ioError, -- :: IOError -> IO a - userError, -- :: String -> IOError - catch, -- :: IO a -> (IOError -> IO a) -> IO a - interact, -- :: (String -> String) -> IO () - - putChar, -- :: Char -> IO () - putStr, -- :: String -> IO () - putStrLn, -- :: String -> IO () - print, -- :: Show a => a -> IO () - getChar, -- :: IO Char - getLine, -- :: IO String - getContents, -- :: IO String - readFile, -- :: FilePath -> IO String - writeFile, -- :: FilePath -> String -> IO () - appendFile, -- :: FilePath -> String -> IO () - readIO, -- :: Read a => String -> IO a - readLn, -- :: Read a => IO a - -#if !defined(__HUGS__) && !defined(__NHC__) - hPutBuf, -- :: Handle -> Ptr a -> Int -> IO () - hGetBuf, -- :: Handle -> Ptr a -> Int -> IO Int -#endif - - fixIO, -- :: (a -> IO a) -> IO a - -#if !defined(__HUGS__) && !defined(__NHC__) - hSetEcho, -- :: Handle -> Bool -> IO () - hGetEcho, -- :: Handle -> IO Bool - - hIsTerminalDevice, -- :: Handle -> IO Bool + -- ** Terminal operations (not portable: GHC\/Hugs only) + +#if !defined(__NHC__) + hIsTerminalDevice, -- :: Handle -> IO Bool + + hSetEcho, -- :: Handle -> Bool -> IO () + hGetEcho, -- :: Handle -> IO Bool #endif + + -- ** Showing handle state (not portable: GHC only) + +#ifdef __GLASGOW_HASKELL__ + hShow, -- :: Handle -> IO String +#endif + + -- * Text input and output + + -- ** Text input + + hWaitForInput, -- :: Handle -> Int -> IO Bool + hReady, -- :: Handle -> IO Bool + hGetChar, -- :: Handle -> IO Char + hGetLine, -- :: Handle -> IO [Char] + hLookAhead, -- :: Handle -> IO Char + hGetContents, -- :: Handle -> IO [Char] + + -- ** Text output + + hPutChar, -- :: Handle -> Char -> IO () + hPutStr, -- :: Handle -> [Char] -> IO () + hPutStrLn, -- :: Handle -> [Char] -> IO () + hPrint, -- :: Show a => Handle -> a -> IO () + + -- ** Special cases for standard input and output + + -- | These functions are also exported by the "Prelude". + + interact, -- :: (String -> String) -> IO () + putChar, -- :: Char -> IO () + putStr, -- :: String -> IO () + putStrLn, -- :: String -> IO () + print, -- :: Show a => a -> IO () + getChar, -- :: IO Char + getLine, -- :: IO String + getContents, -- :: IO String + readIO, -- :: Read a => String -> IO a + readLn, -- :: Read a => IO a + + -- * Binary input and output + + withBinaryFile, + openBinaryFile, -- :: FilePath -> IOMode -> IO Handle + hSetBinaryMode, -- :: Handle -> Bool -> IO () + hPutBuf, -- :: Handle -> Ptr a -> Int -> IO () + hGetBuf, -- :: Handle -> Ptr a -> Int -> IO Int +#if !defined(__NHC__) && !defined(__HUGS__) + hPutBufNonBlocking, -- :: Handle -> Ptr a -> Int -> IO Int + hGetBufNonBlocking, -- :: Handle -> Ptr a -> Int -> IO Int +#endif + + -- * Temporary files + + openTempFile, + openBinaryTempFile, ) where +import Control.Exception hiding (bracket) + +#ifndef __NHC__ +import Data.Bits +import Data.List +import Data.Maybe +import Foreign.C.Error +import Foreign.C.String +import System.Posix.Internals +#endif + +#ifdef __GLASGOW_HASKELL__ +import GHC.IOBase as ExceptionBase +#endif +#ifdef __HUGS__ +import Hugs.Exception as ExceptionBase +#endif + #ifdef __GLASGOW_HASKELL__ import GHC.Base -import GHC.IOBase -- Together these four Prelude modules define -import GHC.Handle -- all the stuff exported by IO for the GHC version +import GHC.IOBase -- Together these four Prelude modules define +import GHC.Handle -- all the stuff exported by IO for the GHC version import GHC.IO -import GHC.ST ( fixST ) import GHC.Exception import GHC.Num import GHC.Read @@ -119,6 +193,10 @@ import GHC.Show #ifdef __HUGS__ import Hugs.IO import Hugs.IOExts +import Hugs.IORef +import Hugs.Prelude ( throw, Exception(NonTermination) ) +import Control.Exception ( bracket ) +import System.IO.Unsafe ( unsafeInterleaveIO ) #endif #ifdef __NHC__ @@ -147,108 +225,349 @@ import IO , hGetContents -- :: Handle -> IO [Char] , hPutChar -- :: Handle -> Char -> IO () , hPutStr -- :: Handle -> [Char] -> IO () + , hPutStrLn -- :: Handle -> [Char] -> IO () + , hPrint -- :: Handle -> [Char] -> IO () + , hReady -- :: Handle -> [Char] -> IO () , hIsOpen, hIsClosed -- :: Handle -> IO Bool , hIsReadable, hIsWritable -- :: Handle -> IO Bool , hIsSeekable -- :: Handle -> IO Bool - , isAlreadyExistsError, isDoesNotExistError -- :: IOError -> Bool - , isAlreadyInUseError, isFullError - , isEOFError, isIllegalOperation - , isPermissionError, isUserError - , ioeGetErrorString -- :: IOError -> String - , ioeGetHandle -- :: IOError -> Maybe Handle - , ioeGetFileName -- :: IOError -> Maybe FilePath + , bracket , IO () , FilePath -- :: String - , IOError - , ioError -- :: IOError -> IO a - , userError -- :: String -> IOError - , catch -- :: IO a -> (IOError -> IO a) -> IO a ) -import NHC.Internal (unsafePerformIO) +import NHC.IOExtras (fixIO, hPutBuf, hGetBuf) +import NHC.FFI (Ptr) #endif -import System.IO.Error - -- ----------------------------------------------------------------------------- -- Standard IO -#ifndef __HUGS__ +#ifdef __GLASGOW_HASKELL__ +-- | Write a character to the standard output device +-- (same as 'hPutChar' 'stdout'). + putChar :: Char -> IO () putChar c = hPutChar stdout c +-- | Write a string to the standard output device +-- (same as 'hPutStr' 'stdout'). + putStr :: String -> IO () putStr s = hPutStr stdout s +-- | The same as 'putStr', but adds a newline character. + putStrLn :: String -> IO () putStrLn s = do putStr s putChar '\n' +-- | The 'print' function outputs a value of any printable type to the +-- standard output device. +-- Printable types are those that are instances of class 'Show'; 'print' +-- converts values to strings for output using the 'show' operation and +-- adds a newline. +-- +-- For example, a program to print the first 20 integers and their +-- powers of 2 could be written as: +-- +-- > main = print ([(n, 2^n) | n <- [0..19]]) + print :: Show a => a -> IO () print x = putStrLn (show x) +-- | Read a character from the standard input device +-- (same as 'hGetChar' 'stdin'). + getChar :: IO Char getChar = hGetChar stdin +-- | Read a line from the standard input device +-- (same as 'hGetLine' 'stdin'). + getLine :: IO String getLine = hGetLine stdin +-- | The 'getContents' operation returns all user input as a single string, +-- which is read lazily as it is needed +-- (same as 'hGetContents' 'stdin'). + getContents :: IO String getContents = hGetContents stdin +-- | The 'interact' function takes a function of type @String->String@ +-- as its argument. The entire input from the standard input device is +-- passed to this function as its argument, and the resulting string is +-- output on the standard output device. + interact :: (String -> String) -> IO () interact f = do s <- getContents putStr (f s) +-- | The 'readFile' function reads a file and +-- returns the contents of the file as a string. +-- The file is read lazily, on demand, as with 'getContents'. + readFile :: FilePath -> IO String -readFile name = openFile name ReadMode >>= hGetContents +readFile name = openFile name ReadMode >>= hGetContents + +-- | The computation 'writeFile' @file str@ function writes the string @str@, +-- to the file @file@. +writeFile :: FilePath -> String -> IO () +writeFile f txt = withFile f WriteMode (\ hdl -> hPutStr hdl txt) -writeFile :: FilePath -> String -> IO () -writeFile name str = do - hdl <- openFile name WriteMode - hPutStr hdl str - hClose hdl +-- | The computation 'appendFile' @file str@ function appends the string @str@, +-- to the file @file@. +-- +-- Note that 'writeFile' and 'appendFile' write a literal string +-- to a file. To write a value of any printable type, as with 'print', +-- use the 'show' function to convert the value to a string first. +-- +-- > main = appendFile "squares" (show [(x,x*x) | x <- [0,0.1..2]]) appendFile :: FilePath -> String -> IO () -appendFile name str = do - hdl <- openFile name AppendMode - hPutStr hdl str - hClose hdl +appendFile f txt = withFile f AppendMode (\ hdl -> hPutStr hdl txt) + +-- | The 'readLn' function combines 'getLine' and 'readIO'. readLn :: Read a => IO a readLn = do l <- getLine r <- readIO l return r --- raises an exception instead of an error +-- | The 'readIO' function is similar to 'read' except that it signals +-- parse failure to the 'IO' monad instead of terminating the program. + readIO :: Read a => String -> IO a readIO s = case (do { (x,t) <- reads s ; - ("","") <- lex t ; + ("","") <- lex t ; return x }) of - [x] -> return x - [] -> ioError (userError "Prelude.readIO: no parse") - _ -> ioError (userError "Prelude.readIO: ambiguous parse") -#endif /* __HUGS__ */ + [x] -> return x + [] -> ioError (userError "Prelude.readIO: no parse") + _ -> ioError (userError "Prelude.readIO: ambiguous parse") +#endif /* __GLASGOW_HASKELL__ */ + +#ifndef __NHC__ +-- | Computation 'hReady' @hdl@ indicates whether at least one item is +-- available for input from handle @hdl@. +-- +-- This operation may fail with: +-- +-- * 'System.IO.Error.isEOFError' if the end of file has been reached. -hReady :: Handle -> IO Bool -hReady h = hWaitForInput h 0 +hReady :: Handle -> IO Bool +hReady h = hWaitForInput h 0 -hPutStrLn :: Handle -> String -> IO () +-- | The same as 'hPutStr', but adds a newline character. + +hPutStrLn :: Handle -> String -> IO () hPutStrLn hndl str = do hPutStr hndl str hPutChar hndl '\n' -hPrint :: Show a => Handle -> a -> IO () -hPrint hdl = hPutStrLn hdl . show +-- | Computation 'hPrint' @hdl t@ writes the string representation of @t@ +-- given by the 'shows' function to the file or channel managed by @hdl@ +-- and appends a newline. +-- +-- This operation may fail with: +-- +-- * 'System.IO.Error.isFullError' if the device is full; or +-- +-- * 'System.IO.Error.isPermissionError' if another system resource limit would be exceeded. + +hPrint :: Show a => Handle -> a -> IO () +hPrint hdl = hPutStrLn hdl . show +#endif /* !__NHC__ */ + +-- | @'withFile' name mode act@ opens a file using 'openFile' and passes +-- the resulting handle to the computation @act@. The handle will be +-- closed on exit from 'withFile', whether by normal termination or by +-- raising an exception. +withFile :: FilePath -> IOMode -> (Handle -> IO r) -> IO r +withFile name mode = bracket (openFile name mode) hClose + +-- | @'withBinaryFile' name mode act@ opens a file using 'openBinaryFile' +-- and passes the resulting handle to the computation @act@. The handle +-- will be closed on exit from 'withBinaryFile', whether by normal +-- termination or by raising an exception. +withBinaryFile :: FilePath -> IOMode -> (Handle -> IO r) -> IO r +withBinaryFile name mode = bracket (openBinaryFile name mode) hClose -- --------------------------------------------------------------------------- -- fixIO -#ifdef __GLASGOW_HASKELL__ -fixIO :: (a -> IO a) -> IO a -fixIO m = stToIO (fixST (ioToST . m)) +#if defined(__GLASGOW_HASKELL__) || defined(__HUGS__) +fixIO :: (a -> IO a) -> IO a +fixIO k = do + ref <- newIORef (throw NonTermination) + ans <- unsafeInterleaveIO (readIORef ref) + result <- k ans + writeIORef ref result + return result + +-- NOTE: we do our own explicit black holing here, because GHC's lazy +-- blackholing isn't enough. In an infinite loop, GHC may run the IO +-- computation a few times before it notices the loop, which is wrong. +#endif + +#if defined(__NHC__) +-- Assume a unix platform, where text and binary I/O are identical. +openBinaryFile = openFile +hSetBinaryMode _ _ = return () #endif + +-- | The function creates a temporary file in ReadWrite mode. +-- The created file isn\'t deleted automatically, so you need to delete it manually. +-- +-- The file is creates with permissions such that only the current +-- user can read\/write it. +-- +-- With some exceptions (see below), the file will be created securely +-- in the sense that an attacker should not be able to cause +-- openTempFile to overwrite another file on the filesystem using your +-- credentials, by putting symbolic links (on Unix) in the place where +-- the temporary file is to be created. On Unix the @O_CREAT@ and +-- @O_EXCL@ flags are used to prevent this attack, but note that +-- @O_EXCL@ is sometimes not supported on NFS filesystems, so if you +-- rely on this behaviour it is best to use local filesystems only. +-- +openTempFile :: FilePath -- ^ Directory in which to create the file + -> String -- ^ File name template. If the template is \"foo.ext\" then + -- the created file will be \"fooXXX.ext\" where XXX is some + -- random number. + -> IO (FilePath, Handle) +openTempFile tmp_dir template = openTempFile' "openTempFile" tmp_dir template False + +-- | Like 'openTempFile', but opens the file in binary mode. See 'openBinaryFile' for more comments. +openBinaryTempFile :: FilePath -> String -> IO (FilePath, Handle) +openBinaryTempFile tmp_dir template = openTempFile' "openBinaryTempFile" tmp_dir template True + +openTempFile' :: String -> FilePath -> String -> Bool -> IO (FilePath, Handle) +openTempFile' loc tmp_dir template binary = do + pid <- c_getpid + findTempName pid + where + -- We split off the last extension, so we can use .foo.ext files + -- for temporary files (hidden on Unix OSes). Unfortunately we're + -- below filepath in the hierarchy here. + (prefix,suffix) = + case break (== '.') $ reverse template of + -- First case: template contains no '.'s. Just re-reverse it. + (rev_suffix, "") -> (reverse rev_suffix, "") + -- Second case: template contains at least one '.'. Strip the + -- dot from the prefix and prepend it to the suffix (if we don't + -- do this, the unique number will get added after the '.' and + -- thus be part of the extension, which is wrong.) + (rev_suffix, '.':rest) -> (reverse rest, '.':reverse rev_suffix) + -- Otherwise, something is wrong, because (break (== '.')) should + -- always return a pair with either the empty string or a string + -- beginning with '.' as the second component. + _ -> error "bug in System.IO.openTempFile" + +#ifndef __NHC__ + oflags1 = rw_flags .|. o_EXCL + + binary_flags + | binary = o_BINARY + | otherwise = 0 + + oflags = oflags1 .|. binary_flags +#endif + #ifdef __NHC__ -fixIO :: (a -> IO a) -> IO a -fixIO f = let x = unsafePerformIO (f x) in return x + findTempName x = do h <- openFile filepath ReadWriteMode + return (filepath, h) +#else + findTempName x = do + fd <- withCString filepath $ \ f -> + c_open f oflags 0o600 + if fd < 0 + then do + errno <- getErrno + if errno == eEXIST + then findTempName (x+1) + else ioError (errnoToIOError loc errno Nothing (Just tmp_dir)) + else do + -- XXX We want to tell fdToHandle what the filepath is, + -- as any exceptions etc will only be able to report the + -- fd currently + h <- fdToHandle fd + `ExceptionBase.catchAny` \e -> do c_close fd; throw e + return (filepath, h) +#endif + where + filename = prefix ++ show x ++ suffix + filepath = tmp_dir `combine` filename + + -- XXX bits copied from System.FilePath, since that's not available here + combine a b + | null b = a + | null a = b + | last a == pathSeparator = a ++ b + | otherwise = a ++ [pathSeparator] ++ b + +#if __HUGS__ + fdToHandle fd = openFd (fromIntegral fd) False ReadWriteMode binary +#endif + +-- XXX Should use filepath library +pathSeparator :: Char +#ifdef mingw32_HOST_OS +pathSeparator = '\\' +#else +pathSeparator = '/' +#endif + +#ifndef __NHC__ +-- XXX Copied from GHC.Handle +std_flags = o_NONBLOCK .|. o_NOCTTY +output_flags = std_flags .|. o_CREAT +read_flags = std_flags .|. o_RDONLY +write_flags = output_flags .|. o_WRONLY +rw_flags = output_flags .|. o_RDWR +append_flags = write_flags .|. o_APPEND +#endif + +#ifdef __NHC__ +foreign import ccall "getpid" c_getpid :: IO Int +#endif + +-- $locking +-- Implementations should enforce as far as possible, at least locally to the +-- Haskell process, multiple-reader single-writer locking on files. +-- That is, /there may either be many handles on the same file which manage +-- input, or just one handle on the file which manages output/. If any +-- open or semi-closed handle is managing a file for output, no new +-- handle can be allocated for that file. If any open or semi-closed +-- handle is managing a file for input, new handles can only be allocated +-- if they do not manage output. Whether two files are the same is +-- implementation-dependent, but they should normally be the same if they +-- have the same absolute path name and neither has been renamed, for +-- example. +-- +-- /Warning/: the 'readFile' operation holds a semi-closed handle on +-- the file until the entire contents of the file have been consumed. +-- It follows that an attempt to write to a file (using 'writeFile', for +-- example) that was earlier opened by 'readFile' will usually result in +-- failure with 'System.IO.Error.isAlreadyInUseError'. + +-- ----------------------------------------------------------------------------- +-- Utils + +#ifdef __GLASGOW_HASKELL__ +-- Copied here to avoid recursive dependency with Control.Exception +bracket + :: IO a -- ^ computation to run first (\"acquire resource\") + -> (a -> IO b) -- ^ computation to run last (\"release resource\") + -> (a -> IO c) -- ^ computation to run in-between + -> IO c -- returns the value from the in-between computation +bracket before after thing = + block (do + a <- before + r <- catchAny + (unblock (thing a)) + (\e -> do { after a; throw e }) + after a + return r + ) #endif