X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=System%2FIO.hs;h=29996d4d730025a816835fe6076167e88963f0fe;hb=33a57fb5a398b4ac78061732eb3e506aa5c0fb60;hp=b28e1dc2706d2ca30e50d96482ac1cccc1ed2d44;hpb=bb49ec07b01f68599a49ce04473bd9616c739687;p=ghc-base.git diff --git a/System/IO.hs b/System/IO.hs index b28e1dc..29996d4 100644 --- a/System/IO.hs +++ b/System/IO.hs @@ -1,81 +1,138 @@ -{-# OPTIONS -fno-implicit-prelude #-} +{-# OPTIONS_GHC -fno-implicit-prelude #-} ----------------------------------------------------------------------------- --- +-- | -- Module : System.IO -- Copyright : (c) The University of Glasgow 2001 --- License : BSD-style (see the file libraries/core/LICENSE) +-- License : BSD-style (see the file libraries/base/LICENSE) -- -- Maintainer : libraries@haskell.org --- Stability : provisional +-- Stability : stable -- Portability : portable -- --- $Id: IO.hs,v 1.6 2002/03/14 12:09:52 simonmar Exp $ --- -- The standard IO library. -- ----------------------------------------------------------------------------- module System.IO ( + -- * The IO monad + + IO, -- instance MonadFix + fixIO, -- :: (a -> IO a) -> IO a + + -- * Files and handles + + FilePath, -- :: String + Handle, -- abstract, instance of: Eq, Show. - HandlePosn(..), -- abstract, instance of: Eq, Show. - IOMode(ReadMode,WriteMode,AppendMode,ReadWriteMode), - BufferMode(NoBuffering,LineBuffering,BlockBuffering), - SeekMode(AbsoluteSeek,RelativeSeek,SeekFromEnd), + -- ** 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), hSetBuffering, -- :: Handle -> BufferMode -> IO () hGetBuffering, -- :: Handle -> IO BufferMode hFlush, -- :: Handle -> IO () + + -- ** Repositioning handles + hGetPosn, -- :: Handle -> IO HandlePosn hSetPosn, -- :: HandlePosn -> IO () + HandlePosn, -- abstract, instance of: Eq, Show. + hSeek, -- :: Handle -> SeekMode -> Integer -> IO () + SeekMode(AbsoluteSeek,RelativeSeek,SeekFromEnd), +#if !defined(__NHC__) hTell, -- :: Handle -> IO Integer +#endif + + -- ** Handle properties + + hIsOpen, hIsClosed, -- :: Handle -> IO Bool + hIsReadable, hIsWritable, -- :: Handle -> IO Bool + hIsSeekable, -- :: 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 () - 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 + -- ** Special cases for standard input and output - try, -- :: IO a -> IO (Either IOError a) - bracket, -- :: IO a -> (a -> IO b) -> (a -> IO c) -> IO c - bracket_, -- :: IO a -> (a -> IO b) -> IO c -> IO c + -- | These functions are also exported by the "Prelude". - -- Non-standard extension (but will hopefully become standard with 1.5) is - -- to export the Prelude io functions via IO (in addition to exporting them - -- from the prelude...for now.) - 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 () @@ -83,87 +140,204 @@ module System.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 + -- * 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 - - fixIO, -- :: (a -> IO a) -> IO a +#if !defined(__NHC__) && !defined(__HUGS__) + hPutBufNonBlocking, -- :: Handle -> Ptr a -> Int -> IO Int + hGetBufNonBlocking, -- :: Handle -> Ptr a -> Int -> IO Int +#endif - hSetEcho, -- :: Handle -> Bool -> IO () - hGetEcho, -- :: Handle -> IO Bool + -- * Temporary files (not portable: GHC\/Hugs only) - hIsTerminalDevice, -- :: Handle -> IO Bool +#if !defined(__NHC__) + openTempFile, + openBinaryTempFile, +#endif ) where +#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.Exception as ExceptionBase hiding (catch) +#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.IO -import GHC.ST ( fixST ) import GHC.Exception import GHC.Num import GHC.Read import GHC.Show #endif -import System.IO.Error +#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__ +import IO + ( Handle () + , HandlePosn () + , IOMode (ReadMode,WriteMode,AppendMode,ReadWriteMode) + , BufferMode (NoBuffering,LineBuffering,BlockBuffering) + , SeekMode (AbsoluteSeek,RelativeSeek,SeekFromEnd) + , stdin, stdout, stderr + , openFile -- :: 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 + , hFlush -- :: Handle -> IO () + , hGetPosn -- :: Handle -> IO HandlePosn + , hSetPosn -- :: HandlePosn -> IO () + , hSeek -- :: Handle -> SeekMode -> Integer -> IO () + , hWaitForInput -- :: Handle -> Int -> 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 -- :: Handle -> [Char] -> IO () + , hReady -- :: Handle -> [Char] -> IO () + , hIsOpen, hIsClosed -- :: Handle -> IO Bool + , hIsReadable, hIsWritable -- :: Handle -> IO Bool + , hIsSeekable -- :: Handle -> IO Bool + , bracket + + , IO () + , FilePath -- :: String + ) +import NHC.IOExtras (fixIO, hPutBuf, hGetBuf) +import NHC.FFI (Ptr) +#endif -- ----------------------------------------------------------------------------- -- Standard IO +#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 -writeFile :: FilePath -> String -> IO () -writeFile name str = do - hdl <- openFile name WriteMode - hPutStr hdl str - hClose hdl +-- | 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) + +-- | 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 ; @@ -171,22 +345,197 @@ readIO s = case (do { (x,t) <- reads s ; [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 +-- | The same as 'hPutStr', but adds a newline character. + hPutStrLn :: Handle -> String -> IO () hPutStrLn hndl str = do hPutStr hndl str hPutChar hndl '\n' +-- | 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 +#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 + +#ifndef __NHC__ +-- | The function creates a temporary file in ReadWrite mode. +-- The created file isn\'t deleted automatically, so you need to delete it manually. +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" + + oflags1 = rw_flags .|. o_EXCL + + binary_flags + | binary = o_BINARY + | otherwise = 0 + + oflags = oflags1 .|. binary_flags + + findTempName x = do + fd <- withCString filepath $ \ f -> + c_open f oflags 0o666 + 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.catchException` \e -> do c_close fd; throw e + return (filepath, h) + where + filename = prefix ++ show x ++ suffix + filepath = tmp_dir ++ [pathSeparator] ++ filename +#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 + +-- 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 + +-- $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__ -fixIO :: (a -> IO a) -> IO a -fixIO m = stToIO (fixST (ioToST . m)) +-- 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 <- catchException + (unblock (thing a)) + (\e -> do { after a; throw e }) + after a + return r + ) #endif