#undef DEBUG_DUMP
--- -----------------------------------------------------------------------------
--- $Id: IO.hs,v 1.5 2002/02/11 12:28:31 simonmar Exp $
+-----------------------------------------------------------------------------
+-- |
+-- Module : GHC.IO
+-- Copyright : (c) The University of Glasgow, 1992-2001
+-- License : see libraries/base/LICENSE
+--
+-- Maintainer : libraries@haskell.org
+-- Stability : internal
+-- Portability : non-portable
--
--- (c) The University of Glasgow, 1992-2001
+-- String I\/O functions
--
+-----------------------------------------------------------------------------
module GHC.IO (
hWaitForInput, hGetChar, hGetLine, hGetContents, hPutChar, hPutStr,
import System.IO.Error
import Data.Maybe
import Control.Monad
+import System.Posix.Internals
import GHC.Enum
import GHC.Base
-import GHC.Posix
import GHC.IOBase
import GHC.Handle -- much of the real stuff is in here
import GHC.Real
import GHC.Num
import GHC.Show
import GHC.List
-import GHC.Exception ( ioError, catch, throw )
+import GHC.Exception ( ioError, catch )
import GHC.Conc
-- ---------------------------------------------------------------------------
-- Simple input operations
--- Computation "hReady hdl" indicates whether at least
--- one item is available for input from handle "hdl".
-
-- If hWaitForInput finds anything in the Handle's buffer, it
-- immediately returns. If not, it tries to read from the underlying
-- OS handle. Notice that for buffered Handles connected to terminals
-- this means waiting until a complete line is available.
+-- | Computation 'hWaitForInput' @hdl t@
+-- waits until input is available on handle @hdl@.
+-- It returns 'True' as soon as input is available on @hdl@,
+-- or 'False' if no input is available within @t@ milliseconds.
+--
+-- This operation may fail with:
+--
+-- * 'isEOFError' if the end of file has been reached.
+
hWaitForInput :: Handle -> Int -> IO Bool
hWaitForInput h msecs = do
wantReadableHandle "hWaitForInput" h $ \ handle_ -> do
-- ---------------------------------------------------------------------------
-- hGetChar
--- hGetChar reads the next character from a handle,
--- blocking until a character is available.
+-- | Computation 'hGetChar' @hdl@ reads a character from the file or
+-- channel managed by @hdl@, blocking until a character is available.
+--
+-- This operation may fail with:
+--
+-- * 'isEOFError' if the end of file has been reached.
hGetChar :: Handle -> IO Char
hGetChar handle =
new_buf <- fillReadBuffer fd True (haIsStream handle_) buf
hGetcBuffered fd ref new_buf
BlockBuffering _ -> do
- new_buf <- fillReadBuffer fd False (haIsStream handle_) buf
+ new_buf <- fillReadBuffer fd True (haIsStream handle_) buf
+ -- ^^^^
+ -- don't wait for a completely full buffer.
hGetcBuffered fd ref new_buf
NoBuffering -> do
-- make use of the minimal buffer we already have
let raw = bufBuf buf
- r <- throwErrnoIfMinus1RetryMayBlock "hGetChar"
- (read_off_ba (fromIntegral fd) (haIsStream handle_) raw 0 1)
- (threadWaitRead fd)
+ r <- readRawBuffer "hGetChar" (fromIntegral fd) (haIsStream handle_) raw 0 1
if r == 0
then ioe_EOF
else do (c,_) <- readCharFromBuffer raw 0
-- ---------------------------------------------------------------------------
-- hGetLine
--- If EOF is reached before EOL is encountered, ignore the EOF and
--- return the partial line. Next attempt at calling hGetLine on the
--- handle will yield an EOF IO exception though.
-
-- ToDo: the unbuffered case is wrong: it doesn't lock the handle for
-- the duration.
+
+-- | Computation 'hGetLine' @hdl@ reads a line from the file or
+-- channel managed by @hdl@.
+--
+-- This operation may fail with:
+--
+-- * 'isEOFError' if the end of file is encountered when reading
+-- the /first/ character of the line.
+--
+-- If 'hGetLine' encounters end-of-file at any other point while reading
+-- in a line, it is treated as a line terminator and the (partial)
+-- line is returned.
+
hGetLine :: Handle -> IO String
hGetLine h = do
m <- wantReadableHandle "hGetLine" h $ \ handle_ -> do
#endif
xs <- unpack raw r off
+
+ -- if eol == True, then off is the offset of the '\n'
+ -- otherwise off == w and the buffer is now empty.
if eol
- then do if w == off + 1
- then writeIORef ref buf{ bufRPtr=0, bufWPtr=0 }
- else writeIORef ref buf{ bufRPtr = off + 1 }
+ then do if (w == off + 1)
+ then writeIORef ref buf{ bufRPtr=0, bufWPtr=0 }
+ else writeIORef ref buf{ bufRPtr = off + 1 }
return (concat (reverse (xs:xss)))
else do
maybe_buf <- maybeFillReadBuffer (haFD handle_) True (haIsStream handle_)
case maybe_buf of
-- Nothing indicates we caught an EOF, and we may have a
-- partial line to return.
- Nothing -> let str = concat (reverse (xs:xss)) in
- if not (null str)
- then return str
- else ioe_EOF
+ Nothing -> do
+ writeIORef ref buf{ bufRPtr=0, bufWPtr=0 }
+ let str = concat (reverse (xs:xss))
+ if not (null str)
+ then return str
+ else ioe_EOF
Just new_buf ->
hGetLineBufferedLoop handle_ ref new_buf (xs:xss)
)
(\e -> do if isEOFError e
then return Nothing
- else throw e)
+ else ioError e)
unpack :: RawBuffer -> Int -> Int -> IO [Char]
-- -----------------------------------------------------------------------------
-- hGetContents
--- hGetContents returns the list of characters corresponding to the
--- unread portion of the channel or file managed by the handle, which
--- is made semi-closed.
-
-- hGetContents on a DuplexHandle only affects the read side: you can
-- carry on writing to it afterwards.
+-- | Computation 'hGetContents' @hdl@ returns the list of characters
+-- corresponding to the unread portion of the channel or file managed
+-- by @hdl@, which is put into an intermediate state, /semi-closed/.
+-- In this state, @hdl@ is effectively closed,
+-- but items are read from @hdl@ on demand and accumulated in a special
+-- list returned by 'hGetContents' @hdl@.
+--
+-- Any operation that fails because a handle is closed,
+-- also fails if a handle is semi-closed. The only exception is 'hClose'.
+-- A semi-closed handle becomes closed:
+--
+-- * if 'hClose' is applied to it;
+--
+-- * if an I\/O error occurs when reading an item from the handle;
+--
+-- * or once the entire contents of the handle has been read.
+--
+-- Once a semi-closed handle becomes closed, the contents of the
+-- associated list becomes fixed. The contents of this final list is
+-- only partially specified: it will contain at least all the items of
+-- the stream that were evaluated prior to the handle becoming closed.
+--
+-- Any I\/O errors encountered while a handle is semi-closed are simply
+-- discarded.
+--
+-- This operation may fail with:
+--
+-- * 'isEOFError' if the end of file has been reached.
+
hGetContents :: Handle -> IO String
hGetContents handle =
withHandle "hGetContents" handle $ \handle_ ->
NoBuffering -> do
-- make use of the minimal buffer we already have
let raw = bufBuf buf
- r <- throwErrnoIfMinus1RetryMayBlock "lazyRead"
- (read_off_ba (fromIntegral fd) (haIsStream handle_) raw 0 1)
- (threadWaitRead fd)
+ r <- readRawBuffer "lazyRead" (fromIntegral fd) (haIsStream handle_) raw 0 1
if r == 0
then do handle_ <- hClose_help handle_
return (handle_, "")
unpackAcc :: RawBuffer -> Int -> Int -> [Char] -> IO [Char]
-unpackAcc buf r 0 acc = return ""
+unpackAcc buf r 0 acc = return acc
unpackAcc buf (I# r) (I# len) acc = IO $ \s -> unpack acc (len -# 1#) s
where
unpack acc i s
-- ---------------------------------------------------------------------------
-- hPutChar
--- `hPutChar hdl ch' writes the character `ch' to the file or channel
--- managed by `hdl'. Characters may be buffered if buffering is
--- enabled for `hdl'.
+-- | Computation 'hPutChar' @hdl ch@ writes the character @ch@ to the
+-- file or channel managed by @hdl@. Characters may be buffered if
+-- buffering is enabled for @hdl@.
+--
+-- This operation may fail with:
+--
+-- * 'isFullError' if the device is full; or
+--
+-- * 'isPermissionError' if another system resource limit would be exceeded.
hPutChar :: Handle -> Char -> IO ()
hPutChar handle c =
LineBuffering -> hPutcBuffered handle_ True c
BlockBuffering _ -> hPutcBuffered handle_ False c
NoBuffering ->
- withObject (castCharToCChar c) $ \buf ->
- throwErrnoIfMinus1RetryMayBlock_ "hPutChar"
- (write_off (fromIntegral fd) (haIsStream handle_) buf 0 1)
- (threadWaitWrite fd)
-
+ withObject (castCharToCChar c) $ \buf -> do
+ writeRawBufferPtr "hPutChar" (fromIntegral fd) (haIsStream handle_) buf 0 1
+ return ()
hPutcBuffered handle_ is_line c = do
let ref = haBuffer handle_
-- ---------------------------------------------------------------------------
-- hPutStr
--- `hPutStr hdl s' writes the string `s' to the file or
--- hannel managed by `hdl', buffering the output if needs be.
-
-- We go to some trouble to avoid keeping the handle locked while we're
-- evaluating the string argument to hPutStr, in case doing so triggers another
-- I/O operation on the same handle which would lead to deadlock. The classic
-- maybe just swapping the buffers over (if the handle's buffer was
-- empty). See commitBuffer below.
+-- | Computation 'hPutStr' @hdl s@ writes the string
+-- @s@ to the file or channel managed by @hdl@.
+--
+-- This operation may fail with:
+--
+-- * 'isFullError' if the device is full; or
+--
+-- * 'isPermissionError' if another system resource limit would be exceeded.
+
hPutStr :: Handle -> String -> IO ()
hPutStr handle str = do
buffer_mode <- wantWritableHandle "hPutStr" handle
-- ---------------------------------------------------------------------------
-- Reading/writing sequences of bytes.
-{-
-Semantics of hGetBuf:
-
- - hGetBuf reads data into the buffer until either
-
- (a) EOF is reached
- (b) the buffer is full
-
- It returns the amount of data actually read. This may
- be zero in case (a). hGetBuf never raises
- an EOF exception, it always returns zero instead.
-
- If the handle is a pipe or socket, and the writing end
- is closed, hGetBuf will behave as for condition (a).
-
-Semantics of hPutBuf:
-
- - hPutBuf writes data from the buffer to the handle
- until the buffer is empty. It returns ().
-
- If the handle is a pipe or socket, and the reading end is
- closed, hPutBuf will raise a ResourceVanished exception.
- (If this is a POSIX system, and the program has not
- asked to ignore SIGPIPE, then a SIGPIPE may be delivered
- instead, whose default action is to terminate the program).
--}
-
-- ---------------------------------------------------------------------------
-- hPutBuf
+-- | 'hPutBuf' @hdl buf count@ writes @count@ 8-bit bytes from the
+-- buffer @buf@ to the handle @hdl@. It returns ().
+--
+-- This operation may fail with:
+--
+-- * 'ResourceVanished' if the handle is a pipe or socket, and the
+-- reading end is closed. (If this is a POSIX system, and the program
+-- has not asked to ignore SIGPIPE, then a SIGPIPE may be delivered
+-- instead, whose default action is to terminate the program).
+
hPutBuf :: Handle -- handle to write to
-> Ptr a -- address of buffer
-> Int -- number of bytes of data in buffer
-> IO ()
hPutBuf handle ptr count
- | count <= 0 = illegalBufferSize handle "hPutBuf" count
+ | count == 0 = return ()
+ | count < 0 = illegalBufferSize handle "hPutBuf" count
| otherwise =
wantWritableHandle "hPutBuf" handle $
\ handle_@Handle__{ haFD=fd, haBuffer=ref, haIsStream=is_stream } -> do
else do flushed_buf <- flushWriteBuffer fd is_stream old_buf
writeIORef ref flushed_buf
-- ToDo: should just memcpy instead of writing if possible
- writeChunk fd ptr count
+ writeChunk fd is_stream (castPtr ptr) count
-writeChunk :: FD -> Ptr a -> Int -> IO ()
-writeChunk fd ptr bytes = loop 0 bytes
+writeChunk :: FD -> Bool -> Ptr CChar -> Int -> IO ()
+writeChunk fd is_stream ptr bytes = loop 0 bytes
where
loop :: Int -> Int -> IO ()
loop _ bytes | bytes <= 0 = return ()
loop off bytes = do
r <- fromIntegral `liftM`
- throwErrnoIfMinus1RetryMayBlock "writeChunk"
- (c_write (fromIntegral fd) (ptr `plusPtr` off) (fromIntegral bytes))
- (threadWaitWrite fd)
+ writeRawBufferPtr "writeChunk" (fromIntegral fd) is_stream ptr
+ off (fromIntegral bytes)
-- write can't return 0
loop (off + r) (bytes - r)
-- ---------------------------------------------------------------------------
-- hGetBuf
+-- | 'hGetBuf' @hdl buf count@ reads data from the handle @hdl@
+-- into the buffer @buf@ until either EOF is reached or
+-- @count@ 8-bit bytes have been read.
+-- It returns the number of bytes actually read. This may be zero if
+-- EOF was reached before any data was read (or if @count@ is zero).
+--
+-- 'hGetBuf' never raises an EOF exception, instead it returns a value
+-- smaller than @count@.
+--
+-- If the handle is a pipe or socket, and the writing end
+-- is closed, 'hGetBuf' will behave as if EOF was reached.
+
hGetBuf :: Handle -> Ptr a -> Int -> IO Int
hGetBuf handle ptr count
- | count <= 0 = illegalBufferSize handle "hGetBuf" count
+ | count == 0 = return 0
+ | count < 0 = illegalBufferSize handle "hGetBuf" count
| otherwise =
wantReadableHandle "hGetBuf" handle $
- \ handle_@Handle__{ haFD=fd, haBuffer=ref } -> do
+ \ handle_@Handle__{ haFD=fd, haBuffer=ref, haIsStream=is_stream } -> do
buf@Buffer{ bufBuf=raw, bufWPtr=w, bufRPtr=r } <- readIORef ref
if bufferEmpty buf
- then readChunk fd ptr count
+ then readChunk fd is_stream ptr count
else do
let avail = w - r
copied <- if (count >= avail)
let remaining = count - copied
if remaining > 0
- then do rest <- readChunk fd (ptr `plusPtr` copied) remaining
+ then do rest <- readChunk fd is_stream (ptr `plusPtr` copied) remaining
return (rest + copied)
else return count
-readChunk :: FD -> Ptr a -> Int -> IO Int
-readChunk fd ptr bytes = loop 0 bytes
+readChunk :: FD -> Bool -> Ptr a -> Int -> IO Int
+readChunk fd is_stream ptr bytes = loop 0 bytes
where
loop :: Int -> Int -> IO Int
loop off bytes | bytes <= 0 = return off
loop off bytes = do
r <- fromIntegral `liftM`
- throwErrnoIfMinus1RetryMayBlock "readChunk"
- (c_read (fromIntegral fd) (ptr `plusPtr` off) (fromIntegral bytes))
- (threadWaitRead fd)
+ readRawBufferPtr "readChunk" (fromIntegral fd) is_stream
+ (castPtr ptr) off (fromIntegral bytes)
if r == 0
then return off
else loop (off + r) (bytes - r)
ioError (userError "slurpFile: file too big")
else do
let sz_i = fromIntegral sz
+ if sz_i == 0 then return (nullPtr, 0) else do
chunk <- mallocBytes sz_i
r <- hGetBuf handle chunk sz_i
hClose handle
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