GHC.IO.FD

Raw read/write operations on file descriptors

Documentation

data FD

Constructors

FD

Fields

• fdFD :: !CInt
• fdIsNonBlocking :: !Int

Instances

BufferedIO FD

Since: base-4.1.0.0

Defined in GHC.IO.FD

Methods

newBuffer :: FD -> BufferState -> IO (Buffer Word8)

fillReadBuffer :: FD -> Buffer Word8 -> IO (Int, Buffer Word8)

fillReadBuffer0 :: FD -> Buffer Word8 -> IO (Maybe Int, Buffer Word8)

emptyWriteBuffer :: FD -> Buffer Word8 -> IO (Buffer Word8)

flushWriteBuffer :: FD -> Buffer Word8 -> IO (Buffer Word8)

flushWriteBuffer0 :: FD -> Buffer Word8 -> IO (Int, Buffer Word8)

IODevice FD

Since: base-4.1.0.0

Defined in GHC.IO.FD

Methods

ready :: FD -> Bool -> Int -> IO Bool

close :: FD -> IO ()

isTerminal :: FD -> IO Bool

isSeekable :: FD -> IO Bool

seek :: FD -> SeekMode -> Integer -> IO Integer

tell :: FD -> IO Integer

getSize :: FD -> IO Integer

setSize :: FD -> Integer -> IO ()

setEcho :: FD -> Bool -> IO ()

getEcho :: FD -> IO Bool

setRaw :: FD -> Bool -> IO ()

devType :: FD -> IO IODeviceType

dup :: FD -> IO FD

dup2 :: FD -> FD -> IO FD

RawIO FD

Since: base-4.1.0.0

Defined in GHC.IO.FD

Methods

read :: FD -> Ptr Word8 -> Word64 -> Int -> IO Int

readNonBlocking :: FD -> Ptr Word8 -> Word64 -> Int -> IO (Maybe Int)

write :: FD -> Ptr Word8 -> Word64 -> Int -> IO ()

writeNonBlocking :: FD -> Ptr Word8 -> Word64 -> Int -> IO Int

Show FD

Since: base-4.1.0.0

Defined in GHC.IO.FD

Methods

showsPrec :: Int -> FD -> ShowS

show :: FD -> String

showList :: [FD] -> ShowS

openFileWith

Arguments

:: FilePath

file to open

-> IOMode

mode in which to open the file

-> Bool

open the file in non-blocking mode?

-> (FD -> IODeviceType -> IO r)

act1: An action to perform on the file descriptor with the masking state restored and an exception handler that closes the file on exception.

-> ((forall x. IO x -> IO x) -> r -> IO s)

act2: An action to perform with async exceptions masked and no exception handler.

-> IO s

Open a file and make an FD for it. Truncates the file to zero size when the IOMode is WriteMode.

openFileWith takes two actions, act1 and act2, to perform after opening the file.

act1 is passed a file descriptor and I/O device type for the newly opened file. If an exception occurs in act1, then the file will be closed. act1 must not close the file itself. If it does so and then receives an exception, then the exception handler will attempt to close it again, which is impermissable.

act2 is performed with asynchronous exceptions masked. It is passed a function to restore the masking state and the result of act1. It /must not/ throw an exception (or deliver one via an interruptible operation) without first closing the file or arranging for it to be closed. act2 may close the file, but is not required to do so. If act2 leaves the file open, then the file will remain open on return from openFileWith.

Code calling openFileWith that wishes to install a finalizer to close the file should do so in act2. Doing so in act1 could potentially close the file in the finalizer first and then in the exception handler. See openFile' for an example of this use. Regardless, the caller is responsible for ensuring that the file is eventually closed, perhaps using bracket.

openFile

Arguments

:: FilePath

file to open

-> IOMode

mode in which to open the file

-> Bool

open the file in non-blocking mode?

-> IO (FD, IODeviceType)

Open a file and make an FD for it. Truncates the file to zero size when the IOMode is WriteMode. This function is difficult to use without potentially leaking the file descriptor on exception. In particular, it must be used with exceptions masked, which is a bit rude because the thread will be uninterruptible while the file path is being encoded. Use openFileWith instead.

mkFD

Arguments

:: CInt

-> IOMode

-> Maybe (IODeviceType, CDev, CIno)

-> Bool

is a socket (on Windows)

-> Bool

is in non-blocking mode on Unix

-> IO (FD, IODeviceType)

Make a FD from an existing file descriptor. Fails if the FD refers to a directory. If the FD refers to a file, mkFD locks the file according to the Haskell 2010 single writer/multiple reader locking semantics (this is why we need the IOMode argument too).

release :: FD -> IO ()

setNonBlockingMode :: FD -> Bool -> IO FD

readRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO Int

readRawBufferPtrNoBlock :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO Int

writeRawBufferPtr :: String -> FD -> Ptr Word8 -> Int -> CSize -> IO CInt

stdin :: FD

stdout :: FD

stderr :: FD