    {-# LANGUAGE CPP #-}

    -- |
    -- Module      : Network.Socket.ByteString.Lazy
    -- Copyright   : (c) Bryan O'Sullivan 2009
    -- License     : BSD-style
    --
    -- Maintainer  : bos@serpentine.com
    -- Stability   : experimental
    -- Portability : POSIX, GHC
    --
    -- This module provides access to the BSD /socket/ interface.  For detailed
    -- documentation, consult your favorite POSIX socket reference. All functions
    -- communicate failures by converting the error number to an
    -- 'System.IO.Error.IOError'.
    --
    -- This module is made to be imported with "Network.Socket" like so:
    --
    -- > import Network.Socket
    -- > import Network.Socket.ByteString.Lazy
    -- > import Prelude hiding (getContents)
    module Network.Socket.ByteString.Lazy (
        -- * Send data to a socket
        send,
        sendAll,
        sendWithFds,

        -- * Receive data from a socket
        getContents,
        recv,
    ) where

    import Data.ByteString.Lazy.Internal (
        ByteString (..),
        defaultChunkSize,
     )
    import Network.Socket (ShutdownCmd (..), shutdown)
    import System.IO.Error (catchIOError)
    import System.IO.Unsafe (unsafeInterleaveIO)
    import System.Posix.Types (Fd (..))
    import Prelude hiding (getContents)

    #if defined(mingw32_HOST_OS)
    import Network.Socket.ByteString.Lazy.Windows  (send, sendAll)
    #else
    import Network.Socket.ByteString.Lazy.Posix    (send, sendAll)
    #endif

    import qualified Data.ByteString as S
    import qualified Data.ByteString.Lazy as L
    import qualified Network.Socket.ByteString as N
    import Network.Socket.Imports
    import Network.Socket.Types

    -- | Send data and file descriptors over a UNIX-domain socket in
    --   a single system call. This function does not work on Windows.
    sendWithFds
        :: Socket
        -- ^ Socket
        -> ByteString
        -- ^ Data to send
        -> [Fd]
        -- ^ File descriptors
        -> IO ()
    sendWithFds :: Socket -> ByteString -> [Fd] -> IO ()
    sendWithFds Socket
    s ByteString
    lbs [Fd]
    fds = Socket -> [ByteString] -> [Fd] -> IO ()
    N.sendManyWithFds Socket
    s (ByteString -> [ByteString]
    L.toChunks ByteString
    lbs) [Fd]
    fds

    -- -----------------------------------------------------------------------------
    -- Receiving

    -- | Receive data from the socket.  The socket must be in a connected
    -- state.  Data is received on demand, in chunks; each chunk will be
    -- sized to reflect the amount of data received by individual 'recv'
    -- calls.
    --
    -- All remaining data from the socket is consumed.  When there is no
    -- more data to be received, the receiving side of the socket is shut
    -- down.  If there is an error and an exception is thrown, the socket
    -- is not shut down.
    getContents
        :: Socket
        -- ^ Connected socket
        -> IO ByteString
        -- ^ Data received
    getContents :: Socket -> IO ByteString
    getContents Socket
    s = IO ByteString
    loop
      where
        loop :: IO ByteString
    loop = IO ByteString -> IO ByteString
    forall a. IO a -> IO a
    unsafeInterleaveIO (IO ByteString -> IO ByteString) -> IO ByteString -> IO ByteString
    forall a b. (a -> b) -> a -> b
    $ do
            sbs <- Socket -> Int -> IO ByteString
    N.recv Socket
    s Int
    defaultChunkSize
            if S.null sbs
                then do
                    shutdown s ShutdownReceive `catchIOError` const (return ())
                    return Empty
                else Chunk sbs <$> loop

    -- | Receive data from the socket.  The socket must be in a connected
    -- state.  This function may return fewer bytes than specified.  If
    -- the received data is longer than the specified length, it may be
    -- discarded depending on the type of socket.  This function may block
    -- until a message arrives.
    --
    -- If there is no more data to be received, returns an empty 'ByteString'.
    recv
        :: Socket
        -- ^ Connected socket
        -> Int64
        -- ^ Maximum number of bytes to receive
        -> IO ByteString
        -- ^ Data received
    recv :: Socket -> Int64 -> IO ByteString
    recv Socket
    s Int64
    nbytes = ByteString -> ByteString
    chunk (ByteString -> ByteString) -> IO ByteString -> IO ByteString
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> Socket -> Int -> IO ByteString
    N.recv Socket
    s (Int64 -> Int
    forall a b. (Integral a, Num b) => a -> b
    fromIntegral Int64
    nbytes)
      where
        chunk :: ByteString -> ByteString
    chunk ByteString
    k
            | ByteString -> Bool
    S.null ByteString
    k = ByteString
    Empty
            | Bool
    otherwise = ByteString -> ByteString -> ByteString
    Chunk ByteString
    k ByteString
    Empty