System.Socket.Unsafe

Documentation

newtype Socket f t p

A generic socket type. Use socket to create a new socket.

The socket is just an MVar-wrapped file descriptor. The Socket constructor is exported trough the unsafe module in order to make this library easily extensible, but it is usually not necessary nor advised to work directly on the file descriptor. If you do, the following rules must be obeyed:

• Make sure not to deadlock. Use withMVar or similar.
• The lock must not be held during a blocking call. This would make it impossible to send and receive simultaneously or to close the socket.
• The lock must be held when calling operations that use the file descriptor. Otherwise the socket might get closed or even reused by another thread/capability which might result in reading from or writing on a totally different socket. This is a security nightmare!
• The socket is non-blocking and all the code relies on that assumption. You need to use GHC's eventing mechanism primitives to block until something happens. The former rules forbid to use threadWaitRead as it does not separate between registering the file descriptor (for which the lock must be held) and the actual waiting (for which you must not hold the lock). Also see this thread and read the library code to see how the problem is currently circumvented.

Constructors

Socket (MVar Fd)

Unsafe operations

unsafeSend

unsafeSend :: Socket a t p -> Ptr b -> CSize -> MessageFlags -> IO CInt

Like send, but using Ptr and length instead of a ByteString.

This function is unsafe. bufPtr must refer to a buffer which size is at least bufSize bytes.

unsafeSendTo

unsafeSendTo :: Socket f t p -> Ptr b -> CSize -> MessageFlags -> Ptr (SocketAddress f) -> CInt -> IO CInt

Like sendTo, but using Ptr and length instead of a ByteString.

This function is unsafe. bufPtr must refer to a buffer which size is at least bufSize bytes.

unsafeReceive

unsafeReceive :: Socket a t p -> Ptr b -> CSize -> MessageFlags -> IO CInt

Like receive, but using Ptr and length instead of a ByteString.

This function is unsafe. bufPtr must refer to a buffer which size is at least bufSize bytes.

unsafeReceiveFrom

unsafeReceiveFrom :: Socket f t p -> Ptr b -> CSize -> MessageFlags -> Ptr (SocketAddress f) -> Ptr CInt -> IO CInt

Like receiveFrom, but using Ptr and length instead of a ByteString.

This function is unsafe. bufPtr must refer to a buffer which size is at least bufSize bytes.

unsafeGetSocketOption

unsafeGetSocketOption :: Storable a => Socket f t p -> CInt -> CInt -> IO a

unsafeSetSocketOption

unsafeSetSocketOption :: Storable a => Socket f t p -> CInt -> CInt -> a -> IO ()

Waiting for events

waitRead

waitRead :: Socket f t p -> Int -> IO ()

waitWrite

waitWrite :: Socket f t p -> Int -> IO ()

waitConnected

waitConnected :: Socket f t p -> IO ()

tryWaitRetryLoop

tryWaitRetryLoop :: Socket f t p -> (Socket f t p -> Int -> IO ()) -> (Fd -> Ptr CInt -> IO CInt) -> IO CInt