Network.Socket.Internal

A module containing semi-public Socket internals. Modules which extend the Socket module will need to use this module while ideally most users will be able to make do with the public interface.

Socket error functions

throwSocketError

Arguments

:: String

textual description of the error location

-> IO a

Throw an IOError corresponding to the current socket error.

throwSocketErrorCode :: String -> CInt -> IO a

Like throwSocketError, but the error code is supplied as an argument.

On Windows, do not use errno. Use a system error code instead.

Guards for socket operations that may fail

throwSocketErrorIfMinus1_

Arguments

:: (Eq a, Num a)

=> String

textual description of the location

-> IO a

the IO operation to be executed

-> IO ()

Throw an IOError corresponding to the current socket error if the IO action returns a result of -1. Discards the result of the IO action after error handling.

throwSocketErrorIfMinus1Retry

Arguments

:: (Eq a, Num a)

=> String

textual description of the location

-> IO a

the IO operation to be executed

-> IO a

Throw an IOError corresponding to the current socket error if the IO action returns a result of -1, but retries in case of an interrupted operation.

throwSocketErrorIfMinus1Retry_

Arguments

:: (Eq a, Num a)

=> String

textual description of the location

-> IO a

the IO operation to be executed

-> IO ()

Throw an IOError corresponding to the current socket error if the IO action returns a result of -1, but retries in case of an interrupted operation. Discards the result of the IO action after error handling.

throwSocketErrorIfMinus1RetryMayBlock

Arguments

:: (Eq a, Num a)

=> String

textual description of the location

-> IO b

action to execute before retrying if an immediate retry would block

-> IO a

the IO operation to be executed

-> IO a

Throw an IOError corresponding to the current socket error if the IO action returns a result of -1, but retries in case of an interrupted operation. Checks for operations that would block and executes an alternative action before retrying in that case.

Guards that wait and retry if the operation would block

These guards are based on throwSocketErrorIfMinus1RetryMayBlock. They wait for socket readiness if the action fails with EWOULDBLOCK or similar.

throwSocketErrorWaitRead :: (Eq a, Num a) => Socket -> String -> IO a -> IO a

Like throwSocketErrorIfMinus1Retry, but if the action fails with EWOULDBLOCK or similar, wait for the socket to be read-ready, and try again.

throwSocketErrorWaitWrite :: (Eq a, Num a) => Socket -> String -> IO a -> IO a

Like throwSocketErrorIfMinus1Retry, but if the action fails with EWOULDBLOCK or similar, wait for the socket to be write-ready, and try again.

Initialization

withSocketsDo :: IO a -> IO a

With older versions of the network library (version 2.6.0.2 or earlier) on Windows operating systems, the networking subsystem must be initialised using withSocketsDo before any networking operations can be used. eg.

main = withSocketsDo $ do {...}

It is fine to nest calls to withSocketsDo, and to perform networking operations after withSocketsDo has returned.

withSocketsDo is not necessary for the current network library. However, for compatibility with older versions on Windows, it is good practice to always call withSocketsDo (it's very cheap).

Low-level helpers

zeroMemory :: Ptr a -> CSize -> IO ()

Zero a structure.