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35ecbd5 Jan 14, 2013
@tibbe @bsl
49 lines (40 sloc) 1.62 KB
{-# LANGUAGE CPP #-}
{-# OPTIONS_GHC -funbox-strict-fields #-}
-- | Support module for the POSIX 'sendmsg' system call.
module Network.Socket.ByteString.MsgHdr
( MsgHdr(..)
) where
#include <sys/types.h>
#include <sys/socket.h>
import Foreign.C.Types (CInt, CSize, CUInt)
import Foreign.Ptr (Ptr)
import Foreign.Storable (Storable(..))
import Network.Socket (SockAddr)
import Network.Socket.Internal (zeroMemory)
import Network.Socket.ByteString.IOVec (IOVec)
-- We don't use msg_control, msg_controllen, and msg_flags as these
-- don't exist on OpenSolaris.
data MsgHdr = MsgHdr
{ msgName :: !(Ptr SockAddr)
, msgNameLen :: !CUInt
, msgIov :: !(Ptr IOVec)
, msgIovLen :: !CSize
}
instance Storable MsgHdr where
sizeOf _ = (#const sizeof(struct msghdr))
alignment _ = alignment (undefined :: CInt)
peek p = do
name <- (#peek struct msghdr, msg_name) p
nameLen <- (#peek struct msghdr, msg_namelen) p
iov <- (#peek struct msghdr, msg_iov) p
iovLen <- (#peek struct msghdr, msg_iovlen) p
return $ MsgHdr name nameLen iov iovLen
poke p mh = do
-- We need to zero the msg_control, msg_controllen, and msg_flags
-- fields, but they only exist on some platforms (e.g. not on
-- Solaris). Instead of using CPP, we zero the entire struct.
zeroMemory p (#const sizeof(struct msghdr))
(#poke struct msghdr, msg_name) p (msgName mh)
(#poke struct msghdr, msg_namelen) p (msgNameLen mh)
(#poke struct msghdr, msg_iov) p (msgIov mh)
(#poke struct msghdr, msg_iovlen) p (msgIovLen mh)
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