{-# LANGUAGE UnicodeSyntax #-}
{-# LANGUAGE CPP #-}
{-# LANGUAGE ForeignFunctionInterface #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE TypeFamilies #-}

-- | Local address family.
module System.Posix.Socket.Local
  ( LocalAddr(..)
  , aLocalAddr
  , AF_LOCAL(..)
  ) where

import Data.Typeable (Typeable)
import Data.Proxy (Proxy(..))
import Data.Word (Word8)
import Data.ByteString (ByteString)
import qualified Data.ByteString as BS
import qualified Data.ByteString.Internal as BS
import qualified Data.ByteString.Unsafe as BS
import Control.Applicative ((<$>))
import Foreign.Ptr (castPtr, plusPtr)
import Foreign.Storable (Storable(..))
import System.Posix.Socket

#include <sys/socket.h>
#include <sys/un.h>

-- | Local socket family.
data AF_LOCAL = AF_LOCAL deriving (Typeable, Eq, Show)

-- | Local socket address.
data LocalAddr = LocalAddr ByteString
               | NoLocalAddr
               deriving (Typeable, Eq, Ord, Show)

-- | 'LocalAddr' proxy value.
aLocalAddr ∷ Proxy LocalAddr
aLocalAddr = Proxy

instance SockAddr LocalAddr where
  sockAddrMaxSize _ = #{size struct sockaddr_un}
  sockAddrSize (LocalAddr path) = #{offset struct sockaddr_un, sun_path}
                                + BS.length path + 1
  sockAddrSize NoLocalAddr = #{size sa_family_t}
  peekSockAddr p sz = do
    let offset = #{offset struct sockaddr_un, sun_path}
    if sz < offset + 1
      then return NoLocalAddr
      else LocalAddr <$> BS.packCStringLen
                           (castPtr $ plusPtr p offset, sz - offset - 1)
  pokeSockAddr p (LocalAddr path) = do
    let offset = #{offset struct sockaddr_un, sun_path}
    BS.unsafeUseAsCStringLen path $ \(pBs, len) → do
      BS.memcpy (castPtr $ plusPtr p offset) (castPtr pBs) (fromIntegral len)
      poke (castPtr $ plusPtr p $ offset + len) (0 ∷ Word8)
  pokeSockAddr _ NoLocalAddr = return ()

instance SockFamily AF_LOCAL where
  type SockFamilyAddr AF_LOCAL = LocalAddr
  sockFamilyCode _ = #const AF_LOCAL