    {-# LINE 1 "Network/BSD.hsc" #-}
    {-# LANGUAGE CPP, NondecreasingIndentation, DeriveDataTypeable, BangPatterns #-}

    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Network.BSD
    -- Copyright   :  (c) The University of Glasgow 2001
    -- SPDX-License-Identifier: BSD-3-Clause
    --
    -- Maintainer  :  libraries@haskell.org
    -- Stability   :  experimental
    -- Portability :  non-portable
    --
    -- The "Network.BSD" module defines Haskell bindings to network
    -- programming functionality (mostly [network database operations](http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netdb.h.html))
    -- provided by BSD Unix derivatives.
    --
    -- __NOTE__: Some of the types are reexported from "Network.Socket" in order to make the @network-bsd@ API self-contained.
    --
    -- == Windows compatibility
    --
    -- The following functions are not exported by "Network.BSD" on the
    -- Windows platform:
    --
    -- * 'getHostEntries', 'setHostEntry', 'getHostEntry', 'endHostEntry'
    -- * 'getServiceEntries', 'getServiceEntry', 'setServiceEntry', 'endServiceEntry'
    -- * 'getProtocolEntries', 'setProtocolEntry', 'getProtocolEntry', 'endProtocolEntry'
    -- * 'getNetworkByName', 'getNetworkByAddr', 'getNetworkEntries',
    --   'setNetworkEntry', 'getNetworkEntry', 'endNetworkEntry'
    --
    -----------------------------------------------------------------------------

    #include "HsNetDef.h"

    module Network.BSD
        (
        -- * Host names and network addresses
          N.HostName
        , N.HostAddress
          -- NB: We're explicit here to reduce the risk of inadvertently leaking through new constructors w/o reflecting this in @network-bsd@'s API version
        , N.Family(AF_UNSPEC, AF_UNIX, AF_INET, AF_INET6, AF_IMPLINK, AF_PUP, AF_CHAOS, AF_NS, AF_NBS, AF_ECMA, AF_DATAKIT, AF_CCITT, AF_SNA, AF_DECnet, AF_DLI, AF_LAT, AF_HYLINK, AF_APPLETALK, AF_ROUTE, AF_NETBIOS, AF_NIT, AF_802, AF_ISO, AF_OSI, AF_NETMAN, AF_X25, AF_AX25, AF_OSINET, AF_GOSSIP, AF_IPX, Pseudo_AF_XTP, AF_CTF, AF_WAN, AF_SDL, AF_NETWARE, AF_NDD, AF_INTF, AF_COIP, AF_CNT, Pseudo_AF_RTIP, Pseudo_AF_PIP, AF_SIP, AF_ISDN, Pseudo_AF_KEY, AF_NATM, AF_ARP, Pseudo_AF_HDRCMPLT, AF_ENCAP, AF_LINK, AF_RAW, AF_RIF, AF_NETROM, AF_BRIDGE, AF_ATMPVC, AF_ROSE, AF_NETBEUI, AF_SECURITY, AF_PACKET, AF_ASH, AF_ECONET, AF_ATMSVC, AF_IRDA, AF_PPPOX, AF_WANPIPE, AF_BLUETOOTH, AF_CAN)
        , getHostName

        , HostEntry(..)
        , getHostByName
        , getHostByAddr
        , hostAddress

    {-# LINE 50 "Network/BSD.hsc" #-}
        , getHostEntries

        -- ** Low level functionality
        , setHostEntry
        , getHostEntry
        , endHostEntry

    {-# LINE 57 "Network/BSD.hsc" #-}

        -- * Service names
        , ServiceEntry(..)
        , N.ServiceName
        , N.PortNumber
        , getServiceByName
        , getServiceByPort
        , getServicePortNumber

    {-# LINE 67 "Network/BSD.hsc" #-}
        , getServiceEntries

        -- ** Low level functionality
        , getServiceEntry
        , setServiceEntry
        , endServiceEntry

    {-# LINE 74 "Network/BSD.hsc" #-}

        -- * Protocol names
        , ProtocolName
        , N.ProtocolNumber
        , ProtocolEntry(..)
        , getProtocolByName
        , getProtocolByNumber
        , getProtocolNumber
        , N.defaultProtocol

    {-# LINE 85 "Network/BSD.hsc" #-}
        , getProtocolEntries
        -- ** Low level functionality
        , setProtocolEntry
        , getProtocolEntry
        , endProtocolEntry

    {-# LINE 91 "Network/BSD.hsc" #-}

        -- * Network names
        , NetworkName
        , NetworkAddr
        , NetworkEntry(..)

    {-# LINE 98 "Network/BSD.hsc" #-}
        , getNetworkByName
        , getNetworkByAddr
        , getNetworkEntries
        -- ** Low level functionality
        , setNetworkEntry
        , getNetworkEntry
        , endNetworkEntry

    {-# LINE 106 "Network/BSD.hsc" #-}

        -- * Interface names
        , N.ifNameToIndex

        ) where

    import qualified Network.Socket as N

    import Control.Concurrent (MVar, newMVar, withMVar)
    import qualified Control.Exception as E
    import Foreign.C.String (CString, peekCString, withCString)

    {-# LINE 120 "Network/BSD.hsc" #-}
    import Foreign.C.Types ( CInt(..), CULong(..), CSize(..) )
    import Foreign.Ptr (Ptr, nullPtr)
    import Foreign.Storable (Storable(..))
    import Foreign.Marshal.Array (allocaArray0, peekArray0)
    import Foreign.Marshal.Utils (with, fromBool)
    import Data.Typeable
    import System.IO.Error (ioeSetErrorString, mkIOError)
    import System.IO.Unsafe (unsafePerformIO)

    import GHC.IO.Exception

    import Control.DeepSeq (NFData(rnf))
    import Control.Monad (liftM)

    import Network.Socket.Internal (throwSocketErrorIfMinus1_)

    -- ---------------------------------------------------------------------------
    -- Basic Types

    type ProtocolName = String

    -- ---------------------------------------------------------------------------
    -- Service Database Access

    -- Calling getServiceByName for a given service and protocol returns
    -- the systems service entry.  This should be used to find the port
    -- numbers for standard protocols such as SMTP and FTP.  The remaining
    -- three functions should be used for browsing the service database
    -- sequentially.

    -- Calling setServiceEntry with True indicates that the service
    -- database should be left open between calls to getServiceEntry.  To
    -- close the database a call to endServiceEntry is required.  This
    -- database file is usually stored in the file /etc/services.

    -- | Representation of the POSIX @servent@ structure defined in [<netdb.h>](http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netdb.h.html).
    data ServiceEntry  =
      ServiceEntry  {
         serviceName     :: N.ServiceName,    -- ^ Official service name
         serviceAliases  :: [N.ServiceName],  -- ^ aliases
         servicePort     :: N.PortNumber,     -- ^ Port Number
         serviceProtocol :: ProtocolName      -- ^ Protocol to use
      } deriving (Show, Typeable)

    -- | @since 2.8.1.0
    instance NFData ServiceEntry where
       -- TODO: PortNumber is a newtype over Word16; add NFData instance to `network`
       rnf (ServiceEntry n a !_pn pr) = rnf (n,a,pr)

    instance Storable ServiceEntry where
       sizeOf    _ = 32
    {-# LINE 171 "Network/BSD.hsc" #-}
       alignment _ = alignment (undefined :: CInt) -- ???

       peek p = do
            s_name    <- ((\hsc_ptr -> peekByteOff hsc_ptr 0)) p >>= peekCString
    {-# LINE 175 "Network/BSD.hsc" #-}
            s_aliases <- ((\hsc_ptr -> peekByteOff hsc_ptr 8)) p
    {-# LINE 176 "Network/BSD.hsc" #-}
                               >>= peekArray0 nullPtr
                               >>= mapM peekCString
            s_port    <- ((\hsc_ptr -> peekByteOff hsc_ptr 16)) p
    {-# LINE 179 "Network/BSD.hsc" #-}
            s_proto   <- ((\hsc_ptr -> peekByteOff hsc_ptr 24)) p >>= peekCString
    {-# LINE 180 "Network/BSD.hsc" #-}
            return (ServiceEntry {
                            serviceName     = s_name,
                            serviceAliases  = s_aliases,

    {-# LINE 186 "Network/BSD.hsc" #-}
                               -- s_port is already in network byte order, but it
                               -- might be the wrong size.
                            servicePort     = (fromIntegral (s_port :: CInt)),

    {-# LINE 190 "Network/BSD.hsc" #-}
                            serviceProtocol = s_proto
                    })

       poke = throwUnsupportedOperationPoke "ServiceEntry"

    -- | Get service by name.
    getServiceByName :: N.ServiceName         -- Service Name
                     -> ProtocolName        -- Protocol Name
                     -> IO ServiceEntry     -- Service Entry
    getServiceByName name proto = withLock $ do
     withCString name  $ \ cstr_name  -> do
     withCString proto $ \ cstr_proto -> do
     throwNoSuchThingIfNull "Network.BSD.getServiceByName" "no such service entry"
       $ c_getservbyname cstr_name cstr_proto
     >>= peek

    foreign import CALLCONV unsafe "getservbyname"
      c_getservbyname :: CString -> CString -> IO (Ptr ServiceEntry)

    -- | Get the service given a 'N.PortNumber' and 'ProtocolName'.
    getServiceByPort :: N.PortNumber -> ProtocolName -> IO ServiceEntry
    getServiceByPort port proto = withLock $ do
     withCString proto $ \ cstr_proto -> do
     throwNoSuchThingIfNull "Network.BSD.getServiceByPort" "no such service entry"
       $ c_getservbyport (fromIntegral port) cstr_proto
     >>= peek

    foreign import CALLCONV unsafe "getservbyport"
      c_getservbyport :: CInt -> CString -> IO (Ptr ServiceEntry)

    -- | Get the 'N.PortNumber' corresponding to the 'N.ServiceName'.
    getServicePortNumber :: N.ServiceName -> IO N.PortNumber
    getServicePortNumber name = do
        (ServiceEntry _ _ port _) <- getServiceByName name "tcp"
        return port

    {-# LINE 228 "Network/BSD.hsc" #-}

    -- | @getservent(3)@.
    getServiceEntry :: IO ServiceEntry
    getServiceEntry = withLock getServiceEntry'

    getServiceEntry' :: IO ServiceEntry
    getServiceEntry' = do
      throwNoSuchThingIfNull "Network.BSD.getServiceEntry" "no such service entry"
        $ c_getservent
      >>= peek

    foreign import ccall unsafe "getservent" c_getservent :: IO (Ptr ServiceEntry)

    -- | @setservent(3)@.
    setServiceEntry :: Bool -> IO ()
    setServiceEntry = withLock . setServiceEntry'

    setServiceEntry' :: Bool -> IO ()
    setServiceEntry' flg = c_setservent (fromBool flg)

    foreign import ccall unsafe  "setservent" c_setservent :: CInt -> IO ()

    -- | @endservent(3)@.
    endServiceEntry :: IO ()
    endServiceEntry = withLock $ c_endservent

    foreign import ccall unsafe  "endservent" c_endservent :: IO ()

    -- | Retrieve list of all 'ServiceEntry' via @getservent(3)@.
    getServiceEntries :: Bool -> IO [ServiceEntry]
    getServiceEntries stayOpen = withLock $ do
      setServiceEntry' stayOpen
      getEntries getServiceEntry' c_endservent

    {-# LINE 262 "Network/BSD.hsc" #-}

    -- ---------------------------------------------------------------------------
    -- Protocol Entries

    -- The following relate directly to the corresponding UNIX C
    -- calls for returning the protocol entries. The protocol entry is
    -- represented by the Haskell type ProtocolEntry.

    -- As for setServiceEntry above, calling setProtocolEntry.
    -- determines whether or not the protocol database file, usually
    -- @/etc/protocols@, is to be kept open between calls of
    -- getProtocolEntry. Similarly,

    -- | Representation of the POSIX @protoent@ structure defined in [<netdb.h>](http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netdb.h.html).
    data ProtocolEntry =
      ProtocolEntry  {
         protoName    :: ProtocolName,      -- ^ Official name
         protoAliases :: [ProtocolName],    -- ^ aliases
         protoNumber  :: N.ProtocolNumber   -- ^ Protocol number
      } deriving (Read, Show, Typeable)

    -- | @since 2.8.1.0
    instance NFData ProtocolEntry where
       -- NB: deepseq-1.3 didn't have `NFData CInt` yet; but we don't need it
       rnf (ProtocolEntry na a !_nu) = rnf (na,a)

    instance Storable ProtocolEntry where
       sizeOf    _ = 24
    {-# LINE 290 "Network/BSD.hsc" #-}
       alignment _ = alignment (undefined :: CInt) -- ???

       peek p = do
            p_name    <- ((\hsc_ptr -> peekByteOff hsc_ptr 0)) p >>= peekCString
    {-# LINE 294 "Network/BSD.hsc" #-}
            p_aliases <- ((\hsc_ptr -> peekByteOff hsc_ptr 8)) p
    {-# LINE 295 "Network/BSD.hsc" #-}
                               >>= peekArray0 nullPtr
                               >>= mapM peekCString

    {-# LINE 304 "Network/BSD.hsc" #-}
            p_proto        <- ((\hsc_ptr -> peekByteOff hsc_ptr 16)) p
    {-# LINE 305 "Network/BSD.hsc" #-}

    {-# LINE 306 "Network/BSD.hsc" #-}
            return (ProtocolEntry {
                            protoName    = p_name,
                            protoAliases = p_aliases,
                            protoNumber  = p_proto
                    })

       poke = throwUnsupportedOperationPoke "ProtocolEntry"

    -- | @getprotobyname(3)@.
    getProtocolByName :: ProtocolName -> IO ProtocolEntry
    getProtocolByName name = withLock $ do
     withCString name $ \ name_cstr -> do
     throwNoSuchThingIfNull "Network.BSD.getProtocolByName" ("no such protocol name: " ++ name)
       $ c_getprotobyname name_cstr
     >>= peek

    foreign import  CALLCONV unsafe  "getprotobyname"
       c_getprotobyname :: CString -> IO (Ptr ProtocolEntry)

    -- | @getprotobynumber(3)@.
    getProtocolByNumber :: N.ProtocolNumber -> IO ProtocolEntry
    getProtocolByNumber num = withLock $ do
     throwNoSuchThingIfNull "Network.BSD.getProtocolByNumber" ("no such protocol number: " ++ show num)
       $ c_getprotobynumber (fromIntegral num)
     >>= peek

    foreign import CALLCONV unsafe  "getprotobynumber"
       c_getprotobynumber :: CInt -> IO (Ptr ProtocolEntry)

    -- | @getprotobyname(3)@.
    getProtocolNumber :: ProtocolName -> IO N.ProtocolNumber
    getProtocolNumber proto = do
     (ProtocolEntry _ _ num) <- getProtocolByName proto
     return num

    {-# LINE 343 "Network/BSD.hsc" #-}
    -- | @getprotoent(3)@.
    getProtocolEntry :: IO ProtocolEntry    -- Next Protocol Entry from DB
    getProtocolEntry = withLock getProtocolEntry'

    getProtocolEntry' :: IO ProtocolEntry
    getProtocolEntry' = do
      ent <- throwNoSuchThingIfNull "Network.BSD.getProtocolEntry" "no such protocol entry"
               $ c_getprotoent
      peek ent

    foreign import ccall unsafe  "getprotoent" c_getprotoent :: IO (Ptr ProtocolEntry)

    -- | @setprotoent(3)@.
    setProtocolEntry :: Bool -> IO ()       -- Keep DB Open ?
    setProtocolEntry = withLock . setProtocolEntry'

    setProtocolEntry' :: Bool -> IO ()       -- Keep DB Open ?
    setProtocolEntry' flg = c_setprotoent (fromBool flg)

    foreign import ccall unsafe "setprotoent" c_setprotoent :: CInt -> IO ()

    -- | @endprotoent(3)@.
    endProtocolEntry :: IO ()
    endProtocolEntry = withLock $ c_endprotoent

    foreign import ccall unsafe "endprotoent" c_endprotoent :: IO ()

    -- | Retrieve list of all 'ProtocolEntry' via @getprotoent(3)@.
    getProtocolEntries :: Bool -> IO [ProtocolEntry]
    getProtocolEntries stayOpen = withLock $ do
      setProtocolEntry' stayOpen
      getEntries getProtocolEntry' c_endprotoent

    {-# LINE 377 "Network/BSD.hsc" #-}

    -- ---------------------------------------------------------------------------
    -- Host lookups

    -- | Representation of the POSIX @hostent@ structure defined in [<netdb.h>](http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netdb.h.html).
    data HostEntry =
      HostEntry  {
         hostName      :: N.HostName,         -- ^ Official name of the host
         hostAliases   :: [N.HostName],       -- ^ Alternative names of the host
         hostFamily    :: N.Family,           -- ^ Address type (currently @AF_INET@)
         hostAddresses :: [N.HostAddress]     -- ^ Set of network addresses for the host
      } deriving (Read, Show, Typeable)

    -- | @since 2.8.1.0
    instance NFData HostEntry where
       -- TODO: NFData N.Family
       rnf (HostEntry n al !_f ad) = rnf (n,al,ad)

    instance Storable HostEntry where
       sizeOf    _ = 32
    {-# LINE 397 "Network/BSD.hsc" #-}
       alignment _ = alignment (undefined :: CInt) -- ???

       peek p = do
            h_name       <- ((\hsc_ptr -> peekByteOff hsc_ptr 0)) p >>= peekCString
    {-# LINE 401 "Network/BSD.hsc" #-}
            h_aliases    <- ((\hsc_ptr -> peekByteOff hsc_ptr 8)) p
    {-# LINE 402 "Network/BSD.hsc" #-}
                                    >>= peekArray0 nullPtr
                                    >>= mapM peekCString
            h_addrtype   <- ((\hsc_ptr -> peekByteOff hsc_ptr 16)) p
    {-# LINE 405 "Network/BSD.hsc" #-}
            -- h_length       <- (#peek struct hostent, h_length) p
            h_addr_list  <- ((\hsc_ptr -> peekByteOff hsc_ptr 24)) p
    {-# LINE 407 "Network/BSD.hsc" #-}
                                    >>= peekArray0 nullPtr
                                    >>= mapM peek
            return (HostEntry {
                            hostName       = h_name,
                            hostAliases    = h_aliases,

    {-# LINE 415 "Network/BSD.hsc" #-}
                            hostFamily     = N.unpackFamily h_addrtype,

    {-# LINE 417 "Network/BSD.hsc" #-}
                            hostAddresses  = h_addr_list
                    })

       poke = throwUnsupportedOperationPoke "HostEntry"

    -- convenience function:
    -- | Convenience function extracting one address in a 'HostEntry'.
    -- Returns 'error' if 'HostEntry' contains no addresses.
    hostAddress :: HostEntry -> N.HostAddress
    hostAddress (HostEntry nm _ _ ls) =
     case ls of
       []    -> error $ "Network.BSD.hostAddress: empty network address list for " ++ nm
       (x:_) -> x

    -- getHostByName must use the same lock as the *hostent functions
    -- may cause problems if called concurrently.

    -- | Resolve a 'N.HostName' to IPv4 address.
    getHostByName :: N.HostName -> IO HostEntry
    getHostByName name = withLock $ do
      withCString name $ \ name_cstr -> do
       ent <- throwNoSuchThingIfNull "Network.BSD.getHostByName" "no such host entry"
                    $ c_gethostbyname name_cstr
       peek ent

    foreign import CALLCONV safe "gethostbyname"
       c_gethostbyname :: CString -> IO (Ptr HostEntry)

    -- The locking of gethostbyaddr is similar to gethostbyname.
    -- | Get a 'HostEntry' corresponding to the given address and family.
    -- Note that only IPv4 is currently supported.
    getHostByAddr :: N.Family -> N.HostAddress -> IO HostEntry
    getHostByAddr family addr = do
     with addr $ \ ptr_addr -> withLock $ do
     throwNoSuchThingIfNull "Network.BSD.getHostByAddr" "no such host entry"
       $ c_gethostbyaddr ptr_addr (fromIntegral (sizeOf addr)) (N.packFamily family)
     >>= peek

    foreign import CALLCONV safe "gethostbyaddr"
       c_gethostbyaddr :: Ptr N.HostAddress -> CInt -> CInt -> IO (Ptr HostEntry)

    {-# LINE 461 "Network/BSD.hsc" #-}
    -- | @gethostent(3)@.
    getHostEntry :: IO HostEntry
    getHostEntry = withLock getHostEntry

    getHostEntry' :: IO HostEntry
    getHostEntry' = do
      throwNoSuchThingIfNull "Network.BSD.getHostEntry" "unable to retrieve host entry"
        $ c_gethostent
      >>= peek

    foreign import ccall unsafe "gethostent" c_gethostent :: IO (Ptr HostEntry)

    -- | @sethostent(3)@.
    setHostEntry :: Bool -> IO ()
    setHostEntry = withLock . setHostEntry'

    setHostEntry' :: Bool -> IO ()
    setHostEntry' flg = c_sethostent (fromBool flg)

    foreign import ccall unsafe "sethostent" c_sethostent :: CInt -> IO ()

    -- | @endhostent(3)@.
    endHostEntry :: IO ()
    endHostEntry = withLock $ c_endhostent

    foreign import ccall unsafe "endhostent" c_endhostent :: IO ()

    -- | Retrieve list of all 'HostEntry' via @gethostent(3)@.
    getHostEntries :: Bool -> IO [HostEntry]
    getHostEntries stayOpen = withLock $ do
      setHostEntry' stayOpen
      getEntries getHostEntry' c_endhostent

    {-# LINE 495 "Network/BSD.hsc" #-}

    -- ---------------------------------------------------------------------------
    -- Accessing network information

    -- Same set of access functions as for accessing host,protocol and
    -- service system info, this time for the types of networks supported.

    -- network addresses are represented in host byte order.
    type NetworkAddr = CULong

    type NetworkName = String

    -- | Representation of the POSIX @netent@ structure defined in [<netdb.h>](http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/netdb.h.html).
    data NetworkEntry =
      NetworkEntry {
         networkName        :: NetworkName,   -- ^ Official network name
         networkAliases     :: [NetworkName], -- ^ aliases
         networkFamily      :: N.Family,      -- ^ Network address type
         networkAddress     :: NetworkAddr    -- ^ Network number
       } deriving (Read, Show, Typeable)

    -- | @since 2.8.1.0
    instance NFData NetworkEntry where
       -- NB: We avoid relying on the `NFData CULong` instance which isn't available in deepseq-1.3 yet
       rnf (NetworkEntry n al !_f !_ad) = rnf (n,al)

    instance Storable NetworkEntry where
       sizeOf    _ = 32
    {-# LINE 523 "Network/BSD.hsc" #-}
       alignment _ = alignment (undefined :: CInt) -- ???

       peek p = do
            n_name         <- ((\hsc_ptr -> peekByteOff hsc_ptr 0)) p >>= peekCString
    {-# LINE 527 "Network/BSD.hsc" #-}
            n_aliases      <- ((\hsc_ptr -> peekByteOff hsc_ptr 8)) p
    {-# LINE 528 "Network/BSD.hsc" #-}
                                    >>= peekArray0 nullPtr
                                    >>= mapM peekCString
            n_addrtype     <- ((\hsc_ptr -> peekByteOff hsc_ptr 16)) p
    {-# LINE 531 "Network/BSD.hsc" #-}
            n_net          <- ((\hsc_ptr -> peekByteOff hsc_ptr 20)) p
    {-# LINE 532 "Network/BSD.hsc" #-}
            return (NetworkEntry {
                            networkName      = n_name,
                            networkAliases   = n_aliases,
                            networkFamily    = N.unpackFamily (fromIntegral (n_addrtype :: CInt)),
                            networkAddress   = n_net
                    })

       poke = throwUnsupportedOperationPoke "NetworkEntry"

    {-# LINE 543 "Network/BSD.hsc" #-}
    -- | @getnetbyname(3)@.
    getNetworkByName :: NetworkName -> IO NetworkEntry
    getNetworkByName name = withLock $ do
     withCString name $ \ name_cstr -> do
      throwNoSuchThingIfNull "Network.BSD.getNetworkByName" "no such network entry"
        $ c_getnetbyname name_cstr
      >>= peek

    foreign import ccall unsafe "getnetbyname"
       c_getnetbyname  :: CString -> IO (Ptr NetworkEntry)

    -- | @getnetbyaddr(3)@.
    getNetworkByAddr :: NetworkAddr -> N.Family -> IO NetworkEntry
    getNetworkByAddr addr family = withLock $ do
     throwNoSuchThingIfNull "Network.BSD.getNetworkByAddr" "no such network entry"
       $ c_getnetbyaddr addr (N.packFamily family)
     >>= peek

    foreign import ccall unsafe "getnetbyaddr"
       c_getnetbyaddr  :: NetworkAddr -> CInt -> IO (Ptr NetworkEntry)

    -- | @getnetent(3)@.
    getNetworkEntry :: IO NetworkEntry
    getNetworkEntry = withLock getNetworkEntry'

    getNetworkEntry' :: IO NetworkEntry
    getNetworkEntry' = do
      throwNoSuchThingIfNull "Network.BSD.getNetworkEntry" "no more network entries"
        $ c_getnetent
      >>= peek

    foreign import ccall unsafe "getnetent" c_getnetent :: IO (Ptr NetworkEntry)

    -- | Open the network name database. The parameter specifies
    -- whether a connection is maintained open between various
    -- networkEntry calls
    --
    -- @setnetent(3)@.
    setNetworkEntry :: Bool -> IO ()
    setNetworkEntry = withLock . setNetworkEntry'

    setNetworkEntry' :: Bool -> IO ()
    setNetworkEntry' flg = c_setnetent (fromBool flg)

    foreign import ccall unsafe "setnetent" c_setnetent :: CInt -> IO ()

    -- | Close the connection to the network name database.
    --
    -- @endnetent(3)@.
    endNetworkEntry :: IO ()
    endNetworkEntry = withLock $ c_endnetent

    foreign import ccall unsafe "endnetent" c_endnetent :: IO ()

    -- | Get the list of network entries via @getnetent(3)@.
    getNetworkEntries :: Bool -> IO [NetworkEntry]
    getNetworkEntries stayOpen = withLock $ do
      setNetworkEntry' stayOpen
      getEntries getNetworkEntry' c_endnetent

    {-# LINE 603 "Network/BSD.hsc" #-}

    -- Mutex for name service lockdown

    {-# NOINLINE lock #-}
    lock :: MVar ()
    lock = unsafePerformIO $ N.withSocketsDo $ newMVar ()

    withLock :: IO a -> IO a
    withLock act = withMVar lock (\_ -> act)

    -- ---------------------------------------------------------------------------
    -- Miscellaneous Functions

    -- | Calling 'getHostName' returns the standard host name for the current
    -- processor, as set at boot time.
    --
    -- @gethostname(2)@.
    getHostName :: IO N.HostName
    getHostName = do
      let size = 256
      allocaArray0 size $ \ cstr -> do
        throwSocketErrorIfMinus1_ "Network.BSD.getHostName" $ c_gethostname cstr (fromIntegral size)
        peekCString cstr

    foreign import CALLCONV unsafe "gethostname"
       c_gethostname :: CString -> CSize -> IO CInt

    -- Helper function used by the exported functions that provides a
    -- Haskellised view of the enumerator functions:

    getEntries :: IO a  -- read
               -> IO () -- at end
               -> IO [a]
    getEntries getOne atEnd = loop
      where
        loop = do
          vv <- E.catch (liftM Just getOne)
                (\ e -> let _types = e :: IOException in return Nothing)
          case vv of
            Nothing -> return []
            Just v  -> loop >>= \ vs -> atEnd >> return (v:vs)

    throwNoSuchThingIfNull :: String -> String -> IO (Ptr a) -> IO (Ptr a)
    throwNoSuchThingIfNull loc desc act = do
      ptr <- act
      if (ptr == nullPtr)
       then ioError (ioeSetErrorString (mkIOError NoSuchThing loc Nothing Nothing) desc)
       else return ptr

    throwUnsupportedOperationPoke :: String -> Ptr a -> a -> IO ()
    throwUnsupportedOperationPoke typ _ _ =
      ioError $ ioeSetErrorString ioe "Operation not implemented"
      where
        ioe = mkIOError UnsupportedOperation
                        ("Network.BSD: instance Storable " ++ typ ++ ": poke")
                        Nothing
                        Nothing