1 {-# OPTIONS_GHC -cpp #-}
2 -----------------------------------------------------------------------------
4 -- Module : GHC.ConsoleHandler
5 -- Copyright : (c) The University of Glasgow
6 -- License : see libraries/base/LICENSE
8 -- Maintainer : cvs-ghc@haskell.org
9 -- Stability : internal
10 -- Portability : non-portable (GHC extensions)
12 -- NB. the contents of this module are only available on Windows.
14 -- Installing Win32 console handlers.
16 -----------------------------------------------------------------------------
18 module GHC.ConsoleHandler
19 #if !defined(mingw32_HOST_OS) && !defined(__HADDOCK__)
21 import Prelude -- necessary to get dependencies right
22 #else /* whole file */
33 import Prelude -- necessary to get dependencies right
40 import Control.Exception (onException)
45 | Catch (ConsoleEvent -> IO ())
47 -- | Allows Windows console events to be caught and handled. To
48 -- handle a console event, call 'installHandler' passing the
49 -- appropriate 'Handler' value. When the event is received, if the
50 -- 'Handler' value is @Catch f@, then a new thread will be spawned by
51 -- the system to execute @f e@, where @e@ is the 'ConsoleEvent' that
54 -- Note that console events can only be received by an application
55 -- running in a Windows console. Certain environments that look like consoles
56 -- do not support console events, these include:
58 -- * Cygwin shells with @CYGWIN=tty@ set (if you don't set @CYGWIN=tty@,
59 -- then a Cygwin shell behaves like a Windows console).
60 -- * Cygwin xterm and rxvt windows
61 -- * MSYS rxvt windows
63 -- In order for your application to receive console events, avoid running
64 -- it in one of these environments.
66 installHandler :: Handler -> IO Handler
67 installHandler handler
69 modifyMVar win32ConsoleHandler $ \old_h -> do
73 r <- rts_installHandler STG_SIG_DFL nullPtr
74 return (no_handler, r)
76 r <- rts_installHandler STG_SIG_IGN nullPtr
77 return (no_handler, r)
79 r <- rts_installHandler STG_SIG_HAN nullPtr
83 STG_SIG_DFL -> return Default
84 STG_SIG_IGN -> return Ignore
85 STG_SIG_HAN -> return (Catch old_h)
86 _ -> error "installHandler: Bad threaded rc value"
87 return (new_h, prev_handler)
93 Default -> rts_installHandler STG_SIG_DFL p_sp
94 Ignore -> rts_installHandler STG_SIG_IGN p_sp
96 v <- newStablePtr (toHandler h)
98 rts_installHandler STG_SIG_HAN p_sp
100 STG_SIG_DFL -> return Default
101 STG_SIG_IGN -> return Ignore
104 oldh <- deRefStablePtr osptr
105 -- stable pointer is no longer in use, free it.
107 return (Catch (\ ev -> oldh (fromConsoleEvent ev)))
108 _ -> error "installHandler: Bad non-threaded rc value"
110 fromConsoleEvent ev =
112 ControlC -> 0 {- CTRL_C_EVENT-}
113 Break -> 1 {- CTRL_BREAK_EVENT-}
114 Close -> 2 {- CTRL_CLOSE_EVENT-}
115 Logoff -> 5 {- CTRL_LOGOFF_EVENT-}
116 Shutdown -> 6 {- CTRL_SHUTDOWN_EVENT-}
118 toHandler hdlr ev = do
119 case toWin32ConsoleEvent ev of
120 -- see rts/win32/ConsoleHandler.c for comments as to why
121 -- rts_ConsoleHandlerDone is called here.
122 Just x -> hdlr x >> rts_ConsoleHandlerDone ev
123 Nothing -> return () -- silently ignore..
125 no_handler = error "win32ConsoleHandler"
127 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
129 foreign import ccall unsafe "RtsExternal.h rts_InstallConsoleEvent"
130 rts_installHandler :: CInt -> Ptr (StablePtr (CInt -> IO ())) -> IO CInt
131 foreign import ccall unsafe "RtsExternal.h rts_ConsoleHandlerDone"
132 rts_ConsoleHandlerDone :: CInt -> IO ()
135 flushConsole :: Handle -> IO ()
137 wantReadableHandle "flushConsole" h $ \ h_ ->
138 throwErrnoIfMinus1Retry_ "flushConsole"
139 (flush_console_fd (fromIntegral (haFD h_)))
141 foreign import ccall unsafe "consUtils.h flush_input_console__"
142 flush_console_fd :: CInt -> IO CInt
144 -- XXX Copied from Control.Concurrent.MVar
145 modifyMVar :: MVar a -> (a -> IO (a,b)) -> IO b
149 (a',b) <- unblock (io a) `onException` putMVar m a
152 #endif /* mingw32_HOST_OS */