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 #else /* whole file */
29 #include "rts/Signals.h"
35 import GHC.IO.Exception
36 import GHC.IO.Handle.Types
37 import GHC.IO.Handle.Internals
39 import Control.Concurrent.MVar
42 #ifdef mingw32_HOST_OS
50 | Catch (ConsoleEvent -> IO ())
52 -- | Allows Windows console events to be caught and handled. To
53 -- handle a console event, call 'installHandler' passing the
54 -- appropriate 'Handler' value. When the event is received, if the
55 -- 'Handler' value is @Catch f@, then a new thread will be spawned by
56 -- the system to execute @f e@, where @e@ is the 'ConsoleEvent' that
59 -- Note that console events can only be received by an application
60 -- running in a Windows console. Certain environments that look like consoles
61 -- do not support console events, these include:
63 -- * Cygwin shells with @CYGWIN=tty@ set (if you don't set @CYGWIN=tty@,
64 -- then a Cygwin shell behaves like a Windows console).
65 -- * Cygwin xterm and rxvt windows
66 -- * MSYS rxvt windows
68 -- In order for your application to receive console events, avoid running
69 -- it in one of these environments.
71 installHandler :: Handler -> IO Handler
72 installHandler handler
74 modifyMVar win32ConsoleHandler $ \old_h -> do
78 r <- rts_installHandler STG_SIG_DFL nullPtr
79 return (no_handler, r)
81 r <- rts_installHandler STG_SIG_IGN nullPtr
82 return (no_handler, r)
84 r <- rts_installHandler STG_SIG_HAN nullPtr
88 STG_SIG_DFL -> return Default
89 STG_SIG_IGN -> return Ignore
90 STG_SIG_HAN -> return (Catch old_h)
91 _ -> error "installHandler: Bad threaded rc value"
92 return (new_h, prev_handler)
98 Default -> rts_installHandler STG_SIG_DFL p_sp
99 Ignore -> rts_installHandler STG_SIG_IGN p_sp
101 v <- newStablePtr (toHandler h)
103 rts_installHandler STG_SIG_HAN p_sp
105 STG_SIG_DFL -> return Default
106 STG_SIG_IGN -> return Ignore
109 oldh <- deRefStablePtr osptr
110 -- stable pointer is no longer in use, free it.
112 return (Catch (\ ev -> oldh (fromConsoleEvent ev)))
113 _ -> error "installHandler: Bad non-threaded rc value"
115 fromConsoleEvent ev =
117 ControlC -> 0 {- CTRL_C_EVENT-}
118 Break -> 1 {- CTRL_BREAK_EVENT-}
119 Close -> 2 {- CTRL_CLOSE_EVENT-}
120 Logoff -> 5 {- CTRL_LOGOFF_EVENT-}
121 Shutdown -> 6 {- CTRL_SHUTDOWN_EVENT-}
123 toHandler hdlr ev = do
124 case toWin32ConsoleEvent ev of
125 -- see rts/win32/ConsoleHandler.c for comments as to why
126 -- rts_ConsoleHandlerDone is called here.
127 Just x -> hdlr x >> rts_ConsoleHandlerDone ev
128 Nothing -> return () -- silently ignore..
130 no_handler = error "win32ConsoleHandler"
132 foreign import ccall "rtsSupportsBoundThreads" threaded :: Bool
134 foreign import ccall unsafe "RtsExternal.h rts_InstallConsoleEvent"
135 rts_installHandler :: CInt -> Ptr (StablePtr (CInt -> IO ())) -> IO CInt
136 foreign import ccall unsafe "RtsExternal.h rts_ConsoleHandlerDone"
137 rts_ConsoleHandlerDone :: CInt -> IO ()
140 flushConsole :: Handle -> IO ()
142 wantReadableHandle_ "flushConsole" h $ \ Handle__{haDevice=dev} ->
144 Nothing -> ioException $
145 IOError (Just h) IllegalOperation "flushConsole"
146 "handle is not a file descriptor" Nothing Nothing
148 throwErrnoIfMinus1Retry_ "flushConsole" $
149 flush_console_fd (fdFD fd)
151 foreign import ccall unsafe "consUtils.h flush_input_console__"
152 flush_console_fd :: CInt -> IO CInt
154 #endif /* mingw32_HOST_OS */