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|
{-# LANGUAGE Trustworthy #-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE CPP #-}
-----------------------------------------------------------------------------
-- |
-- Module : GHC.ConsoleHandler
-- Copyright : (c) The University of Glasgow
-- License : see libraries/base/LICENSE
--
-- Maintainer : cvs-ghc@haskell.org
-- Stability : internal
-- Portability : non-portable (GHC extensions)
--
-- NB. the contents of this module are only available on Windows.
--
-- Installing Win32 console handlers.
--
-----------------------------------------------------------------------------
module GHC.ConsoleHandler
#if !defined(mingw32_HOST_OS)
where
import GHC.Base () -- dummy dependency
#else /* whole file */
( Handler(..)
, installHandler
, ConsoleEvent(..)
, flushConsole
) where
{-
#include "rts/Signals.h"
Note: this #include is inside a Haskell comment
but it brings into scope some #defines
that are used by CPP below (eg STG_SIG_DFL).
Having it in a comment means that there's no
danger that C-like crap will be misunderstood
by GHC
-}
import GHC.Base
import Foreign
import Foreign.C
import GHC.IO.FD
import GHC.IO.Exception
import GHC.IO.Handle.Types
import GHC.IO.Handle.Internals
import GHC.Conc
import Control.Concurrent.MVar
import Data.Typeable
data Handler
= Default
| Ignore
| Catch (ConsoleEvent -> IO ())
-- | Allows Windows console events to be caught and handled. To
-- handle a console event, call 'installHandler' passing the
-- appropriate 'Handler' value. When the event is received, if the
-- 'Handler' value is @Catch f@, then a new thread will be spawned by
-- the system to execute @f e@, where @e@ is the 'ConsoleEvent' that
-- was received.
--
-- Note that console events can only be received by an application
-- running in a Windows console. Certain environments that look like consoles
-- do not support console events, these include:
--
-- * Cygwin shells with @CYGWIN=tty@ set (if you don't set @CYGWIN=tty@,
-- then a Cygwin shell behaves like a Windows console).
-- * Cygwin xterm and rxvt windows
-- * MSYS rxvt windows
--
-- In order for your application to receive console events, avoid running
-- it in one of these environments.
--
installHandler :: Handler -> IO Handler
installHandler handler
| threaded =
modifyMVar win32ConsoleHandler $ \old_h -> do
(new_h,rc) <-
case handler of
Default -> do
r <- rts_installHandler STG_SIG_DFL nullPtr
return (no_handler, r)
Ignore -> do
r <- rts_installHandler STG_SIG_IGN nullPtr
return (no_handler, r)
Catch h -> do
r <- rts_installHandler STG_SIG_HAN nullPtr
return (h, r)
prev_handler <-
case rc of
STG_SIG_DFL -> return Default
STG_SIG_IGN -> return Ignore
STG_SIG_HAN -> return (Catch old_h)
_ -> errorWithoutStackTrace "installHandler: Bad threaded rc value"
return (new_h, prev_handler)
| otherwise =
alloca $ \ p_sp -> do
rc <-
case handler of
Default -> rts_installHandler STG_SIG_DFL p_sp
Ignore -> rts_installHandler STG_SIG_IGN p_sp
Catch h -> do
v <- newStablePtr (toHandler h)
poke p_sp v
rts_installHandler STG_SIG_HAN p_sp
case rc of
STG_SIG_DFL -> return Default
STG_SIG_IGN -> return Ignore
STG_SIG_HAN -> do
osptr <- peek p_sp
oldh <- deRefStablePtr osptr
-- stable pointer is no longer in use, free it.
freeStablePtr osptr
return (Catch (\ ev -> oldh (fromConsoleEvent ev)))
_ -> errorWithoutStackTrace "installHandler: Bad non-threaded rc value"
where
fromConsoleEvent ev =
case ev of
ControlC -> 0 {- CTRL_C_EVENT-}
Break -> 1 {- CTRL_BREAK_EVENT-}
Close -> 2 {- CTRL_CLOSE_EVENT-}
Logoff -> 5 {- CTRL_LOGOFF_EVENT-}
Shutdown -> 6 {- CTRL_SHUTDOWN_EVENT-}
toHandler hdlr ev = do
case toWin32ConsoleEvent ev of
-- see rts/win32/ConsoleHandler.c for comments as to why
-- rts_ConsoleHandlerDone is called here.
Just x -> hdlr x >> rts_ConsoleHandlerDone ev
Nothing -> return () -- silently ignore..
no_handler = errorWithoutStackTrace "win32ConsoleHandler"
foreign import ccall unsafe "rtsSupportsBoundThreads" threaded :: Bool
foreign import ccall unsafe "RtsExternal.h rts_InstallConsoleEvent"
rts_installHandler :: CInt -> Ptr (StablePtr (CInt -> IO ())) -> IO CInt
foreign import ccall unsafe "RtsExternal.h rts_ConsoleHandlerDone"
rts_ConsoleHandlerDone :: CInt -> IO ()
flushConsole :: Handle -> IO ()
flushConsole h =
wantReadableHandle_ "flushConsole" h $ \ Handle__{haDevice=dev} ->
case cast dev of
Nothing -> ioException $
IOError (Just h) IllegalOperation "flushConsole"
"handle is not a file descriptor" Nothing Nothing
Just fd -> do
throwErrnoIfMinus1Retry_ "flushConsole" $
flush_console_fd (fdFD fd)
foreign import ccall unsafe "consUtils.h flush_input_console__"
flush_console_fd :: CInt -> IO CInt
#endif /* mingw32_HOST_OS */
|
