compiler: fix trac issue #9817

Summary:
When we call runHandlers, we must pass it a ForeignPtr. To ensure that
this happens, we introduce a wrapper that receives a plain Ptr and
converts it into a ForeignPtr. Then we adjust startSignalHandlers in
rts/posix/Signals.c to call the wrapper instead of calling runHandlers
directly.

Reviewers: hvr, austin, rwbarton, simonmar

Reviewed By: austin, simonmar

Subscribers: simonmar, thomie, carter

Differential Revision: https://phabricator.haskell.org/D515

GHC Trac Issues: #9817

1 files changed, 10 insertions, 1 deletions

diff --git a/libraries/base/GHC/Conc/Signal.hs b/libraries/base/GHC/Conc/Signal.hs
index 3f5eacb572..4afccf2496 100644
--- a/libraries/base/GHC/Conc/Signal.hs
+++ b/libraries/base/GHC/Conc/Signal.hs
@@ -6,15 +6,17 @@ module GHC.Conc.Signal
         , HandlerFun
         , setHandler
         , runHandlers
+        , runHandlersPtr
         ) where
 
 import Control.Concurrent.MVar (MVar, newMVar, withMVar)
 import Data.Dynamic (Dynamic)
 import Foreign.C.Types (CInt)
-import Foreign.ForeignPtr (ForeignPtr)
+import Foreign.ForeignPtr (ForeignPtr, newForeignPtr)
 import Foreign.StablePtr (castPtrToStablePtr, castStablePtrToPtr,
                           deRefStablePtr, freeStablePtr, newStablePtr)
 import Foreign.Ptr (Ptr, castPtr)
+import Foreign.Marshal.Alloc (finalizerFree)
 import GHC.Arr (inRange)
 import GHC.Base
 import GHC.Conc.Sync (forkIO)
@@ -70,6 +72,13 @@ runHandlers p_info sig = do
                 Just (f,_)  -> do _ <- forkIO (f p_info)
                                   return ()
 
+-- It is our responsibility to free the memory buffer, so we create a
+-- foreignPtr.
+runHandlersPtr :: Ptr Word8 -> Signal -> IO ()
+runHandlersPtr p s = do
+  fp <- newForeignPtr finalizerFree p
+  runHandlers fp s
+
 -- Machinery needed to ensure that we only have one copy of certain
 -- CAFs in this module even when the base package is present twice, as
 -- it is when base is dynamically loaded into GHCi.  The RTS keeps