Kill child process instead of sending SIGTERM

If the child is currently between DisableInterrupts and
EnableInterrupts and we decide to terminate it, it will not respond to
sigterm.

osek-verification.cabal

@@ -50,6 +50,7 @@ library
                      , microlens-th >= 0.4 && < 0.5
                      , unordered-containers >= 0.2 && <0.3
                      , hashable >= 1.2 && < 1.3
+                     , unix >= 2.7 && <2.8
   default-language:    Haskell2010
   ghc-options:         -Wall -fno-warn-name-shadowing
 

src/Search/Search.hs

@@ -18,6 +18,8 @@ import qualified Data.Text.IO as T
 import           System.Exit
 import           System.IO
 import           System.Process
+import           System.Process.Internals (withProcessHandle, ProcessHandle__(..))
+import           System.Posix.Signals (signalProcess, sigKILL)
 
 import           Data.Aeson
 import qualified Data.Graph.Inductive as G
@@ -130,6 +132,12 @@ driver' elimEpsis dumpJSON debug prog startVertex = do
 
   loop
 
+killProcess :: ProcessHandle -> IO ()
+killProcess handle = withProcessHandle handle $ \ph ->
+  case ph of
+    OpenHandle pid -> signalProcess sigKILL pid
+    _ -> return ()
+
 oneProgRun :: FilePath -> DebugOutput -> IORef State -> Maybe [Bool] -> IO ()
 oneProgRun prog debug state trace = do
   (Just pstdin, Just pstdout, _, handle) <- createProcess (proc prog []) { std_in = CreatePipe, std_out = CreatePipe }
@@ -144,7 +152,7 @@ oneProgRun prog debug state trace = do
           let (next, s') = handleDecision x (s^.curTrace) s
           writeIORef state s'
           case next of
-            Restart -> terminateProcess handle >> mapM_ hClose [pstdin, pstdout]
+            Restart -> killProcess handle >> mapM_ hClose [pstdin, pstdout]
             Continue x' -> do
               makeDecision pstdin state x'
               loop
@@ -152,7 +160,7 @@ oneProgRun prog debug state trace = do
         EOF -> do
           getProcessExitCode handle >>= \case
             Nothing -> -- process still running, send SIGTERM
-              terminateProcess handle
+              killProcess handle
             Just ExitSuccess ->
               return () -- do nothing
             Just (ExitFailure code) -> do