runInteractiveProcess is broken

[Peter Simons]

I managed to get runInteractiveProcess to work after all.
Here is the code:

> import System.Posix.Signals
> import System.IO hiding ( catch, try )
> import System.Exit ( ExitCode(..) )
> import System.Process
> import Control.Concurrent
> import Child   -- http://cryp.to/child/Child.hs
>
> test :: IO ()
> test = do
>   installHandler sigCHLD (Catch (return ())) Nothing
>   (_,_,_, pid) <- runInteractiveProcess "/usr/bin/sleep" ["1"] Nothing Nothing
>   sleep 5
>   safeGetExitCode pid >>= print
>
> safeGetExitCode :: ProcessHandle -> IO ExitCode
> safeGetExitCode pid =
>   timeout (10*1000000) (getRCLoop) >>=
>   maybe (fail "timeout while waiting for external process") return
>     where
>     getRCLoop = getProcessExitCode pid >>=
>                 maybe (sleep 1 >> getRCLoop) return

The culprit seems to be: If you don't accept sigCHLD, you
lose. If you use waitForProcess, you lose. Threaded RTS or
not doesn't seem to make a difference.

Peter