System/Posix/Process/Internals.hs

    {-# LANGUAGE CApiFFI #-}
    {-# LANGUAGE Trustworthy #-}

    module System.Posix.Process.Internals (
           pPrPr_disableITimers, c_execvpe,
           decipherWaitStatus, ProcessStatus(..) ) where

    import Foreign
    import Foreign.C
    import System.Exit
    import System.IO.Error
    import GHC.Conc (Signal)

    -- | The exit status of a process
    data ProcessStatus
       = Exited ExitCode        -- ^ the process exited by calling
                                -- @exit()@ or returning from @main@
       | Terminated Signal Bool -- ^ the process was terminated by a
                                -- signal, the @Bool@ is @True@ if a core
                                -- dump was produced
                                --
                                -- @since 2.7.0.0
       | Stopped Signal         -- ^ the process was stopped by a signal
       deriving (Eq, Ord, Show)

    -- this function disables the itimer, which would otherwise cause confusing
    -- signals to be sent to the new process.
    foreign import capi unsafe "Rts.h stopTimer"
      pPrPr_disableITimers :: IO ()

    foreign import ccall unsafe "__hsunix_execvpe"
      c_execvpe :: CString -> Ptr CString -> Ptr CString -> IO CInt

    decipherWaitStatus :: CInt -> IO ProcessStatus
    decipherWaitStatus wstat =
      if c_WIFEXITED wstat /= 0
          then do
            let exitstatus = c_WEXITSTATUS wstat
            if exitstatus == 0
               then return (Exited ExitSuccess)
               else return (Exited (ExitFailure (fromIntegral exitstatus)))
          else do
            if c_WIFSIGNALED wstat /= 0
               then do
                    let termsig    = c_WTERMSIG wstat
                    let coredumped = c_WCOREDUMP wstat /= 0
                    return (Terminated termsig coredumped)
               else do
                    if c_WIFSTOPPED wstat /= 0
                       then do
                            let stopsig = c_WSTOPSIG wstat
                            return (Stopped stopsig)
                       else do
                            ioError (mkIOError illegalOperationErrorType
                                       "waitStatus" Nothing Nothing)

    foreign import capi unsafe "HsUnix.h WIFEXITED"
      c_WIFEXITED :: CInt -> CInt

    foreign import capi unsafe "HsUnix.h WEXITSTATUS"
      c_WEXITSTATUS :: CInt -> CInt

    foreign import capi unsafe "HsUnix.h WIFSIGNALED"
      c_WIFSIGNALED :: CInt -> CInt

    foreign import capi unsafe "HsUnix.h WTERMSIG"
      c_WTERMSIG :: CInt -> CInt

    foreign import capi unsafe "HsUnix.h WIFSTOPPED"
      c_WIFSTOPPED :: CInt -> CInt

    foreign import capi unsafe "HsUnix.h WSTOPSIG"
      c_WSTOPSIG :: CInt -> CInt

    foreign import capi unsafe "HsUnix.h WCOREDUMP"
      c_WCOREDUMP :: CInt -> CInt