diff options
Diffstat (limited to 'System/Posix/Process/Common.hsc')
| -rw-r--r-- | System/Posix/Process/Common.hsc | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/System/Posix/Process/Common.hsc b/System/Posix/Process/Common.hsc index 51c75b3..1b504df 100644 --- a/System/Posix/Process/Common.hsc +++ b/System/Posix/Process/Common.hsc @@ -81,7 +81,9 @@ import System.Posix.Types import Control.Monad #ifdef __GLASGOW_HASKELL__ +import Control.Exception.Base ( bracket, getMaskingState, MaskingState(..) ) -- used by forkProcess import GHC.TopHandler ( runIO ) +import GHC.IO ( unsafeUnmask, uninterruptibleMask_ ) #endif #ifdef __HUGS__ @@ -278,6 +280,9 @@ threads will be copied to the child process. On success, 'forkProcess' returns the child's 'ProcessID' to the parent process; in case of an error, an exception is thrown. +The exception masking state of the executed action is inherited +(c.f. 'forkIO'), see also 'forkProcessWithUnmask' (/since: 2.7.0.0/). + 'forkProcess' comes with a giant warning: since any other running threads are not copied into the child process, it's easy to go wrong: e.g. by accessing some shared resource that was held by another thread @@ -286,10 +291,19 @@ in the parent. forkProcess :: IO () -> IO ProcessID forkProcess action = do - stable <- newStablePtr (runIO action) - pid <- throwErrnoIfMinus1 "forkProcess" (forkProcessPrim stable) - freeStablePtr stable - return pid + -- wrap action to re-establish caller's masking state, as + -- 'forkProcessPrim' starts in 'MaskedInterruptible' state by + -- default; see also #1048 + mstate <- getMaskingState + let action' = case mstate of + Unmasked -> unsafeUnmask action + MaskedInterruptible -> action + MaskedUninterruptible -> uninterruptibleMask_ action + + bracket + (newStablePtr (runIO action')) + freeStablePtr + (\stable -> throwErrnoIfMinus1 "forkProcess" (forkProcessPrim stable)) foreign import ccall "forkProcess" forkProcessPrim :: StablePtr (IO ()) -> IO CPid #endif /* __GLASGOW_HASKELL__ */ |