The RTS chokes on SIGPIPE (happens with runInteractiveCommand)
Consider the following code.
-- code based on example by steven_ashley on #haskell import System.Process import System.IO import Control.Exception main = do data <- readFile "core" (inp,out,err,pid) <- runInteractiveCommand "cat" print "before" finally (hPutStr inp data) (print "after")
This program, when run with a large enough
core file in the current directory, will print
"before" and then exit.
What happens (according to
strace) is that the RTS closes the input end of the output pipe of the
cat process (the one associated with the
out variable). Then,
cat tries to write some of its output and gets killed by
SIGPIPE. This in turn closes the input end of its input pipe. When the Haskell program writes its next chunk of data, it is killed by
I believe the right fix for this is for the RTS to ignore
SIGPIPE. The write syscall would then return
EPIPE in the above scenario, which can be handled by the normal exception mechanism.