(with apologies to D. Adams)
Hi,
The code enclosed, works as expected for 2.10, works for
proto-3.03-15-Jul but breaks for 3.03 (latest from the CVS). The
problems seems to be something to do with handles: you write something
to it, but it doesn't go to the pipe.
With the code I am working right now (the SQL thingy) the problem
shows up as non-termination, while it happily terminates under proto.
Feel free to get back to me if you want to see the real code, but the
enclosed demonstrates that there is something wrong.
Thanks,
Laszlo & Liuhai
--------------------------------------------------------------------
module Main(main) where
import IO
import Posix
import System
main = do
a <- echoIt "aaa"
putStrLn a
where
aaa = "aaa" : aaa
echoIt x = do
(inH, outH) <- exec "/bin/cat" []
hPutStr inH x
fd <- handleToFd inH
fdClose fd
x <- hGetContents outH
return x
exec :: String -> [String] -> IO (Handle, Handle)
exec cmd args = do
(pWriteFd, cReadFd) <- createPipe
(cWriteFd, pReadFd) <- createPipe
child <- forkProcess
case child of
Just x -> do -- parent
pWriteH <- fdToHandle pWriteFd
pReadH <- fdToHandle pReadFd
fdClose cReadFd
fdClose cWriteFd
hSetBuffering pWriteH NoBuffering
hSetBuffering pReadH NoBuffering
return (pWriteH, pReadH)
Nothing -> do -- child
-- replace stdin, stdout with read and write end of the pipe.
dupTo cReadFd stdInput
dupTo cWriteFd stdOutput
fdClose pReadFd
fdClose pWriteFd
executeFile cmd True args Nothing
exitWith ExitSuccess
