Laszlo Nemeth writes:
>
> 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.
>
There's a couple of problems here:
- the problem with hClose not closing the underlying file descriptor
has been fixed (and quite a long time ago too), so, instead of,
fd <- handleToFd inH
fdClose fd
do
hClose inH
A little bit nicer, and should do the right thing in the presence
of Handle buffering.
- it looks as if you're working on a platform that gives you back
a duplex pipe via pipe() (Solaris?), since the version of 'exec'
you're gets the input and output fd's wrong (I thought I sent
you guys a fixed version of this a while ago..?) Instead, try
using the version appended instead and have another go.
hth,
--sigbjorn
exec :: String -> [String] -> IO (Handle, Handle)
exec cmd args = do
(cReadFd, pWriteFd) <- createPipe
(pReadFd, cWriteFd) <- createPipe
child <- forkProcess
case child of
Just x -> do -- parent
fdClose cReadFd
fdClose cWriteFd
pWriteH <- fdToHandle pWriteFd
pReadH <- fdToHandle pReadFd
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
fdClose cReadFd
fdClose cWriteFd
exitWith ExitSuccess
