[Haskell-cafe] Re: sendfile leaking descriptors on Linux?

[Bardur Arantsson]

Brandon S. Allbery KF8NH wrote:
> On Feb 5, 2010, at 02:56 , Bardur Arantsson wrote:
[--snip--]
> 
> "Broken pipe" is normally handled as a signal, and is only mapped to an 
> error if SIGPIPE is set to SIG_IGN.  I can well imagine that the SIGPIPE 
> signal handler isn't closing resources properly; a workaround would be 
> to use the System.Posix.Signals API to ignore SIGPIPE, but I don't know 
> if that would work as a general solution (it would depend on what other 
> uses of pipes/sockets exist).

It was a good idea, but it doesn't seem to help to add

	installHandler sigPIPE Ignore (Just fullSignalSet)

to the main function. (Given the package name I assume 
System.Posix.Signals works similarly to regular old signals, i.e. 
globally per-process.)

This is really starting to drive me round the bend...

One further thing I've noticed: When compiling on my 64-bit machine,
ghc issues the following warnings:

Linux.hsc:41: warning: format ‘%d’ expects type ‘int’, but argument 3 
has type ‘long unsigned int’
Linux.hsc:45: warning: format ‘%d’ expects type ‘int’, but argument 3 
has type ‘long unsigned int’
Linux.hsc:45: warning: format ‘%d’ expects type ‘int’, but argument 3 
has type ‘long unsigned int’
Linux.hsc:45: warning: format ‘%d’ expects type ‘int’, but argument 3 
has type ‘long unsigned int’

Those lines are:

39: -- max num of bytes in one send
40: maxBytes :: Int64
41: maxBytes = fromIntegral (maxBound :: (#type ssize_t))

and

44: foreign import ccall unsafe "sendfile64" c_sendfile
45:   :: Fd -> Fd -> Ptr (#type off_t) -> (#type size_t) -> IO (#type 
ssize_t)


This looks like a typical 32/64-bit problem, but normally I would expect 
any real run-time problems caused by a problematic conversion in the FFI 
to crash the whole process. Maybe I'm wrong about this...

Cheers,