From: Eleanor McHugh <eleanor@...>
Date: 2009-08-03T23:41:40+09:00
Subject: Re: JRuby, ffi, bad file descriptor

On 3 Aug 2009, at 14:06, Charles Oliver Nutter wrote:
> Ahhh. Yeah I see the problem.
>
> In JRuby, because we don't normally have access to the "real" file
> descriptor for any IO channel, all our logic for fileno is basically
> fake. We keep an artificial list of numbers that map to IO channels
> and use that as our file descriptor table. In this case, you're
> pulling in a real file descriptor from the system, which does not
> exist in our table, so we raise an error.
>
> In order for us to support arbitrary descriptors in our IO we'd
> probably need an implementation of IO that used all low-level C APIs
> rather than Java IO APIs. There's currently no (public) way to get
> from a file descriptor to an IO channel in Java APIs.
>
> So I'll divert this issue by asking: what does this get you that our
> built-in tempfile support does not? We do not use MRI's tempfile.rb;
> we've implemented our own on top of Java's tempfile support that
> performs quite a bit better. Perhaps there's a missing feature we can
> add.
>
> It would also be worth discussing this with Wayne Meissner. It would
> certainly be *nice* if we could transparently support real file
> descriptors, and he may know a way to do it.

I'd be interested in support for that as well if it's possible: a lot  
of fun tricks on Unix platforms rely on misappropriating file  
descriptors and injecting them into IO objects.


Ellie

Eleanor McHugh
Games With Brains
http://slides.games-with-brains.net
----
raise ArgumentError unless @reality.responds_to? :reason