[IronPython] IronPython and file descriptors

[Dino Viehland]

(now I've replied to the correct thread...)



Can you open a feature request on CodePlex?  It's certainly an interesting idea to ponder and I'm leaning towards it but there's lots of details to be gotten right.



Do you know if this needs to work w/ sockets as well?  (There's also the question of can we make it work with sockets?  :))



There'll be a bunch of places we need to update (nt, socket, file, select, etc...) so I think it'll have to wait until 2.1 instead of coming in a minor update like 2.0.1.


From: users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com] On Behalf Of Michael Foord
Sent: Monday, December 15, 2008 12:53 PM
To: Discussion of IronPython
Subject: Re: [IronPython] IronPython and file descriptors


2008/12/15 Dino Viehland <dinov at microsoft.com<mailto:dinov at microsoft.com>>
Presumably CPython is linking against msvcrt and is using the C abstraction rather than calling the Win32 APIs which return handles directly.

As Curt said the biggest problem for us is that .NET does not expose C file descriptors.  Therefore we could fix this by P/Invoking out to msvcrt.  For users on other platforms we'd need to either add support for their platform or hope that their handles == C runtime file descriptors.  For something like fileno maybe this is ok because it's an interop point only - or are there any non-interop uses of fileno in the world?

What do people think of this?  This would be the 1st place where we would add a P/Invoke so I'd want to tread lightly and make sure this is really the right thing to do.


Well, some way of doing this is needed if certain Python C extensions are to work with Ironclad. Perhaps a global or per engine setting that allows file handles to be associated with a C descriptor. Users of Ironclad could switch it on if they wished and take the consequences.

Michael Foord



-----Original Message-----
From: users-bounces at lists.ironpython.com<mailto:users-bounces at lists.ironpython.com> [mailto:users-bounces at lists.ironpython.com<mailto:users-bounces at lists.ironpython.com>] On Behalf Of Slide
Sent: Monday, December 15, 2008 10:21 AM
To: Discussion of IronPython
Subject: Re: [IronPython] IronPython and file descriptors

On Mon, Dec 15, 2008 at 11:18 AM, Tom Wright
<tom.wright at resolversystems.com<mailto:tom.wright at resolversystems.com>> wrote:
> Agreed. It is certainly possible with some work to get a file descriptor and
> pass it to C code.
>
> This is not the problem, however. Ironclad's aim (eventually) is to allow
> *arbitrary* C extensions  to work with Ironpython without changing the
> extensions. Ctypes aim is to allow arbitrary C code to be run by python
> (possibly in other python libraries which you really don't want to modify).
>
> In CPython .fileno() is a file descriptor and some modules use this fact
> (specifically PIL) by passing file descriptors as integers into C code. I do
> not know how one can make this code work in IronPython unless .fileno()
> returns a file descriptor.
>
> The game here is not making a particular C library work with IronPython by
> modifying this library but making as many libraries as possible work without
> modification. Of course whether this is worthwhile depends on how many
> libraries rely on this fact.
>
> Sorry - I hope this is a little clearer.
>
> Tom


How does CPython get the file descriptor for fileno()? Does it just
return the HANDLE on Windows?

slide
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