[IronPython] IronPython and file descriptors

[Michael Foord]

Dino Viehland wrote:
>
> (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.
>

Tom will have to comment on whether it is needed for sockets as well. 
Not yet I guess. :-)

Tom created an issue on Codeplex - I've added a comment to that:

http://www.codeplex.com/IronPython/WorkItem/View.aspx?WorkItemId=20242

Michael
>
> *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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