Re: [Sbcl-devel] READ-CHAR-NO-HANG Hangs

[Elliott S. <ell...@gm...>]

On Jan 10, 2008 1:03 AM, Nikodemus Siivola <nik...@ra...> wrote:
> On 1/10/08, Elliott Slaughter <ell...@gm...> wrote:
>
> > I've been trying to write a non-hanging read function for a project I
> > am working on. The code below works except that after the user presses
> > a key, SBCL hangs until the user presses enter. In the test loop
> > below, the loop runs properly (read-some returns immediately) until
> > the user presses a letter, causing the read-some (and thus the loop)
> > to hang until the user presses enter.
>
> Are you on Windows by any chance? This works for me as expected on
> posixoid platforms, and our Windows implementation for SYSREAD-MAY-BLOCK-P
> in src/code/fd-stream.lisp is quite different from all other platforms.

Yes. And I just confirmed that it works fine under linux.

> I'm not sure if this can be done on Windows without changing the Console
> state, and I'm equally unsure if it's kosher for READ-CHAR-NO-HANG to do
> that behind the user's back. (Similarly as we don't frob tcattrs on other
> platforms.)
>
> Hm. We seem to be using just ReadFile on Windows. It might be that we should
> use ReadConsole in this case.
>
>  http://msdn2.microsoft.com/en-us/library/ms684958(VS.85).aspx
>
> ...but I don't have a Windows development box at the moment, so I cannot
> look into this properly. I am happy to merge code from intrepid Windows
> hackers, however.

I don't really know enough about windows specific programming to help
you... I just happened to be running my code on windows at the time.
But I would be happy to test anything you come up with.


-- 
Elliott Slaughter

"Any road followed precisely to its end leads precisely nowhere." -
Frank Herbert