[Gcl-devel] Re: Server sockets with GCL?

[Chris Hall]

Jeff Dalton <address@hidden> writes:

> When I did socket stuff in GCL in order to write an HTTP server,
> I wrote a function called accept-socket-connection that returned
> an df (ie, an int), and I wrote something called fdopen that
> would return a Lisp input or output stream.  Then
>
> (defun socket-connection-stream (s)
>   (let ((fd (accept-socket-connection s)))
>     (make-two-way-stream
>       (fdopen fd :input)
>       (fdopen fd :output))))
>
> fdopen was named after the C procedure that makes a FILE from an fd.
>
> I could then do normal I/O with the resulting stream.
>

I found an 'accept-socket-connection' in the GCL Tk support code, for
use with the GCL Tk server, apparently.  Camm has mentioned though, that
TK-oriented socket C code seems to expecting magic numbers in the packet
headers - whatever that mean, I haven't gotten that far with C sockets
yet.

> All of this was reasonably straightforward to do using the C
> interface.
>
> I'm not sure how freely available my code is, though it's supposed
> to become open source as part of O-Plan (an AI planning system)
> at some point.
>
> However, I'd be ahppy to try to help other people with such
> things where I can.

Thanks!  Hopefully, it won't be necessary, though. ;-D

>
> BTW, is there any documentation for the GCL C interface.
> My copy of the KCL manual was destroyed in a fire, and I
> couldn't find anything on-line.

As for 'official' docs, in gcl-si.info (gcl-si.info-4, to be precise), I
found:

  * DEFENTRY - appears to be the GCL eqivalent of the FFI?  A way to
    call C routines from Lisp.  Minimal example, I haven't tried it
    (yet!), but it looks sufficient from here.

  * DEFCFUN - the reverse of DEFENTRY, apparently.  Allows calling GCL
    Lisp functions from C.  Minimal example, haven't tried.

  * CLINES - embed line(s) of C in an GCL function.  Inline C?  The
    hacker in me immediately thinks "And if the C compiler on your
    system supports inline assembler . . ." :-D

This may be enough to get me started, at least.

I also poked around a bit in the source for GCL - there are some _old_
examples of calling X11 from GCL, and some interesting Tk examples -
there is also gcl-tk.info, FWIW.

Thanks again,
+Chris

-- 
What is life? It is the flash of a firefly in the night. It is the
breath of a buffalo in the wintertime. It is the little shadow which
runs across the grass and loses itself in the sunset.
--- Crowfoot's last words (1890), Blackfoot warrior and orator.

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