Gambit-list Novembre 2004

gambit-list@iro.umontreal.ca

4 participants
5 discussions

Re: [gambit-list] Using read in a networked environment
by Bradley Lucier 27 Nov '04

27 Nov '04

On Nov 26, 2004, at 6:03 PM, Eric Merritt wrote: > I am using gambit to write a client/server application. I am *very* > tempted to just use the read and write functions provided with gambit > for the protocol. I don't think this is a problem sense the resulting > forms will never be evaled. However, there is one issue and that is if > an attacker pumps a *very* large sexpr into the server filling > available memory. I believe that gambit interns all symbols from a read, so an attacker can simply send multiple different symbols until your memory is exhausted. Brad

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Using read in a networked environment
by Eric Merritt 26 Nov '04

26 Nov '04

I am using gambit to write a client/server application. I am *very* tempted to just use the read and write functions provided with gambit for the protocol. I don't think this is a problem sense the resulting forms will never be evaled. However, there is one issue and that is if an attacker pumps a *very* large sexpr into the server filling available memory. As far as I can tell there isn't a way to define a maximum amount of data on a read. There are two obvious solutions to this. The first is to hack the read function slightly to allow this. The other is to just bite the bullet and write a custom protocol (again ;). I hate modifying standard functions and I hate reimplementing something that already exists and mostly works. Perhaps one of you have some advice. -- I'm a programmer, I don't have to spell correctly; I just have to spell consistently

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"Interesting" compiler errors
by Sebastian Hoffmann 17 Nov '04

17 Nov '04

Hello, I'm working on OpenGL-bindings for Gambit ATM. The beginnings are at http://sarg.kollektiv-hamburg.de/~garou/scmGL.scm, the output generated by 'gsc -dynamic' at http://sarg.kollektiv-hamburg.de/~garou/errlog.txt To be honest, I don't have even the slightest glimpse of a clue what went wrong there... Sebastian -- This signature is subject to change without further notice.

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What's the purpose of ##scheme-file-extensions?
by Bradley Lucier 08 Nov '04

08 Nov '04

In _io.scm we find the definition (define ##scheme-file-extensions #f) (set! ##scheme-file-extensions '((".scm" . #f) (".six" . six))) and this is used in gsc somehow so that % gsc -c -expansion interp.gsc doesn't work (unrecognized file type), yet % gsc > (compile-file-to-c "interp.gsc" '(expansion)) does work. So what's the point of having ##scheme-file-extensions? It just seems to get in the way. Brad

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Re: [gambit-list] FFI & threads
by JURKSCH＠focus.ping.de 03 Nov '04

03 Nov '04

> You could create a Scheme port from the file descriptor and then use > the normal I/O operations on that. Here is some (untested) code to > illustrate how this can be done: > (define direction-in 1) > (define direction-out 2) > (define direction-inout 3) > (define (fd->port fd mode) (##open-predefined mode '(fd-port) fd)) > (define fd (get-fd-using-ffi!)) > (define my-port (fd->port fd direction-inout)) > ... use my-port like a normal port ... Thanks, this solves one part of the problem. But the scheme code must not read or write any byte from/to my-port. And I don't see a way to implement (if (foreign-function-tells-io-would-block) (suspend-me-until-io-will-not-block)) without reading or writing. Regards Hermann P.S.: Is ##open-predefined considered stable?

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Gambit-list Novembre 2004