[racket] Too Many Redirects (Apache)

From: Jay McCarthy (jay.mccarthy at gmail.com)
Date: Sat Sep 17 00:34:29 EDT 2011

Unfortunately serve/servlet does not have a way to know when it's
ready. However, serve does provide a confirmation-channel argument
that sends back which port was opened, so you could listen to that.
That's kind of a pain in the neck, because even though you have
dispatch/servlet it's not very nice.

However, something I've done before for the same effect is to wait for
the banner to be printed (it uses confirmation-channel so it knows
what port to report in the banner). You can see this at:


Another thing to do would be to start the server in one thread, then
use another thread to poll the port until it gets a response, and then
setuid in that thread.


On Fri, Sep 16, 2011 at 1:50 PM, Jeremy Kun <kun.jeremy at gmail.com> wrote:
> Right so I just have to call set-uid once on the first start request,
> because serve/servlet hangs. Is there a slicker way to have serve/servlet
> call some given initialization function once after doing it's work and
> before receiving any requests? I don't see anything for that in the
> documentation, but maybe I missed it. Anyway, what I have works at least.
> Exactly how unsafe is it? Is it just unportable?
> And thanks, Eli, but I'm less scared of hard-coding my known ruid than
> having a piece of data floating around with a pointer to my passwd. (even if
> it's hashed)
> Jeremy
> On Fri, Sep 16, 2011 at 1:26 PM, John Clements <clements at brinckerhoff.org>
> wrote:
>> On Sep 16, 2011, at 11:03 AM, Jay McCarthy wrote:
>> > I think you can use ffi-lib with #f because it is already attached.
>> Yeah, okay, looks like this works:
>> #lang racket
>> (require ffi/unsafe)
>> ;; return type is "gid_t". Safe to use int?
>> (define setuid
>>  (get-ffi-obj "setuid" (ffi-lib #f)
>>               (_fun _int -> _int)))
>> (setuid 0)
>> ... naturally, the setuid 0 fails, you'd have to start as root and go
>> down. Also, you'd need to do that *after* the listen on port 80.
>> John

Jay McCarthy <jay at cs.byu.edu>
Assistant Professor / Brigham Young University

"The glory of God is Intelligence" - D&C 93

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