guile-www-2.9 (www cgi) does not support mod-lisp/fastcgi style uses

[Alan Grover]

guile-www-2.9 (www cgi) captures the CGI Environment once. If the 
containing process is called to serve a subsequent request, the values 
will usually be wrong. The current implementation is not friendly to 
mod-lisp/fastcgi uses (or testing!).

Module: www cgi
Version: 2.9

The *env-alist* constructs an alist at module-load time, composed of 
delayed "getenv" calls. Thus, while the values are not captured at 
module-load time, they are memoized the first time they are accessed.

"The value of the promise is cached (or "memoized") so that if it is 
forced a second time, the previously computed value is returned" [r5rs, 
Control Features]. I could find no mechanism to un-memoize.

Note that this may lead to different CGI values being captured during 
different requests. For example, the first request may capture the URI, 
the next request may capture its PATH-INFO, and so on.

I don't know the behavior of promises in threads, so I do not know if 
the module will misbehave in a threaded-server model.

There may be other values that are not re-initialized by "init", I have 
not attempted to be comprehensive.

A suggest patch that resets the promises at "init" time is:

cgi.scm

43c43,45
< (define *env-alist*
---
> (define *env-alist* #f)
> (define (make-env-alist)
>  (set! *env-alist*
98c100
<                                 #\, types)))))))))
---
>                                 #\, types))))))))))
117a120
>   (make-env-alist)
>   (set! form-variables '())

I'm working on a suggested change to (www cgi) that will include this 
patch. It should be available within the next 2 days.

--
Alan Grover
address@hidden
+1.734.476.0969