Re: How to simple exit in CGI?

On Wed, Mar 29, 2017 at 02:15:04AM +0200, Pascal Bourguignon wrote:

> > *** - Ctrl-C: User break
> > Break 1 [1]> 
> 
> Well, it looks like test.cgi was hung, not printing anything, and
> that your web server decided to kill it with a SIGINT.  This was
> interpreted as a C-c by clisp, and entered into the debugger, then
> the web server took that output and returned it.

Yes, that is what I assume.

> Here’s how I catch and report errors, saving them into files:
> 
> I’ve left the call to (error "Simulated error.”)  for your tests.  
> You must remove it (and recompile with make) before trying it for real.
> 
> In this case, we want to catch the errors before issuing the
> headers, so I collect them into a string errout, and then depending
> on whether there was an error to compute query, I print an error web
> page, or perform the normal processing.

Thank you much.
Good to know, I will be using it now.

>     <1/89> #<system-function show-stack> 3
>     <2/82> #<compiled-function system::print-backtrace>
>     <3/78> #<compiled-function jean-cgi::print-backtrace>
>     [64] frame binding variables (~ = dynamically):
>       | ~ *print-level* <--> nil
>     Printed 3 frames
>     ERROR while ((setf jean-cgi::query (or (error "Simulated error.") (getenv "QUERY_STRING") (alexandria.0.dev:read-stream-content-into-string *standard-input*)))):
>     Simulated error.
> 
>     [pjb@despina :0.0 jean]$ 
> 
> Works nicely, the error is detected and reported.
> After having removed the call to error, it works as expected:
> 
>     [pjb@despina :0.0 jean]$ sudo rm /tmp/jean-cgi.*
>     Password:
>     [pjb@despina :0.0 jean]$ ./jean.cgi </dev/null
>     Status: 302 Found
>     Location: http://localhost
> 
> 
>     Got query: ""
>     at url: "http://localhost”


So it works for you?

I have tried now with 3-4 web servers.

If I let this like following:

       (let ((errout (with-output-to-string (*error-output*)
                       (reporting-errors
                        (setf query (or (getenv "QUERY_STRING")
                                        (alexandria:read-stream-content-into-string *standard-input*)))))))

I do not wait this time long, maybe 3-4 seconds, then I get:

wget -O /dev/shm/test "http://localhost/test.cgi"; less /dev/shm/test 
--2017-03-29 10:46:46--  http://localhost/test.cgi
Resolving localhost... 127.0.0.1
Connecting to localhost|127.0.0.1|:80... connected.
HTTP request sent, awaiting response... 500 Internal Server Error
2017-03-29 10:46:53 ERROR 500: Internal Server Error.

and /tmp/jean-cgi.trace is empty, no other file.

What is wrong on my side that is different to your side? It works on
your side, and not on my side.

Jean

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