From: Rafael Sadowski <rafael@sizeofvoid.org>
Subject: Re: slowcgi: preserve PARAMS order in the CGI environment
To: tech@openbsd.org
Date: Mon, 13 Jul 2026 21:50:07 +0200

On Mon Jul 13, 2026 at 07:25:12PM +0200, Florian Obser wrote:
> On 2026-07-13 16:50 +02, Rafael Sadowski <rafael@sizeofvoid.org> wrote:
> > I fixed the order in httpd ("tail insert during  read from conf"
> > followed by "tail insert" during copying) but still had an incorrect
> > order because of slowcgi.
> 
> Out of idle curiosity, why is this important?
> 
> slist_init(3) has this:
> 
>      Singly-linked lists are the simplest of the five data structures and
>      support only the above functionality.  Singly-linked lists are ideal for
>      applications with large datasets and few or no removals, or for
>      implementing a LIFO queue.
> 
>      Simple queues and singly-linked tail queues add the following
>      functionality:
> 
>            1.   Entries can be added at the end of a list.
> 
>      However:
> 
>            1.   All list insertions must specify the head of the list.
>            2.   Each head entry requires two pointers rather than one.
>            3.   Code size is about 15% greater and operations run about 20%
>                 slower than singly-linked lists.
> 
> I'm not opposed to the change (it reads OK), but it does not come for
> free. Btw. there is a copy of slowcgi.c in usr.sbin/bgplgd...
> 

Thanks Florian, good point. I haven't found a use case where the order
would matter.

If anyone has a use case, we can go with that, but I doubt it.

It was only important for my test(tm), but I could see from the logs that it
was correct in httpd.