PHP with open_basedir performance problem

[Arkadi Shishlov]

Stanislav Sedov wrote:
> I'd suggest you to disable open_basedir at all or roll out specialized
> implementation. I had a lot of similar problems with open_basedir in
> the past, so I just rewrote it to match our specific security policy.

Can you share a hint how exactly this specialized implementation may look like?
The requirement is simple: php script working under apache mod_php can't open files outside of 
virtual host document root whenever php safe mode is enabled or disabled. Website owners can create 
symlinks.
I understand the open_basedir is kinda flawed security measure, and safe_mode is a primary safeguard 
with mod_php, but it would be nice to get it working under FreeBSD too.

> Most basedir problems are linked with the fact it produce a lot of lstast/
> readlinks on every require, include or open command. On Linux it pereforms
> even worse, as they implemented readlink there by hand, and, of course,
> their implementation isn't particulry good.

But there is no high sys cpu usage on Linux in contrary to FreeBSD, as reported by original author 
of the thread..?
Do you have numbers or benchmark ready? I see the number of syscalls required is astonishing (on 
Linux) but doesn't cause any problem at first look.