Hello,

With the following value:
'/sites/cavalex.com/html:/usr/local/tool/php4/lib/php'
for the open_basedir variable, all these commands
work without error (or warning):

$zip = zip_open("/sites/cavalex.com/html/test.zip");
$zip = zip_open("/tmp/test.zip");
$zip = zip_open("/sites/other.net/html/test2.zip");

I was waiting for an open_basedir restriction for 
the two last. Probably a lack of test for this 
open command.

--- config ----

safe_mode  On

open_basedir
/sites/cavalex.com/html:/usr/local/tool/php4/lib/php

--- compil ---
zziplib-0.11.15.tar.gz
apache-2.3.24
php-4.2.0
'./configure' '--prefix=/usr/local/tool/php4' '--with-apxs=/usr/local/tool/apache/bin/apxs' '--with-mysql=/usr/local/tool/mysql' '--with-pgsql=/usr' '--with-zlib' '--with-bz2' '--with-zip=/usr/local/tool/zziplib' '--with-dom=/usr/lib' '--with-gd=/usr/local' '--with-ttf' '--with-freetype-dir=/usr/local/tool/freetype' '--with-t1lib=/usr/local/tool/t1lib' '--with-pdflib=/usr/local/tool/pdflib' '--with-bcmath' '--with-tiff-dir=/usr/lib' '--with-png-dir=/usr/lib' '--with-jpeg-dir=/usr/lib' '--with-xpm-dir=/usr/X11R6' '--with-iconv' '--disable-debug' '--enable-xslt' '--with-xslt-sablot=/usr/local/tool/Sablot' '--with-expat-dir=/usr/local/tool/expat' '--enable-safe-mode' '--enable-memory-limit' '--enable-ftp' '--enable-calendar' '--enable-trans-sid=yes' '--enable-sysvshm=yes' '--enable-sysvsem=yes' '--enable-debug=no' '--enable-force-cgi-redirect=yes'