I'm facing a challenge with a customer running a site we built on a hosting environment that is quite restrictive. We used to use htdig to add search functionality, but the hoster doesn't allow execution of binaries.

I've taken a look at several search engine implementations, but so far, none match all requirements:

• Zend Framework's lucene search: requires PHP5, but we have to run it on PHP4

• phpdig: uses exec() to perform the search, but we are running in safe mode
• google: layout not flexible enough
• htdig: requires execution of binaries, which is not allowed
• perlfect: requires execution of perl, which is not allowed

Maybe isearch is an option but I cannot find a lot of info about it.

The requirements are simple, but restrictive:

• Should be usable/integratable in a PHP4 based site

• Should run with safe mode on
• Layout should be customisable
• Should not require execution of perl or binaries, at least not for the search part (uploading an index that is created on a separate machine is somewhat acceptable although not prefered)
• Should be spider based, so no database query based search engine

Free Software/Open Source/Free as in Free Beer would be nice, but is no strict requirement.

Anybody any suggestion? What are you guys using?