I have php installed trough a fastCGI module.

Is there a way to restrict the module (php.exe) read / write permissions to only the directory (+ subdirs) of the IIS site that is calling it?

I need this to prevent one IIS PHP site from having access to files outside its own directory.

How to do this? Is there a setting in php.ini or in the IIS configuration?

I believe such a feature could exist, because when a file on the server is requested the root path of the site is also known, all it would take is that IIS passes this path to the php module, and the php module should on its end allow only IO operations within this path.

PS: I know it is possible to achieve this by using a different windows account for each website, this is not an option.