Intercepting fopen, mysql_connect, and similar functions for migration

I'm migrating a website from one server to another, and my file paths and dbs have changed. For example /a/b/c/foo.txt on the old machine is at /x/y/z/foo.txt on the new machine. The MySQL db "foo" on the old machine is "bar" on the new machine. Can I intercept fopen() and mysql_connect() so that when PHP does fopen("/a/b/c/foo.txt"), I magically (using Zend functions or method overloading or anything else) convert it at runtime to fopen("/x/y/z/foo.txt"). Same thing so that mysql_connect("foo") becomes mysql_connect("bar"). The code is badly written: doing a search/replace in the code wouldn't really work. I really want to "hook" fopen()/mysql_connect() and similar commands so I can tweak their args before they actually execute. Is there any hope? Sort of like an LD_PRELOAD for PHP? -- We're just a Bunch Of Regular Guys, a collective group that's trying to understand and assimilate technology. We feel that resistance to new ideas and technology is unwise and ultimately futile.