Entities, ext/xml and libxml 2.7

As many people have found out, entity handling in ext/xml is broken when used with libxml2 2.7.0-2.7.2. The problem lies with the way pre-defined entities are handled; or rather not handled when used with one of the newer libxml2 versions. The entities, &, < , >, ' and " never get passed to the user's callbacks, causing a big problem in quite a number of applications out there. Needless to say, I've received a good amount of hate mail over this problem. Got to love people. You never hear how grateful anyone ever is, but sure as hell once there is a problem they are all over you. Anyways, I digress.

Although I have been telling people for a few years now that they should use XMLReader rather than ext/xml, this breakage was not intentional; no matter what anyone says – Yes, I've had a few throw that out there. The good news is that the problem has finally been fixed, but will require both an updated PHP (5.2.9+) and libxml2-2.7.3, although none of them have yet been released. Until things are available, the available options are to either compile your own builds using the code from the libxml2 and PHP repositories, don't upgrade to libxml2 2.7.x yet if you haven't yet done so, build ext/xml with expat rather than libxml2, or lastly, convert your PHP code to use XMLReader.

My parting thought on this to everyone is just switch to the XMLReader extension. It's faster, easier to use and much more powerful.