Since this website gets a lot of spam (ongoing investigations are currently in force in order to analyse the spambots' patterns, a post will be made here when they have been stopped) and this website also has a comments feed powered by atom.gen.php, I have had a chance to test atom.gen.php out in the wild with real data.

I discovered, unfortunately, that the script didn't handle invalid utf-8 and non printable characters very well, and this lead to the feed getting broken because XML doesn't like certain specific characters. This has now been fixed.

If you handle user input and use atom.gen.php to turn it into a feed, you will want to grab an updated copy of the script (quick link here) and overwrite your previous copy in order to fix this.

As well as fixing that, I also added a new option, $usecdata. This controls whether the <content> tag's contents should be wrapped in <![CDATA[...]]>. This should add extra protection again html / javascript injection attacks breaking your feeds. It defaults to false, though, so you need to manually enable it by setting it to true.

The reference has been updated accordingly.

If you find another bug, please comment below. You will recieve full credit at the top of the file (especially if you provide a fix!).