Drupal Debugging - Fun with CCK, Links and Token.module


I had to debug our TLC website this morning, as it was pointed out to me that parts were misbehaving, and that some content hadn't survived the upgrade from Drupal 4.7 to Drupal 5.2. The missing content was easy, for the most part. It's just a matter of renaming the tables to use the content_TABLE format expected by the current CCK module. The exact table names that are expected are listed in the node_type table, under the "orig_type" field - just prepend "content_" to the "orig_type" value for the table name, and CCK should find everything just fine.

One of the CCK content types used the weburl field type under Drupal 4.7, but this has apparently been replaced by "link" in Drupal 5's version of CCK. That's fine, I'll just swap out the data. Shouldn't be too bad.

What got puzzling, though, was that after switching to link, I was getting segmentation faults on the webserver every time I tried to view, save, or template a CCK content type containing a link. WTF? At first, I didn't make the connection that it was link that was causing problems. Eventually, I created a "test" CCK content type, containing the same fields as the offending content type (every time I tried to view anything in our "Simple Resource" content type, hell was unleashed). I reproduced the same set of fields, and BOOM, Simple Resource was also bringing down the server. So, I started removing fields. Didn't take long, since the content type had a total of 2 fields. I started with the Link field. And the content saved, viewed, and templated just fine.

AHAH! It's something wrong with Link! Maybe it's trying to validate the URL? Maybe it's trying to download the content at the other end of the URL to do some processing?

Nope. Turns out, Link may use the token.module to parse out bits of the URL. But token.module was getting caught in a recursive loop. I had to install token.module to support the current version of pathauto.module - I need that, so I can't disable token.module. Turns out, there's an easy way to avoid this recursion-killing-the-webserver segmentation fault problem. In the CCK definition for the link field, just uncheck the "Allow Tokens" option. Yeah. It's that easy. But it took me all frigging morning to figure out what the problem was, and about 5 seconds to fix it once it was identified.

Links that were useful in diagnosing and solving this:


drupal  tlc 

See Also