filed under: programming, rainskit.com, tagging, tru_tags, usability

Posted 393 days ago

I’m working on the next version of tru_tags and one of its major features is the ability to create a tag-based archive page, like this one. After implementing the feature, I tried it out, and I liked it so much that I decided to use it on this site. Specifically, I removed the old “About” page, merged some of that content into the “Links” page (and generally edited that page), and put the “Archive” page in where the About page used to be.

This should all make sense if you look at the menu links at the top of the site. For those of you reading this via the feed – click here to see it.

It’s a really interesting page to browse through – I find it strangely fascinating to see so clearly all the articles I’ve written, and how they clump together. I’ve also used it a few times as a faster way to get to a specific page. It’s somehow more powerful than the normal tag cloud, functionally and emotionally, and that surprises me.

Or maybe it’s just late :)

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filed under: family, geek, netbsd, programming

Posted 908 days ago

Waaaay back in April of 2006, my cousin Karen (and her husband David) had a hard drive failure, resulting in the loss of all their digital pictures of their baby daughter Ella. They didn’t have backups, and they didn’t have prints. Computer shops weren’t able to help, and clean-room data recovery was too expensive. Eventually, they gave up on it and sent an email to the family asking if we could send them copies of any pictures we had.

I, being a geek, offered to take a look at the drive and see if I could get anything off of it. They, lacking any better options, sent the drive to me so I could give it a shot.

I dropped the drive into my NetBSD machine and sure enough, the BIOS recognized it. That meant that the drive was still physically working, and that I might have a chance at getting whatever data was left off the drive. I was able to mount the drive (read-only) and read data from it, which meant that there was a good chance of finding at least some of the pictures.

I did a bunch of googling and learned a lot about home-brew data recovery. To sum it up, I learned that you need:

1. A copy of the dd utility that supports the conv=noerror argument. (netbsd’s dd does)
2. A handy program that knows how to find images on a raw drive image. (See below)

I was able to make a copy of the bad drive (onto a good drive of mine) using dd and the instructions on this page. There were a lot of bad drive sectors encountered during the copy, which was to be expected given the fact that the drive had failed in the first place, but I was hopeful about finding at least some of the images. And having the drive copy was a big win – it meant that I could work with a copy that wouldn’t get worse if the hard drive took a dive.

The hard part was finding a program that could recover the images. For a long time I thought I was going to have to write my own, and that seemed a daunting task, but I finally found this guy who had this exact same problem and already wrote this program. It was exactly what I needed – a program that would find and extract images from a raw drive!

The only problem was that jpg-recover was running at about 15kb/s. At that rate, getting through the 80gb hard drive would have taken about 60 days to finish. I didn’t have 60 days (without interruption!) to wait.

So I dug into the code and discovered that it was horribly innefficient. It was reading data one byte at a time, checking for an image after each byte read, and just generally not being smart about performance. I set about improving it.

I was able to do so. My version takes more memory (a configurable amount) but it runs much faster: at about 12000kb/s. That’s 800x faster :) At that rate, it only took about two hours to finish, finding (after some tuning) 4,422 potential images, of which 187 were uncorrupted pictures of Ella – including this one.

That felt good :)

I’ve published my version of the program as jpg-recover-faster. It’s a perl script, so you’ll need perl. I make no guarantees about the lack of bugs – use this script at your own risk. It may eat your children. ;)

You’ll want to read the comment at the top of the script before using it, and the other pages listed above will help you figure out how to use it. Feel free to post comments here with questions or suggestions.

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filed under: geek, programming, textpattern

Posted 935 days ago

I recently submitted a patch to Textpattern to refactor some of the code to eliminate a lot of duplication and allow me to generate tag-based RSS feeds from my plugin. My patch has been applied to the “crockery” branch and will be a part of Textpattern 4.1. Cool!

Update: I’m in it again (in 4.0.5 and 4.1) with my comment patch. Cooler!

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filed under: geek, programming, textpattern

Posted 947 days ago

(In case the title didn’t warn you, non-geeks probably won’t be interested in this article.)

Textpattern has a “feature” whereby HTML tags are completely stripped out of visitor comments, presumably to close a common security hole. I’ve created a patch for Textpattern 4.0.4 that changes it such that HTML tags in comments are allowed, but the relevant characters (<, >, &, ‘, “) are converted to entity codes and therefore aren’t treated as HTML delimiters and therefore aren’t a security concern.

Net effect: it’s possible to post HTML code examples in article comments. I’ll post such a comment right after I post this article, just to prove the point.

I’ll be announcing the patch in the txp-dev mailing list and on the forums, and inviting Textpattern developers to use this article as a place to test such comments. Hopefully it will be merged into the next official Textpattern release, so I don’t have to maintain this patch for more than a few months.

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