nick.recoil.org - Home

AppleTV & Ubuntu hacking

2008-05-05T23:04:00Z

I’ve finally enabled SSH on my long dormant AppleTV, and am integrating it into my DVB / Rails / Beanstalk / MySQL system for processing data. I’ve used the Patchstick image available from atv4windows. I ended up unpacking and dd’ing the image from the Mac, but the process remains exactly the same. I now have Perian, ssh and a slew of other things enabled, and all I need now is to attempt the hack to get composite output working. I’ve yet to take the plunge and replace my old CRT with an LCD TV.

Incidentally, for anyone looking to figure out the ssh username and password for your freshly enabled ssh daemon, they are both frontrow, and that user has passwordless sudo privileges.

I also had a minor breakthrough with my x86_64 Ubuntu 8.04 machine. I have a Zyxel G-202 Wireless USB stick, to keep the number of trailing wires to a minimum, but I kept getting an error saying:

1	zd1211rw error ioread32(CF_REG1): -110

Which was exceedingly unhelpful. I eventually tried disabling hi-speed USB from the BIOS, and rebooted to find it sprang into life immediately. Great! What was even more strange that when I rebooted and reset the BIOS back to enable USB 2.0, the G-202 kept working. I’m unsure whether this is due to the device not being cold booted, and I’ve yet to see if it stops working after I power the system off, but so far so good, and I don’t need to resort to NDIS.

Mongrel init.d script

2008-04-07T12:50:00Z

I’ve slightly modified Bojan Mihelac’s Mongrel init.d script to cope with the situation where there are stale PID files left from a server failure.


#!/bin/env ruby
#
# mongrel Startup script for Mongrel by Tim Morgan, modified by bmihelac and Nick Ludlam
# Originally from http://source.mihelac.org/2007/3/27/customized-mongrel-startup-script
#
# chkconfig: 2345 85 15
# description: mongrel manages Mongrel
#

apps = [
  {:app => 'app1'},
  {:app => 'app2'},
  {:app => 'app3'}
]

default_port = 8000
default_options = {
  :app_dir => '/var/www',  :environment => 'production'
}

pid_location = "log/mongrel.pid"

if ['stop', 'restart'].include? ARGV.first
  apps.each do |app|
    options = default_options.merge(app)
    path = File.join options[:app_dir], options[:app], "current"
    puts "Stopping #{path}..."
    `/usr/local/bin/mongrel_rails stop -c #{path} -P #{pid_location}`
  end
end

if ['start', 'restart'].include? ARGV.first
  apps.each do |app|
    options = default_options.merge(app)
    path = File.join options[:app_dir], options[:app], "current"
    port = options[:port] || default_port
    pid_file = File.join path, pid_location

    # Check and remove stale PID file. Platform needs "ps -p" support
    if File.exists?(pid_file)
      old_pid = File.read(pid_file)
      `ps -p #{old_pid}`
      if old_pid.to_i > 0 && $?.exitstatus == 1
        puts "Removing stale PID file"
        File.unlink(pid_file)
      end
    end

    puts "Starting #{options[:app]} on #{port}..."
    `/usr/local/bin/mongrel_rails start -d -p #{port} -e #{options[:environment]} -c #{path} -P log/mongrel.pid`
    default_port = port + 1

  end
end

unless ['start', 'stop', 'restart'].include? ARGV.first
    puts "Usage: mongrel {start|stop|restart}"
    exit
end

MacPorts contributions

2008-04-01T10:27:00Z

I’ve been accepted as a committer to MacPorts, initially to look after beanstalkd, but I’ll hopefully extend what I contribute to. I’ve been a consumer of Macports (née Darwinports) for a long while, and use it regularly to create my local development environment on the Mac. As of today, I have 98 ports installed, from ImageMagick to zlib, and I’m happy to be giving back some effort to something I get so much value from.

Saving my blown Seagate Barracuda 7200.10 hard drive

2008-03-21T13:59:00Z

Whilst messing around with my Mini ITX box, I managed to touch the power connector onto the drive backwards, blowing one of the components near the connector. I noticed that the controller board is screwed on with standard torx screws, so I took them out, curious about the connector to the main chassis.

After removing them, the board came away easily, and uses pressure pads as a connection mechanism, rather than ribbon cable or other methods. This set me wondering about whether this would be a replaceable part. I contacted Seagate, who told me that they don’t supply them separately. I then wondered about getting an identical drive, and replacing the old board with one from the new drive, so I went ahead and ordered a replacement; I’d need it anyway, even if this attempt at data recovery failed.

After it arrived, and I’d done the swap, I turned on the machine, and back came my drive with all my data on it, safe and sound. I did worry about whether the IDE controller boards carry some kind of mapping table that’s specific to a particular set of platters, but this isn’t the case, it seems. Unfortunately I’ve no way of repairing the original blown board. Replacing surface mount components is tricky.

For anybody wondering, you can replace the controller board for a Seagate Barracuda 7200.10 500GB drive with no ill effects.

Stalling Wi-fi uploads on Mac OS X 10.5.2

2008-03-03T12:22:00Z

I was sitting in my local wifi-enabled cafe in London for the first time yesterday, and was struck with a peculiar problem. I could attach to their Wi-fi network properly, and browsing webpages worked fine, but trying to scp a small file to one of the recoil.org servers was stalling at exactly 2064kB.

I had a quick glance around for the problem on Google, and a thread turned up on the Apple message board. These people were discussing the same symptoms as I was having; An scp would start out fine, but stall after a particular amount of data had transfered. Following lots of discussion about tuning net.inet.tcp.delayed_ack, I tried fiddling with all sort of sysctl and ifconfig settings for the best part of an hour, and eventually had success.

I had to drop the MTU of en1 down from 1500 all the way down to 1400 for the problems to go away. The more common settings you might find via Google such as 1492 didn’t resolve the issue. For those of you who might have arrived here looking at similar issues, type the following into a Terminal window:


 sudo ifconfig en1 mtu 1400

I’m not entirely sure what was going on, but Path MTU discovery is turned on by default on the Mac. By blocking ICMP packets on the Wifi network, it may cause issues with the discovery system. If people are more familiar with the networking circumstances here, drop me a comment/email.

DSVideo released to the public

2008-02-12T21:02:00Z

After a lot of behind-the-scenes development and testing, Dominic and I have released DSVideo to the world. It’s an multi-platform open-source wavelet video encoder and a player for the Nintendo DS. Head on over to see what all the fuss is about.

Mephisto plugin to allow self-updating links

2007-09-10T00:52:00Z

I’ve placed a page under code which details a little plugin I’ve been working on for Mephisto. It’s designed to make links in your templates which need to point to the latest software release always valid. It scans a directory according to a shell glob expression, and gives back a block with the file path, name and version as local variables.

The shell glob expression can be passed in via the liquid template, as per normal with mephisto plugins, or it can be passed in as a special tag attached to the page which is being rendered. This allows per-page links, rather than per-template, and gives greater flexibility.

More information is on the dynamic file link page.

Computer Lib

2007-09-06T20:10:16Z

I’ve just got hold of my first edition print of Computer Lib/Dream Machines by Ted Nelson. It’s an amazingly inspirational read, and covers a bewildering number of topics. It’s a shame that it’s a little too large to take on holiday with me to Italy.

Freeview's timeshifted channels

2007-09-04T19:54:00Z

Certain channels exist on Freeview which are nothing but timeshifted content from another channel. By convention, these have been called plus 1 channels, so ITV2+1 is a channel devoted to showing exactly what is on ITV2, delayed by one hour….except it doesn’t.

The image above was shown last night between roughly 10 and 12pm, during the time when ITV2 was showing Beverly Hills Cop II. Now I would think this is because ITV2 has paid for a particular number of showings during a given time period, and technically speaking, ITV2+1 broadcasting it would constitute as another showing, and that would push it over that figure. This might also be related to whether or not the content had been shown on ITV1 before ITV2, as is often the case.

This is, of course, a ridiculous waste of precious terrestrial bandwidth, and I wonder just how profitable it is for these +1 channels to be maintained. The usual way people would arrive at watching content on a +1 channel is if they’ve seen something on the non-timeshifted channel, and would like to see it from the beginning. This means the programme would have to be at least 1 hour long to begin with, and be sufficiently compelling to make people bother to find the +1 version of the channel.

These channels are also rendered useless when the viewer has a set-top box with a hard disk, and the box records the content they are interested in.

Last but not least, why not timeshift ITV1, which appeals to a larger audience? Perhaps there would be even less actual content for an ITV1+1 due to these rights restrictions. It would all depend on how much content is bought, and on what terms. Having said that, ITV1 is billed as “Top viewing”, whereas ITV2 is billed as “Top US shows”, according to the ITV website, which would suggest ITV2 has more bought content.

I also think messages like the one above reduce the amount of trust the viewer has in a +1 channel. If they find something they would like to view from the beginning, but they’ve previously been denied the chance because of those legal reasons, they might not return in the future. This is exacerbated by the fact that no information is given to the viewer to suggest why the content can’t be shown, and it is left to them to puzzle it out.

Starbucks short cappuccino

2007-07-11T18:05:00Z

For some reason, I was reading the Slate article on the mysterious Short Capuccino from Starbucks, and I thought I’d try it out in my local. The guy serving me, as described in the Slate article, didn’t bat an eyelid when I asked. 1.95 UKP for a regular Tall cappuccino, and 1.75 UKP for a Short cappuccino, and it’s definitely a better amount of milk in my opinion.

This has been brought to you by the trashy coffee department

Wordwrap - A fantastic NDS homebrew game

2007-05-10T11:34:00Z

I’ve spent much of my recent commuting time hunched over my NDS, playing Wordwrap

It’s a very simple game which presents you with a number of letters, and you have to construct as many words out of them as possible, with or without a time limit, depending on your chosen game type. Simple, but very very engrossing.

Who killed Mrs De Ropp?

2007-05-06T13:36:00Z

For BBC4’s Edwardian Birth of Now season, they’ve commissioned a number of interesting programmes, but none quite as interesting as Who Killed Mrs De Ropp?, which is based on three short stories by Saki. People have been likening Saki to a proto-Roald Dahl, but these stories definitely have a stronger appeal to adults, as mentioned in an interview with Ben Daniels in TV and Satellite Week magazine. Daniels stars as the narrator, playing both Saki, and one of characters in the first story. The music, colour and directing are all fantastic, and one of the nicest touches is the seamless integration of the cut-out/silhouette style animation, representing the children’s imaginations, with the live action of the actors.

Well worth watching, if you get an opportunity

Fetching Railscasts with Hpricot

2007-05-06T11:13:00Z

In the spirit of why’s original nostrils , I’ve made a small Hpricot script to fetch me a set of screencasts from Railscasts


require 'rubygems'
require 'hpricot'
require 'open-uri'

uri='http://railscasts.com/episodes/'
from,to=*ARGV.map { |arg| arg.to_i }
(from..to).to_a.each do |ep|
  doc = Hpricot(open("#{uri}#{ep}"))
  puts (doc/'div.download').first.at('a')['href']
end

Then invoke by


ruby railscasts_downloader.rb 15 20 | xargs -n1 wget

A quick note

2007-04-16T23:11:00Z

Just a very quick note to say that I’ve rolled out Mephisto as the tool which hosts this blog, after a somewhat par-for-the-course migration from Typo. I’ve done a little template styling, but most of the wrangling was re-hosting assets, and fiddling with database contents. I’m posting up more content about my recent work soon

Hacking Growl support into SSHKeychain on Mac OS X

2006-09-08T20:14:00Z

After being inspired by Anil, I have also managed to eliminate the incredibly annoying way SSHKeychain creates modal alert boxes which get buried under every other window on your desktop, and prevent you from interacting with it before you dismiss them.

There are two aspects to my hackery. One is to introduce a very simple sleep() call before the application responds to the kIOMessageSystemHasPoweredOn message, which gets posted after a system has awoken from sleep. This stops any SSH tunnels you have defined from being initialised before the system has re-associated with its network properly. This is an issue more frequently encountered with wireless networks, which are slightly slower to respond, and the main reason I started this work. I was sick of hunting for, and clicking away endless boxes informing me that “The tunnel has unexpectedly terminated and could not be restarted.”

I have also managed to hack Growl support in to the application. The new alert panels look like this:

The messages are much less intrusive, and won’t prevent you from restarting any SSH tunnels if you just ignore them, unlike the current NSRunAlertPanel() method.

Incidentally, it’s worth mentioning here that I find SSH tunnels very very useful for being able to send email via SMTP no matter which network you are connected to. I have a permanent tunnel set up from localhost:2525 to the recoil.org servers, and it means I only need one outbound server definition within Mail.app.