BigSmoke » Rowan Rodrik

Why doesn’t he just…

Rowan Rodrik — Sat, 04 Feb 2012 17:50:53 +0000

You know the conversation. You had the conversation:
“Why doesn’t he just …”
“I don’t understand why he can’t simply …”
“If he’d only …”

Usually followed by: “I used to, but I …”
Or: “At least you have (not) …”

Well, I had this conversation, but at least I …
I am writing about it, so that at least you …

You know the truth:
No, he can’t just …
At least, he couldn’t …

Now, you might …
But if it’d be so easy to …
You wouldn’t be congratulating each other that …
You’re just slightly better than him …

How does it feel?
Safe?

If only you would …

Commenting fixed for blog.bigsmoke.us

Rowan Rodrik — Sat, 04 Feb 2012 11:10:31 +0000

To my great surprise, thanks to Tobias Sjösten, I found out that commenting was broken on blog.bigsmoke.us. I couldn’t pinpoint the exact problem, but it must have been introduced with some WordPress upgrade somewhere along the line. I never noticed it because it did work for logged in users. (If I must really guess, I suspect a silent ReCaptcha version compatibility problem.)

Upgrading WordPress and wp-recaptcha to their latest versions (3.3.1 and 3.1.4 respectively) seems to have solved the problem.

Psychopathic Saturday

Rowan Rodrik — Sat, 21 Jan 2012 12:30:46 +0000

I’m trying to pump up myself to write a piece of text about psychopathy. All three other group members already wrote their part. We’re making a scientific poster titled “Is there a psychopath hidden in your brain?” But, do I even want to know? It’s all very close to home, with a mother who’s been accusing her ex-husband (my dad) of being a psychopath for, like, forever, and, simultaneously, this monkey in my brain, pointing it’s accusative little finger straight at me.

I am naked and feeling very vulnerable

Rowan Rodrik — Thu, 19 Jan 2012 22:12:56 +0000

There are many clever ways to tell you this. There are many ways to deceive. But in the end I feel that more often than not the deception merely serves to reinforce that image of a very vulnerable naked man.

Thus: “I am naked and feeling very vulnerable.”

MediaWiki ConfirmEdit/QuestyCaptcha extension

Rowan Rodrik — Tue, 17 Jan 2012 13:43:44 +0000

Since I moved my LDAP wiki over from DokuWiki to MediaWiki, I’ve been burried by a daily torrent of spam. Just like with my tropical timber investments wiki, the ReCaptcha extension (with pretty intrusive settings) doesn’t seem to do much to stop this shitstream.

How do the spammers do this? Do they primarily trick visitors of other websites into solving this captchas for them or do they employ spam-sweatshops in third-world countries? Fuck them! I’m trying something new.

I’ve upgraded to the ConfirmEdit extension. (ReCaptcha has also moved into this extension.) This allows me to try different Captcha types. The one I was most interested in is QuestyChaptcha, which allows me to define a set of questions which the user needs to answer. I’m now trying it out with the following question:

$wgCaptchaQuestions[] = array( 'question' => "LDAP stands for ...", 'answer' => "Lightweight Directory Access Protocol" );

I don’t think it’s a particularly good question, since it’s incredibly easy to Google. But, we’ll see, and in the mean time I’ll try to come up with one or two questions that are context-sensitive, yet easy enough to answer for anyone with some knowledge of LDAP. If you have an idea, please leave a comment.

Safari: don’t give gzipped content a .gz extension

Rowan Rodrik — Sun, 15 Jan 2012 22:39:13 +0000

Yesterday, while helping Caloe with the website for her company De Buitenkok, I came across the mother of all stupid bugs in Safari . Me having recently announced payformystay.com, I loaded it up in Apple’s hipster browser only to notice that the CSS wasn’t loaded. Oops!

Reloading didn’t help, but … going over to the development version, everything loaded just fine. Conclusion? My recent optimizations—concatenating + gzipping all javascript and css—somehow fucked up payformystay for Safari users. The 14 Safari visitors (16.28% of our small group of alpha users) I received since the sixth must have gotten a pretty bleak image of the technical abilities of payformystay.com’s Chief Technician (me).

The old `cat | gzip`

So, what happened?

To reduce the number of HTTP requests per page for all the JavaScript/CSS stuff (especially when none of it is in the browser cache yet), I made a few changes to my build file to scrape the of my layout template (layout.php), which I made to look something like this:

 if (DEV_MODE): ?>
  "stylesheet" type="text/css" href="/layout/jquery.ui.selectmenu.css" />                                   
  "stylesheet" type="text/css" href="/layout/fancybox/jquery.fancybox-1.3.4.css" />                         
  "stylesheet" type="text/css" href="/layout/style.css" />                                                  
 
                                            
                                               
                                 
                                        
                                               
                              
                                    
                               
 else: # if (!DEV_MODE) ?>
  "/layout/motherofall.css.gz?2" rel="stylesheet" type="text/css" />
  
 endif ?>

It’s very simple: All the files with a “&lt!--MERGE ME-->” comment on the same line got concatenated and gzipped into motherofall.css.gz and 3rdparty.js.gz respectively, like so:

MERGE_JS_FILES := $(shell grep '' layout/layout.php|sed -e 's/^.*

I chose to directly reference the gzipped version of the css/js, even though I had a .htaccess files in place (within /layout/) which was perfectly capable of using the right Content-Encoding for each Accept-Encoding.

`$ cat /layout/.htaccess`

AddEncoding gzip .gz
 
RewriteEngine On
 
RewriteCond %{HTTP:Accept-Encoding} gzip
RewriteCond %{REQUEST_FILENAME}.gz -f
RewriteRule ^(.*)$ $1.gz [QSA,L]
 

ForceType text/css

 

ForceType application/javascript

You may notice that the .htaccess file contains some configuration to make sure that the .gz files are not served as something like application/gzip-compressed.

Anyway, I went to see if there were any browsers left that do not yet Accept-Encoding: gzip and could find none. When, yesterday, I was faced with an unstyled version of my homepage, my first reaction was (after the one where I was like hitting reload 20 times, embarrassedly mumbling something about “those damn browser-caches!”): “O then, apparently, Safari must be some exception to the rule that browsers have all been supporting gzip encoding for like forever!”

No, it isn’t so. Apparently Safari ignores the Content-Type header for any resource with an URL ending in .gz. Yes, that’s right. Safari understand Content-Encoding: gzip just fine. Not problems. Just don’t call it .gz.

The new `cat ; gzip`

So, let’s remove the .gz suffix from these files and be done with it. The .htaccess was already capable of instructing all necessary negotiations to be able to properly serve the gzipped version only when it’s accepted (which is always, but I digress).

A few adjustments to my Makefile:

MERGE_JS_FILES := $(shell grep '' layout/layout.php|sed -e 's/^.*

That’s it. I welcome back all 14 Safari users looking for paid work abroad! Be it that you’re looking for international work in Africa, in America, in Asia or in Europe, please come visit and have a look at what we have on offer.

Announcing payformystay.com

Rowan Rodrik — Fri, 06 Jan 2012 21:04:37 +0000

Januari the first, a very good day to announce a new project that I’ve been working on this past year. Which I did, on Facebook and Twitter. Now, five days later, it’s time te repeat the announcement to give it some much-needed link-juice. I know that normal people don’t follow this blog. (I don’t even follow this blog!) But it does have PageRank. And it does have 4000 monthly visitors. Time for some link-whoring!

PFMS search screen - top

PFMS search screen - bottom

payformystay.com is a website for adventurers who’re looking for paid work abroad. Whether you want to work in Europe, work in Afrika, work in Asia, work in Australia or whether you just want to do some seasonal work anywhere but home (grape picking, strawberry harvest, whatever you fancy). Of course we have many types of work: office jobs, tourism jobs, healthcare jobs, childcare jobs, wildlife jobs, anything.

The cool thing about payformystay, though, is that we only sport paid jobs. So, no wrestling through page after page of crappy offers where some evil cunt swine tries to make you pay for your own work. That’s right! Job offers on payformystay.com must at the very least include full board (something like a bed or tent and 3 meals daily) or enough pay to cover these basic living expenses! Offers are audited and violators are fed to the spammers.

Go get yourself a piece of the action:

payformystay.com – where people get paid to go on adventure

Peace out. End of announcement.

Have fun! Be scared! Be tough! And be safe!

Ubuntu Desktop Linux and Acer TravelMate 7513WSMi

Rowan Rodrik — Wed, 02 Feb 2011 22:55:17 +0000

My youngest sister has retired her big-ass (17″) Acer TravelMate (model 7513WSMi 7510) with a more modern offering from Sony. That was last year. Now, she thought it’d be a good idea to donate it to our oldest sister. But since the thing has always “run” like a pig with Windows Vista, her girl-geek instincts thought it better if I’d equip the old monster with Ubuntu Linux instead.

AMD 64bit

I’m also considering upgrading my own laptop to 64 bit. (They’ve told me that, really, the 32 bit age is over.) So, the first thing I’m trying to find out (now that I’m getting on the 64 bit train) is if this thing supports 64 bit. I can’t really think of a quick way to find out, so I’m just going to create a 64bit installation CD and see how that works.

…

Or, I could have just popped open the hood to see the “AMD Turion64x2 Mobile Technology” sticker.

Installation

After changing the boot order, the installation CD (burned from my T61 using “wodim -data ubuntu-10.10-desktop-amd64.iso”) seems to be booting despite the worrying sounds that seem to indicate that the laptop is trying to rip apart and eat the disc.

I’m surprised how good the current installation program looks and that it asks me if I want to “download updates while installing” and “install third-party software”. Nice.

Great idea to ask all the annoying questions (timezone, etc.) during installation instead of after! I’m amused with how much I’m behind the time if I see all the promotional screens for new and improved software which is meant to keep me inspired during the installation process. “OpenOffice.org is fully compatible with Microsoft Office[...]” Am I really that much behind with the times? Nah, I can’t imagine. I must still have some very, very nasty Excel sheet lying around somewhere, gathering dust. If I feed that monster of a thing to OpenOffice, then I’m pretty sure… Yeah, that’s going to be fun.

Post-installation configuration

I had expected to spend at least an hour or two hunting around forums to find solutions for obscure driver-related issues and other nuisances. But no issues popped up. It just worked. Ubuntu is very compatible with the Acer TravelMate 7513WSMi!

So, I spent some of the time saved on setting a user pic and a few other niceties, but I refrained from doing anything fancy, because I’ve figured out a new sister support strategy that I might blog about later. (It involves a four-hour work-week…)

[For my own reference, I started on the first draft of this post on Januari 14.]

Making a shell-script run with setuid root

Rowan Rodrik — Wed, 02 Feb 2011 22:45:50 +0000

If you want to run a process with root privileges that you can invoke as a less unprivileged user, you can make the program setuid root. This can be very useful, for example, when you want a PHP or CGI script to call a backup process, or to create a new site or irrevocably delete you whole system. The latter example points to a serious security problem: if anyone can figure out a way to make your program do something you don’t want, you’re screwed, because you just gave them root privileges to wreak maximum havoc. That’s why, normally, scripts (anything executed by an interpreter by the kernel because of a shebang) won’t get elevated privileges when you set their setuid bit.

To understand the setuid bit, let’s first see what happens when I try to cat a file that belongs to root:

su -
# I am now root; fear me
touch no-one-can-touch-me
chmod 600 no-one-can-touch-me
exit
cat no-one-can-touch-me
# cat: Permission denied

Next, I’ll create a shell script that cats the file:

#!/bin/bash
 
cat no-one-can-touch-me

And make the script setuid root:

su -
chown root:root script.sh
chmod +xs script.sh

If I now execute the script, I still get the permission denied. What I need to make this work is a wrapper program. For that, I refer to Wiebe’s post about the same subject. (Yeah, I know: why bother publishing this if Wiebe already did an excellent job explaining? Well, I just hate to throw away an otherwise fine draft.)

Remove appending slash from a path using Sed

Rowan Rodrik — Sat, 29 Jan 2011 19:49:26 +0000

Here’s how you can remove the appending slash from a path using sed, the stream editor:

echo /just/a/path/ | sed -e 's#/$##'
# Output: /just/a/path
 
# And, if there isn't an appending slash, nothing happens:
 
echo /just/another/path | sed -e 's#/$##'
# Output: /just/another/path

It works quite simple. Sed executes expression (-e) on its standard input. The expression is a substitution using regular expressions. The #-sign is the delimiter. The part (#/) between the first two hash signs is the matching expression and the (empty) part between the second and the third hash sign is the replacement expression. This expression (“s#/$##”) basically says: replace all occurrences of “/” at the end of the line (the dollar sign is the end-of-line anchor) with nothing.

To use this in a script is easy-peasy. Suppose $1 is a system path that may or may not include an appending slash:

#!/bin/bash
 
sanitized_path=`echo "$1" | sed -e 's#/$##'`
 
echo $sanitized_path

This script outputs its first parameter with the appending slash removed.