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Test-driven development in Perl

There’s an impressively in-depth presentation from [OSCON 2008](http://en.oreilly.com/oscon2008/public/schedule/proceedings) about [Practical Test Driven Development in Perl](http://assets.en.oreilly.com/1/event/12/Practical%20Test-driven%20Development%20Presentation.pdf). It covers Test::More, Test::Class, Test::Differences, Test::Deep and Test::MockObject.

I also found the following to be interesting: [Even Faster Web Sites](http://assets.en.oreilly.com/1/event/12/Even%20Faster%20Web%20Sites%20Presentation%202.ppt) and [Pro PostgreSQL](http://assets.en.oreilly.com/1/event/12/Pro%20PostgreSQL%20Presentation.odp). Reading these helps me to know a little bit about what I don’t know.

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Visualize your hard drive using a TreeMap viewer

Every once in a while, I get low on disk space, and hunting for large directories or files to delete can be difficult manually. [Tree Map visualization](http://en.wikipedia.org/wiki/Treemap) tools make the job easier. There’s [WinDirStat](http://windirstat.info/) for Windows, [KDirStat](http://kdirstat.sourceforge.net) for KDE, and [Disk Usage Analyzer](http://live.gnome.org/GnomeUtils/Baobab) (baobab) for Gnome.

![TreeMap Image](http://library.gnome.org/users/baobab/stable/figures/baobab_fullscan.png.en)

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Article: A Patent Lie, and other patent happenings

Timothy B. Lee of the Cato Institute wrote [A Patent Lie](http://www.nytimes.com/2007/06/09/opinion/09lee.html?_r=3&oref=slogin&oref=slogin&oref=slogin), in which he explains why copyright is better for the software industry than patents:

> Don’t software companies need patent protection? In fact, companies, especially those that are focused on innovation, don’t: software is already protected by copyright law, and there’s no reason any industry needs both types of protection. The rules of copyright are simpler and protection is available to everyone at very low cost. In contrast, the patent system is cumbersome and expensive. Applying for patents and conducting patent searches can cost tens of thousands of dollars. That is not a huge burden for large companies like Microsoft, but it can be a serious burden for the small start-up firms that produce some of the most important software innovations.

The good news about software patents is that [they’ve been weakened](http://en.wikipedia.org/wiki/KSR_v._Teleflex) so that patent troll companies can’t wreak quite as much havoc as they have in the past. Now there’s not as much money in it. Apparently, [patent troll companies are getting smarter](http://www.linuxworld.com/community/?q=node/16789) about working with open source — most recently with RedHat:

> Trolls need to collect money to survive, and open source vendors can’t give it to them. The good news from this settlement [with RedHat], and [Blackboard’s](http://www.linuxworld.com/news/2007/020107-blackboard-no-action-against-open-source.html), is that trolls are realizing that hitting an open source company is like robbing a store where the safe is on a time lock. They can do damage and hurt people, but the money isn’t available to them.

The settlement was also [documented by Groklaw](http://www.groklaw.net/article.php?story=20080611191302741).

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Products to avoid

The nice thing about mass-market commercial software is that I can purchase it at a small fraction of the cost to develop it myself, which I would never do because I don’t have the time. Unfortunately, home-user mass-market software seems to lack quality. Here are some that I recommend against.

* [Greeting Card Factory](http://www.google.com/search?q=greeting+card+factory). When I opened the package, I discovered that the software shipped on about six separate CDs! I purchased the software in 2007 — an enlightened age where most people have DVD drives. I’m impatient, and disliked having to play disk jockey to install the software. Once installed, I discovered that it’s cumbersome to use — too much clicking with the mouse required to get the job done. There’s no good preview of card greeting messages in the template browser, so I have to load each one in, click through the buttons to see the message, and then start all over again to find an appropriate card. It sure is a waste of time. The best greeting card software I’ve used was American Greetings, but that version was designed years ago and required inserting CDs to load some of the cards. Hallmark’s software was the most polished, robust, and least annoying, but I liked the quality of cards from American Greetings better.

UPDATE: There is a good way to preview greeting card messages in the template browser — you have to increase the zoom level to the maximum, and additional preview controls become visible.

* Symantec and McAffe AntiVirus. They slow down a computer too much (by 20% or more!). Anything that annoys my grandmother about activation is too much of a hassle. Switch to [AVG Free](http://www.google.com/search?q=AVG+free). I run Vista with an unprivileged account, and so far, I haven’t needed AV. I ran AVG Free on Windows XP for several years, and never got a virus — because I didn’t download and install random software — and because my user account didn’t have administrative privileges.

There’s hardware to avoid as well:

* [Kodak printers](http://printers.kodak.com/). I decided to give a Kodak printer a try because of the promise of cheaper ink. The printer has been a constant hassle ever since we purchased it. Just tonight, even after selecting the best print quality, it still printed every other line as faded and smudgy. My wife seems to know the ritual to make it print better, but she’s not here at the moment. Avoid Kodak printers at all costs. Go with an Epson or an HP — they provide quality results. If a laser printer fits your needs, they’re usually more reliable than an inkjet printer.

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Fedora 9, NVidia, VMWare Server

I’ve upgraded four systems to Fedora 9 in the past couple of weeks. For those that have NVidia cards, it was a bumpy ride until NVidia released a [new driver](http://www.nvidia.com/object/linux_display_ia32_173.08.html). To install it as a pre-built RPM package, see [this blog post](http://nareshv.blogspot.com/2008/04/fedora-9-rawhide-and-latest-nvidia-179.html).

For the system that runs VMWare Server, it was necessary to [upgrade to version 1.0.6](http://www.howtoforge.com/vmware-server-installation-on-a-fedora9-desktop), which supports the 2.6.25 kernel shipped with Fedora 9.

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NoMachine NX, Fedora 9 and SELinux

I upgraded from Fedora 7 to Fedora 9 using [preupgrade](http://fedoraproject.org/wiki/PreUpgrade), and then I couldn’t connect to the [NoMachine NX Server](http://www.nomachine.com/). It’s due to SELinux, again (I [wrote about this earlier](http://jaredrobinson.com/blog/?p=89)). The approach to solve it is still the same, although the policy is different:

Here’s what my audit.log messages looked like:

May 30 07:48:03 localhost kernel: type=1400 audit(1212155283.470:7): avc: denied { getattr } for pid=876 \
comm=”sshd” path=”/usr/NX/home/nx/.ssh/authorized_keys2″ dev=sda2 ino=70976 \
scontext=system_u:system_r:sshd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:usr_t:s0 tclass=file \
May 30 08:22:35 localhost kernel: type=1400 audit(1212157355.873:9): avc: denied { read } for pid=872 \
comm=”sshd” name=”authorized_keys2″ dev=sda2 ino=70976 \
scontext=system_u:system_r:sshd_t:s0-s0:c0.c1023 tcontext=system_u:object_r:usr_t:s0 tclass=file

Here’s how I created and inserted the policy:

cd /etc/selinux
cat /var/log/audit/audit.log | audit2allow -M nx
semodule -i nx.pp

And here’s the nx.te file:

module nx 1.0;
require {
type sshd_t;
type usr_t;
class file { read getattr };
}
#============= sshd_t ==============
allow sshd_t usr_t:file { read getattr };

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Open Source Security report from Coverity

[Coverity](http://www.coverity.com) has published it’s [Open Source Scan Report 2008](http://coverity.com/library/pdf/Coverity-Scan_Open_Source_Report_2008.pdf), which details the security status of several open source projects. Here’s my summary:

* The overall security of open source projects is improving.
* There’s a linear relationship between the amount of code and the amount of bugs.
* Surprisingly, there’s no relation between function length and defect density.

Projects with exceptionally low defect density include Amanda, NTP, OpenPAM, OpenVPN, Perl, PHP, Python, TCL, Postfix, Samba, curl, libvorbis and vim.

The top two security defects are

1. NULL pointer dereference
2. Resource leak

I got to preview [Coverity Prevent](http://www.coverity.com/html/prod_prevent.html) at a previous job, and it rocks at finding real bugs in code, with a very low rate of false positives.

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Attempt to patent a mental process

David A. Wheeler says, “The US Court of Appeals for the Federal Circuit in Washington, DC just heard arguments in the Bilski case, where the appellant (Bilski) is arguing that a completely mental process should get a patent. The fact that this was even entertained demonstrates why the patent system has truly descended into new levels of madness. At least the PTO rejected the application.”

Wheeler goes on to explain why [patents on information is lunacy](http://www.dwheeler.com/blog/2008/05/09#bilski-information-is-physical)

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What programs are listening to the network?

Sometimes, I’d like to know what programs on my system are listening to the network, and to quote the Perl motto, “there’s more than one way to do it”. On Linux, there’s `lsof -Pi` and `netstat -p`. On Windows XP and Vista, there’s the built-in `netstat -b[v] -a` and a separate utility called [tcpview](http://technet.microsoft.com/en-us/sysinternals/bb897437.aspx). I’ve included example usages and outputs.

__lsof__ (Linux)

sudo lsof -Pni

COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME
python 1886 root 4u IPv4 6621 TCP 127.0.0.1:2207 (LISTEN)
cupsd 1898 root 3u IPv4 6663 TCP 127.0.0.1:631 (LISTEN)
cupsd 1898 root 4u IPv6 6664 TCP [::1]:631 (LISTEN)
cupsd 1898 root 6u IPv4 6667 UDP *:631
sshd 1912 root 3u IPv4 6711 TCP *:22 (LISTEN)
httpd 20084 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20085 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20086 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20087 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20088 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20089 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20090 apache 4u IPv6 7293 TCP *:80 (LISTEN)
httpd 20091 apache 4u IPv6 7293 TCP *:80 (LISTEN)

__netstat__ (Linux)

sudo netstat -lp –inet –numeric-hosts

Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:ssh 0.0.0.0:* LISTEN 1912/sshd
tcp 0 0 127.0.0.1:ipp 0.0.0.0:* LISTEN 1898/cupsd
tcp 0 0 127.0.0.1:2207 0.0.0.0:* LISTEN 1886/python
udp 0 0 0.0.0.0:ipp 0.0.0.0:* 1898/cupsd

Where’s `httpd`? It should be there, and it is, when I exclude the `–inet` option:

Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 :::http :::* LISTEN 2038/httpd
tcp 0 0 ::1:ipp :::* LISTEN 1898/cupsd

__TcpView__ (Windows)

[Download](http://technet.microsoft.com/en-us/sysinternals/bb897437.aspx) and start TcpView. From the menu, choose File > Save. Here’s the output from the file.

Process Protocol Local Address Remote Address State
svchost.exe:1064 TCP jareds-xp:epmapi jareds-xp:0 LISTENING
System:4 TCP jareds-xp:microsoft-ds jareds-xp:0 LISTENING
svchost.exe:976 TCP jareds-xp:3389i jareds-xp:0 LISTENING
nxssh.exe:2032 TCP jareds-xp:11000 jareds-xp:0 LISTENING

__netstat__ (Windows)

Note that this runs quite slowly on Windows.

netstat -bva

Active Connections

Proto Local Address Foreign Address State PID
TCP jareds-xp:epmap jareds-xp.mydomain.com:0 LISTENING 1064
c:\windows\system32\WS2_32.dll
C:\WINDOWS\system32\RPCRT4.dll
c:\windows\system32\rpcss.dll
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\ADVAPI32.dll
[svchost.exe]

TCP jareds-xp:microsoft-ds jareds-xp.mydomain.com:0 LISTENING 4
— unknown component(s) —
[System]

TCP jareds-xp:3389 jareds-xp.mydomain.com:0 LISTENING 976
— unknown component(s) —
c:\windows\system32\rpcss.dll
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\ADVAPI32.dll
[svchost.exe]

TCP jareds-xp:11000 jareds-xp.mydomain.com:0 LISTENING 2032
[nxssh.exe]

TCP jareds-xp:3389 jareds-xp.mydomain.com:0 LISTENING 976
— unknown component(s) —
c:\windows\system32\rpcss.dll
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\ADVAPI32.dll
[svchost.exe]