Debian – Page 48

My Debian Activities in June 2012

July 2, 2012 by Raphaël Hertzog

This is my monthly summary of my Debian related activities. If you’re among the people who made a donation to support my work (168.12 €, thanks everybody!), then you can learn how I spent your money. Otherwise it’s just an interesting status update on my various projects.

Dpkg

This month, I resumed my work on dpkg. I concentrated my efforts on some “polishing” of the “3.0 (quilt)” format. With the latest version (1.16.6 — which was uploaded to unstable shortly before the freeze), dpkg-source restores the source tree in a clean state after a failed patch application (#652970), doesn’t overwrite the patch header from the pre-existing automatic patch, updates automatically debian/source/include-binaries during dpkg-source –commit, and supports a new –no-unapply-patches option for those who dislike the auto-unapplication at the end of the process when the patches were not applied at the start.

I wanted to go further and offer a new feature that could insert the automatic patch at the bottom of the quilt series but I have been short on time to complete this feature. I just managed to factorize all the quilt handling in a dedicated Perl module (Dpkg::Source::Quilt) to have cleaner code in the module handling the source format (Dpkg::Source::Package::V3::quilt).

For those who wonder, this feature is meant primarily for the X Strike Force team which maintains packages in Git and are doings lots of upstream cherry-picks (to fix regressions, etc.). But they also use quilt on top of that tree to keep some lasting Debian specific changes. With the 1.0 format, the “automatic diff” is a bit messy but at least it gets smaller automatically when a new upstream release gets out, there’s nothing to clean out. I’d like them to be able to use “3.0 (quilt)” while keeping their workflow. I’m leaning towards allowing “--auto-commit=first:cherry-picks” that would name the automatic patch “cherry-picks” and put it in the first position in the quilt series. (Opinions welcome on that feature, BTW)

Packaging

There’s been quite some packaging in this last month before the freeze:

I packaged CppUTest (a test framework for C/C++), and I wrote an article about it.
I prepared a stable update of Publican to fix a missing dependency. I also updated the unstable version to include a backport of a fix that some user requested me to include.
I updated dh-linktree to improve its documentation (following a discussion that happened on debian-devel) and to deal properly with trailing slashes in its input (#673408).
I sponsored dblatex 0.3.4-1 and ledgersmb 1.3.18-1.
I updated gnome-shell-timer to a new upstream snapshot that was tagged as compatible with GNOME 3.4 (#6776516).
I packaged wordpress 3.4 and spent a whole day triaging the old bugs that accumulated. A few days later I developed a new infrastructure to properly manage plugins/themes/language files. The canonical directory where the user is expected to drop his custom plugins/themes is now in /var/lib/wordpress/wp-content/ and the official plugins/themes are “installed” there with symlinks pointing back to /srv/data/web/vhosts/wp.freexian.com/htdocs/wp-content/ where they actually reside.
I wanted to commit 2 patches for the developers-reference but then I noticed that some translations were complete and were waiting for an upload. So I cleaned the packaging (switch to dh) and I uploaded version 3.4.8 before committing the patches for #678710 and #678712.

While doing all this packaging work, I found 2 possible improvements that I filed as bug reports:

#676606: debcommit should be able to identify alone that a new release is prepared (when the distribution field of the changelog changes from UNRELEASED to something else).
#679132: lintian outputs false positives for the tag package-uses-local-diversion when neither –local nor –package is given on the dpkg-divert command line.

Debian France Booth at Solutions Linux

From June 19th to June 21th, I manned the Debian France booth at Solutions Linux together with Carl Chenet, Tanguy Ortolo and other members of the association. We answered lots of questions, sold all t-shirts and umbrellas that Carl imported from Germany and Switzerland (we really need to get our own merchandising stuff produced in France!), got people to join the association. We also presented a printed copy of the Debian Administrator’s Handbook and of the corresponding French book.

You can see Carl, me and Tanguy on this picture (click on it to see a bigger picture, thanks to Sébastien Dubois of Evolix for this one!):

I know lots of people are preparing for Debconf but I decided to not attend this year, the price of the air plane ticket was a bit too hefty for me and it was also in partial conflict with our family vacations. I thought about attending the Libre Software Meeting instead but alas I won’t go there either (but Roland Mas will be there!), I have too much work to complete before my own vacation in 2 weeks.

Thanks

See you next month for a new summary of my activities.

Test Driven Development with CppUTest, now in Debian

June 25, 2012 by Raphaël Hertzog

I have recently read Test Driven Development with Embedded C by James W. Grenning and published by Pragmatic Programmers.

I really enjoyed the book: while I was aware of the huge benefits of having a comprehensive test suite, I never studied seriously the principles behind Test Driven Development (TDD) and this book makes a good introduction to the topic. At the same time it focuses on the C language and contains lots of examples on how you can create tests even for projects which have to interact with hardware or other unpredictable components (the key is to create many abstractions) using all the possibilities that C offers.

The author convincingly argues that developing code with TDD forces you to create a modular design that is easier to evolve when the underlying requirements change. He also highlights how the tests serve as reference documentation of the API.

James W. Grenning recommends CppUTest as his xUnit test framework of choice. When I wanted to try this test framework, I discovered that it was not available in Debian. I decided to package it because it has some interesting features not offered by the contenders (at least not to my knowledge). It’s now available in Debian and in Ubuntu.

First, it doesn’t require any explicit registration of tests and has a very lightweight syntax. The small downside is that CppUTest requires the usage of C++ for the tests. But C++ is compatible with C so it doesn’t matter much if you have a C++ compiler for your target. On the contrary, usage of variables and methods scoped to the test group makes it easy to write clear tests. Here’s a short sample of test code:

extern "C" {
#include "timer.h"
#include "timefn.h"
}
 
#include "CppUTest/TestHarness.h"
 
static Time the_time;
static const int start_sec = 123;
static const int start_nsec = 456789000;
static const int delay_sec = 8;
static const int delay_nsec = 111111000; // start_nsec + delay_nsec < 10^9
 
TEST_GROUP(Timer)
{
    /* Class variables available to all tests in the group */
    Timer timer;
    Delay remaining;
 
    /* Standard setup/teardown methods of xUnit tests */
    void setup() {
        timer = timer_new();
        time_set(&the_time, start_sec, start_nsec);
        /* [...] */
    }
 
    void teardown() {
        timer_free(timer);
        /* [...] */
    }
 
    /* Helper functions specific to the test group */
    void start_timer_with_delay(long sec, long nsec)
    {
        timer_set_real_delay(timer, sec, nsec);
        timer_start(timer);
    }
 
    void ensure_remaining_is(long sec, long nsec)
    {
        CHECK_EQUAL(sec, delay_get_seconds(remaining));
        CHECK_EQUAL(nsec, delay_get_nanoseconds(remaining));
    }
};
 
TEST(Timer, NewIsNotStarted)
{
    CHECK(!timer->started);
}
/* [...] */
TEST(Timer, GetRemainingTimeWithNanosecondPrecision_ShiftOfSeconds)
{
    start_timer_with_delay(delay_sec, delay_nsec);
    time_set(&the_time, start_sec + delay_sec - 5, start_nsec + delay_nsec + 1000);
 
    remaining = timer_get_remaining_time(timer);
 
    ensure_remaining_is(4, 999999000);
}

To run those tests, you just need this boilerplate code in a main.cpp:

#include "CppUTest/CommandLineTestRunner.h"
 
int main(int argc, char** argv)
{
   return CommandLineTestRunner::RunAllTests(argc, argv);
}

Another interesting feature is its integrated memory leak detection system. Any test that hasn’t released allocated memory at the end of the “teardown” process will be marked as failed.

The upstream developers have made some unusual choices (static library only, installation in a private directory) but this will likely change with the switch to an automake and autoconf-based build system. I have reported the oddities that I found and I requested them to provide a pkg-config file to make it easier to compile and link unit tests exploiting CppUTest.

I already used CppUTest to develop a small application running on an embedded Linux. At some point, I might try to use CppUTest for dpkg development. I believe that it makes for a good fit. dpkg is already C++ ready since dselect is written in C++ and reuses a good part of dpkg’s code.

In any case, if you like Test Driven Development and are writing C or C++ based applications, I invite you to try CppUTest.

My Debian Activities in May 2012

June 1, 2012 by Raphaël Hertzog

This is my monthly summary of my Debian related activities. If you’re among the people who made a donation to support my work (338.26 €, thanks everybody!), then you can learn how I spent your money. Otherwise it’s just an interesting status update on my various projects.

Dpkg

Like last month, I did almost nothing concerning dpkg. This will probably change in June now that the book is out…

The only thing worth noting is that I have helped Carey Underwood who was trying to diagnose why btrfs was performing so badly when unpacking Debian packages (compared to ext4). Apparently this already resulted in some btrfs improvements.

But not as much as what could be hoped. The sync_file_range() calls that dpkg are doing only force the writeback of the underlying data and not of the meta-data. So the numerous fsync() that follow still create many journal transactions that would be better handled as one big transaction. As a proof of this, replacing the fsync() with a sync() brings the performance on par with ext4.

(Beware this is my own recollection of the discussion, while it should be close to the truth, it’s probably not 100% accurate when speaking of the brtfs behaviour)

Packaging

I uploaded new versions of smarty-gettext and smarty-validate because they were uninstallable after the removal of smarty. The whole history of smarty in Debian/Ubuntu has been a big FAIL since the start.

Once upon a time, there was a smarty package and some plugins. Everything was great except that the files were installed in a way that differs from the upstream recommendations. So Ubuntu changed the path in their version of the package and did not check whether it broke anything else (and it did break all the plugins). Despite the brokenness of the plugins, this divergence survived for years. So several packages that were using Smarty were modified to use dpkg-vendor to use the correct path depending on whether it was built on Debian or Ubuntu.

In 2010, Smarty 3.0 has been released and instead of upgrading the smarty package to this version, one of the smarty co-maintainers introduced a smarty3 package that used yet another path (despite the fact that smarty 3 had a mode to be compatible with smarty 2).
At some point, I informed him that he had to handle the migration of users of smarty to smarty3… he acknowledged and then lost interest in smarty (“I’m no longer using it”) and did nothing.

After some more bitrot, smarty has been forcefully orphaned in August 2011 by a member of the security team. And in March this year, it has been removed from unstable despite the fact that it still had reverse dependencies (usually removals only happen when they impact no other packages, I don’t know why this wasn’t the case here).

At least the brokenness attracted some attention to the situation and Mike Gabriel contacted me about it. I offered him to take over the various packages since they all needed a real maintainer and he accepted. I sponsored his uploads of all smarty related packages (bringing in the latest upstream versions at the same time).

In the end, the situation is looking better now, except that there’s no migration path from users who rely on smarty in Squeeze. They will discover that they need smarty3 in Wheezy and that the various paths have to be adjusted. It’s probably acceptable since the new upstream versions are no longer backwards compatible with smarty 2…

The Debian Administrator’s Handbook

At the start of the month, I was busy preparing the release of the book. I introduced the publican-debian package to unstable, it’s a Publican brand (aka a set of CSS and XSL stylesheets to tailor the output of Publican) using the Debian colors and using the Debian logo. This brand is used by the book.

I also created the debian-handbook package and setup the public Git repository on alioth.debian.org.

I was ready or so I thought. A few hours after the announce, the website became unusable because the numerous visitors were exhausting the maximum number of client connections. And I could not increase the limit due to Apache’s memory usage (with PHP and WordPress). We quickly off-loaded most of the static files traffic to another machine and we setup bittorrent. The problem was solved for the short term. Thousands of persons downloaded the ebook and to this date, 135 copies of the paperback have been sold.

Then I took a one-week vacation. Even though I had no Internet at the place I was, I wandered in the street to find a “Freewifi” wifi network (customers of the Free ISP can use those freely) to stay on top of incoming email. We quickly received some bug reports and I dealt with the easy ones (typos and the like) on the fly.

When I came back at home, I manually placed 54 lulu orders for the people who opted for the paperback as reward during the fundraising campaign. A bit tedious but it had to be done (if only Lulu supported a way to batch many orders at once…).

I also wanted a long term solution to avoid the use of an external host to serve static files (should a new traffic spike arrive…). So I installed nginx as a front-end. It serves static files directly, as well as WordPress pages which have been cached by wp-super-cache. Apache is still here listening on a local port and responding to the remaining queries forwarded by nginx. Once I’ll migrate to wheezy, I might completely ditch apache in favor of php5-fpm to handle the PHP pages.

Last but not least, I wanted to bootstrap the various translations that people offered to contribute. I wrote some documentation for interested translators and blogged about it. It’s shaping up nicely… check it out if you’re interested to help!

Thanks

See you next month for a new summary of my activities.

The Debian Administrator’s Handbook is available

May 10, 2012 by Raphaël Hertzog

I am so glad that we managed to complete this project. Roland and I have spent countless hours on this book since December, both for the translation itself and also for all the things that we tend to forget: a nice book cover, a great book layout for the print version, coordinating the work of reviewers, registering as an editor to get an ISBN, etc. I think I will come back to this in a future article because some parts of the story are interesting.

In the mean time, enjoy the DFSG-free Debian Administrator’s Handbook:

get it from unstable with apt-get install debian-handbook;
browse the online version;
get the paperback or the ebook (available as PDF, EPUB, MOBI);
grab the sources with git clone git://anonscm.debian.org/debian-handbook/debian-handbook.git and contribute a translation 🙂

Check out the official announce (there’s a discount for early buyers of the paperback).

Dpkg

Packaging

Debian France Booth at Solutions Linux

Thanks

Dpkg

Packaging

The Debian Administrator’s Handbook

Thanks

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