After the studies of the rebuild of the Debian archive using clang 2.9 & 3.0 and 3.1, the results of the 3.2 rebuild have been published on http://clang.debian.net. The percentage of failure is the same as clang 3.1: 12.1% of failure. That means that on 18264 packages, 2204 failed to be built with clang (it was 17710/2137 with the version 3.1). The fact that the percentage is the same can be explained by at least two reasons:
First, some upstreams packages have been fixed to be built correctly with clang.
Second, the new warnings + -Werror (example: -Wsometimes-uninitialized) introduced in clang 3.2 triggered some new build failures. To conclude, I think that the 3.2 release confirms the turning point of the 3.1. In term of support of the C and C++ standard, clang has now reached an equivalent quality to gcc (with better detection of errors and an extended set of warnings in -Wall).
Now, from the perspective of the Debian rebuilds, the decrease of number of failures will come from the upstream developers improving their codes (exemple of the error non-void function should return a value) or the Debian Developer/maintainer fixing the programming errors.

One of the drawback of C is the hard memory management. It is because of this aspect that Clang provides a way to detect, at runtime, memory errors. Called Address Sanitizer, it allows, while the program is running, to keep track of the memory and detect typical errors (out-of-bound accesses, use of a variable after a free, etc).

# With the following packages (version 3.2-1~exp3)
$ sudo apt-get install clang clang-3.2 compiler-rt -t experimental

Taking the simple following example, even if the errors are obvious, compilers will accept this code.

#include <stdlib.h>
int main()
char *x = (char*)malloc(10 * sizeof(char*));
free(x);
return x[5];

Built and run with:

$ clang -O1 -g -fsanitize=address -fno-omit-frame-pointer foo.c -o foo
$ ./foo &> memoryDebug.log

The previous command will generate a log file. Log which can be post processed with the asan_symbolize command.

$ asan_symbolize memoryDebug.log

which will give:

=================================================================
==21368== ERROR: AddressSanitizer: heap-use-after-free on address 0x7fb22e547f45 at pc 0x408c44 bp 0x7ffff60c10b0 sp 0x7ffff60c10a8
READ of size 1 at 0x7fb22e547f45 thread T0
    #0 0x408c43 in main /tmp/foo.c:5
    #1 0x7fb22d99f6ac in __libc_start_main /home/adconrad/eglibc-2.16/csu/libc-start.c:227
0x7fb22e547f45 is located 5 bytes inside of 80-byte region [0x7fb22e547f40,0x7fb22e547f90)
freed by thread T0 here:
    #0 0x408c90 in __interceptor_free ??:0
    #1 0x408c0a in main /tmp/foo.c:4
    #2 0x7fb22d99f6ac in __libc_start_main /home/adconrad/eglibc-2.16/csu/libc-start.c:227
previously allocated by thread T0 here:
    #0 0x408d50 in __interceptor_malloc ??:0
    #1 0x408bff in main /tmp/foo.c:3
    #2 0x7fb22d99f6ac in __libc_start_main /home/adconrad/eglibc-2.16/csu/libc-start.c:227
Shadow byte and word:
  0x1ff645ca8fe8: fd
  0x1ff645ca8fe8: fd fd fd fd fd fd fd fd
More shadow bytes:
  0x1ff645ca8fc8: fa fa fa fa fa fa fa fa
  0x1ff645ca8fd0: fa fa fa fa fa fa fa fa
  0x1ff645ca8fd8: fa fa fa fa fa fa fa fa
  0x1ff645ca8fe0: fa fa fa fa fa fa fa fa
=>0x1ff645ca8fe8: fd fd fd fd fd fd fd fd
  0x1ff645ca8ff0: fd fd fd fd fd fd fd fd
  0x1ff645ca8ff8: fa fa fa fa fa fa fa fa
  0x1ff645ca9000: fa fa fa fa fa fa fa fa
  0x1ff645ca9008: fa fa fa fa fa fa fa fa
Stats: 0M malloced (0M for red zones) by 1 calls
Stats: 0M realloced by 0 calls
Stats: 0M freed by 1 calls
Stats: 0M really freed by 0 calls
Stats: 0M (128 full pages) mmaped in 1 calls
  mmaps   by size class: 8:2047;
  mallocs by size class: 8:1;
  frees   by size class: 8:1;
  rfrees  by size class:
Stats: malloc large: 0 small slow: 1
==21368== ABORTING

The main advantage compare to valgrind is that asan is supposed to be way more faster. Threads can be also tricking to develop.
With the following example from stolen from upstream:

#include <pthread.h>
int Global;
void *Thread1(void *x)
Global = 42;
return x;
int main()
pthread_t t;
pthread_create(&t, NULL, Thread1, NULL);
Global = 43;
pthread_join(t, NULL);
return Global;

$ clang -fsanitize=thread -g -O1 foo2.c -fPIE -pie -o foo
$ ./foo
==================
WARNING: ThreadSanitizer: data race (pid=21416)
  Write of size 4 at 0x7f2f1a214a50 by thread 1:
    #0 Thread1 /tmp/foo2.c:4 (exe+0x00000000f850)
  Previous write of size 4 at 0x7f2f1a214a50 by main thread:
    #0 main /tmp/foo2.c:10 (exe+0x00000000f8a4)
  Thread 1 (tid=21417, running) created at:
    #0 pthread_create ??:0 (exe+0x00000001267e)
    #1 main /tmp/foo2.c:9 (exe+0x00000000f894)
==================
ThreadSanitizer: reported 1 warnings

Note that clang also provides scan-build, a static analyzer for memory issues. Not as powerful as the Address Sanitizer (it only works on a file), it provides some excellent reports. See the Wouter's blog post on this subject or the automatic report of scan-build on Scilab.

This is my monthly summary of my free software related activities. If you re among the people who made a donation to support my work (836.78 , thanks everybody!), then you can learn how I spent your money. Otherwise it s just an interesting status update on my various projects. Debian Packaging I uploaded Zim 0.58, WordPress 3.5 (and I had to file a ticket about the availability of sources of minified javascript files again) and another security update for python-django (696535). Speaking of python-django, I forwarded one bug report of Anders Kaseorg concerning Django s bash completion (#695811). I also sponsored the upload of ledgersmb 1.3.25-1. Other Debian work I contributed some patches to improve debian-installer support in live-build. I also added a work-around for bug #652946 in live-installer and committed a fix for this same bug in a jessie branch of partman-target. I also prepared a bugfix for a counter-productive behavior of choose-mirror (#695261, it was not possible to override the codename of the release to install via preseed if you install from a CD with a full base system). I discovered an oddity in the Packages.diff/Index file for the architectures armhf and s390x, I reported it to ftpmasters in #696792. (All those issues were discovered while working for a customer) Debian France I spent quite some time on Debian France this month again. I started by setting up an internal gitolite to manage our accounting/administrative documents. Then I updated galette, the web application that we are using to manage our database of members. In the process, I filed two bugs that we discovered. I immediately tested Galette by registering 4 members that joined during the former mini-Debconf in Paris. We have plans to automate the membership renewal process so we have opened a Paypal account. This month we also cleared the last steps so that I and Sylvestre Ledru have full control on the Debian France bank account. I also registered the new officers at the Tribunal d instance de Sarreguemines . Salt bug reports During the last mini-debconf, I discovered Salt (thanks to Julien Cristau!) and since I had to switch some servers of mine, I took this opportunity to upgrade to wheezy and try out salt at the same time. It took much more time than expected but the result is pleasant. The configuration of all my servers is now well documented/specified in a central Git repository, and moving services is much easier than before. In the process, I filed quite some bugs (#2865, #2851, #2866 and #2875), most of them have been fixed in the 0.11.1 release that just happened. Thanks I wish you a happy new year and all the best for 2013! See you next month for a new summary of my activities.

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A bit more than two weeks after the Mini Debconf in Paris, I am glad to say that the videos of the event are finally published (the sound is not very good for the 4 first presentations, sorry about that).
They will be also available on the new IRILL website with a video player when ready.
All slides are also available on the page of the event. I believe that there is a consensus about the quality of the event. We had around 150 people attending to the event, many interesting and various talks.
As usual, it was nice to meet some old and new friends from Debian.
Group picture by Frederic Lehobey
For those who wonder, I am confident there will be a 2013 Parisian Mini Debconf. Various feedbacks about the event:
Lucas Nussbaum
Stefano Zacchiroli
Vincent Untz
Raphael Hertzog
Pietro Abate
Logilab (Julien Cristau)
The 'official' Debian news And, once more, many thanks to the sponsors!

This is my monthly summary of my free software related activities. If you re among the people who made a donation to support my work (692.20 , thanks everybody!), then you can learn how I spent your money. Otherwise it s just an interesting status update on my various projects. Misc packaging I updated the publican package (a tool for publishing material authored in DocBook XML) with version 3.0, a major new upstream version. As with any important update, it had its share of problems and I created two patches that I sent upstream. I uploaded the package to experimental since we re in freeze. The Debian Administrator s Handbook Since the translation teams have been working for a few months, I wanted to put the result of their work online. I did it and I blogged about it on debian-handbook.info. By the way, we have a Polish translation that just started. This took quite some time because many translators were not well versed with Docbook XML and its structure. So I fixed their mistakes and asked the Weblate developer (Michal Cihar) to implement new checks to avoid those basic XML mistakes. I also added a couple of build scripts to the git repository to make it easier to rebuild translations in multiple formats. I used this opportunity to file a couple of bugs I encountered with Publican (concerning ePub output mainly, and custom brands). I also blogged about our plans to update the book for Wheezy. Roland started to work on it but I did not have the time yet. Debian France The officers (president, treasurer, secretary) have just changed and we had to organize the transition. As the new president, I got administrator access on our Gandi virtual machine (france.debian.net) as well as access to our bank account. I got also got a bunch of administrative papers retracing the history of the association. Carl Chenet (the former president) gave them to me during the mini-debconf that was organized in Paris. Indeed, Sylvestre Ledru and Mehdi Dogguy organized our second mini-debconf Paris and they did it very well. It was a great success with over 100 attendants each of the 2 days it lasted (November 24-25th). Carl managed a merchandising booth that was well stuffed (Luca Capello also brought goodies of Debian.ch) I gave small lightning talk to present the ideas behind my Librement project (it s about funding free software developers). BTW I have not been very good at it, it was only my second lightning talk and I have been a bit too verbose. The talk did not fit in my 5 minutes time slot Back from the mini-debconf, I have been trying to delegate some projects (like get a real website, improve the work-flow of members management, update our server which was still running Lenny). Julien Cristau was willing to upgrade the server did not exactly knew how to upgrade the kernel (it s a bit special since Gandi manages the kernel on the Xen hypervisor side). So I took care of this part and also did some cleanup (adding a backup with its associated remote disk, tweaking the email configuration). And Julien completed the upgrade on November 30th. Alexandre Delano volunteered to have a try at the website and Emmanuel Bouthenot has been looking a bit to see if there was something better than Galette to handle our members. It looks like we ll stay with Galette but have to take care of upgrading it to a newer version. I also processed the first membership applications and organized a vote to extend the board of administrators (since we have two vacant seats). On Monday, we should be back to 9 administrators. Librement Except for the talk during the mini-debconf, I did not do much on this project. That said I got an answer from the Autorit de Contr le Prudentiel saying that I might be eligible for the exemption case (see discussion of last month) and that I should fill out a form to get a confirmation. I also contacted Tunz.com who might be able to provide the services I need (their E-money manager product in particular). They have the required accreditation as a banking/credit institution and are willing to partner with enterprises who setup platforms where you must manage flows of money between several parties. I m now waiting for details such as the cost of their various services. I expect to have much more to show next month I m working with two developers to implement the first building blocks of all this. Thanks See you next month for a new summary of my activities.

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rc bugs, cloud, and getting involved This past week-end has been rather intense. In addition to another, non free software related event I was volunteering for, I had the pleasure to participate in the 2nd Paris mini DebConf. Once again, the organization has been great and the average quality of the talks have been very high. I'd say talk quality is now totally up to par with the yearly full blown DebConf (and yes, talks have been in English ). If I had to single the talk that intrigued me the most, I'd name Joss' talk on large GNOME deployments: it's full of insights on the GNOME architecture and of tips useful to all power users, no matter the size of your GNOME "deployment". For more info on the talks have a look at the program. To catch up with the talks you missed you can peruse the slides there and/or keep an eye on http://video.debian.net, where we usually post conference videos "when they are ready". At the conference I've also witnessed the usual healthy mix of country origins that I remember from the previous Paris mini DebConf. Once again I've been happy to meet (and host!) Debian friends from many countries including Germany, Switzerland, Italy, Greece, Finland, you name it. Kudos to the organizers (hi Sylvestre and Mehdi!) and to all the volunteers who made this possible. On my part, I didn't have any full blown talk scheduled (ETOOMANYTALKS struck me this month ) but I did book two lightning talks slots that I've used for:

• rambling on RC bugs and the effects of long freezes on Debian
• presenting the debian-cloud initiative, which is rather new but incredibly active and effective despite its infancy

On the subject of lightning talks, I also recommend to promote Lucas' talk on how to get involved in Debian. It's dense and straight to the point, able to both convey useful tips and point wannabe contributors to the most useful contributions they can make to Debian.

Next week end, November 24th and 25th, the mini Debconf will take place at EPITA in Paris. Mehdi Dogguy and I worked hard on the organization and on building a great program for this 2012 conference. This mini debconf will cover many subjects like Gnome (both as upstream and downstream), the Release team, how the Linux is packaged in Debian, etc.
The keynote will be "Free software and Debian, 20 years after" by Roberto Di Cosmo. Also, some merchandising will be proposed during the event by the association Debian France. Here is a quick list: Polos

Long-sleeved polo
40 euros - 10 pieces
Sleeveless polo
25 euros - 100 pieces Thanks to Tanguy Ortolo for taking take of the order. Buff

Buff Debian
18 euros - 75 pieces. It is described as Original Multifunctional Headwear. Real life example in video.
I love them! Finally, we will sell two kinds of Debian branded Sticker Portable:

Sticker Debian
1 euro - 100 pieces. They can be also ordered on the it2l website. Thanks to J r me Lemaire for providing these great products. If these products are successful, we will probably produce more for FOSDEM! For more information about the conference:
The official website
Wiki page for subscription

(doh, I nearly had it. I just got #690019, #690020 and #690022 for l10n stuff) Bartek Krawczyk reported Debian bug #690000 on Monday October 8th, against guake. And my friend Sylvestre Ledru, the package maintainer, now has to fix it instead of trying to promote the use of Scilab over proprietary alternatives in the French aerospace research organizations..:-) Bug #680000 was reported as of July 2nd: 3 months and 8 days for 10,000 bugs. This is a VERY significant drop in the bug reporting rate in Debian. Last time, I wrote: "How will the wheezy freeze affect this? We'll see in two months!". We have the answer: the wheezy freeze triggerred an important drop in bug reporting rate in Debian. My general feeling is somehow different: for whatever reason, I feel like the *overall* activity in the project has dropped significantly. I seem to have less mails to read, less bugs reported against my packages, even less heated discussions here and there, as well as several very quiet channels on IRC. Am I pessimistic when feeling that the overall momentum is sliding out of Debian? Maybe I am, so, folks, please make me optimistic and move you fingers out of the place where they are and help releasing that damn penguin. Apart from that, our next milestone (apart from the wheezy release!) will be bug #700000. Remember the bet?. It looks like the probability of Kartik Mistry winning it is now away (he bet for Now 8th 2012) and the best position is hel by David Pr vot (he bet for December 12th). On the other hand, my own chances are increasing if the bug rate drop is confirmed and if bug #700000 is reported in more than 3 months (I bet for February 14th 2013, guess why?). We'll see that in a few weeks!

This is my monthly summary of my Debian related activities. If you re among the people who made a donation to support my work (1086.48 , thanks everybody!), then you can learn how I spent your money. Otherwise it s just an interesting status update on my various projects. Dpkg I am subscribed to Launchpad s dpkg bug tracker and I was getting annoyed with the amount of noise I got under the form of bug reports that look like package foo failed to install/upgrade: package foo is already installed and configured . Those reports are a combination of a bug in APT and of random other failures (often hardware related like corrupted .deb files, or I/O errors, but sometimes also real problems in other packages) but they always end up assigned on dpkg (because dpkg is outputting an error message complaining about APT s decision to configure something that doesn t have to be configured). I simply don t have the time required to manually process and inspect all those reports, so I decided to filter them at the apport level with a new Ubuntu bug pattern that indicates that those reports are a duplicate of LP#541595. Thanks to this, the dpkg bug count quickly went down from 130 to about 80. Packaging I sponsored a new upstream version of ledgersmb. I quickly updated WordPress to version 3.4.2 since it contains security relevant fixes. I also pushed a small update of nautilus-dropbox fixing #686863 because upstream renamed the binary package that they hand out on their website from nautilus-dropbox to dropbox. Their dropbox package only conflicts with old versions of nautilus-dropbox and not with the version that Debian is shipping and thus I had to add a Conflicts on our side to forbid co-installation of both packages. Testing wheezy s installation I bought a new laptop (Lenovo Thinkpad X230) and used this as an excuse to test Wheezy s installation process. It worked mostly fine except for two things:

1. First I noticed that it would not accept my passphrase for my encrypted partition during early boot this turned out to be already reported as #619711 but was no longer getting any attention from the package maintainer. After some IRC discussion with Julien Cristau, we prodded Michael Prokop who had apparently already offered to take care of this issue. I tested his updated package and the result got quickly uploaded.
2. I had weird networking problems that turned out to be related to the lack of the loopback network (i.e. on localhost). This was the result of a broken /etc/network/interfaces: it had been incorrectly modified by NetworkManager. I reported this in #688355. This issue affects people with IPv6 enabled networks.

Debian France There s a resurgence of activity in Debian France. Sylvestre Ledru is leading the organization of a mini-debconf in Paris on November 24-25th. And Tanguy Ortolo is now taking care of some merchandising (Polo shirts, to change from the usual T-Shirt). I might give a talk during this mini-debconf, possibly about multi-arch. Misc It s been a few months that I noticed a 2 second lag of gnome-shell everytime that smuxi (my IRC client) sent a notification. It s very annoying, you have the impression that the entire machine freezes. So I contacted Mirco Bauer on #smuxi and we investigated a bit. It turns out that smuxi is using an old version of the notification protocol where the picture is sent as a bytestream leading to huge dbus messages. This is clearly sub-optimal so smuxi will be fixed to be able to send the path of the picture instead of the picture itself. On the other hand, it s really a bug of gnome-shell that it freezes during the time it takes to handle the bigger-than-usual dbus message. So I also filed a bug on GNOME Shell (Bugzilla #683829) to get this fixed. Librement: funding free software work I started a new project with the goal of helping free software developers to fund their free software work. It s still mostly vaporware for now but I have a public code repository, a nice logo and lots of ideas. If the topic is of interest to you, and you d like to be involved, feel free to get in touch. Otherwise stay tuned. Thanks See you next month for a new summary of my activities.

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This is my monthly summary of my Debian related activities. If you re among the people who made a donation to support my work (88.41 , thanks everybody!), then you can learn how I spent your money. Otherwise it s just an interesting status update on my various projects. This month has again been a short one since I have mostly been in vacation during the last 2 weeks. Dpkg Things are relatively quiet during the freeze. I only took care of fixing 3 bugs: a regression of 3.0 (quilt) (#683547), a segfault of dpkg-query -W -f (commit) and a bad auto-completion for French users (#685863). Testing the upgrade to wheezy We got several reports of wheezy upgrade that failed because dpkg ran the trigger while the dependencies of the package with pending triggers are not satisfied. Unfortunately fixing this in dpkg is not without problems (see #671711 for details) so Guillem decided to defer this fix for Jessie. My suggestion of an intermediary solution has fallen in limbo. Instead we now have to find solutions for each case where this can fail (example of failure: 680626). Another way to avoid those errors is to ensure that triggers are run as late as possible. We can improve this in multiple ways. The first way is to modify most triggers so that they use the interest-noawait directive. In that case, the packages activating the trigger will be immediately marked as configured (instead of triggers-awaited ) and the trigger will thus not need to be run as part of further dependency solving logic. But as of today, there s no package using this new feature yet despite a nudge on debian-devel-announce. The second way is to modify APT to use dpkg no-triggers, and to let the trigger processing for the end (with a last dpkg configure -a call). I requested this early in the wheezy timeframe but for various reasons, the APT maintainers did not act on it. I pinged them again in #626599 but it s now too late for wheezy. I find this a bit sad because I have been using those options for the entire wheezy cycle and it worked fine for me (and I used them for a dist-upgrade on my wife s laptop too). It would have been good to have all this in place for wheezy so that we don t have to suffer from the same problems during the jessie upgrade, but unless someone steps up to steer those changes, it seems unlikely to happen. Instead, we re back to finding klumsy work-arounds in individual packages. Packaging I prepared security updates for python-django (1.4.1 for unstable,
1.2.3-3+squeeze3 for stable). I packaged a new upstream version for cpputest (3.2-1). I reviewed ledgersmb 1.3.21-1 prepared by Robert James Clay and asked him to prepare another version with further fixes. I released nautilus-dropbox 1.4.0-2 with supplementary changes of my own to support https_proxy and to display better diagnostic information when the download fails. With the help of Paul van der Vlis and Michael Ziegler, we did what was required to be able to migrate python-django-registration 0.8 to Wheezy even though it s a new upstream version with backwards incompatible changes. Thanks to Adam D. Barratt who unblocked the package, we now have the right version in Wheezy despite the fact that I missed the freeze deadline. Debian France Julien Cristau reminded the board of Debian France that we have to elect officers (President, Secretary, Treasurer) as the current officers have withdrawn. I was somewhat afraid that nobody would take over so I pinged each member to try to get new volunteers. We now have volunteers (me, Julien Danjou and Sylvestre Ledru) and we re waiting until Julien finds some time to run the election. Misc With the help of DSA, I setup antispam rules for the owner@packages.qa.debian.org alias because I was getting tired by the amount of spam. In the process, they asked me to write a wiki page for dsa.debian.org to document everything so that they can refer to it for future queries. I did it but it looks like that they did not apply my patch yet. I also tested an upstream patch for gnome-keyring (see bugzilla #681081) that reintroduces the support of forgetting GPG passphrases after a specified amount of time. Thanks See you next month for a new summary of my activities.

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In the process of installing and configuring wanna-build, I had lots of problems. Because there was almost no documentation on the subject (and some of the existing was outdated), I had to figure out how everything works by reading the source code and asking people on IRC and mailing lists. I use the most recent version (from git) and since it s not stable, there were some problems and bugs. I fixed several bugs in order to set the system up. I also documented every step so now there s documentation on everything I have done. I uploaded the documentation on installing and configuring wanna-build [0]. I installed and configured reprepro on a local machine in order to use it with wanna-build. In the process I made step-by step setup instructions [1]. I installed and configured sbuild. The lastest version of sbuild contains filters but they don t work. Their purpose is to keep only the necessary variables in the environment, but apparenly the configuration file which should set them is never read. That leaves the filter list empty which causes the environment to be empty. I had to disable them to keep my work going. I installed buildd. I had some problems setting it up there was a bug in the scripts related to parsing the configuration file. I was pointed to a helpful bug report on the topic and with some additional changes I eventually got it working. In the process I had to read some of the source code of buildd. I made a patch that fixes a bug in the manual page of reprepro and got it approved. I contacted the Alioth admin team via the web site, requesting to use their server for my project Clang for build services . I got approved and I created a git repository where I m now uploading my work. The repository that I use to upload changes to sbuild and buildd is [2]. I add the name of the used compiler to the control file and to the name of the deb package. I wrote a function for parsing the debian/rules file looking for hard-coded compiler there. If there is such compiler, which is different from the one chosen as a default, the building proccess exits with a clear error. I made changes to wanna-build, dpkg, sbuild and buildd to fix bugs in them and make it possible to use a compiler different from gcc for the build process.
After my work a build compiler can be set easily. If a package can not be built with that compiler, the build process fails with a clear error. I also modified the pgstatus web interface to display build logs and create reports on user request. I wrote complete documentation about setting up wanna-build, reprepro and buildd ([0] and [1]). This makes a fully functional buildd infrastructure. Now we have a full step by step tutorial. Me and Sylvestre Ledru who was my great mentor, modified the buildd daemon so it will be possible to be run several instances of it for different architectures on a single physical server. I made a lot of changes to pgstatus this is a web interface to the wanna-build database. I had to add some features and fix several problems. In the process I read some of the code of pgstatus and buildd-tools. Now I have a better understanding of how they work. I added a new feature in pgstatus that allows the user to create a full report of the state of all builds. When a designated reports page is opened, a table with the current state of the builds is shown, together with a list of all the reports saved to files for the current distribution and architecture. The reports can be downloaded directly from the
interface. They are stored in JSON format. The log files were not accessible from pgstatus because of lack of implementation and bugs. I created a script that reads emails sent by wanna-build and extracts log files from them. I made changes to wanna-build so that it feeds the database with the necessary information about package history. I updated the wanna-build patch to include these changes. As a result the buildd logs can now be opened from the web interface of pgstatus. I applied a patch that fixes bug [3] so that config_schroot.sh (this script installs and sets the default compiler) starts with the necessary privileges. I added a new feature to sbuild that allows scripts to be run right after the dependencies are installed in the chroot and before the actual package starts building. Now anybody can configure sbuild to run such a script by modifying the appropriate configuration file. By adding the following lines: $external_commands =
chroot-pre-build-commands => [
['/root/purge-gcc.sh'],
],
; The script /root/purge-gcc.sh is run by sbuild in the chroot. This script can be necessary to set everything in the environment so that packages are built exactly as needed. Me and my mentor used this to replace gcc with a script that removes all gcc-specific packages so that we can be sure whether a package uses clang or not. I have a fully functional buildd infrastructure installed on my development system. In order to get it running, I made several patches: dpkg.patch The main patch with a lot of changes related to compiler support for building.
wanna_build.patch Fixes bugs and makes wanna-build feed the database with package history information.
sbuild.patch Fixes bugs and work-arounds the problem that some sbuild scripts are called without reading the configuration file of sbuild. Adds configuration option that allows scripts to be run right after the dependencies are installed in the chroot and before the actual package starts building.
pgstatus.patch Fixes bugs and adds reports page to pgstatus. Me and my mentor contacted the Debian wanna-build team to connect our new service with Debian. We explained what the current state of the project is and what we need from them. I thank my mentor Sylvestre Ledru for his presentation on DebConf 12 ([4], [5]). He showed our project and it was seen that people are interested in it. A nice resume of his talk has been made by Michael Larabel on Phoronix [6]. I tested everything thoroughly to make sure my changes don t break anything. I am happy to say that the project is now finished. ==== [0] http://wiki.debian.org/DebianWannaBuildInfrastructureOnOneServer
[1] http://wiki.debian.org/SetupBuildServiceForWanna-build
[2] http://anonscm.debian.org/gitweb/?p=pkg-llvm/clang-build.git;a=summary
[3] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=608840
[4] http://sylvestre.ledru.info/blog/media/5/rebuild-debian-presentation-clang-July-10.pdf
[5] http://meetings-archive.debian.net/pub/debian-meetings/2012/debconf12/high/884_Build_Debian_with_another_compiler.ogv
[6] http://www.phoronix.com/scan.php?page=news_item&px=MTEzODQ

Thanks to the work of Andrej Belym, Debian has now a new C++ standard library. This work has been done in the context of the Google Summer of Code 2012.
Available in Debian Experimental, this new packages provides both the runtime libraries (libc++abi1) and the C++ headers (libc++-dev). With this library, it is possible to build a C++-based program without any dependency on libstdc++. For example, as detailed in README.Debian, with the (amazing) C++ code:

// foo.cpp
#include <iostream> int main()
std::cout < < "plop" << std::endl;
return 0;

build with clang++ (or g++) will give:

$ clang++ -o plop foo.cpp
$ ldd plop grep c++
libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f15791cb000)

Using libc++, it will drop the dependency on libstdc++ to use lib++

$ clang++ -stdlib=libc++ -o plop foo.cpp
$ ldd plop grep c++
libc++.so.1 => /usr/lib/x86_64-linux-gnu/libc++.so.1 (0x00007f87464df000)

For the record, it is not that trivial to do with g++. The command being:

g++ -nostdlib -lc++ -lc++abi -std=c++11 -o plop /usr/lib/x86_64-linux-gnu/crt1.o /usr/lib/x86_64-linux-gnu/crti.o foo.cpp /usr/lib/x86_64-linux-gnu/crtn.o -isystem/usr/include/c++/v1 -lc -lgcc_s

Besides this change, libc++ provides a support of C++ 11, considered as "correct" against the C++11 standard by upstream.

// bar.cpp
#include <chrono>
int main()
return 0;

clang++ -stdlib=libc++ -o bar bar.cpp

More information:

• libc++ website
• libc++abi website
• libc++abi Specification

The lunch and dinner catering was outdoors which was novel. The food was generally good if a little limited for those of us with less straightforward dietary requirements.

A couple week ago, during the last debconf (Debian Conference) in Managua/Nicaragua, I presented the latest developments about the inclusion of clang in the Debian architecture. To sum up (details are available in the slides and the video), the rebuild of the Debian archive with Clang 3.1 increased the number of failures from 8.8 to 12.1%. The main reason is that further checks have been added to clang. With Paul Tagliamonte as co-mentor and Alexander Pashaliyski as a GSoC student, we made great progress in bringing Clang as A new compiler in the Debian infrastructure. The various feedbacks that I had during Debconf were pretty good. It interests many people for reasons like Quality Assurance (more checks), performances, hackability or to decorrelate Debian and GCC. Build Debian with another compiler - Slides
Build Debian with another compiler - Video A nice resume of my talk has been made by Michael Larabel on Phoronix:
Decoupling GCC From Debian By Using LLVM/Clang

A couple week ago, during the last debconf (Debian Conference) in Managua/Nicaragua, I presented the latest developments about the inclusion of clang in the Debian architecture. To sum up (details are available in the slides and the video), the rebuild of the Debian archive with Clang 3.1 increased the number of failures from 8.8 to 12.1%. The main reason is that further checks have been added to clang. With Paul Tagliamonte as co-mentor and Alexander Pashaliyski as a GSoC student, we made great progress in bringing Clang as A new compiler in the Debian infrastructure. The various feedback that I had during Debconf were pretty good. It interests many people for reasons like Quality Assurance (more checks), performances, hackability or to decorrelate Debian and GCC. Build Debian with another compiler - Slides
Build Debian with another compiler - Video A nice resume of my talk has been made by Michael Larabel on Phoronix:
Decoupling GCC From Debian By Using LLVM/Clang

During my various chats and presentations on LLVM/Clang, one of the common criticism on LLVM/Clang is about the Apple's (supposed?) control on the platform. Even if I am not concerned by this concern, here are some statistics about the development. Basically, I used the git history to build a list of all the author. If domain names were clear (ex: @google.com, @apple.com, etc), I used them for the paternity of the commit. If there were not clear (ex: @gmail.com, @me.com), I dig on the web to find the employer (Linkedin was my friend). Of course, identifying individuals are pretty tough. Their percentages can be considered as a minimal figure.

To sum up, we can easily see that the percentage of contributions of Apple is decreasing over the time.
However, we all know that the number of commits is not the best metric to measure the control of one on a project. Source: Processed data (please contact me in case of mistake)

A couple weeks ago, I have been interviewed by the news site "Free Libre open source software for science and engineering" about Scilab and my work in Scilab Enterprises.
I am happy to share it:
http://www.floss4science.com/scilab-an-interview-with-sylvestre-ledru/.

I ve recently found myself in need of more then one sbuild chroot, each one set up slightly differently then the next. For a while, providing different behavior with unstable and sid was all well and good, but I figure, like any good computer scientist, I should solve the general problem. As a result, I ve written an sbuild wrapper to help maintain sanity. It uses a series of symbolic links to hide everything out of the way, and some bash hackery. Basically, I ve set up a /var/sbuild directory, full of a few different files. For each distribution, there is one folder, one symbolic link and up to two other files. There s the dist.d file (such as /var/sbuild/sid.d) that contains all the variants , dist symbolic link (such as /var/sbuild/sid) which points to the currently active chroot, and up to two lock files. The script will default to sid-default (that is to say, exactly, /var/sbuild/sid.d/sid-default - which is a symbolc link to the default chroot), but may take two arguments, in the order of variant, then dist. Currently, I have two chroots, one for gcc, and one for clang (set up like Sylvestre used for cland.d.n) but I may add some more with different setups. Currently the behavior is to have the second wait kindly if you kick off two sbuilds at once, and fail out a third. There are a bunch of bugs, and I m not sure that this will work very well, but it s working. The next step is to combine this with unionfs overlays to help protect accidentally trashing the chroots. You can find the script on my GitHub, pasted below.

#!/bin/bash
DIST="sid"
VARIANT="default"
SBUILD=/var/sbuild
if [ "x$1" != "x" ]; then
    VARIANT=$1
fi
if [ "x$2" != "x" ]; then
    DIST=$2
fi
if [ -e $SBUILD/$DIST.lock ]; then
    PID= cat $SBUILD/$DIST.lock 
    echo "W: We *must* wait for the finish of PID $PID"
    echo "W: Blocking execution until this file is removed."
    if [ -e $SBUILD/$DIST.wait ]; then
        echo "E: Someone else is waiting. Bombing out."
        exit 2
    fi
    echo $$ > $SBUILD/$DIST.wait
    while [ -e $SBUILD/$DIST.lock ]; do
        sleep 1
    done
    echo "I: Dropping out of lock. Purging wait."
    rm $SBUILD/$DIST.wait
fi
echo "I: Aquiring lock"
echo $$ > $SBUILD/$DIST.lock
CURRENT=$(basename  ls -xl $SBUILD/$DIST   awk ' print $11 ' )
# We set up the name like:
#   dist-variant
# such as "sid-clang" is cool.
#echo "I: We're currently $CURRENT."
if [ "x$CURRENT" == "x$DIST-$VARIANT" ]; then
    echo "I: This matches the desired setup. No action."
else
    if [ -e $SBUILD/$DIST.d/$DIST-$VARIANT ]; then
        echo "I: Re-setting $DIST symlink."
        rm $SBUILD/$DIST
        ln -s $SBUILD/$DIST.d/$DIST-$VARIANT $SBUILD/$DIST
    else
        echo "E: No such dist! Looking in $SBUILD/$DIST.d/$DIST-$VARIANT."
        exit 1
    fi
fi
echo "I: "
echo "I: Dist:    $DIST"
echo "I: Variant: $VARIANT"
echo "I: "
# echo "I: Before we go farther, we're updating."
# sbuild-update -d $DIST --upgrade
sbuild -d $DIST
echo "I: Releasing lock"
rm $SBUILD/$DIST.lock

Released a few days ago, I am happy to announce that LLVM and clang 3.1 are already available in the Debian archive in Unstable. RC versions were already available for the last few weeks in Debian experimental. They are very likely to be part of wheezy.
We will soon try a new rebuild of the Debian archive with the version 3.1. Talking about clang, a couple of months ago, I proposed a GSoC project to extend the Debian infrastructure in order to use clang instead gcc to build Debian packages. The goal is not to replace gcc but it is more about building packages with a new compiler. With Paul Tagliamonte as co-mentor, Alexander Pashaliyski is going to work during the summer on this subject. The final deliverables should be:

• Build services modified to be able to use clang instead of gcc/g++
• Integration into the Debian infrastructure (buildd.d.o, and similar services)
• An easy way to switch of compiler between gcc/g++ and clang
• A way to build a package with a different compiler (gcc, clang, intel compiler, etc)
• Time permitting, a fully clang-built Debian installation

For now, Alexander is working on an installation of the wanna-build and buildd services in order to have a dedicated testing environment.

The statistics of the "who wrote Linux x.y.z" series date back to at least 2.6.20. According to my experience talking with users and Free Software enthusiasts, those statistics really make a dent in the public perception of who is giving back upstream. Obviously, one should not take a single upstream, even if it is as important as the Linux kernel, as a measure of how much a given Free Software entity is giving back upstream overall. But users still seem to be fascinated by them. As a result, I have often had to answer the question: why Debian doesn't show up on those statistics?. My answer has always been something along the lines that Debian Developers who maintain Linux kernel packages, the almighty Debian Kernel Team, do that mostly as part of their volunteer engagement in Debian. As a consequence, they do not earmark their contributions as if they worked for a company and they add up to the hobbyist count instead (although you can you can routinely spot individual Debian Kernel Team members among the most active contributors for specific Linux releases). The above is the true and honest answer. But every time I've given it, I couldn't help feeling that the user who asked went home with a "yeah, well" afterthought. If you don't want to take my word of it, fine. Here is what Greg K-H had to say about Debian contributions in a recent blog post about the stable Linux kernel:

I would personally like to thank the Debian kernel developers, specifically Ben Hutchings, Maximilian Attems, Dann Frazier, Bastian Blank, and Moritz Muehlenhoff. They went above and beyond what any "normal" developer would have done, ferreting patches out of the kernel.org releases and the different vendor kernels and bug tracking systems, backporting them to the 2.6.32 kernel, testing, and then forwarding them on to me. Their dedication to their user community is amazing for such a "volunteer" group of developers. I firmly believe that without their help, the 2.6.32 kernel would not have been the success that it was. The users of Red Hat and SuSE products owe them a great debt. Buy them a beer the next time you see them, they more than deserve it.

I'll take good care of following his wise advice. Please do the same.

---

(Thanks to Sylvestre for pointing me to Greg's blog post.)