Search Results: "ag"

20 July 2017

Benjamin Mako Hill: Testing Our Theories About Eternal September

Graph of subscribers and moderators over time in /r/NoSleep. The image is taken from our 2016 CHI paper.
Last year at CHI 2016, my research group published a qualitative study examining the effects of a large influx of newcomers to the /r/nosleep online community in Reddit. Our study began with the observation that most research on sustained waves of newcomers focuses on the destructive effect of newcomers and frequently invokes Usenet s infamous Eternal September. Our qualitative study argued that the /r/nosleep community managed its surge of newcomers gracefully through strategic preparation by moderators, technological systems to reign in on norm violations, and a shared sense of protecting the community s immersive environment among participants. We are thrilled that, less a year after the publication of our study, Zhiyuan Jerry Lin and a group of researchers at Stanford have published a quantitative test of our study s findings! Lin analyzed 45 million comments and upvote patterns from 10 Reddit communities that a massive inundation of newcomers like the one we studied on /r/nosleep. Lin s group found that these communities retained their quality despite a slight dip in its initial growth period. Our team discussed doing a quantitative study like Lin s at some length and our paper ends with a lament that our findings merely reflected, propositions for testing in future work. Lin s study provides exactly such a test! Lin et al. s results suggest that our qualitative findings generalize and that sustained influx of newcomers need not doom a community to a descent into an Eternal September. Through strong moderation and the use of a voting system, the subreddits analyzed by Lin appear to retain their identities despite the surge of new users. There are always limits to research projects work quantitative and qualitative. We think the Lin s paper compliments ours beautifully, we are excited that Lin built on our work, and we re thrilled that our propositions seem to have held up! This blog post was written with Charlie Kiene. Our paper about /r/nosleep, written with Charlie Kiene and Andr s Monroy-Hern ndez, was published in the Proceedings of CHI 2016 and is released as open access. Lin s paper was published in the Proceedings of ICWSM 2017 and is also available online.

19 July 2017

Dirk Eddelbuettel: RcppAPT 0.0.4

A new version of RcppAPT -- our interface from R to the C++ library behind the awesome apt, apt-get, apt-cache, ... commands and their cache powering Debian, Ubuntu and the like -- arrived on CRAN yesterday. We added a few more functions in order to compute on the package graph. A concrete example is shown in this vignette which determines the (minimal) set of remaining Debian packages requiring a rebuild under R 3.4.* to update their .C() and .Fortran() registration code. It has been used for the binNMU request #868558. As we also added a NEWS file, its (complete) content covering all releases follows below.

Changes in version 0.0.4 (2017-07-16)
  • New function getDepends
  • New function reverseDepends
  • Added package registration code
  • Added usage examples in scripts directory
  • Added vignette, also in docs as rendered copy

Changes in version 0.0.3 (2016-12-07)
  • Added dumpPackages, showSrc

Changes in version 0.0.2 (2016-04-04)
  • Added reverseDepends, dumpPackages, showSrc

Changes in version 0.0.1 (2015-02-20)
  • Initial version with getPackages and hasPackages

A bit more information about the package is available here as well as as the GitHub repo.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

18 July 2017

Daniel Silverstone: Yay, finished my degree at last

A little while back, in June, I sat my last exam for what I hoped would be the last module in my degree. For seven years, I've been working on a degree with the Open University and have been taking advantage of the opportunity to have a somewhat self-directed course load by taking the 'Open' degree track. When asked why I bothered to do this, I guess my answer has been a little varied. In principle it's because I felt like I'd already done a year's worth of degree and didn't want it wasted, but it's also because I have been, in the dim and distant past, overlooked for jobs simply because I had no degree and thus was an easy "bin the CV". Fed up with this, I decided to commit to the Open University and thus began my journey toward 'qualification' in 2010. I started by transferring the level 1 credits from my stint at UCL back in 1998/1999 which were in a combination of basic programming in Java, some mathematics including things like RSA, and some psychology and AI courses which at the time were aiming at a degree called 'Computer Science with Cognitive Sciences'. Then I took level 2 courses, M263 (Building blocks of software), TA212 (The technology of music) and MS221 (Exploring mathematics). I really enjoyed the mathematics course and so... At level 3 I took MT365 (Graphs, networks and design), M362 (Developing concurrent distributed systems), TM351 (Data management and analysis - which I ended up hating), and finally finishing this June with TM355 (Communications technology). I received an email this evening telling me the module result for TM355 had been posted, and I logged in to find I had done well enough to be offered my degree. I could have claimed my degree 18+ months ago, but I persevered through another two courses in order to qualify for an honours degree which I have now been awarded. Since I don't particularly fancy any ceremonial awarding, I just went through the clicky clicky and accepted my qualification of 'Batchelor of Science (Honours) Open, Upper Second-class Honours (2.1)' which grants me the letters 'BSc (Hons) Open (Open)' which, knowing me, will likely never even make it onto my CV because I'm too lazy. It has been a significant effort, over the course of the past few years, to complete a degree without giving up too much of my personal commitments. In addition to earning the degree, I have worked, for six of the seven years it has taken, for Codethink doing interesting work in and around Linux systems and Trustable software. I have designed and built Git server software which is in use in some universities, and many companies, along with a good few of my F/LOSS colleagues. And I've still managed to find time to attend plays, watch films, read an average of 2 novel-length stories a week (some of which were even real books), and be a member of the Manchester Hackspace. Right now, I'm looking forward to a stress free couple of weeks, followed by an immense amount of fun at Debconf17 in Montr al!

Foteini Tsiami: Internationalization, part three

The first builds of the LTSP Manager were uploaded and ready for testing. Testing involves installing or purging the ltsp-manager package, along with its dependencies, and using its GUI to configure LTSP, create users, groups, shared folders etc. Obviously, those tasks are better done on a clean system. And the question that emerges is: how can we start from a clean state, without having to reinstall the operating system each time? My mentors pointed me to an answer for that: VirtualBox snapshots. VirtualBox is a virtualization application (others are KVM or VMware) that allows users to install an operating system like Debian in a contained environment inside their host operating system. It comes with an easy to use GUI, and supports snapshots, which are points in time where we mark the guest operating system state, and can revert to that state later on. So I started by installing Debian Stretch with the MATE desktop environment in VirtualBox, and I took a snapshot immediately after the installation. Now whenever I want to test LTSP Manager, I revert to that snapshot, and that way I have a clean system where I can properly check the installation procedure and all of its features!

Reproducible builds folks: Reproducible Builds: week 116 in Stretch cycle

Here's what happened in the Reproducible Builds effort between Sunday July 9 and Saturday July 15 2017: Packages reviewed and fixed, and bugs filed Reviews of unreproducible packages 13 package reviews have been added, 12 have been updated and 19 have been removed in this week, adding to our knowledge about identified issues. 2 issue types have been added: 3 issue types have been updated: Weekly QA work During our reproducibility testing, FTBFS bugs have been detected and reported by: diffoscope development Version 84 was uploaded to unstable by Mattia Rizzolo. It included contributions already reported from the previous weeks, as well as new ones: After the release, development continued in git with contributions from: strip-nondeterminism development Versions 0.036-1, 0.037-1 and 0.038-1 were uploaded to unstable by Chris Lamb. They included contributions from: reprotest development Development continued in git with contributions from: buildinfo.debian.net development tests.reproducible-builds.org Misc. This week's edition was written by Bernhard M. Wiedemann, Chris Lamb, Mattia Rizzolo, Vagrant Cascadian & reviewed by a bunch of Reproducible Builds folks on IRC & the mailing lists.

Matthew Garrett: Avoiding TPM PCR fragility using Secure Boot

In measured boot, each component of the boot process is "measured" (ie, hashed and that hash recorded) in a register in the Trusted Platform Module (TPM) build into the system. The TPM has several different registers (Platform Configuration Registers, or PCRs) which are typically used for different purposes - for instance, PCR0 contains measurements of various system firmware components, PCR2 contains any option ROMs, PCR4 contains information about the partition table and the bootloader. The allocation of these is defined by the PC Client working group of the Trusted Computing Group. However, once the boot loader takes over, we're outside the spec[1].

One important thing to note here is that the TPM doesn't actually have any ability to directly interfere with the boot process. If you try to boot modified code on a system, the TPM will contain different measurements but boot will still succeed. What the TPM can do is refuse to hand over secrets unless the measurements are correct. This allows for configurations where your disk encryption key can be stored in the TPM and then handed over automatically if the measurements are unaltered. If anybody interferes with your boot process then the measurements will be different, the TPM will refuse to hand over the key, your disk will remain encrypted and whoever's trying to compromise your machine will be sad.

The problem here is that a lot of things can affect the measurements. Upgrading your bootloader or kernel will do so. At that point if you reboot your disk fails to unlock and you become unhappy. To get around this your update system needs to notice that a new component is about to be installed, generate the new expected hashes and re-seal the secret to the TPM using the new hashes. If there are several different points in the update where this can happen, this can quite easily go wrong. And if it goes wrong, you're back to being unhappy.

Is there a way to improve this? Surprisingly, the answer is "yes" and the people to thank are Microsoft. Appendix A of a basically entirely unrelated spec defines a mechanism for storing the UEFI Secure Boot policy and used keys in PCR 7 of the TPM. The idea here is that you trust your OS vendor (since otherwise they could just backdoor your system anyway), so anything signed by your OS vendor is acceptable. If someone tries to boot something signed by a different vendor then PCR 7 will be different. If someone disables secure boot, PCR 7 will be different. If you upgrade your bootloader or kernel, PCR 7 will be the same. This simplifies things significantly.

I've put together a (not well-tested) patchset for Shim that adds support for including Shim's measurements in PCR 7. In conjunction with appropriate firmware, it should then be straightforward to seal secrets to PCR 7 and not worry about things breaking over system updates. This makes tying things like disk encryption keys to the TPM much more reasonable.

However, there's still one pretty major problem, which is that the initramfs (ie, the component responsible for setting up the disk encryption in the first place) isn't signed and isn't included in PCR 7[2]. An attacker can simply modify it to stash any TPM-backed secrets or mount the encrypted filesystem and then drop to a root prompt. This, uh, reduces the utility of the entire exercise.

The simplest solution to this that I've come up with depends on how Linux implements initramfs files. In its simplest form, an initramfs is just a cpio archive. In its slightly more complicated form, it's a compressed cpio archive. And in its peak form of evolution, it's a series of compressed cpio archives concatenated together. As the kernel reads each one in turn, it extracts it over the previous ones. That means that any files in the final archive will overwrite files of the same name in previous archives.

My proposal is to generate a small initramfs whose sole job is to get secrets from the TPM and stash them in the kernel keyring, and then measure an additional value into PCR 7 in order to ensure that the secrets can't be obtained again. Later disk encryption setup will then be able to set up dm-crypt using the secret already stored within the kernel. This small initramfs will be built into the signed kernel image, and the bootloader will be responsible for appending it to the end of any user-provided initramfs. This means that the TPM will only grant access to the secrets while trustworthy code is running - once the secret is in the kernel it will only be available for in-kernel use, and once PCR 7 has been modified the TPM won't give it to anyone else. A similar approach for some kernel command-line arguments (the kernel, module-init-tools and systemd all interpret the kernel command line left-to-right, with later arguments overriding earlier ones) would make it possible to ensure that certain kernel configuration options (such as the iommu) weren't overridable by an attacker.

There's obviously a few things that have to be done here (standardise how to embed such an initramfs in the kernel image, ensure that luks knows how to use the kernel keyring, teach all relevant bootloaders how to handle these images), but overall this should make it practical to use PCR 7 as a mechanism for supporting TPM-backed disk encryption secrets on Linux without introducing a hug support burden in the process.

[1] The patchset I've posted to add measured boot support to Grub use PCRs 8 and 9 to measure various components during the boot process, but other bootloaders may have different policies.

[2] This is because most Linux systems generate the initramfs locally rather than shipping it pre-built. It may also get rebuilt on various userspace updates, even if the kernel hasn't changed. Including it in PCR 7 would entirely break the fragility guarantees and defeat the point of all of this.

comment count unavailable comments

Norbert Preining: Calibre and rar support

Thanks to the cooperation with upstream authors and the maintainer Martin Pitt, the Calibre package in Debian is now up-to-date at version 3.4.0, and has adopted a more standard packaging following upstream. In particular, all the desktop files and man pages have been replaced by what is shipped by Calibre. What remains to be done is work on RAR support.
Rar support is necessary in the case that the eBook uses rar as compression, which happens quite often in comic books (cbr extension). Calibre 3 has split out rar support into a dynamically loaded module, so what needs to be done is packaging it. I have prepared a package for the Python library unrardll which allows Calibre to read rar-compressed ebooks, but it depends on the unrar shared library, which unfortunately is not built in Debian. I have sent a patch to fix this to the maintainer, see bug 720051, but without reaction from the maintainer. Thus, I am publishing updated packages for unrar shipping also libunrar5, and unrardll Python package in my calibre repository. After installing python-unrardll Calibre will happily import meta-data from rar-compressed eBooks, as well as display them. 
deb http://www.preining.info/debian/ calibre main
deb-src http://www.preining.info/debian/ calibre main
The releases are signed with my Debian key 0x6CACA448860CDC13 Enjoy

17 July 2017

Steinar H. Gunderson: Solskogen 2017: Nageru all the things

Solskogen 2017 is over! What a blast that was; I especially enjoyed that so many old-timers came back to visit, it really made the party for me. This was the first year we were using Nageru for not only the stream but also for the bigscreen mix, and I was very relieved to see the lack of problems; I've had nightmares about crashes with 150+ people watching (plus 200-ish more on stream), but there were no crashes and hardly a dropped frame. The transition to a real mixing solution as well as from HDMI to SDI everywhere gave us a lot of new opportunities, which allowed a number of creative setups, some of them cobbled together on-the-spot: It's been a lot of fun, but also a lot of work. And work will continue for an even better show next year after some sleep. :-)

16 July 2017

Jose M. Calhariz: Crossgrading a complex Desktop and Debian Developer machine running Debian 9

This article is an experiment in progress, please recheck, while I am updating with the new information. I have a very old installation of Debian, possibly since v2, dot not remember, that I have upgraded since then both in software and hardware. Now the hardware is 64bits, runs a kernel of 64bits but the run-time is still 32bits. For 99% of tasks this is very good. Now that I have made many simulations I may have found a solution to do a crossgrade of my desktop. I write here the tentative procedure and I will update with more ideias on the problems that I may found. First you need to install a 64bits kernel and boot with it. See my previous post on how to do it. Second you need to do a bootstrap of crossgrading and the instalation of all the libs as amd64: 
 apt-get update
 apt-get upgrade
 apt-get clean
 dpkg --list > original.dpkg
 apt-get --download-only install dpkg:amd64 tar:amd64 apt:amd64 bash:amd64 dash:amd64 init:amd64 mawk:amd64
 cd /var/cache/apt/archives/
 dpkg --install dpkg_*amd64.deb tar_*amd64.deb apt_*amd64.deb bash_*amd64.deb dash_*amd64.deb *.deb
 dpkg --configure --pending
 dpkg -i --skip-same-version dpkg_*_amd64.deb apt_*_amd64.deb bash_*_amd64.deb dash_*_amd64.deb mawk_*_amd64.deb *.deb
 
 for pack32 in $(grep i386 original.dpkg    egrep "^ii "   awk ' print $2 ' ) ; do 
   echo $pack32 ; 
   if dpkg --status $pack32   grep -q "Multi-Arch: same" ; then 
     apt-get --download-only install -y --allow-remove-essential $ pack32%:i386 :amd64 ; 
   fi ; 
 done
 dpkg --install /var/cache/apt/archives/*_amd64.deb
 dpkg --install /var/cache/apt/archives/*_amd64.deb
 dpkg --print-architecture
 dpkg --print-foreign-architectures
But this procedure does not prevent the "apt-get install" to have broken dependencies. So trying to install the core packages and the libraries using "dpkg -i". 
apt-get update
apt-get upgrade
apt-get autoremove
apt-get clean
dpkg --list > original.dpkg
apt-get --download-only install dpkg:amd64 tar:amd64 apt:amd64 bash:amd64 dash:amd64 init:amd64 mawk:amd64
for pack32 in $(grep i386 original.dpkg   egrep "^ii "   awk ' print $2 ' ) ; do 
  echo $pack32 ; 
  if dpkg --status $pack32   grep -q "Multi-Arch: same" ; then 
    apt-get --download-only install -y --allow-remove-essential $ pack32%:i386 :amd64 ; 
  fi ; 
done
cd /var/cache/apt/archives/
dpkg --install dpkg_*amd64.deb tar_*amd64.deb apt_*amd64.deb bash_*amd64.deb dash_*amd64.deb *.deb
dpkg --configure --pending
dpkg --install --skip-same-version dpkg_*_amd64.deb apt_*_amd64.deb bash_*_amd64.deb dash_*_amd64.deb mawk_*_amd64.deb *.deb
dpkg --remove libcurl4-openssl-dev
dpkg -i libcurl4-openssl-dev_*_amd64.deb
Remove packages until all there is no brokens packages 
dpkg --print-architecture
dpkg --print-foreign-architectures
apt-get --fix-broken --allow-remove-essential install
Still broken, because apt-get removed dpkg So instead of only installing the libs with dpkg -i, I am going to try to install all the packages with dpkg -i: 
apt-get update
apt-get upgrade
apt-get autoremove
apt-get clean
dpkg --list > original.dpkg
apt-get --download-only install dpkg:amd64 tar:amd64 apt:amd64 bash:amd64 dash:amd64 init:amd64 mawk:amd64
for pack32 in $(grep i386 original.dpkg   egrep "^ii "   awk ' print $2 ' ) ; do 
  echo $pack32 ; 
  apt-get --download-only install -y --allow-remove-essential $ pack32%:i386 :amd64 ; 
done
cd /var/cache/apt/archives/
dpkg --install dpkg_*amd64.deb tar_*amd64.deb apt_*amd64.deb bash_*amd64.deb dash_*amd64.deb *.deb
dpkg --configure --pending
dpkg --install --skip-same-version dpkg_*_amd64.deb apt_*_amd64.deb bash_*_amd64.deb dash_*_amd64.deb mawk_*_amd64.deb *.deb
dpkg --configure --pending
Remove packages and reinstall selected packages until you fix all off them. Follow the trial for my machine: 
dpkg --remove rkhunter
dpkg --remove libmarco-private1:i386 marco mate-control-center mate-desktop-environment-core mate-desktop-environment-core  mate-desktop-environment mate-desktop-environment-core mate-desktop-environment-extras
dpkg --remove libmate-menu2:i386 libmate-window-settings1:i386 mate-panel mate-screensaver python-mate-menu libmate-slab0:i386 mozo mate-menus
dpkg --remove libmate-menu2:i386 mate-panel python-mate-menu mate-applets mate-menus
dpkg -i libmate-menu2_1.16.0-2_amd64.deb
dpkg --remove  gir1.2-ibus-1.0:i386 gnome-shell gnome-shell-extensions gdm3 gnome-session
dpkg --remove  gir1.2-ibus-1.0:i386
dpkg --remove libmateweather1:i386
dpkg -i libmateweather1_1.16.1-2_amd64.deb
apt-get --fix-broken --download-only install
dpkg --skip-same-version --install dpkg_*amd64.deb tar_*amd64.deb apt_*amd64.deb bash_*amd64.deb dash_*amd64.deb *.deb
dpkg --configure --pending
dpkg -i python_2.7.13-2_amd64.deb
dpkg --configure --pending
dpkg -i perl_5.24.1-3+deb9u1_amd64.deb perl-base_5.24.1-3+deb9u1_amd64.deb
dpkg -i exim4-daemon-light_4.89-2+deb9u1_amd64.deb exim4-base_4.89-2+deb9u1_amd64.deb
dpkg -i libuuid-perl_0.27-1_amd64.deb
dpkg --configure --pending
dpkg --install gstreamer1.0-plugins-bad_1.10.4-1_amd64.deb libmpeg2encpp-2.1-0_1%3a2.1.0+debian-5_amd64.deb libmplex2-2.1-0_1%3a2.1.0+debian-5_amd64.deb
dpkg --configure --pending
dpkg --audit
Now fixing broken dependencies on apt-get. Found no other way than removing all the broken packages. 
dpkg --remove $(apt-get --fix-broken install   cut -f 2 -d ' ' )
apt-get install $(grep -v ":i386" ~/original.dpkg   egrep "^ii"   grep -v "aiccu"   grep -v "acroread"   grep -v "flash-player-properties"   grep -v "flashplayer-mozilla"   egrep -v "tp-flash-marillat"   awk ' print $2 ')

Vasudev Kamath: Overriding version information from setup.py with pbr

I recently raised a pull request on zfec for converting its python packaging from pure setup.py to pbr based. Today I got review from Brian Warner and one of the issue mentioned was python setup.py --version is not giving same output as previous version of setup.py. Previous version used versioneer which extracts version information needed from VCS tags. Versioneer also provides flexibility of specifying type of VCS used, style of version, tag prefix (for VCS) etc. pbr also does extract version information from git tag but it expects git tag to be of format tags/refs/x.y.z format but zfec used a zfec- prefix to tag (example zfec-1.4.24) and pbr does not process this. End result, I get a version in format 0.0.devNN where NN is number of commits in the repository from its inception. Me and Brian spent few hours trying to figure out a way to tell pbr that we would like to override version information it auto deduces, but there was none other than putting version string in PBR_VERSION environment variable. That documentation was contributed by me 3 years back to pbr project. So finally I used versioneer to create a version string and put it in the environment variable PBR_VERSION. 
import os
import versioneer
os.environ['PBR_VERSION'] = versioneer.get_version()
...
setup(
    setup_requires=['pbr'],
    pbr=True,
    ext_modules=extensions
)
And added below snippet to setup.cfg which is how versioneer can be configured with various information including tag prefixes. 
[versioneer]
VCS = git
style = pep440
versionfile_source = zfec/_version.py
versionfile_build = zfec/_version.py
tag_prefix = zfec-
parentdir_prefix = zfec-
Though this work around gets the work done, it does not feel correct to set environment variable to change the logic of other part of same program. If you guys know the better way do let me know!. Also probably I should consider filing an feature request against pbr to provide a way to pass tag prefix for version calculation logic.

Lior Kaplan: PDO_IBM: tracking changes publicly

As part of my work at Zend (now a RogueWave company), I maintain the various patch sets. One of those is the changes for PDO_IBM extension for PHP. After some patch exchange I decided it s would be easier to manage the whole process over a public git repository, and maybe gain some more review / feedback along the way. Info at https://github.com/kaplanlior/pecl-database-pdo_ibm/commits/zend-patches Another aspect of this, is having IBMi specific patches from YIPS (young i professionals) at http://www.youngiprofessionals.com/wiki/index.php/XMLService/PHP, which itself are patches on top of vanilla releases. Info at https://github.com/kaplanlior/pecl-database-pdo_ibm/commits/zend-patches-for-yips So keeping track over these changes as well is easier while using git s ability to rebase efficiently, so when a new release is done, I can adapt my patches quite easily. Make sure the changes can be back and forward ported between vanilla and IBMi versions of the extension.
Filed under: PHP

15 July 2017

Joey Hess: Functional Reactive Propellor

I wrote this code, and it made me super happy! 
data Variety = Installer   Target
    deriving (Eq)
seed :: UserInput -> Versioned Variety Host
seed userinput ver = host "foo"
    & ver (   (== Installer) --> hostname "installer"
          < > (== Target)    --> hostname (inputHostname userinput)
          )
    & osDebian Unstable X86_64
    & Apt.stdSourcesList
    & Apt.installed ["linux-image-amd64"]
    & Grub.installed PC
    & XFCE.installed
    & ver (   (== Installer) --> desktopUser defaultUser
          < > (== Target)    --> desktopUser (inputUsername userinput)
          )
    & ver (   (== Installer) --> autostartInstaller )
This is doing so much in so little space and with so little fuss! It's completely defining two different versions of a Host. One version is the Installer, which in turn installs the Target. The code above provides all the information that propellor needs to convert a copy of the Installer into the Target, which it can do very efficiently. For example, it knows that the default user account should be deleted, and a new user account created based on the user's input of their name. The germ of this idea comes from a short presentation I made about propellor in Portland several years ago. I was describing RevertableProperty, and Joachim Breitner pointed out that to use it, the user essentially has to keep track of the evolution of their Host in their head. It would be better for propellor to know what past versions looked like, so it can know when a RevertableProperty needs to be reverted. I didn't see a way to address the objection for years. I was hung up on the problem that propellor's properties can't be compared for equality, because functions can't be compared for equality (generally). And on the problem that it would be hard for propellor to pull old versions of a Host out of git. But then I ran into the situation where I needed these two closely related hosts to be defined in a single file, and it all fell into place. The basic idea is that propellor first reverts all the revertible properties for other versions. Then it ensures the property for the current version. Another use for it would be if you wanted to be able to roll back changes to a Host. For example: 
foos :: Versioned Int Host
foos ver = host "foo"
    & hostname "foo.example.com"
    & ver (   (== 1) --> Apache.modEnabled "mpm_worker"
          < > (>= 2) --> Apache.modEnabled "mpm_event"
          )
    & ver ( (>= 3)   --> Apt.unattendedUpgrades )
foo :: Host
foo = foos  version  (4 :: Int)
Versioned properties can also be defined: 
foobar :: Versioned Int -> RevertableProperty DebianLike DebianLike
foobar ver =
    ver (   (== 1) --> (Apt.installed "foo" <!> Apt.removed "foo")
        < > (== 2) --> (Apt.installed "bar" <!> Apt.removed "bar")
        )
Notice that I've embedded a small DSL for versioning into the propellor config file syntax. While implementing versioning took all day, that part was super easy; Haskell config files win again! API documentation for this feature PS: Not really FRP, probably. But time-varying in a FRP-like way.
Development of this was sponsored by Jake Vosloo on Patreon.

Dirk Eddelbuettel: Rcpp 0.12.12: Rounding some corners

The twelveth update in the 0.12.* series of Rcpp landed on CRAN this morning, following two days of testing at CRAN preceded by five full reverse-depends checks we did (and which are always logged in this GitHub repo). The Debian package has been built and uploaded; Windows and macOS binaries should follow at CRAN as usual. This 0.12.12 release follows the 0.12.0 release from late July, the 0.12.1 release in September, the 0.12.2 release in November, the 0.12.3 release in January, the 0.12.4 release in March, the 0.12.5 release in May, the 0.12.6 release in July, the 0.12.7 release in September, the 0.12.8 release in November, the 0.12.9 release in January, the 0.12.10.release in March, and the 0.12.11.release in May making it the sixteenth release at the steady and predictable bi-montly release frequency. Rcpp has become the most popular way of enhancing GNU R with C or C++ code. As of today, 1097 packages (and hence 71 more since the last release in May) on CRAN depend on Rcpp for making analytical code go faster and further, along with another 91 in BioConductor. This releases contain a fairly large number of fairly small and focused pull requests most of which either correct some corner cases or improve other aspects. JJ tirelessly improved the package registration added in the previous release and following R 3.4.0. Kirill tidied up a number of small issues allowing us to run compilation in even more verbose modes---usually a good thing. Jeroen, Elias Pipping and Yo Gong all contributed as well, and we thank everybody for their contributions. All changes are listed below in some detail.

Changes in Rcpp version 0.12.12 (2017-07-13)
  • Changes in Rcpp API:
    • The tinyformat.h header now ends in a newline (#701).
    • Fixed rare protection error that occurred when fetching stack traces during the construction of an Rcpp exception (Kirill M ller in #706).
    • Compilation is now also possibly on Haiku-OS (Yo Gong in #708 addressing #707).
    • Dimension attributes are explicitly cast to int (Kirill M ller in #715).
    • Unused arguments are no longer declared (Kirill M ller in #716).
    • Visibility of exported functions is now supported via the R macro atttribute_visible (Jeroen Ooms in #720).
    • The no_init() constructor accepts R_xlen_t (Kirill M ller in #730).
    • Loop unrolling used R_xlen_t (Kirill M ller in #731).
    • Two unused-variables warnings are now avoided (Jeff Pollock in #732).
  • Changes in Rcpp Attributes:
    • Execute tools::package_native_routine_registration_skeleton within package rather than current working directory (JJ in #697).
    • The R portion no longer uses dir.exists to no require R 3.2.0 or newer (Elias Pipping in #698).
    • Fix native registration for exports with name attribute (JJ in #703 addressing #702).
    • Automatically register init functions for Rcpp Modules (JJ in #705 addressing #704).
    • Add Shield around parameters in Rcpp::interfaces (JJ in #713 addressing #712).
    • Replace dot (".") with underscore ("_") in package names when generating native routine registrations (JJ in #722 addressing #721).
    • Generate C++ native routines with underscore ("_") prefix to avoid exporting when standard exportPattern is used in NAMESPACE (JJ in #725 addressing #723).

Thanks to CRANberries, you can also look at a diff to the previous release. As always, even fuller details are on the Rcpp Changelog page and the Rcpp page which also leads to the downloads page, the browseable doxygen docs and zip files of doxygen output for the standard formats. A local directory has source and documentation too. Questions, comments etc should go to the rcpp-devel mailing list off the R-Forge page.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

Junichi Uekawa: revisiting libjson-spirit.

revisiting libjson-spirit. I tried compiling a program that uses libjson-spirit and noticed that it still is broken. New programs compiled against the header does not link with the provided static library. Trying to rebuild it fixes it, but it uses compat version 8, and that needs to be fixed (trivially). hmm... actually code doesn't build anymore and there's multiple new upstream versions. ... and then I noticed that it was a stale copy already removed from Debian repository. What's a good C++ json implementation these days?

Vasudev Kamath: debcargo: Replacing subprocess crate with git2 crate

In my previous post I talked about using subprocess crate to extract beginning and ending year from git repository for generating debian/copyright file. In this post I'm going to talk on how I replaced subprocess with native git2 crate and achieved the same result in much cleaner and safer way. git2 is a native Rust crate which provides access to Git repository internals. git2 does not involve any unsafe invocation as it is built against libgit2-sys which is actually using Rust FFI to directly bind to underlying libgit library. Below is the new copyright_fromgit function with git2 crate. 
fn copyright_fromgit(repo_url: &str) -> Result<String>  
   let tempdir = TempDir::new_in(".", "debcargo")?;
   let repo = Repository::clone(repo_url, tempdir.path())?;
   let mut revwalker = repo.revwalk()?;
   revwalker.push_head()?;
   // Get the latest and first commit id. This is bit ugly
   let latest_id = revwalker.next().unwrap()?;
   let first_id = revwalker.last().unwrap()?; // revwalker ends here is consumed by last
   let first_commit = repo.find_commit(first_id)?;
   let latest_commit = repo.find_commit(latest_id)?;
   let first_year =
       DateTime::<Utc>::from_utc(
               NaiveDateTime::from_timestamp(first_commit.time().seconds(), 0),
               Utc).year();
   let latest_year =
       DateTime::<Utc>::from_utc(
             NaiveDateTime::from_timestamp(latest_commit.time().seconds(), 0),
             Utc).year();
   let notice = match first_year.cmp(&latest_year)  
       Ordering::Equal => format!(" ", first_year),
       _ => format!(" - ,", first_year, latest_year),
    ;
   Ok(notice)
So here is what I'm doing
  1. Use git2::Repository::clone to clone the given URL. We are thus avoiding exec of git clone command.
  2. Get a revision walker object. git2::RevWalk implements Iterator trait and allows walking through the git history. This is what we are using to avoid exec of git log command.
  3. revwalker.push_head() is important because we want to tell revwalker from where we want to walk the history. In this case we are asking it to walk history from repository HEAD. Without this line next line will not work. (Learned it in hard way :-) ).
  4. Then we extract git2::Oid which is we can say similar to commit hash and can be used to lookup a particular commit. We take latest commit hash using RevWalk::next call and the first commit using Revwalk::last, note the order this is because Revwalk::last consumes the revwalker so doing it in reverse order will make borrow checker unhappy :-). This replaces exec of head -n1 command.
  5. Look up the git2::Commit objects using git2::Repository::find_commit
  6. Then convert the git2::Time to chrono::DateTime and take out the years.
After this change I found an obvious error which went unnoticed in previous version, that is if there was no repository key in Cargo.toml. When there was no repo URL git clone exec did not error out and our shell commands happily extracted year from the debcargo repository!. Well since I was testing code from debcargo repository It never failed, but when I executed from non-git repository folder git threw an error but that was git log and not git clone. This error was spotted right away because git2 threw me an error that I gave it empty URL. When it comes to performance I see that debcargo is faster compared to previous version. This makes sense because previously it was doing 5 fork and exec system calls and now that is avoided.

14 July 2017

Chris Lamb: Installation birthday

Fancy receiving congratulations on the anniversary of when you installed your system? Installing the installation-birthday package on your Debian machines will celebrate each birthday of your system by automatically sending a message to the local system administrator. The installation date is based on the system installation time, not the package itself. installation-birthday is available in Debian 9 ("stretch") via the stretch-backports repository, as well as in the testing and unstable distributions: 
$ apt install installation-birthday
Enjoy, and patches welcome. :)

Norbert Preining: TeX Live contrib repository (re)new(ed)

It is my pleasure to announce the renewal/rework/restart of the TeX Live contrib repository service. The repository is collecting packages that cannot enter TeX Live directly (mostly due to license reasons), but are free to distribute. The basic idea is to provide a repository mimicking Debian s nonfree branch. The packages on this site are not distributed inside TeX Live proper for one or another of the following reasons: In short, anything related to TeX that can not be on TeX Live but can still legally be distributed over the Internet can hav e a placeon TLContrib. Currently there are 52 packages in the repository, falling roughly into the following categories: The full list of packages can be seen here. The ultimate goal is to provide a companion to the core TeX Live (tlnet) distribution in much the same way as Debian s non-free tree is a companion to the normal distribution. The goal is not to replace TeX Live: packages that could go into TeX Live itself should stay (or be added) there. TLContrib is simply trying to fill in a gap in the current distribution system. Quick Start If you are running the current version of TeX Live, which is 2017 at the moment, the following code will suffice: 
  tlmgr repository add http://contrib.texlive.info/current tlcontrib
  tlmgr pinning add tlcontrib '*'
In future there might be releases for certain years. Verification The packages are signed with my GnuPG RSA key: 0x6CACA448860CDC13. tlmgr will automatically verify authenticity if you add my key: 
  curl -fsSL https://www.preining.info/rsa.asc   tlmgr key add -
After that tlmgr will tell you about failed authentication of this repository. History Taco Hoekwater started in 2010, but it hasn t seen much activity in recent years. Taco agreed to hand it over to myself, who is currently maintaining the repository. Big thanks to Taco for his long support and cooperation. In contrast to the original tlcontrib page, we don t offer an automatic upload of packages or user registration. If you want to add packages here, see below. Adding packages If you want to see a package included here that cannot enter TeX Live proper, the following ways are possible (from most appreciated to least appreciated): Git repository The packages are kept in a git repository and the tlmgr repo is built from after changes. The location is https://git.texlive.info/tlcontrib. Enjoy.

13 July 2017

Lars Wirzenius: Adding Yakking to Planet Debian

In a case of blatant self-promotion, I am going to add the Yakking RSS feed to the Planet Debian aggregation. (But really because I think some of the readership of Planet Debian may be interested in the content.) Yakking is a group blog by a few friends aimed at new free software contributors. From the front page description:
Welcome to Yakking. This is a blog for topics relevant to someone new to free software development. We assume you are already familiar with computers, and are curious about participating in the production of free software. You don't need to be a programmer: software development requires a wide variety of skills, and you can be a valued core contributor to a project without being a programmer.
If anyone objects, please let me know.

Lucy Wayland: Basic Chilli Template

Amounts are to taste:
[Stage one]
Chopped red onion
Chopped garlic
Chopped fresh ginger
Chopped big red chillies (mild)
Chopped birds eye chillies (red or green, quite hot)
Chopped scotch bonnets (hot)
[Fry onion in some olive oil. When getting translucent, and rest of ingredients. May need to add some more oil. When the garlic is browning. On to stage two.]
[Stage two]
Some tins of chopped tomato
Some tomato puree
Some basil
Some thyme
Bay leaf optional
Some sliced mushroom
Some chopped capsicum pepper
Some kidney beans
Other beans optional (butter beans are nice)
Lentils optional (Pro tip: if adding lentils to adding lentils, especially red lentils, I recommend adding some garam masala as well. Lifts the flavour.)
Veggie mince optional
Pearled barley very optional
Stock (some reclaimed from swilling water around tom tims)
Water to keep topping up with if it get too sticky or dry
Dash of red wine optional
Worcester sauce optional
Any other flavouring you feel like optional (I quite often add random herbs or spices
[[Secret ingredient: a spoonful of Marmite]]
[Cook everything up together, but wait until there is enough fluid before you add the dry/sticky ingredients in.]
[Serve with carb of choice. I currently fond of using Ryvita as dipper instead of tortilla chips.]
[Also serve with a a cooler such as natural yogurt, soured cream or something else. You want more than one type of chilli in there to broaden the flavour. I use all three, plus occasionally others as well. If you are feeling masochistic you can go hotter than scotch bonnets, but I although you may get something of the same heat, I think you lose something in the flavour. BTW if you get the chance, of all the tortilla chips, I think blue corn ones are the best. Only seem to find them in health food shops. There you go. It s a Zen recipe, which is why I couldn t give you a link. You just do it until it looks right, feels right, tastes right. And with practice you get it better and better.

12 July 2017

Jose M. Calhariz: Crossgrading a minimal install of Debian 9

By testing the previous instructions for a full crosgrade I run into trouble. Here is the results of my tests to do a full crossgrade of a minimal installation of Debian inside a VM. First you need to install a 64bits kernel and boot with it. See my previous post on how to do it. Second you need to do a bootstrap of crossgrading: 
 apt-get clean
 apt-get upgrade
 apt-get --download-only install dpkg:amd64 tar:amd64 apt:amd64 bash:amd64 dash:amd64 init:amd64
 dpkg --install /var/cache/apt/archives/*_amd64.deb
 dpkg --install /var/cache/apt/archives/*_amd64.deb
 dpkg --print-architecture
 dpkg --print-foreign-architectures
 apt-get --fix-broken --allow-remove-essential install
Third do a full crossgrade: 
 apt-get install --allow-remove-essential $(dpkg --list   grep :i386   awk ' print $2 '   sed -e s/:i386// )
This procedure seams to be a little fragile, but worked most of the time for me.

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