There are two software projects that have had huge influence on the -quality of free software, and I wanted to mention both in case someone -do not yet know them.
- -The first one is valgrind, a -tool to detect and expose errors in the memory handling of programs. -It is easy to use, all one need to do is to run 'valgrind program', -and it will report any problems on stdout. It is even better if the -program include debug information. With debug information, it is able -to report the source file name and line number where the problem -occurs. It can report things like 'reading past memory block in file -X line N, the memory block was allocated in file Y, line M', and -'using uninitialised value in control logic'. This tool has made it -trivial to investigate reproducible crash bugs in programs, and have -reduced the number of this kind of bugs in free software a lot. - -
The second one is -Coverity which is -a source code checker. It is able to process the source of a program -and find problems in the logic without running the program. It -started out as the Stanford Checker and became well known when it was -used to find bugs in the Linux kernel. It is now a commercial tool -and the company behind it is running -a community service for the -free software community, where a lot of free software projects get -their source checked for free. Several thousand defects have been -found and fixed so far. It can find errors like 'lock L taken in file -X line N is never released if exiting in line M', or 'the code in file -Y lines O to P can never be executed'. The projects included in the -community service project have managed to get rid of a lot of -reliability problems thanks to Coverity.
- -I believe tools like this, that are able to automatically find -errors in the source, are vital to improve the quality of software and -make sure we can get rid of the crashing and failing software we are -surrounded by today.
+The last few days I have done some upgrade testing in Debian, to +see if the upgrade from Lenny to Squeeze will go smoothly. A few bugs +have been discovered and reported in the process +(#585410 in nagios3-cgi, +#584879 already fixed in +enscript and #584861 in +kdebase-workspace-data), and to get a more regular testing going on, I +am working on a script to automate the test.
+ +The idea is to create a Lenny chroot and use tasksel to install a +Gnome or KDE desktop installation inside the chroot before upgrading +it. To ensure no services are started in the chroot, a policy-rc.d +script is inserted. To make sure tasksel believe it is to install a +desktop on a laptop, the tasksel tests are replaced in the chroot +(only acceptable because this is a throw-away chroot).
+ +A naive upgrade from Lenny to Squeeze using aptitude dist-upgrade +currently always fail because udev refuses to upgrade with the kernel +in Lenny, so to avoid that problem the file /etc/udev/kernel-upgrade +is created. The bug report +#566000 make me suspect +this problem do not trigger in a chroot, but I touch the file anyway +to make sure the upgrade go well. Testing on virtual and real +hardware have failed me because of udev so far, and creating this file +do the trick in such settings anyway. This is a +known +issue and the current udev behaviour is intended by the udev +maintainer because he lack the resources to rewrite udev to keep +working with old kernels or something like that. I really wish the +udev upstream would keep udev backwards compatible, to avoid such +upgrade problem, but given that they fail to do so, I guess +documenting the way out of this mess is the best option we got for +Debian Squeeze.
+ +Anyway, back to the task at hand, testing upgrades. This test +script, which I call upgrade-test for now, is doing the +trick:
+ +
+#!/bin/sh
+set -ex
+
+if [ "$1" ] ; then
+ desktop=$1
+else
+ desktop=gnome
+fi
+
+from=lenny
+to=squeeze
+
+exec < /dev/null
+unset LANG
+mirror=http://ftp.skolelinux.org/debian
+tmpdir=chroot-$from-upgrade-$to-$desktop
+fuser -mv .
+debootstrap $from $tmpdir $mirror
+chroot $tmpdir aptitude update
+cat > $tmpdir/usr/sbin/policy-rc.d <<EOF
+#!/bin/sh
+exit 101
+EOF
+chmod a+rx $tmpdir/usr/sbin/policy-rc.d
+exit_cleanup() {
+ umount $tmpdir/proc
+}
+mount -t proc proc $tmpdir/proc
+# Make sure proc is unmounted also on failure
+trap exit_cleanup EXIT INT
+
+chroot $tmpdir aptitude -y install debconf-utils
+
+# Make sure tasksel autoselection trigger. It need the test scripts
+# to return the correct answers.
+echo tasksel tasksel/desktop multiselect $desktop | \
+ chroot $tmpdir debconf-set-selections
+
+# Include the desktop and laptop task
+for test in desktop laptop ; do
+ echo > $tmpdir/usr/lib/tasksel/tests/$test <<EOF
+#!/bin/sh
+exit 2
+EOF
+ chmod a+rx $tmpdir/usr/lib/tasksel/tests/$test
+done
+
+DEBIAN_FRONTEND=noninteractive
+DEBIAN_PRIORITY=critical
+export DEBIAN_FRONTEND DEBIAN_PRIORITY
+chroot $tmpdir tasksel --new-install
+
+echo deb $mirror $to main > $tmpdir/etc/apt/sources.list
+chroot $tmpdir aptitude update
+touch $tmpdir/etc/udev/kernel-upgrade
+chroot $tmpdir aptitude -y dist-upgrade
+fuser -mv
+I suspect it would be useful to test upgrades with both apt-get and +with aptitude, but I have not had time to look at how they behave +differently so far. I hope to get a cron job running to do the test +regularly and post the result on the web. The Gnome upgrade currently +work, while the KDE upgrade fail because of the bug in +kdebase-workspace-data
+ +I am not quite sure what kind of extract from the huge upgrade logs +(KDE 167 KiB, Gnome 516 KiB) it make sense to include in this blog +post, so I will refrain from trying. I can report that for Gnome, +aptitude report 760 packages upgraded, 448 newly installed, 129 to +remove and 1 not upgraded and 1024MB need to be downloaded while for +KDE the same numbers are 702 packages upgraded, 507 newly installed, +193 to remove and 0 not upgraded and 1117MB need to be downloaded
+ +I am very happy to notice that the Gnome desktop + laptop upgrade +is able to migrate to dependency based boot sequencing and parallel +booting without a hitch. Was unsure if there were still bugs with +packages failing to clean up their obsolete init.d script during +upgrades, and no such problem seem to affect the Gnome desktop+laptop +packages.
