August 2010 – muellis blog

FOSS.in 2010 does take place \o/

I am delighted to see that this years FOSS.in will indeed take place. There were rumours about it not happening but fortunately you will have the opportunity to have a great time from 2010-12-15 to 2010-12-17!

You might have realised already, that his is only three days:

This year, the event is 3 days instead of the usual 5 days – a 5 day event was simply too exhausting for everyone (participants and team). Also, we have moved the event into the middle of December, to give students of colleges that usually have their exams end-November or early-December a chance to attend. Our American friends will be happy to note that we have moved the event safely out of Thanksgiving range

As last year, I expect the conference to be great. I do hope, that GNOME will be well represented, especially since GNOME-3 will be released and we have the potential to attract many new hackers. Also, because the KDE folks were staffed very well and we were not.

Got a N900 yay

A while back, during FOSS.in, I participated at a Maemo “hacking” contents. The goal was to produce something valuable for Maemo and get a N900 in return. I basically ported Gajim to the N900 and, drumroll, I won! *yay*

Unfortunately, it took them a while to ship that thing so that I received it half a year later or so. But then it was amazingly fast. I received a parcel from Helsinki (2031km far away) which was sent 20hrs earlier. The parcel thus was traveling at ~100km/h. Great service, DHL! Thanks a million Nokia, Thanks Maemo Bangalore!

I really like the N900 because it’s a Linux based device. Well, there is Android, right? But Nokia actually does send it’s patches upstream and they invite you to get root on the device you own. Plus everything is pretty much standard. There is D-Bus, there GTK+, there is Python, there is Linux, … Hence, building and running stuff is pretty easy. I am looking forward to run my DNS Tunnel and DOOM and play around with the USB.

I am now busy playing with my new N900.

Practicum Status Update Week 10

As mentioned in the last report, I skipped one week in favour of the GUADEC.

I had a funny C problem. Consider the following two functions:

 
static int
safe_read (void *data, size_t length, FILE* file)
{
	int status = fread(data, length, 1, file);
 
	if (status == -1) error_report("%s: read packet (%lu) data on stream %p "
								   "failed (%d): %s",
								   __FUNCTION__, length, file,
								   status, strerror(errno));
	status = fflush(file);
	return status;
}
 
static int
safe_write (void *data, size_t length, FILE* file)
{
	int status = fwrite(data, length, 1, file);
 
	if (status == -1) error_report("%s: writing packet (%lu) data on stream %p "
								   "failed (%d): %s",
								   __FUNCTION__, length, file,
								   status, strerror(errno));
	status = fflush(file);
	return status;
}

Now you might want to deduplicate the code and make it one big and two small functions:

 
static int
safe_operation (size_t (func) (void *, size_t, size_t, FILE*), void *data, size_t length, FILE* file)
{
	int status = func(data, length, 1, file);
	const char *funcstr = "undeclared";
 
//	switch (*func) {
//		case fread:
//			funcstr = "read";
//			break;
//		case fwrite:
//			funcstr = "write";
//			break;
//		default:
//			funcstr = "?";
//			break;
//	}
 
	if (status == -1) error_report("%s: %s (%p) packet (%lu) data on stream %p "
								   "failed (%d): %s",
								   __FUNCTION__, funcstr, *func, length, file,
								   status, strerror(errno));
	status = fflush(file);
	return status;
}

but it wouldn’t compile because fread and fwrite have slightly different signatures.
The solution is to:

 
typedef size_t (*fwrite_fn)(const void * __restrict, size_t, size_t, FILE * __restrict);
 
static int
safe_operation (fwrite_fn func, void *data, size_t length, FILE* file)
{
        int status = func(data, length, 1, file);
        const char *funcstr = "undeclared";
 
        if (status == -1) error_report("%s: %s (%p) packet (%lu) data on stream %p "
                                                                   "failed (%d): %s",
                                                                   __FUNCTION__, funcstr, *func, length, file,
                                                                   status, strerror(errno));
        status = fflush(file);
        return status;
}
 
int
main(void)
{
        int x;
 
        safe_operation((fwrite_fn)fread, &amp;x, sizeof x, stderr);
        safe_operation(fwrite, &amp;x, sizeof x, stderr);
        return 0;
}

Thanks to Roland for pointing that out.

On smth unrelated: Fought with OpenSSL and it’s API and documentation. But more on that in a different post.
Fortunately, only Gajim crashed once. Well rhythmbox locks up, too, as it always does

Annoyed by the fact, that it takes ages to “make” a freshly made kernel!

muelli@bigbox ~/git/linux-2.6 $ time make 
  CHK     include/linux/version.h
  CHK     include/generated/utsrelease.h
  CALL    scripts/checksyscalls.sh
  CHK     include/generated/compile.h
  CHK     include/linux/version.h
make[2]: `scripts/unifdef' is up to date.
  TEST    posttest
Succeed: decoded and checked 1382728 instructions
Kernel: arch/x86/boot/bzImage is ready  (#14)
  Building modules, stage 2.
  MODPOST 2107 modules
WARNING: modpost: Found 4 section mismatch(es).
To see full details build your kernel with:
'make CONFIG_DEBUG_SECTION_MISMATCH=y'

real	14m7.842s
user	1m33.747s
sys	0m25.388s
muelli@bigbox ~/git/linux-2.6 $

Trying to automatically create a FAT image and fill populate it with the built modules is more cumbersome than expected. guestmount is way too much overhead: It requires qemu and channels the data out over the network (sic!). I just want a FUSE implementation that is capable of writing a FAT image! There seems to be UMFUSE but it’s packaged for Debian/Ubuntu and not for Fedora.Find the sources is quite a challenge (it’s here: https://view-os.svn.sourceforge.net/svnroot/view-os/trunk/fuse-modules/fat) but I can’t build it, because they haven’t really prepared their code for anybody else to build it. After being harassed to generate the ./configure file (autoconf,; aclocal; autoconf), it also wants shtool to be installed AND in a local directory (/.-). I gave up as it kept bugging me about a missing config.sub. But I still wanted to get that FUSE module so I dug up my Ubuntu chroot and apt-get sourced the files, ./configure && make && make install. Beautiful. Turns out, that the official FUSE wiki lists two ways to mount a FATfs: the one I’ve just described and a dead project (FatFuse).

I then threw together this shellscript:

##!/bin/bash
 
MOD_DIR=/tmp/linux-modules/
FAT_IMAGE=/tmp/modules.$$.fat
FAT_MOUNT=/tmp/share/
FAT_TARGET_IMAGE=/tmp/modules.fat
 
make modules_install INSTALL_MOD_PATH="$MOD_DIR" &&
 
bytes=$(( $(du -s $MOD_DIR | awk '{print $1}') + $(( 20 * 1024)) ))
#
# create FAT image
dd if=/dev/zero of=$FAT_IMAGE bs=1024 count=$bytes &&
mkfs.vfat $FAT_IMAGE &&
fusefat -o nonempty -o rw+ $FAT_IMAGE $FAT_MOUNT &&
cp -dRx $MOD_DIR/* $FAT_MOUNT
fusermount -u $FAT_MOUNT &&
echo $FAT_IMAGE &&
ln -sf $FAT_IMAGE $FAT_TARGET_IMAGE

and I start qemu like that:
/opt/muelli/qemu/bin/qemu-system-x86_64 -drive file=/tmp/ubuntu-snapshots.qcow2,if=virtio -kernel ~/git/linux-2.6/arch/x86_64/boot/bzImage -append 'selinux=0 root=/dev/vda init=/sbin/init' -m 1G -drive file=/tmp/modules.fat,if=virtio,readonly=on -monitor stdio -loadvm 1
which allows me to access the module on the FAT drive on /dev/vdb. I can also snapshot the booted machine which saves me an awful lot of time for booting. But it took me quite a while to make QEmu do that, because the snapshot parameter for the disk does not save snapshots! Also, the FAT drive has to marked as readonly for QEmu to only save snapshots on the only remaining writable drive. But QEmu fails to make a drive readonly if the selected interface is IDE. Thus, you need virtio… Thanks to the helpful folks on IRC…

So yeah, all in all, I didn’t make any substantial progress :-/ I hope to finish a Webcam in software soonish though.

GUADEC 2010 – The Hague

I’ve been to GUADEC *yay*! I am going to summarize some of the talks I’ve attended and some of the many seriously interesting conversations I’ve during this week. But in short: This was one of the best GUADECs, progress wise. I met many people, brought my teams (bugsquad and membership-committee) forward, had new inspirations and fixed some bugs 🙂

But the week started with some work. Apparently, the network was not fully set up yet and we had to use a lot of duct tape to set everything up. After people saw me being “in charge” for the network, they started to complain why the network was not running properly 😉 The problem was, that the Uplink was kind of broken. Basically a big firewall blocked that many connections because it thought it was under attack. The solution then was to claim some of the universities IP addresses and do a big SNAT for the users.

Having said that, the network was up and running perfectly on Wednesday, making it a perfectly networked GUADEC 🙂 The last GUADECs usually had some troubles with the connection even after the event started (remember the broken uplink on Gran Canaria or the rather bad wireless situation in Birmingham?).

The Hotel’s wireless was ridiculously expensive. They wanted 10 quid for 24 hours. But I realized, that the default gateway is announced as being at 192.168.1.1 and if you visited that with a web browser, you’d find out that it was a Zyxel VSG-1200. Turns out, documentation is very verbose, including a default username and password… The rest is left as an exercise for the reader. If you didn’t want to go that route, you could easily claim an active MAC-Address and IP and reuse the authentification…

The talks were streamed and I hope recordings will be made available soon. Good summaries were already given in the official GUADEC blog and various others so I won’t go into too much detail, because .

I haven’t seen covered that Xan and Fernando mocked about the newly promulgated Speaker Guidelines which they didn’t respect either. It’s an interesting discussion though. It is obviously a shield for attacks from the outside so that we (as GNOME) can point to these guidelines if one of our speakers might have offended anyone. But do we, as GNOME, need such a thing in first place? And what happens if we refer to those guidelines over and over again but nobody complies with those? Probably nothing. But do we need to lie to ourselves then? Can’t we expect the people to have enough common sense? Do we want to be a community where we can’t assume enough common sense?

An issue that I didn’t really understand was that the usual picking on Canonical took place. Apparently, people expected Canoncial to contribute more since 1999 than they actually did. But they have been founded 2004… That comment summarizes that fact well. Also, I don’t really get why people expect a distributor to engineer stuff in, say, GNOME. I don’t hear anybody complaining about, say, Mandriva or Gentoo.

Bred Kuhn told us to save human lives by rolling out more crypto within GNOME. I couldn’t agree more. But sadly, we have a long way to go. For now, you can’t even handle your OpenPGP key in a sane way, i.e. rolling over to a new key. It strikes me that we still don’t have a concept encrypted end to end communication, i.e. with Telepathy (well, email is too broken to be tackled). Apparently XTLS should be used. But no PKI will be used, thus discouraging the enhancement of the OpenPGP Web of Trust. It would be absolutely brilliant if Telepathy used OpenPGP keys (maybe even create one if none existed). If then spoken with another entity via Telepathy, it could ask the user to verify the other persons identity via, say, a Videochat. That chat would use the public key material for encryption. The assumption is that the two parties know each other and that a man-in-the-middle cannot spoof valid data quick enough. The other persons key would then more or less automatically be signed. I talked a lot to Stef Walter and other people around GNOME-Keyring and Seahorse and we had good ideas. Let’s see how much we can get done.
But we’ll have a long way to go, since GNOME doesn’t even provide fundamental encryption for it’s webservices, i.e. live.gnome.org or even the RequestTracker 🙁

As for the teams I feel responsible for, I met with a few Bugsquad folks and we’ve discussed a few things. I am still in Post-GUADEC mode to get everything off my Todo-List that accumulated over GUADEC. The most immediate action is to get close bugs of deprecated modules and get rid of the products in Bugzilla. Other lower priority issues are to (finally!) organise a bugday and test a JetPack which helps dealing with Bugzilla…

I also had a few discussion related to the GNOME Foundation Membership process. We somehow have to think about the people that feel intimidated joining the GNOME Foundation. Also we will discuss our strategy and policy of evaluating non trivial contributions to GNOME.

Having said all that. I want to that the GNOME Foundation for paying my accommodation and making such a productive week possible.