Search Results: "cas"

12 January 2012

Michal Čihař: Tiny blog improvements

Finally, I've found some time to do some improvements on this blog engine. First thing which was more and more missing is reasonable content for description in HTML headers. This lead to sites like Google+ always fetch the constant text and that did not look that. So now, there is something really relevant to the content, either first paragraph (what is the case for all old entries) or something I can manually edit (in case I won't be too lazy). For automatic extraction I tried several approaches. First attempt was simply extracting first paragraph from Markdown, however I quickly remembered that quite a lot of older posts were written directly in HTML, which made this big failure. Later trying BeautifulSoup on rendered HTML, what lead to missing spaces around text which was originally in links. Finally I discovered html2text, which worked pretty easily and does what I need. In the end the code looks like following: 
def get_auto_summary(self):
    h2t = html2text.HTML2Text()
    h2t.body_width = 0
    h2t.ignore_images = True
    h2t.ignore_links = True
    h2t.ignore_emphasis = True
    text = h2t.handle(self.body.rendered)
    return text.splitlines()[0]
Other change affects Flattr, as providing Flattr links for each posts is now possible even without javascript (it's called Auto-submit URL), I've decided to implement them this way. Let's see how many things will get on Flattr this way (at least it will give me better indication what somebody considered being useful). Thanks for commenters on my older blog post for hints.

Filed under: Django English Website 2 comments Flattr this!

11 January 2012

Jon Dowland: Robert Smith in for John Peel

On 21st October 2004, Robert Smith of the Cure sat in for John Peel whilst he was on holiday and presented his show. This was part of a sequence of people covering for Peel. Off the top of my head Siouxie of the Banshees sat in on another night, but I forget who else. Anyway, sadly, John died a few days later on the 25th. Before John's death, in response to his pre-recorded show being butchered by the BBC, Smith posted an angry message on the Cure's website, which included the tracklisting as he had originally prepared. After John's death was announced, Smith deleted the post from his site, no doubt out of respect for Peel and to avoid any mis-interpretation. I recorded the show onto minidisc when it was broadcast and discovered a lot of music that I loved and hadn't heard of before. I've just stumbled across a copy of Smith's post, including the tracklist, so for historical interest's sake, here it is (with only light typographical editing). If anyone cares enough, I could have a look for that minidisc

Craig Small: MediaServer with Rygel

Rygel XVI

Image by Cayusa via Flickr

Like a lot of people, I have one of those set-top TV boxes that can record TV shows at set times. I made sure that I could get at the files (using a FTP server in this case) and that the files were some sort of common standard (MPEG 4 TS). I also have a bunch of mp3 music files. That s fine when I m on the desktop because the files are local. I wanted to make these available to anyone in the household. DLNA seemed to be a reasonably OK way of doing this, the problem was, how to get it working in Linux? A lot of the problem is that it is hard to find a DLNA only server. Sure MythTV could do it, but it needs a tv tuner or a lot of fiddling around. XMBC can also do it, but it needs to be running a GUI. I even tried mediatomb but could not get the thing to compile as the library calls to mozjs were all using deprecated functions. I just wanted a daemon that served stuff, nothing more; no fancy ui, no need for X just file serving goodness. Rygel is almost that. You could say it is a user server much like a torrent client/server. The nice thing is you can fiddle around with rygel so it becomes close to a real server. This is how I did it. First, I made a rygel user with a home directory, but disabled login. I don t like programs running root if they don t need it and rygel doesn t need it. The home directory needs to be writeable to the rygel user too otherwise the program doesn t work too well. I use /var/local/rygel as its home. For the configuration, copy /etc/rygel.conf to ~rygel/.config/rygel.conf This is the configuration file for rygel. I disabled all of the modules except MediaExport. Make sure you disable Tracker otherwise MediaExport will not work. Tracker is only useful for real users who are logged in and have dbus etc going which this user is certainly not. I made a simple rygeld file in /usr/local/sbin which basically starts the program, forks and grabs the PID to write to a pidfile. This mean it was easier to track the program in the init scripts. 
#!/bin/sh
#
# Rygel daemon handling
RYGEL='/usr/bin/rygel'
RYGEL_ARGS=''
su -s /bin/sh -c "nohup $RYGEL $RYGEL_ARGS > /var/local/rygel/rygel.log 2>&1 &"
rygel
EXIT_CODE=$?
if [ $EXIT_CODE != 0 ] ; then
        return $EXIT_CODE
fi
PGROUP= ps --no-headers -o pgrp $$ 
PID= pgrep -g $PGROUP -f $RYGEL 
echo $PID > /var/run/rygel.pid
exit 0
In case you were wondering, the pgrp finds the program group so the pgrep finds the right rygel process that has the same program group as the starting shell. The init script is a standard init script except the exec flag checks for /usr/bin/rygel but the start line starts /usr/local/sbin/rygeld This is because we want to kill the real rygel process but start it with the script. This setup works rather well. You do get some messages in the logfile about dbus not working but it is harmless. I tried disabling the mpris and external plugins but no matter what flag or configuration file option I tried, they would always try to start and fail with no dbus. Rygel is a a reasonably light-weight way of serving media to your home network. It idles 200 MB virtual with 16MB resident and when idle uses almost no CPU.
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Michal Čihař: Configuring standalone XBMC

I have a laptop used for playing music (and occasionally also videos) which is currently running Windows XP with XBMC. Reinstalling this beast to Linux is on my todo list for ages and now I've finally found time to try that. Starting Debian installer worked like charm and in few minutes I got Debian system running. I've chosen to run sid, well for reason I run it usually on place where I want latest software. Installing XBMC from Debian multimedia worked also fine and you can easily find some howtos for directly starting XBMC. And that's where I ran into trouble - XBMC is damn slow. Notebook has oldish nVidia GeForce FX Go5200 card, which seems to be poorly supported by nouveau (and "Do not file bug reports about this driver." suggest that this is what authors do expect). Okay, I can survive having some binary crap so let's try nVidia proprietary drivers. I've quickly realized that the legacy drivers won't work with recent xserver and probably also not with the kernel. Maybe I should try installing something older, what would run binary drivers, but for now I gave up and system is back on Windows (with all problems I have there...).

Filed under: Debian English Linux 7 comments Flattr this!

10 January 2012

Andrew Pollock: [life] Breaking and entering, with permission

I had a bit of an adventure yesterday, which would have taken some explaining if the police had gotten involved. It went a little something like this... My friend and former co-worker Sara was in the US Virgin Islands for the holidays. Her boyfriend, Karl, flew there separately for the tail end of her time there. Yesterday, I received a phone call from Sara, saying that Karl had managed to fly out to the Virgin Islands without his passport. Apparently you can get there without one, but to get back into the mainland US, you need one. She wanted to know if I could get one of my lock-picking co-workers to break into their apartment and retrieve Karl's passport and mail it them. Karl was supposed to fly out the next day. Attempts by Sara to contact her landlord had failed, so they didn't have many other options (apart from mailing me a key, which would have cost them another day). I asked one of my co-workers, Jason, who I knew was into lock picking, if he was up for it, and he offered to put me in touch with another guy who had dominated the recent lock picking night that he'd run. So now I'm talking to David, who's on board with the mission, but doesn't have his lock picking gear on him. No problem, Jason says he'll lend me his, which was at work with him. So we have a plan. Our friends Ian and Melinda are currently in Australia. They've lent us their car because it's leased, and they have some minimum mileage they're supposed to do and they're under it, so I've been driving to work in their car some days. As it happens, I drove to work in it yesterday. So now David and I set out in a car that neither of us own, with a lock picking set that belongs to another person, to break into an apartment of someone who's in the Virgin Islands. What could possibly go wrong? I'm told that it's not illegal to own a lock picking set, but if you're caught with one on your person and you're not a locksmith, you can get into all sorts of trouble. On top of that I'd have a hard time explaining the car I'm driving. We get to Sara and Karl's condo complex. It has a common gate that visitors would normal get buzzed through. Turns out it's not that hard to climb over. It's got some benign-looking spiky things on top, but I could get a leg over from the left hand side of the gate and jump over without impaling myself. Then I let David in and we proceeded upstairs to Sara and Karl's apartment door, where David set to work. Sara said that just the dead bolt was locked. David started at it with Jason's tools, trying to be as discreet as possible. It was about 3:30pm and there was no one around, but we could hear some noises from the neighbouring apartment (the two front doors were right next to each other). After what felt like about half an hour without success (the last pin of the lock was particularly tricky apparently) David was having to resort to more noisy techniques with the lock, so I decided to take the up-front approach and just inform the next door neighbour what we were doing in case he/she (I think it was a she) decided to call the cops on us. I told her through the door why we were there and what we were doing. She didn't seem to care too much. David then proceeded to start "raking" the lock, essentially brute forcing the pins with a lot of jiggling, and finally managed to pick it and we were in. I quickly found Karl's passport where it was suspected to be, and then we pondered how we were going to lock the door again. We could have just locked the door knob instead of the deadbolt and closed the door behind us, but we weren't sure if Sara and Karl had a key to the doorknob (Sara said they always just locked the deadbolt). Sara was fine with leaving the door unlocked until they got home, but weren't so keen on leaving our fingerprints all over the place and then leaving the door unlocked. David tried to re-pick the deadbolt so that he could lock it via the same means as opened it, and I scouted around for a key. I managed to find a key that locked both the deadbolt and the doorknob, so I took that with us and locked up their apartment. In David's defense, the deadbolt was a bit stiff to lock even with the key. I dropped David back at work, collected my stuff (it was now about 4:30pm) and headed to the UPS Store to ship Karl's passport to him as fast as humanly possible. I just made the 5pm pick up. Today I received an SMS from Sara informing me that they had received the passport. I was very impressed with how fast it got to them. So that was all a bit of an adventure. I'm not sure how much longer Karl is going to have to stay in the Virgin Islands as a result. I'm going to suggest that Sara and Karl leave a spare key with someone in future.

9 January 2012

Craig Small

Following up from the upstream release of a new procps, the debian packages have also been updated. This upload has a significant change in that, I hope, procps is now multi-arch compliant. To make this happen, the libprocps library is now in it s own package, separate from the binaries. It also means that if you have programs not from procps that link to this library they are now broken. I put in a Breaks: line for the three I know about which will need a recompile with a small tweak in the control file and linked statements. As suggested in the multi arch wiki page, I tested the libprocps0-dev package by compiling something against it, in this case another Debian package xmem. Doing this was very useful for teasing out some bugs on the dev package itself that did not appear while linking the library to the procps binaries. In short, the new procps has a lot fewer patches than the old ones and the next version will have less as I have already included the current changes into the upstream git repository. The main differences are now The three are really bugs, especially the last, which is why the patches will disappear next release.

Craig Small: procps 3.32 Debian packages

Following up from the upstream release of a new procps, the debian packages have also been updated. This upload has a significant change in that, I hope, procps is now multi-arch compliant. To make this happen, the libprocps library is now in it s own package, separate from the binaries. It also means that if you have programs not from procps that link to this library they are now broken. I put in a Breaks: line for the three I know about (xmem, guymager and open-vm-tools) which will need a recompile with a small tweak in the control file and linked statements. As suggested in the multi arch implementation wiki page, I tested the libprocps0-dev package by compiling something against it, in this case another Debian package xmem. Doing this was very useful for teasing out some bugs on the dev package itself that did not appear while linking the library to the procps binaries. In short, the new procps has a lot fewer patches than the old ones and the next version will have less as I have already included the current changes into the upstream git repository. The main differences are now The three are really bugs, especially the last, which is why the patches will disappear next release.
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Steve McIntyre: Armhf buildds and status in Debian

Current status Back in September, I wrote about the machines that I set up to help bootstrap the new armhf port in Debian. Basing on Konstantinos' huge efforts in bringing up the new "architecture" in debian-ports, we started importing armhf into the main Debian archive on the 24th of November. Since then, those builders have been churning away night and day to build the huge collection of software that makes up the Debian archive. The current state can be seen on the armhf buildd status page, and there's a nice graph showing how quickly we've managed to run from 0 to over 90% of the archive here. (Click on the image for a larger version, or visit https://buildd.debian.org/stats/ for other versions. We overtook hurd-i386 quickly and are now ahead of the kfreebsd-* architectures. armhf bootstrap graph We've recently brought 3 more similar build machines online (hildegard, howells and hummel), again sponsored by the nice folks at Linaro but now hosted at the York NeuroImaging Centre at the University of York. This gives us both more build horsepower to keep up with building more different bits of Debian (experimental, updates etc.) and more redundancy in case of problems. We now have the vast majority of the archive built, and now a number of us are concentrating on fixing the remaining issues: language bootstraps and bugs. Also, on the 7th of January we were just added into testing, the next step on our path for inclusion as a Debian release architecture. Setting up the machines A lot of people have been asking me about the physical setup I showed in my last blog about these machines, so here's more details for those who are interested. Mount the 6 boards into the mini-rack, connect up the Molex power connectors to each board, attach ethernet cables and turn it all on! Each board comes with a micro-SD card containing uboot and an Ubuntu installation. I've configured uboot to boot off the hard drive directly, but leaving configuration available to use the Ubuntu on the micro-SD as a simple rescue system should the need arise. The Quickstart boards are not ideal physically for two reasons: the lack of SATA power, plus you need to push a power button on each board to boot it - they don't boot automatically the moment power is applied. However, they're quite inexpensive little machines and have done a great job of building the Debian archive so far! The ideal machines for us would also include more RAM at this point. CPU on these is adequate, but the larger C++ packages (yay webkit!) use a huge amount of memory at link time. Linking in swap is not the best thing, performance-wise... :-( UPDATE 2012-01-12: Ian tells me that the newer Quickstart-R boards apparently have a different power controller; these now boot up straight away without needing you to push a button. That sounds useful.

Antonio Terceiro: Life after exec()

From the not necessarily big news, but still useful department. The situation: for Very Good Reasons 1, you want to replace your current process by calling exec(), but you still want to have the chance to do something after the process you exec()ed finishes. This is a simple technique I just came up with: just before replacing the current process by calling exec(), you fork() a process in the background that will wait for the current process id to disappear from the process list, and then does whatever you want to do. A simple proof-of-concept I wrote is composed of two bash programs: wrapper and real. real is really simple: it just waits a few seconds and then prints its process id to the console: 
#!/bin/bash
sleep 5
echo $BASHPID
wrapper is the program that handles the situation we want to exercise: it replaces itself with real, but still has the chance to do something after real finishes. In this case, wrapper notifies the user that real finished. 
#!/bin/bash
echo $BASHPID
real_program_pid=$BASHPID
(
  while ps -p "$real_program_pid" >/dev/null; do
    sleep 0.1s
  done
  notify-send 'real program finished'
) &
exec ./real
One nice property that wrapper explores is that when exec() starts real, it really replaces wrapper, and therefore has the same process id (in this case accessible by bash in the $BASHPID variable). Because of this, the background process that wrapper starts just before the exec() call already knows which process it has to watch for. The actual code for waiting is not optimal, though. I cannot use waitpid() (the wait builtin in bash), since real is not a child process of wrapper. I went with a brute force approach here, and I am pretty sure there is a cheaper way to wait for a random PID without a busy loop (but that wasn t the point here). 1 update: I am aware of the classic fork()/exec() pattern. My Very Good Reasons include the fact that I can t control the flow: I am writing a plugin for a program that calls its plugins in sequence, and after that, calls exec(), but my plugin is interested in doing some work after exec() finishes.

8 January 2012

Niels Thykier: Testing migration and package relations

While looking at the dpkg Breaks-field[0] 
$ aptitude show dpkg
Package: dpkg
[...]
Version: 1.16.1.2
[...]
Breaks: apt (< 0.7.7), aptitude (< 0.4.7-1), dpkg-dev (< 1.15.8), libdpkg-perl (< 1.15.8), pinfo (< 0.6.9-3.1), tkinfo (< 2.8-3.1)
it occurred to me that most (all?) of these relations were irrelevant to Britney when she migrated dpkg 1.16.1.2 to testing. Right now, at least the APT relations are only relevant if you are doing something like a distribution upgrade from Lenny/Squeeze to Wheezy. Similarly, the version constraints in a lot of dependency relations (e.g. libc6 (>= 2.11) ) are satisfied in testing and unstable at the same time. Removing the version constrains on dependencies is a rather minor thing as it is basically just a minor constant time optimization on each dependency check. However, removing an entire clause slightly reduces the problem size a bit. Particularly, the Conflicts/Breaks relations tends to be expensive for us. The first task was to identify the relations that can (or cannot) be simplified. In a Britney run we at most 4 versions of the same package per architecture, though usually only 1 or 2[1]. I devised a small set of rules to simplify the relations. These rules are applied to each package in the relation (atomic proposition, if you will).
  1. If the relation is versioned and it involves a virtual package in any suite, then do not change the relation in any way. Rationale: A virtual package cannot satisfy any versioned relation (Policy Manual 7.5)
  2. If the relation is a dependency (i.e. Pre-Depends or Depends) and the package is not available in any suite, then do not change the relation in any way.
  3. If the relation is versioned and the relation is satisfied in all suites (where the relationed-on package is available), then remove the version constrain. Rationale: If all (present) versions satisfy the relation, then version constrain does not change the semantics.
  4. If the relation is a conflict (i.e. Conflicts or Breaks) and relation is unsatisfiable in all suites, then remove the relation. Rationale: If none of the (present) versions satisfy the conflict-relation, then there is no conflict[2].
The rules are rather conservative in some cases and there is room for improvements. However, one has to remember that removing too few relations costs a bit in runtime, removing too many breaks testing and possibly a lot. Obviously, I prefer the former to the latter (especially because I will be a part of the clean up -crew). I tested my implementation of those four rules above against the current master branch. In short, it produces the same result as the master branch in all the tests so far. In the hand-made test-suite, the tests generally do not have any superfluous relations. Thus, it is slightly slower, though usually within 0.1 seconds of the master branch. On the other hand, in the live-data samples I have collected so far it does vastly better. For the longest run (sample from 2011-12-13), it reduces the runtime with ~70 seconds (from ~215 to ~145 seconds). In the other runs, it reduces total runtime with ~35 and ~2 seconds, respectively. In these samples, only the amd64 and i386 packages are considered (and human hints are ignored). For those interested, the code is available in my branch. :) [0] There is perfectly valid reason for doing that. I might get back to that in a later post. [1] One in unstable, testing, testing-proposed-updates and proposed-updates. The latter may seem a bit weird, but [0] [2] This is the rule that prune relations like the one in the dpkg Breaks-field. Edit: 2011-01/09, clarified that we have at most 4 versions per architecture.

Russell Coker: My First Cruise

A few weeks ago I went on my first cruise, from Sydney to Melbourne on the Dawn Princess. VacationsToGo.com (a discount cruise/resort web site) has a review of the Dawn Princess [1], they give it 4 stars out of a possible 6. The 6 star ships seem to have discount rates in excess of $500 per day per person, much more than I would pay. The per-person rate is based on two people sharing a cabin, it seems that most cabins can be configured as a double bed or twin singles. If there is only one person in a cabin then they pay almost double the normal rate. It seems that most cruise ships have some support for cabins with more than two people (at a discount rate), but the cabins which support that apparently sell out early and don t seem to be available when booking a cheap last-minute deal over the Internet. So if you want a cheap cruise then you need to have an even number of people in your party. The cruise I took was two nights and cost $238 per person, it was advertised at something like $220 but then there are extra fees when you book (which seems to be the standard practice). The Value of Cruises To book a hotel room that is reasonably comfortable (4 star) in Melbourne or Sydney you need to spend more than $100 per night for a two person room if using Wotif.com. The list price of a 4 star hotel room for two people in a central city area can be well over $300 per night. So the cost for a cruise is in the range of city hotel prices. The Main Dining Room (MDR) has a quality of food and service that compares well with city restaurants. The food and service in the Dawn Princess MDR wasn t quite as good as Walter s Wine Bar (one of my favorite restaurants). But Walter s costs about $90 for a four course meal. The Dawn Princess MDR has a standard 5 course meal (with a small number of options for each course) and for no extra charge you can order extra serves. When you make it a 7 course meal the value increases. I really doubt that I could find any restaurant in Melbourne or Sydney that would serve a comparable meal for $119. You could consider a cruise to be either paying for accommodation and getting everything else for free or to be paying for fine dining in the evening and getting everything else for free. Getting both for the price of one (along with entertainment etc) is a great deal! I can recommend a cruise as a good holiday which is rather cheap if you do it right. That is if you want to spend lots of time swimming and eating quality food. How Cruise Companies Make Money There are economies of scale in running a restaurant, so having the MDR packed every night makes it a much more economic operation than a typical restaurant which has quiet nights. But the expenses in providing the services (which involves a crew that is usually almost half the number of passengers) are considerable. Paying $119 per night might cover half the wages of an average crew member but not much more. The casino is one way that the cruise companies make money. I can understand that someone taking a luxury vacation might feel inclined to play blackjack or something else that seems sophisticated. But playing poker machines on a cruise ship is rather sad not that I m complaining, I m happy for other people to subsidise my holidays! Alcohol is rather expensive on board. Some cruise companies allow each passenger to take one bottle of wine and some passengers try to smuggle liquor on board. On the forums some passengers report that they budget to spend $1000 per week on alcohol! If I wanted a holiday that involved drinking that much I d book a hotel at the beach, mix up a thermos full of a good cocktail in my hotel room, and then take my own deck-chair to the beach. It seems that the cruise companies specialise in extracting extra money from passengers (I don t think that my experience with the Dawn Princess is unusual in any way). Possibly the people who pay $1000 per night or more for a cruise don t get the nickel-and-dime treatment, but for affordable cruises I think it s standard. You have to be in the habit of asking the price whenever something is offered and be aware of social pressure to spend money. When I boarded the Dawn Princess there was a queue, which I joined as everyone did. It turned out that the queue was to get a lanyard for holding the key-card (which opens the cabin door and is used for payment). After giving me the lanyard they then told me that it cost $7.95 so I gave it back. Next time I ll take a lanyard from some computer conference and use it to hold the key-card, it s handy to have a lanyard but I don t want to pay $7.95. Finally some things are free at some times but not at others, fruit juice is free at the breakfast buffet but expensive at the lunch buffet. Coffee at the MDR is expensive but it was being served for free at a cafe on deck. How to have a Cheap Cruise VacationsToGo.com is the best discount cruise site I ve found so far [2]. Unfortunately they don t support searching on price, average daily price, or on a customised number of days (I can search for 7 days but not 7 or less). For one of the cheaper vessels it seems that anything less than $120 per night is a good deal and there are occasional deals as low as $70 per night. Princess cruises allows each passenger to bring one bottle of wine on board. If you drink that in your cabin (to avoid corkage fees) then that can save some money on drinks. RumRunnerFlasks.com sells plastic vessels for smuggling liquor on board cruise ships [3]. I wouldn t use one myself but many travelers recommend them highly. Chocolate and other snack foods are quite expensive on board and there are no restrictions on bringing your own, so the cheap options are to bring your own snack food or to snack from the buffet (which is usually open 24*7). Non-alcoholic drinks can be expensive but you can bring your own and use the fridge in your cabin to store it, but you have to bring cans or pressurised bottles so it doesn t look like you are smuggling liquor on board. Generally try not to pay for anything on board, there s enough free stuff if you make good choices. Princess offers free on-board credit (money for buying various stuff on-board) for any cruise that you book while on a cruise. The OBC starts at $25 per person and goes as high as $150 per person depending on how expensive the cruise is. Generally booking cruises while on-board is a bad idea as you can t do Internet searches. But as Princess apparently doesn t allow people outside the US to book through a travel agent and as they only require a refundable deposit that is not specific to any particular cruise there seems no down-side. In retrospect I should have given them a $200 on the off chance that I ll book another cruise with them some time in the next four years. Princess provide a book of discount vouchers in every cabin, mostly this is a guide to what is most profitable for them and thus what you should avoid if you want a cheap holiday. But there are some things that could be useful such as a free thermos cup with any cup of coffee if you buy coffee then you might as well get the free cup. Also they have some free contests that might be worth entering. Entertainment It s standard practice to have theatrical shows on board, some sort of musical is standard and common options include a magic show and comedy (it really depends on which cruise you take). On the Dawn Princess the second seating for dinner started at 8PM (the time apparently varies depending on the cruise schedule) which was the same time as the first show of the evening. I get the impression that this sort of schedule is common so if you want to see two shows in one night then you need to have the early seating for dinner. The cruise that I took lasted two nights and had two shows (a singing/dancing show and a magic show), so it was possible to have the late seating for dinner and still see all the main entertainment unless you wanted to see one show twice. From reading the CruiseCritic.com forum [4] I get the impression that the first seating for dinner is the most popular. On some cruises it s easy to switch from first to second seating but not always possible to switch from second to first. Therefore the best strategy seems to be to book the first seating. Things to do Before Booking a Cruise Read the CruiseCritic.com forum for information about almost everything. Compare prices for a wide variety of cruises to get a feel for what the best deals are. While $100 per night is a great deal for the type of cruise that interests me and is in my region it may not be a good match for the cruises that interest you. Read overview summaries of cruise lines that operate in your area. Some cruise lines cater for particular age groups and interests and are thus unappealing to some people EG anyone who doesn t have children probably won t be interested in Disney cruises. Read reviews of the ships, there is usually a great variation between different ships run by one line. One factor is when the ships have been upgraded with recently developed luxury features. Determine what things need to be booked in advance. Some entertainment options on board support a limited number of people and get booked out early. For example if you want to use the VR golf simulator on the Dawn Princess you should probably check in early and make a reservation as soon as you are on board. The forums are good for determining what needs to be booked early. Also see my post about booking a cruise and some general discussion of cruise related things [5]. Related posts:
  1. Cruises It seems that in theory cruises can make for quite...
  2. Combat Wasps One of the many interesting ideas in Peter F. Hamilton s...
  3. Victoria Hotel Melbourne I have just stayed at the Victoria Hotel Melbourne. I...

7 January 2012

Stefano Zacchiroli: debian donations-fu

The end of the year is a period of time during which many people sit down and decide to donate some money to initiatives that pursue the public good. I have that habit myself. At the end of 2011 I've decided to donate to Wikipedia, as I consider Wikipedia to be one of the greatest achievements of humanity and I see a lot of value in keeping it running on a purely non-profit basis. (Not to mention that it's already quite annoying to see Jimbo's banners one month per year, go figure what would happen if those banners would suddenly turn into permanent advertisement banners!) You may wonder why I haven't donated to Debian, given my involvement in the project. In fact, that involvement is precisely why I didn't donate to Debian: there is some sort of sanity in keeping a distinction between causes to which I donate my spare time (the case of Debian) and those to which I donate money (the case of Wikipedia), and I like to keep that distinction. As DPL, I've the luxury of being cc:-ed on Debian donation notifications that flow through SPI, and I can also check the flow of donations to other Debian trusted organizations. This year, I've been particularly impressed by the high flow of Debian donations during the end of the year. Thank you, donors, it is thanks to your generosity that we keep many Debian activities going. Using the money people like you regularly donate to Debian we: On a more political note, I'm happy to observe that Debian incomes come almost entirely from private citizens. We do have big corporate sponsors, but their contributions tend to be concentrated as specifically earmarked donations for our annual conference. This is good for them, because they get the fancy banners on the DebConf website and at the conference. But it is also good for Debian, because a donation-based economy (as Debian's, with DebConf exception) is less likely to be influenced by the whims of a few big donors. But with (great) donations comes (great) responsibility. In particular, it comes the need of budget transparency. You can't go out soliciting donations and simply say "thanks, your contribution is appreciated". You need to show donors how their money are used, so that they can judge whether they made the right choice in donating to you or not. Whether they will donate again in the future or not granting long term sustainability to your project usually depends on that. So, if you have donated to Debian or are considering doing so in the future, here are a few of places where you can check what we have been doing with donated money: Albeit quite detailed, the above is not enough: we should do better on the transparency of Debian budget. For one thing, the above is too scattered: budget transparency should not depend on (potential) donors mixing and matching too many sources of information. Further more, the above is not even complete: SPI is not the only Debian trusted organization, and the accessibility of information about Debian budgets hosted at other organizations varies quite a bit. We've been working on improving this for the past year or so: we're not there yet, but I'm positive we can have detailed and comprehensive budgets encompassing all Debian trusted organizations published in the coming months . Why has it taken so long and what could possibly be so difficult about it? I think the cause of the delay is twofold:
  1. The disperse nature of Debian adds some difficulties to regular accounting challenges. Contrary to other FOSS projects I'm aware of, we've many different trusted organizations, each one with its own different way of reporting things. The advantage of such a setup is that we can often avoid the costs of money transfers around the world, costs in which we'd incur had we a single organization holding our assets, say, in the US. Still, having too many organizations is counterproductive. This is why for the past 1.5 years I've been working on consolidating our money assets into as few budgets as possible (avoiding, for instance, to use more than one organization per currency).
  2. We tend to be good at recruiting packaging geeks, but not so good at recruiting other kinds of geeks: budget geeks, artwork geeks, journalist geeks, management geeks, etc. But it is upon those other kinds of "geekness" that many activities of "standard" Debian geeks depend. For example: if you want to have a steady flow of new project members, you need to communicate effectively Debian values and make some buzz around them, so that you could hope they get to the right ears. If you want to organize sprints for maintainers to work together you need money donations, and to solicit donations you need a transparent budget. Etc. In the specific case of accounting, we're now lucky enough to have found "standard" Debian geeks who also have a passion for accounting and auditing; but that appaears to be, essentially, a coincidence. If we don't fix the more general problem, I believe our difficulties in recruiting "non-standard" Debian geeks might hurt us quite a bit in the long run.

Steve Kemp: Review of the Panasonic Lumix FS-16 camera

Recently I've been wanting to replace my old point and shoot camera, a Canon PowerShot A620. I've got a pair of DLSR cameras and I do frequently carry one of them out with me, but there are undoubtedly occasions where I'd rather not bother, or where I find myself wanting to take a picture without having one to hand. Unfortunately the PowerShot is pretty large itself, although significantly less so than the DSLRS I possess. (I cannot remember the last time I used the PowerShot outside my flat, that is how rarely it goes outdoors). The PowerShot has been a good camera to me for many years and the three features I liked the most: Picking a replacement camera, even with the help of fine comparison websites like snapsort.com is hard. Cameras have moved on and "improved" a lot over the last few years - to the extent that finding one with a built-in viewfinder is hard. Finding one with a built-in viewfinder and running on easily replaceable batteries was virtually impossible. Eventually I settled on the Panasonic Lumix FS16, which omits both: The way that you use the LCD or viewfinder differs pretty significantly, but the LCD wasn't as bad as I'd feared:
ViewFinder
You hold the camera to your eye, and press the appropriate buttons.
LCD
You typically hold the camera at arms length, which means you're prone to shaking your hands/arms and getting blurry shots. Because you're holding the camera relatively far away from your eyes if you have the sun at your back you're liable to need to squint.
The LCD on the Lumix FS-16 isn't amazing, but neither is it horrific and it is better than expected in dark locations. So after a week what do I think? On the whole it is a fine camera, better than the PowerShot in many ways, and while it has draw-backs none are deal-breakers:
Size
The best camera is one you have with you; on that basis this camera is a clear win being smaller, lighter, and more compact than the Canon. I've taken this camera with me, randomly, to several places and returned with useful and interesting images.
Low Light
Low light performance is pretty poor. With only one manual control you see noise if you're shooting in gloomy pubs, and outdoors. With the flash you can get acceptable pictures if you're careful - but its a tricky thing to get right. (To update this a little: Outdoors at night? No. In a pub with poor lighting you'll be alright.)
Manual Controls
The camera features precisely two manual controls:
  • "Flash on" vs. "Flash off".
  • ISO can be changed from: Auto, 100, 200, 400, 800, 1200 and 1600.
There is no notion of shutter speed, nor is there any ability to change the aperture size. (Though both these values are displayed on the screen as you take a picture I wonder why? As you can't change anything you can't use the information in any useful fashion, and presumably a non-camera-person wouldn't understand what these numbers represent.) The lack of these two controls is a little galling, but pretty common for the low-end P&S cameras.
Video Recording
There is no external MIC so sounds aren't great, but they're not horrible either. Video recordings are limited to the smaller of 8 minutes or 2Gb. So no long films, but short ones look fine. Just be aware that once you start recording focus won't change, nor will zooming work. Compared to the canon the quality is improved; but the Canon allowed you to (optically) zoom whilst recording. Here you can only zoom with your feet.
Recharging Time
When I received the camera it took about an hour to charge. The battery life seems reasonable - the level is 2/3 a week later and I've been shooting, reviewing, and deleting regularly. (Note: I never use USB to transfer pictures, I always remove the card and plug it into my PC. Whether this makes a difference to battery life I don't know.)
Controls
Physical controls are reasonable. There is a mechanical slide-switch to turn on/off. I like that, as it is less prone to being knocked by keys, change, etc. There is also a physical slide-switch to change from "shoot" to "review current images/videos". (Same as my Canon) I think this is a mistake, and don't see why it can't be a soft-button.
Full Auto
There are several modes available in the camera (remember the caveat about lack of aperture/shutter speed) I've been using both full-auto and manual modes, and both are good. Full auto would suit most people - it has clever face-tracking.
Focusing Speed
As expected this is not stellar. Walking to the corner shop the other lunchtime I found a cat in the road, I talked to her and she rubbed herself against my ankles. Could I focus fast enough to catch her looking up at me? No. For static scenes, and candid shots of people it'll suffice. For fast action and moving children probably not a chance.
On balance, the upgrade was worthwhile. ObQuote: "I don't mean to lecture and I don't mean to preach. And I know I'm not your father..." - Spider-Man

Jon Dowland: Flow My Tears, the Policeman Said

The Philip K. Dick Collection The Philip K. Dick Collection
I've just finished reading "Flow My Tears, the Policeman Said" by Philip K Dick, one of 13 novels collected in the Library of America's wonderful "The Philip K. Dick Collection" boxed set. This story has never jumped out at me as one to read with any particular urgency, despite the title being a reference to a composition by my namesake. I was reminded about it whilst listening to one of BBC Radio 4's "Great Lives" broadcasts, where Michael Sheen read a passage from the book. As an aside, the "Great Lives" series is a really interesting listen: I particularly enjoyed their episode on Ludwig Wittgenstein. You can get the whole series in podcast form. Back to the book. It features Dick's trademark theme of fractured realities, perhaps more so than in many of his more well-known works such as Ubik or A Scanner Darkly. It also has much better characterisation than I expect from his writing. His female characters remain as always sinister, threatening, mischevious, but they are at least fleshed out. There is a lot more of an exploration of the human condition than usual. Dick wrote that the novel begun as an attempt to explore different varieties of love. I enjoyed the mystery of the weird goings-on whilst they were mysterious, but I felt mildly let down when the explanation was eventually proffered.

6 January 2012

Matthew Garrett: Firmware bugs considered enraging

Part of our work to make it possible to use UEFI Secure Boot on Linux has been to improve our EFI variable support code. Right now this has a hardcoded assumption that variables are 1024 bytes or smaller, which was true in pre-1.0 versions of the EFI spec. Modern implementations allow the maximum variable size to be determined by the hardware, and with implementations using large key sizes and hashes 1024 bytes isn't really going to cut it. My first attempt at this was a little ugly but also fell foul of the fact that sysfs only allows writes of up to the size of a page - so 4KB on most of the platforms we're caring about. So I've now reimplemented it as a filesystem[1], which is trickier but avoids this problem nicely.

Things were almost working fine - I could read variables of arbitrary sizes, and I could write to existing variables. I was just finishing hooking up new variable creation, but in the process accidentally set the contents of the Boot0002 variable to 0xffffffff 0xffffffff 0x00000000. Boot* variables provide the UEFI firmware with the different configured boot devices on the system - they can point either at a raw device or at a bootloader on a device, and they can do so using various different namespaces. They have a defined format, as documented in chapter 9 of the UEFI spec. At boot time the boot manager reads the variables and attempts to boot from them in a configured order as found in the BootOrder variable.

Now, obviously, 0xffffffff 0x00000000 is unlikely to conform to the specification. And when I rebooted the machine, it gave me a flashing cursor and did nothing. Fair enough - I should be able to choose another boot path from the boot manager. Except the boot manager behaves identically, and I get a flashing cursor and nothing else.

I reported this to the EDK2 development list, and Andrew Fish (who invented EFI back in the 90s) pointed me at the code that's probably responsible. It's in the BDS (Boot Device Selection) library that's part of the UEFI reference implementation from Intel, and you can find it here. The relevant function is BdsLibVariableToOption, which is as follows (with irrelevant bits elided):
BdsLibVariableToOption (
  IN OUT LIST_ENTRY                   *BdsCommonOptionList,
  IN  CHAR16                          *VariableName
  )
 
  UINT16                    FilePathSize;
  UINT8                     *Variable;
  UINT8                     *TempPtr;
  UINTN                     VariableSize;
  VOID                      *LoadOptions;
  UINT32                    LoadOptionsSize;
  CHAR16                    *Description;
  //
  // Read the variable. We will never free this data.
  //
  Variable = BdsLibGetVariableAndSize (
              VariableName,
              &gEfiGlobalVariableGuid,
              &VariableSize
              );
  if (Variable == NULL)  
    return NULL;
So so far so good - we read the variable from flash and put it in Variable, Variable is now 0xffffffff 0xffffffff 0x00000000. If it hadn't existed we'd have skipped over and continued. VariableSize is 12.
  //
  // Get the option attribute
  //
  TempPtr   =  Variable;
  Attribute =  *(UINT32 *) Variable;
  TempPtr   += sizeof (UINT32);
Attribute is now 0xffffffff and TempPtr points to Variable + 4.
  //
  // Get the option's device path size
  //
  FilePathSize =  *(UINT16 *) TempPtr;
  TempPtr      += sizeof (UINT16);
FilePathSize is 0xffff, TempPtr points to Variable + 6.
  //
  // Get the option's description string size
  //
  TempPtr     += StrSize ((CHAR16 *) TempPtr);
TempPtr points to 0xffff 0x0000, so StrSize (which is basically strlen) will be 4. TempPtr now points to Variable + 10.
  //
  // Get the option's device path
  //
  DevicePath =  (EFI_DEVICE_PATH_PROTOCOL *) TempPtr;
  TempPtr    += FilePathSize;
TempPtr now points to Variable + 65545 (FilePathSize is 0xffff).
  LoadOptions     = TempPtr;
  LoadOptionsSize = (UINT32) (VariableSize - (UINTN) (TempPtr - Variable));
LoadOptionsSize is now 12 - (Variable + 65545 - Variable), or 12 - 65545, or -65533. But it's cast to an unsigned 32 bit integer, so it's actually 4294901763.
  Option->LoadOptions = AllocateZeroPool (LoadOptionsSize);
  ASSERT(Option->LoadOptions != NULL);
We attempt to allocate just under 4GB of RAM. This probably fails - if it does the boot manager exits. This probably means game over. But if it somehow succeeds:
CopyMem (Option->LoadOptions, LoadOptions, LoadOptionsSize);
we then proceed to read almost 4GB of content from uninitialised addresses, and since Variable was probably allocated below 4GB that almost certainly includes all of your PCI space (which is typically still below 4GB) and bits of your hardware probably generate very unhappy signals on the bus and you lose anyway.

So now I have a machine that won't boot, and the clear CMOS jumper doesn't clear the flash contents so I have no idea how to recover from it. And because this code is present in the Intel reference implementation, doing the same thing on most other UEFI machines would probably have the same outcome. Thankfully, it's not something people are likely to do by accident - using any of the standard interfaces will always generate a valid entry, so you could only trigger this when modifying variables by hand. But now I need to set up another test machine.

[1] All code in Linux will evolve until the point where it's implemented as a filesystem.

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Mirco Bauer: Smuxi 0.8.9 "One Giant Leap" Release

Smuxi - IRC Client Smuxi 0.8.9 "One Giant Leap" Release
Just in time for 2012 I am very pleased to announce Smuxi 0.8.9 codenamed "One Giant Leap". During the development 56 bug reports and 33 feature requests in 593 commits were worked on making this release a major milestone of the Smuxi project. At the Chaos Communication Congress (28C3) in Berlin I was doing the final development sprint to get 0.8.9 done, which was a very intensive and refreshing experience. Here are the highlights of this release: Development Builds / Rolling Releases After the 0.8 release it became clear that a continious and short development -> test cycle is important to keep the project going quickly. At some point I have received requests if the project is dead while it was more active than ever. The lack of new releases (for about 15 months) lead to this wrong impression. Thus Smuxi can be obtained from development builds now. This includes daily builds for Debian (Squeeze, Wheezy, Sid), Ubuntu (Lucid, Maverick, Natty, Oneiric, Precise) and Windows. Thanks goes to Hannes Tismer for providing the Windows autobuilder and to Canonical for the PPA autobuilder. We invite everyone to use these daily builds to keep track of the latest development of Smuxi. Issues and regressions are fixed in a very short period (usually the same day). Thanks to our users who ran development builds and reported issues which led to many bug fixes prior to this release. On the other hand one of my New Year's resolutions are to "release early, release often" So there should be no nerd left behind... Screenshot of Smuxi 0.8.9 on Mac OS X Mac OS X support With the help of Steven McGrath (Steve[cug]) who created the initial Mac OS X installer for Smuxi we now have official support for Mac OS X. The download page contains the instructions how to obtain and install Smuxi on Mac OS X. This makes the 4th platform where Smuxi can be used on besides Windows, Linux and *BSD. For now Smuxi 0.8.9 doesn't feel as native as it could as it relies on the GTK+ port. We are looking into enhancing the experience though, just stay tuned. Chat History on Disk (Beta) The most exciting feature in this release I think are the "persistent message buffers". With this feature I could solve one of the biggest drawbacks IRC ever had: IRC does not retain any messages you have sent or received. All messages are only relayed to all users. The issue is that if you close your IRC client or even just leave a channel, all your received messages are gone. One workaround in most clients was to create text log files which then contains the chat history, but it is annoying and not user-friendly to open some text file somewhere from your disk to read the history outside of your IRC client. Now with Smuxi 0.8.9 you no longer have this issue, all chat history gets automatically written and read to a message database when you start Smuxi, join channels or open queries! As this feature is not fully stable yet it is not enabled by default. If you want to try it go to: File -> Preferences -> Interface and change "Persistency Type" from "Volatile" to "Persistent", hit OK and restart Smuxi. Now all messages are saved into the database and will automatically be shown. Click here for a screencast of this feature Jabber / XMPP Support (Beta) You probably have friends not on IRC and Twitter, say on Jabber, gTalk or Facebook? This is where the new XMPP engine of Smuxi comes into play. You can send and receive messages to/from them now! The implementation is far from complete, though. It has no buddy list for example and needs only to be treated as a technical preview of what will be coming in future Smuxi releases. Click here for a screencast of this feature Screenshot of Smuxi's Text Interface Text Interface (Alpha) This is the first release that contains a text frontend based on the STFL library. STFL is a library that uses ncurses to draw text based user interface using a markup language (like Glade for GTK+). This frontend is in early alpha state and lacks a lot of interface features and likes to crash. It is still included to attract potential developers who want to enhance this frontend. The frontend can be enabled by passing --enable-frontend-stfl to the configure script and then by executing smuxi-frontend-stfl. NetworkManager Support Everyone with a laptop knows how annoying it can be to suspend and resume when network based applications suddenly go crazy because they have lost the connection and either spew errors or take forever to get back in shape. Smuxi will now detect the network state right away with the help of the new Network Manager support. It automatically reconnects when needed right away for you. Next Generation Internet Support You can now connect to IRC servers using the IPv6 protocol Enhanced Find Group Chat Support Users had real issues to find out how to search for channels, thus Bianca Mix added a neat feature. The /list command will now simply open the Find Group Chat dialog for you. This way everyone used to IRC will find it in no time. Searching for channels on freenode wasn't working correctly, this is now fixed. Smuxi also supports the SAFELIST feature of the IRC protocol now which allows to retrieve a full channel list and do client side search which makes consecutive searches much faster. Enhanced Windows Experience For a long time you could not use Smuxi with the latest GTK# version of 2.12.10 on Windows. The issue was that Smuxi relied on SVG support which 2.12.10 no longer had. Smuxi is no longer using SVG instead it uses pre-scaled PNG images thus it works just fine with GTK# 2.12.10 on Windows now. At the same time the issue that the maximized state of the main window was left when restoring from task bar is fixed with GTK# 2.12.10. Screenshot of Fixed-Sys vs Consolas font Smuxi used by default the FixedSys font on Windows to give it the typical IRC look most people are used to. Since Windows Vista there is a better console-like font available called Consolas. Smuxi will now use the Consolas font instead on Windows Vista or later. Another important enhancement is that Smuxi no longer has issues with multiple GTK+ installs on the same computer, which was getting more common with more popular ported GTK+ applications such as GIMP or Pidgin. SSL for IRC fixed IRC with SSL was only working with the default port of 6697. Thanks to Jo Shields now any port can be used with SSL. Crash Related Issues Desktop notifications could crash Smuxi in case of errors related to the notification system or an absent notification daemon. There was a chance that the crash dialog simply disappeared which made reporting bugs more difficult no longer happens. Rapid use of ctrl+w, /window close (Jimmie Elvenmark) and opening the Find Group Chat dialog on the Smuxi tab do no longer crash. Also number-only network names, /network switch freenode and GTK+ install without SVG support no longer lead into a crash. Enhanced Notice Handling Notices will no longer open query tabs for you instead it will show them on tabs you share with the person who sent it with the server tab as fallback. This also avoids ChanServ, NickServ and spammy IRCop tabs. Twitter fixes Twitter made some changes to their API which broke the Twitter support of Smuxi 0.8. This was taken care of and also a few other issues were solved allowing Smuxi 0.8.9 to work smoothly with Twitter again. Extended Keybindings Smuxi allows now to use the ctrl+tab / ctrl+shift+tab and ctrl+n / ctrl+p keys to switch tabs. The keybindings still work even with a hidden menu bar now. Smuxi Server specific highlights More interactive and much faster synchronization When connecting to a smuxi-server you had to wait till Smuxi finished the synchronization before you could use the interface. Also you could not tell how far the synchronization was and just had to wait till it was completed. With Smuxi 0.8.9 the connect just takes a few seconds and all chats are synchronized in the background with a progress bar so you can use the interface from the first moment on and know how far it is. The speed how much it takes to synchronize all chats also reduced drastictly by 400%! Click here for a screencast of this feature More background communication When using a smuxi-server the interface sometimes had load times like when opening the preferences or when using the nickname completion (Andrew Kannan). These operations are done in the background and no longer blocks the interface. Also when the communication is lost to the smuxi-server the frontend will now automatically reconnect to it in the background. Low Bandwidth Mode When it comes to mobile internet connectivity such as UMTS/HSDPA, Edge and GRPS it can be a real pain to connect to the smuxi-server as it has to transfer all the messages over that. If you just want to ask someone you know then you don't need any old messages to do that. With the "Low Bandwidth Mode" you can now connect to the smuxi-server without loading old messages which makes the connect very quick. You find this option in the engine connect dialog. Stable Protocol Initially I didn't plan to make the protocol of Smuxi stable before the 0.9 release, but as it turned out the 0.8 protocol was good enough to still use it and for that reason Smuxi 0.8.9 is still compatible with 0.8. The 0.8 protocol will see no breakages, instead the next protocol will be on-top or opt-in of the current one. This means future Smuxi versions stay compatible with it. Shutdown Command You can now shutdown the smuxi-server if you like using the /shutdown command. It it safe to use the command, it will do a clean shutdown sequence for you. For example it makes sure all messages are written to disk in the case of enabled persistent message buffers. If you have your smuxi-server daemon monitored (e.g. with runit) it can also automatically be restarted and upgraded this way. Built-in SSH Keyfile Support It is no longer needed to fiddle with the .ssh/config file or pagent to get SSH key authorization working. You can now simply tell Smuxi which SSH keyfile you want to use to connect to your smuxi-server. Updated Translations
  • Catalan (Siegfried-Angel Gevatter Pujals)
  • Danish (Joe Hansen)
  • Finnish (Kalle Kaitala)
  • French (Cl ment Bourgeois)
  • German (Bianca Mix)
  • Italian (Vincenzo Campanella)
  • Portuguese (Americo Monteiro)
  • Spanish (Castilian) (Ricardo A. Hermosilla Carrillo)
New Translations
  • Chinese Simp (Dean Lee)
  • Slovak (Tom Vadina)
  • Swedish (Jimmie Elvenmark)
  • partially Russian (Aleksandr P)
  • partially Turkish (Umut Albayrak)
  • partially Urdu (makki)
Contributors Contributors to this release are the following people:
  • Mirco Bauer (497 commits)
  • Tuukka Hastrup (10 commits)
  • Bianca Mix (10 commits, translations)
  • Cl ment Bourgeois (8 commits, translations)
  • Andrius Bentkus (5 commits)
  • Carlos Mart n Nieto (3 commits)
  • Jimmie Elvenmark (3 commits, translations)
  • Hannes Tismer (1 commit)
  • Jonathan Pryor (1 commit)
  • Jo Shields (1 commit)
  • Siegfried-Angel Gevatter Pujals (translations)
  • Dean Lee (translations)
  • Aleksandr P (translations)
  • Americo Monteiro (translations)
  • Andrew Kannan (translations)
  • Joe Hansen (translations)
  • Kalle Kaitala (translations)
  • makki (translations)
  • Ricardo A. Hermosilla Carrillo (translations)
  • Tom Vadina (translations)
  • Umut Albayrak (translations)
  • Vincenzo Campanella (translations)
Thank you very much for your contributions to Smuxi! After reading this whole pile of text, head over here and grab this smexy stuff!
Posted Sun Jan 1 22:58:29 2012
Copyright 2004-2009 Mirco 'meebey' Bauer

Kai Wasserb ch: Skanlite 0.8 in Debian's experimental suite

In case you haven't heard of Skanlite let me give you a quick overview: Skanlite is a really simple scanning application for KDE 4 (if you used Kooka with KDE 3 you'll probably be happy with Skanlite too). It doesn't offer too much options besides preview and real scans except some basic colour corrections, a selection whether you want colour scans or not and whatever options the SANE driver for your scanner offers. But then it doesn't offer too much options, finds your scanners automatically (if SANE can find them) and suffices most needs. With the basic "what does it do" question out of the way, I'd like to point out, that version 0.8 just entered Debian's experimental suite. The reason for the upload to experimental instead of Sid is, that 0.8 needs a method in KSaneWidget, that was added in the 4.7 branch. Sid has only the 4.6 branch. As soon as KDE 4.7 becomes available in Sid, I'll upload a version of Skanlite to unstable. If you want to give Skanlite 0.8 a try, you need to upgrade most parts of your KDE installation to the 4.7 versions in experimental. So be careful not to break anything (on the other hand 4.7 has been working quite nicely for me so far), maybe try it out in a virtual machine or something similar.

Vincent Fourmond: Graphical connection to a Mac from Linux

For my lab work, I have developed an (almost) cross-platform program based on Qt4 that help us analyze our data. One of the motivations to use Qt was the ability to port the program to other platforms, and in particular MacOSX (half of my team uses them). After installing the required development tools using MacPorts (mind you, the MacOS version of the development tools, not the X11 one), I was able to compile and run the program without a single code change on my bosses' Mac. But here come problems: several things do not work the same way in Mac and in Linux (whereas it should, I think), so additional tweaking and debugging will be necessary.This is where the problem comes in: I don't own a Mac and don't intend to, so I need to connect to my bosses' Mac in order to perform testing. How can I connect to a Mac display ? X11 connection won't work, since my application is a Mac application and not a X11 one. I had him turn on screen sharing (the most basic tick box), which sets up a VNC server on the Mac. Unfortunately, when I connect using the command-line VNC clients available for debian, ie vncviewer (from the packages xvnc4viewer or xtightvncviewer), I get the following problems:

~ vncviewer chrismac
VNC Viewer Free Edition 4.1.1 for X - built Mar 10 2010 22:31:05
Copyright (C) 2002-2005 RealVNC Ltd.
See http://www.realvnc.com for information on VNC.
Wed Dec  7 10:40:41 2011
 CConn:       connected to host chrismac port 5900
 CConnection: Server supports RFB protocol version 3.889
 CConnection: Using RFB protocol version 3.8
 CConnection: No matching security types
 main:        No matching security types

The good news is that remmina is able to connect graphically, although for me it required that I set the display depth to 24 bits (else it seems to connect, but the connection dies immediately). Great, I'll be able to debug, then...
Edit: after a while, I found out that remmina had some drawbacks when connecting to a Mac, such as, at least in my case, a weird problem with Shift: once I hit Shift, I'm never able again to type in lowercase characters, which is quite painful. I tried also Vinagre, who handled that better (but had some quite painful freezing moment), so I must say that I finally found a client I'm happy with: gtkvncviewer.

Robert Collins: Public service announcement: signals implies reentrant code even in Python

This is a tiny PSA prompted by my digging into a deadlock condition in the Launchpad application servers. We were observing a small number of servers stopping cold when we did log rotation, with no particularly rhyme or reason. tl;dr: do not call any non-reentrant code from a Python signal handler. This includes the signal handler itself, queueing tools, multiprocessing, anything with locks (including RLock). Tracking this down I found we were using an RLock from within the signal handler (via a library ) so I filed a bug upstream: http://bugs.python.org/issue13697 Some quick background: when a signal is received by Python, the VM sets a status flag saying that signal X has been received and returns. The next chance that thread 0 gets to run bytecode, (and its always thread 0) the signal handler in Python itself runs. For builtin handlers this is pretty safe e.g. for SIGINT a KeyboardInterrupt is raised. For custom signal handlers, the current frame is pushed and a new stack frame created, which is used to execute the signal handler. Now this means that the previous frame has been interrupted without regard for your code: it might be part way through evaluating a multi-condition if statement, or between receiving the result of a function and storing it in a variable. Its just suspended. If the code you call somehow ends up calling that suspended function (or other methods on the same object, or variations on this theme), there is no guarantee about the state of the object; it becomes very hard to reason about. Consider, for instance, a writelines() call, which you might think is safe. If the internal implementation is for line in lines: foo.write(line) , then a signal handler which also calls writelines, could have what it outputs appear between any two of the lines in writelines. True reentrancy is a step up from multithreading in terms of nastiness, primarily because guarding against it is very hard: a non-reentrant lock around the area needing guarding will force either a deadlock, or an exception from your reentered code; a reentrant lock around it will provide no protection. Both of these things apply because the reentering occurs within the same thread kindof like a generator but without any control or influence on what happens. Safe things to do are: In Launchpad s case, we will be setting a flag variable unconditionally from the signal handler, and the next log write that occurs will lock out other writers, consult the flag, and if needed do a rotation, resetting the flag. Writes after the rotation signal, which don t see the new flag, would be ok. This is the only possible race, if a write to the variable isn t seen by an in-progress or other-thread log write. That is all.

5 January 2012

Jaldhar Vyas: Jeopardy!: The Post-Mortem

By now hopefully you got a chance to see my Jeopardy! episode so it won't be much of a spoiler to mention that I didn't win. It went like this. I flew into LA on the night of October 31st. The taping was to take place on the next two days. Jeopardy! tapes two weeks of shows, two days a week for a total of 10 episodes. Contestants are randomly chosen for one of those 10 episodes but you don't find out which one you will be on until the last minute. Randomness and secrecy have become become a big part of the production process in games since the quiz show scandals of the 1950s. (Interesting fact: it is a Federal felony to tamper with a TV game show.) There were a group of just under 20 0f us altogether waiting to go on. All very nice people. Here in the New York area one tends to equate very intelligent people with "Type A" personalities but we got on well together. Interspersed between the tapings, we had short practice sessions to familiarize ourselves with the studio setup and this is where I first started getting a little apprehensive. Jeopardy! is not just about general knowledge, there is a physical element too in that you have to buzz in by pressing a button on a stick which is wired up to some producers console. You can't buzz in before Alex has finished reading the question and obviously you can't buzz in if someone is already answering the question. If you buzz at the wrong time, your buzzer locks for 0.75 seconds so just jamming your finger on the button. I didn't even get that far as on the entire first day I failed to buzz in at all despite changing hands, changing grip different ways and other strategies. I was pretty despondent by the second day but then miraculously I managed to get the hang of it. So when I was finally selected (for the 3rd game of that day.) I was back to my usual cool self. I was up against Dave Leach and Nicholas Campiz who were returning after having tied in the previous game. And the game did start well enough. Oh one thing you may notice is that Alex mispronounces my name Jaldhal. I knew he did that once or twice and even mentioned it to a producer but it was only viewing the episode right now that I see he does it consistently. I assumed such things would be fixed up in post-editting but I guess not. Oh well, after living in this country for so many years I've learned to be happy whenever two consonants are more or less in the right place. This particular mispronunciation is actually fairly common, even Indian people have been known to make it. The alternative theory is that Alex couldn't read my horrible handwriting which is also plausible. Anyway, I digress. I started off fairly well. My first mistake was in a category about alcoholic drinks. I answered vermouth when the correct response was gin. In my defense I'm a strict teetoler so none of these words mean anything to me. I also earned the disapproval of my superhero fan son by mistaking Dr. Strange for Dr. Doom. I did get the one about Spiderman villain Dr. Octopus so that mollified him somewhat. The highlight of my evening was strangely enough in a category about books of the Bible. I got a Daily Double. It was a risky move but I have always wanted to make a "true" daily double so I threw caution to the winds and wagered everything I had. To my surprise as much as anyones, got the answer right doubling my score. I was in a pretty good position for the Double Jeopardy but thats when Dave started dominating. If you haven't been watching previous games, Dave Leach is arguably the best player this season. Not only is he smart but he is almost supernaturally fast on the buzzer. You can't see because I kept my hands behind the podium but I again and again I would desperately try to ring in on a question I knew the answer to only to be beaten to the punch by Dave. This caused me to start getting a bit reckless and answering questions where I was less than certain which cost me dearly. One particularly dumb mistake was in a category where all the answers were supposed to start with the letter g. I said compass when I should said gyrocompass but actually I should have left that category alone entirely. By the time Final Jeopardy came around winning was no longer an option as Dave was too far in the lead. I was slightly ahead of Nicholas in 2nd place. This is where I again made a strategic error. My original plan to bet nothing in Final Jeopardy but the category was "1930s Novels" and I liked my chances. The clue was read out and it involved an anti-war novel whose author was blacklisted. I was elated. It had to be "All Quiet on the Western Front" right? The blacklist bit gave me pause as the author Erich Maria Remarque was German and this was obviously a reference to the anti-Communist blacklist in the 1950s USA. But somehow I remembered that he had spent the end of his life in Hollywood or maybe I just convinced myself that it was plausible. Evidently my thought process wasn't too crazy because all three of us came up with the same answer. All three of us were wrong. The correct answer was "Johnny Got His Gun" by Daltan Trumbo. In hindsight I knew this but it illustrates the strange ways the mind works. I knew because the video for Metallicas song "One" from "...And Justice for All" is based on the film adaptation of this book. However in a previous orientation session the lady who is the contestant coordinator for Jeopardy! had mentioned AQOTHWF as anexample of something and this got stuck in my brain crowding out the previously known fact. So when all was said and done I ended up in 3rd place. (I bet big whereas Nicholas was more conservative.) Oh well. Despite not winning I had a blast. I fulfilled my dream of appearing on Jeopardy! I met Alex Trebek. (And I should be receiving an autographed picture of us together soon.) My witty banter was sufficiently witty. I made enough money to cover my travel expenses and still have a nice amount left. And I got to meet lots of interesting and wonderful people. So I'm satisfied.

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