Big part of my job is packaging for Fedora Linux (I am pretty sure I haven't mentioned this before :-) ). I have spent last 6 months working on various Java packages, adding new packages to Fedora, updating dependencies etc. I have developed certain workflow which I believe might be of interest to other packagers. So here goes. Most of these hints are about managing patches for your packages. I'll also try to work on concrete package so it won't be completely theoretical.

Let's assume your project already has some history and patches. Let's fix velocity bug 640660 for example. I'll start with steps I took and what they meant, and I'll summarize in the end with rationale what I have gained by using my workflow (and what could be improved).

After modifying BuildRequires and Requires to tomcat6 servlet api I tried to build velocity:

$ fedpkg mock

This is what I got:

---snip----
compile-test:
    [javac] Compiling 125 source files to /builddir/build/BUILD/velocity-1.6.3/bin/test-classes
    [javac] /builddir/build/BUILD/velocity-1.6.3/bin/test-src/org/apache/velocity/test/VelocityServletTestCase.java:135: org.apache.velocity.test.VelocityServletTestCase.MockServletContext is not abstract and does not override abstract method getContextPath() in javax.servlet.ServletContext
    [javac]     static class MockServletContext implements ServletContext
    [javac]            ^
    [javac] Note: /builddir/build/BUILD/velocity-1.6.3/bin/test-src/org/apache/velocity/test/VelocityServletTestCase.java uses or overrides a deprecated API.
    [javac] Note: Recompile with -Xlint:deprecation for details.
    [javac] Note: Some input files use unchecked or unsafe operations.
    [javac] Note: Recompile with -Xlint:unchecked for details.
    [javac] 1 error
BUILD FAILED
/builddir/build/BUILD/velocity-1.6.3/build/build.xml:251: Compile failed; see the compiler error output for details.
Total time: 47 seconds
---snip---

The issue seems simple to fix, just missing stub function in a test case, right? So what now?

$ fedpkg prep
$ mv velocity-1.6.3 velocity-1.6.3.git
$ cd velocity-1.6.3.git
$ git init && git add . && git commit -m 'init'

This effectively created my small git repository for sources and populated it with all files. Using fedpkg prep step we extracted the tarball and applied already existing patches to unpacked sources. I suggest you create shell alias for last three commands as you'll be using it a lot. We moved directory to velocity-1.6.3.git so that next (accidental?) fedpkg prep won't erase our complicated changes (yes it happened to me once. I've had better days). Note that velocity-1.6.3.git is not a temporary directory. I will keep it around after fixing this bug so that I can use git history, diffs and other features in the future. It is especially nice when you have packages with lot of patches on top.

Now we can easily work in our new git repository, edit source file in question and do:

$ git add src/test/org/apache/velocity/test/VelocityServletTestCase.java
$ git commit -m 'Fix test for servlet api 2.5'
$ git format-patch HEAD~1

This created commit with descriptive message and generated a patch file 0001-Fix-test-for-servlet-api-2.5.patch in our current directory. This is how the patch looks like:

From 8758e3c83411ffadc084d241217fc25f1fd31f42 Mon Sep 17 00:00:00 2001
From: Stanislav Ochotnicky <sochotnicky@redhat.com>
Date: Thu, 14 Oct 2010 10:20:52 +0200
Subject: [PATCH] Fix test for servlet api 2.5

---
 .../velocity/test/VelocityServletTestCase.java     |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/src/test/org/apache/velocity/test/VelocityServletTestCase.java b/src/test/org/apache/velocity/test/VelocityServletTestCase.java
index 824583e..ac0ab5c 100644
--- a/src/test/org/apache/velocity/test/VelocityServletTestCase.java
+++ b/src/test/org/apache/velocity/test/VelocityServletTestCase.java
@@ -16,7 +16,7 @@ package org.apache.velocity.test;
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
- * under the License.    
+ * under the License.
  */
 
 import java.io.IOException;
@@ -149,6 +149,11 @@ public class VelocityServletTestCase extends TestCase
             return this;
         }
 
+        public String getContextPath()
+        {
+            return "";
+        }
+
         public String getServletContextName()
         {
             return "VelocityTestContext";
-- 
1.7.2.3

Now that we have patch prepared for velocity we need to use it in the spec file and we're done.

Let's say our first attempted patch wouldn't work as expected and build (or test) still failed. We modify the sources again and do another commit. What we have now is:

$ git log --format=oneline
c15f7e02eaae93b755cc0bfde6def3d6e67d2b0f (HEAD, master) Fix previous commit
3e3d654c142c7028c9c7895579fba204c4c4bf08 Fix test for servlet api 2.5
2f32554ddf892f4cca3f78b1f82a7c3ab169c357 init

We don't want two patches in the spec file for one fix so: time for git magic. You've probably heard of git rebase if you've been using git for a while. What we want to do now is merge last two commits into one, or in git-speak "squash" them. To do this you have to do:

$ git rebase -i HEAD~2

Now your editor should pop-up with this text:

pick 3e3d654 Fix test for servlet api 2.5
pick c15f7e0 Fix previous commit

# Rebase 2f32554..c15f7e0 onto 2f32554
#
# Commands:
#  p, pick = use commit
#  r, reword = use commit, but edit the commit message
#  e, edit = use commit, but stop for amending
#  s, squash = use commit, but meld into previous commit
#  f, fixup = like "squash", but discard this commit's log message
#
# If you remove a line here THAT COMMIT WILL BE LOST.
# However, if you remove everything, the rebase will be aborted.
#

So we just need to change "pick c15f7e0 Fix previous commit" into "squash c15f7e0 Fix previous commit" (you can also use just 's' instead of 'squash'). Save. Close. Another editor window will open with something like this:

# This is a combination of 2 commits.
# The first commit's message is:

Fix test for servlet api 2.5

# This is the 2nd commit message:

Fix previous commit

# Please enter the commit message for your changes. Lines starting
# with '#' will be ignored, and an empty message aborts the commit.

For this case we will delete second message because we just want to pretend our first attempt was perfect :-). Save. Close. Now we have:

$ git log --format=oneline
cbabb6ac43f7bdb8e52ccd09c25cfd0a032b553c (HEAD, master) Fix test for servlet api 2.5
2f32554ddf892f4cca3f78b1f82a7c3ab169c357 init

Repeat as many times as you want. You can also re-order commits and change commit messages with rebase (note that if you just want to change last commit message you can do "git commit --amend"). I generally don't create commits until I have working patch though.

So why do I think all this mumbo-jumbo improves my workflow? Let's see:

• I can have long comments for every patch I create (instead a line or two in spec file)
  
• I can use the same patches to send directly to upstream
  
• I don't have to juggle around with diff and remember what files I changed where
  
• Probably several other things I haven't even realized
  

I have a few things that bother me of course. git format-patch generates filenames that are different from standard practice of %{name}-%{version}-message.patch. This is not a git problem. For packages where only my patches exist I stick with git naming, but when there are different patches I stick with naming they started. Another thing that is bothering me is that creating initial repository by using "fedpkg prep" hides patches that were applied to sources. That's why I am thinking about re-working my packages so that all patches will be in my git repositories as commits with descriptive messages. No need for comments in the spec file anymore. Perhaps someone can suggest other improvements to my approach.

I have been using Digikam for managing my photos for some time. It's pretty neat software and development is progressing quite fast. You can think of it as Lightroom, just without the neat non-destructive editing. But that is coming too, thanks to Google and another round of Summer of Code participants. But I wouldn't be writing this blog post if Digikam was flawless would I? :-)

First I'll describe my work-flow in few short bullet-points :-)

• Shoot a LOT of photos
• Delete almost as many photos
• Geotag, tag/keyword and rate remaining photos
• If it was party or something similar upload to Facebook right away
• Pick few photos and improve them a bit with Gimp (nothing fancy, just crop/levels)
• Upload all photos to Flickr as a backup/sharing place
  

Digikam enables me to work like this, except the last point. Why? Because apparently Digikam developers don't think anyone would update their photos to Flickr without first resizing/recompressing them. This  how flickr export dialog looks like this:


See the problem? Even if I don't chose "Resize photos before uploading" Digikam will still re-compress them which is a Really-Bad-Thing(tm) to do with jpeg files. I had some previous experience with Qt3 and even Qt4. so I though it might be a good idea to look into fixing this small annoyance. I will not bore you with the details how I checked out svn repository with git and rest of the stuff. Here is the result:


If you un-check "Send original file (no resizing)" original settings will appear and you can resize/recompress as much as you want (Blasphemy! Madness!). The patch is not flawless, because it won't prevent you from trying to upload RAW files to Flickr, but it's good enough for me :-) It's not even that big, stats are like this:

 flickrexport/flickrtalker.cpp |   18 ++++++++++++------
 flickrexport/flickrtalker.h   |    2 +-
 flickrexport/flickrwidget.cpp |   34 ++++++++++++++++++++++++++--------
 flickrexport/flickrwidget.h   |    5 +++++
 flickrexport/flickrwindow.cpp |    4 ++++
 flickrexport/flickrwindow.h   |    1 +
 6 files changed, 49 insertions(+), 15 deletions(-)

You can download the patch from my Dropbox for now until the bugreport I created some time ago will get sorted out (don't hold your breath too much though). The patch applies cleanly across all versions of kipi-plugins I tried (from 0.8.something to 1.4.0). Happy uploading.

# easy_install pyqtrailer
should work as long as you have PyQt4 installed. You can just run pyqtrailer now and you should see something like this:


That's it. I will improve/fix it a bit but don't expect too much :-)

What better way to celebrate summer solstice, than by making my computer able to hibernate? Since my last post a lot has happened with me. I got a new phone (HTC Hero FTW!), I finished university, went traveling a bit and I also got a new notebook (because the old one died on me). R.I.P. Thinkpad R51, welcome Thinkpad T500. There are several things I could start writing about now. Starting with how great Hero and Android is to use all the way to today's blog post: How to make my computer hibernate?

Linux has had support for hibernating for quite a few years now and although it's not perfect, it usually works out of the box. What it needs however is swap device big enough so that it can store image of memory for hibernating. Now I hit a problem. When I got my new Thinkpad I thought "Hey, I have 4GB of RAM...why would I need a swap?". And even if I REALLY needed more than 4GB RAM I can still create temporary swap by using swapfile. Unfortunately I couldn't make swapfile on LVM work with TuxOnIce. TuxOnIce also has another alternative to swap or swapfile for hibernating: Using filewriter, which is quite similar to swapfile support, I managed to get it to work (after some work, kernel debugging and one small patch to TuxOnIce).

I set FilewriterLocation in hibernate.conf to point to a place where I wanted to store hibernation file and I set the size to 4GB. As instructed in TuxOnIce HOWTO, I then ran

hibernate --no-suspend

to create this image. It created the file as expected, but when it was supposed to tell me settings for bootloader (resume argument) it silently failed. When I tried again, whole computer froze. I was puzzled. How could this happen? I am using Linux so things like this don't happen! But hey, I should be able to figure out what's wrong with it right? I set up my kernel to include netconsole, and ran hibernate again. This time I caught where the bug happened. The output was something like this:

TuxOnIce: No image found.
BUG: unable to handle kernel paging request at 6539207a
IP: [<c10763a6>] toi_attr_store+0x186/0x2a0
*pdpt = 0000000032732001 *pde = 0000000000000000
Oops: 0000 [#1] PREEMPT SMP
last sysfs file: /sys/power/tuxonice/file/target
Modules linked in: netconsole aes_i586 aes_generic radeon ttm drm_kms_helper drm
 i2c_algo_bit sco bnep ipt_MASQUERADE iptable_nat nf_nat ipt_LOG nf_conntrack_ip
v4 nf_defrag_ipv4 xt_state nf_conntrack ipt_REJECT xt_tcpudp iptable_filter ip_t
ables x_tables rfcomm l2cap vboxnetadp vboxnetflt vboxdrv arc4 iwlagn iwlcore ma
c80211 sdhci_pci snd_hda_codec_conexant sdhci pcmcia e1000e uvcvideo mmc_core cf
g80211 snd_hda_intel yenta_socket btusb rsrc_nonstatic tpm_tis pcspkr pcmcia_cor
e videodev v4l1_compat intel_agp wmi agpgart tpm snd_hda_codec tpm_bios video fu
se xfs raid10 raid1 raid0 md_mod scsi_wait_scan sbp2 ohci1394 ieee1394 usbhid uh
ci_hcd usb_storage ehci_hcd usbcore sr_mod sg uvesafb cfbfillrect cfbimgblt cn c
fbcopyarea [last unloaded: microcode]
 
Pid: 12870, comm: hibernate Not tainted 2.6.33.1-w0rm #16 2082BRG/2082BRG
EIP: 0060:[<c10763a6>] EFLAGS: 00010202 CPU: 0
EIP is at toi_attr_store+0x186/0x2a0
EAX: 00000000 EBX: 36203430 ECX: 00000000 EDX: f231f200
ESI: 65392066 EDI: 00f60062 EBP: f6006331 ESP: f62a7f14
 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process hibernate (pid: 12870, ti=f62a6000 task=f20a0270 task.ti=f62a6000)
Stack:
 00000000 fffffff4 00000001 c1790ca0 00000000 f6e8ab64 c16c75a4 f6d1c380
<0> f62a7f64 c114298d 00000015 00000015 b7709000 f21385c0 f6d1c394 c16c75a4
<0> f6ec7ac0 f21385c0 b7709000 00000015 f62a7f8c c10f207c f62a7f98 00000000
Call Trace:
 [<c114298d>] ? sysfs_write_file+0x9d/0x100
 [<c10f207c>] ? vfs_write+0x9c/0x180
 [<c11428f0>] ? sysfs_write_file+0x0/0x100
 [<c10f221d>] ? sys_write+0x3d/0x70
 [<c1002ccc>] ? sysenter_do_call+0x12/0x22
Code: c7 45 e0 00 00 00 00 3b 5d 08 0f 85 e9 fe ff ff 8b 46 20 85 c0 0f 84 de fe
 ff ff ff d0 8b 7d e0 85 ff 8d 76 00 0f 84 d9 fe ff ff <8b> 46 14 31 d2 e8 60 03
 05 00 8b 46 10 c7 46 14 00 00 00 00 a8
EIP: [<c10763a6>] toi_attr_store+0x186/0x2a0 SS:ESP 0068:f62a7f14
CR2: 000000006539207a
---[ end trace 124a5ee29ef71277 ]---

So what can we deduce from this bug output? Let's go from the top. Bug name (unable to handle kernel paging request) means that it is likely a memory corruption issue. Someone accessed memory that he was not supposed to. IP tells us that function where the error occurred was toi_attr_store in unknown file, unknown line (I don't have debug information included in kernel). There are other information we can get from that output, but I didn't really need them. Quick search through kernel sources told me that toi_attr_store is a function inside kernel/power/tuxonice_sysfs.c. I scanned the code, learning what approximately it did. Then I placed printk statements thorough the function so that I could approximate where inside the function the code fails. After some time I narrowed it down to following snippet:

	if (!result)
    		result = count;

        /* Side effect routine? */
        if (result == count && sysfs_data->write_side_effect)
                sysfs_data->write_side_effect();

        /* Free temporary buffers */
        if (assigned_temp_buffer) {
                toi_free_page(31,
                        (unsigned long) sysfs_data->data.string.variable);
                sysfs_data->data.string.variable = NULL;
        }

Kernel crashed when it tried to call toi_free_page. After a few reboots and printks later I found out that this was just a coincidence, and sysfs_data variable itself became corrupt even before the call to the toi_free_page. Good candidate? Of course: write_side_effect. But what exactly was write_side_effect? This function was passed as an argument, and therefore I wasn't able to easily find out what was real code executed at this point. Time to find out! From my previous debugging attempts I knew code failed while it tried to write location of my resume file into /sys/power/tuxonince/file/target. TuxOnIce code defined handling for string sysfs arguments as such:

#define SYSFS_STRING(_name, _mode, _string, _max_len, _flags, _wse) { \
        .attr = {.name  = _name , .mode   = _mode }, \
        .type = TOI_SYSFS_DATA_STRING, \
        .flags = _flags, \
        .data = { .string = { .variable = _string, .max_length = _max_len } }, \
        .write_side_effect = _wse }

I found this macro used inside tuxonice_file.c source code like this:

 
SYSFS_STRING("target", SYSFS_RW, toi_file_target, 256,
                SYSFS_NEEDS_SM_FOR_WRITE, test_toi_file_target)

So we found our write_side_effect code inside test_toi_file_target function. In one part this function was calling hex_dump_to_buffer to convert device UUID into hexadecimal string. The call looked like this:

 
hex_dump_to_buffer(fs_info->uuid, 16, 32, 1, buf, 50, 0);

This should convert input (fs_info->uuid) into hexadecimal string and store it inside buf. Author of the original code correctly thought about function adding spaces between bytes and therefore need to have more space in the buffer (argument 50 is telling hex_dump_to_buffer how big is output buffer). Unfortunately that same author declared buf as 33 char array. hex_dump_to_buffer therefore stepped outside the buffer and corrupted memory, causing all the problems. I fixed this bug, and sent a patch to the tuxonice-devel mailing list. As of now, it is already in the git repository ready to be released with next bugfix release of TuxOnIce.

That is everything for today, but as I already noted I am using LVM on my system (except root partition) and also use fbsplash for nice animations while rebooting. I am using initrd for this, and I will have another post on that topic.

In next episode: Why I think Gmail is corrupting minds of people and why I hate mobile phones

First a bold note. I already have repository on Gentoo infrastructure for working on my GSoC project. Check it out if you want.

Last time I mentioned I won't go into technical details of my GSoC project any more on this blog. For that you can keep an eye on my project on gentooexperimental and/or gentoo mailing lists, namely gentoo-qa and gentoo-soc. But there is one interesting thing I found out while working on Collagen.

One part of my project was automation of creating of chroot environment for compiling packages. For this I created simple shell script that you can see in my repository. I will pick out one line out of previous version of this script:

mount -o bind,ro "$DIR1" "$DIR2"

What does this line do? Or more specifically what should it do? It should create a virtual copy of conents of directory DIR1 inside directory DIR2. Copy in DIR2 should be read-only, that means no creating new files, no changing of files and so on. This command succeeds and we as far as we know everything should work OK right? Wrong!

Command mentioned above actually fails silently. There is a bug in current linux kernels (2.6.30 as of this day). When you execure mount with "-o bind,ro" as arguments, the "ro" part is silently ignored. Unfortunately it is added to /etc/mtab even if it was ignored. Therefore you would not see that DIR2 is writable unless you tried writing to it yourself. Current proper way to create read-only bind mounts is therefore this:

mount -o bind "$DIR1" "$DIR2"
mount -o remount,ro "$DIR2"

There is issue of race conditions with this approach, but in most situations that should not be a problem. You can find more information about read-only bind mounts in LWN article about the topic.

It's been a week and something since my last post and again quite a lot of things happened. I had several tasks from my last week:

• get in touch with gentoo-infra(structure) team
  
• improve way build logs were handled
• look at possible ways to create tinderbox chroot environments
  
• make it possible to test all versions of dependencies

I managed to get acquainted with gentoo-infra team a bit, and get a few answers too. Remember last time when I was talking about security issues of pickle module when used over untrusted connection?  That's not an issue anymore apparently since we'll be using encrypted connection in final version. We can consider route between Matchbox and Tinderboxen to be friendly environment.

Few people suggested that I look into few similar project Gentoo, namely catalyst and AutotuA. Main feature of catalyst is release engineering, not testing per se. But it can also create tinderboxes (effectively chroot environments). Perhaps some ideas could be used for my project, but so far it seems that catalyst is not the one and only for me. AutotuA is much more similar to collagen (did I mention that's name of my project yet?). There is master server (web application accepting jobs) and slaves (processing jobs). There were quite a few interesting design decisions (such as keeping jobs in git repository) and some of it I will at least reuse. Integration would be possible, but for now I have a feeling that such integration would be just as complicated as writing my own master/slaves. That is because AutotuA is generic system for jobs and their processing not specific for package compilation and testing. I'll keep both projects in mind during my future endeavours.

As far as build log handling goes, my last POC (proof of concept) code simply grabbed stdout/stderr of whole install process. It also used higher-level interfaces for installing packages in gentoo, I switched to lower APIs because I need to do few things higher-level APIs did not offer. Most of these things had to do with dependency handling. Best way to explain what I have to do is using example. But first a little Gentoo package installation introduction. Package "recipes" called ebuilds reside in so-called portage tree. Most packages have more than one ebuild because there are always older and newer versions supported simultaneously. Each of these package versions has its own set of dependencies, that is other packages that need to be installed for package to compile/run. These dependencies look something like this:

=dev-libs/glib-2*
samba? ( >=net-fs/samba-3.0.0 )

This means that package would need any version of glib-2 library, and if samba feature (USE flag) is enabled then also samba version 3 or higher would be required. My task is to verify that package can be compiled with ALL allowed versions of ALL dependencies. Now the promised example.

Lets assume that we want to install package mc (midnight commander). There are currently 2 versions of app-misc/mc in portage: 4.6.2_pre1 and 4.6.1-r4. List of their dependencies is quite long, but to show you principle I'll use just one dependency, namely sys-libs/ncurses. Version 4.6.2 of mc depends on sys-libs/ncurses and version 4.6.1-r4 depends on >=sys-libs/ncurses-5.2-r5. There are currently 2 versions of sys-libs/ncurses in portage: 5.7 and 5.6-r2. Based on these dependencies it should be possible to install package mc (both versions) with either ncurses-5.7 or 5.6-r2. From this point on there is ping-pong of installing ncurses-5.6-r2, then mc-4.6.1-r4/4.6.2_pre1 followed by uninstalling them all and installing ncurses-5.7 and installing mc-4.6.1-r4/4.6.2_pre1. If mc-4.6.2_pre1 fails to compile with ncurses-5.6-r2 we will know that ebuild needs to be modified with dependency >=sys-libs/ncurses-5.7. All this has to be repeated for every dependency for every version of every package in portage tree. Currently there are 26623 ebuilds in portage tree. Now imagine that some of them will have to be compiled even 30-50 times to test all dependency versions. Good thing we will have dedicated tinderboxes for compiling all those ebuilds.

One more thing for now. Gentoo has project management website based on redmine for all of GSoC students on soc.gentooexperimental.org. From now on I will aggregate all of documentation for my project there. This blog will go on will less technical details and I will link to documentation where needed.

Recently I finished all of my duties as a student for this term and I could therefore spend the weekend catching up on GSoC (since I am one week behind schedule). In the end it turned out to be pretty productive weekend.

I'll summarize basic architecture without any images (I'll create them later this week probably when everything will settle down). There are two core packages:

• Matchbox
• Tinderbox

Matchbox is master server that knows what still needs to be compiled and collects all information. There is always only one Matchbox. There can however be more Tinderboxes. These machines connect to Matchbox and ask for next package to emerge (compile). After emerging package they collect information about files in the package, use flags, emerge environment and error logs from compile phase. This information is then sent back to Matchbox. Tinderbox then asks for another file to emerge. repeat while true.

First thing I did was create basic data model for storing data about compiled packages. What use flags were used, error logs and stuff like that. Lot of things are not in the model, for example information about tinderboxes, but for now this will do. UML diagram is on following picture:


This model should allow efficient storage of data and a lot of flexibility to boot. There can be more versions of the same package (of course) and also packages can change package category (happens quite often). We can also collect different data sets based on USE flags.

With basic data model in place it was time for some serious prototyping :-) Naturally I decided to split implementation into two parts, one for each core modules (more to come later). Matchbox is simple listening server waiting for incoming connections. I wanted to simplify network communication for myself, so I used python module pickle. This module is able to create string representation of classes/functions and basic data types. Because of this I was able to use objects as  network messages. Objects representing Matchbox command set:

class MatchboxCommand(object): pass

class GetNextPackage(MatchboxCommand):
    pass

class AddPackageInfo(MatchboxCommand):
    def __init__(self, package_info):
        self.package_info = package_info

On the other side Tinderbox understands these commands (for now):

class MatchboxReply(object): pass

class GetNextPackageReply(MatchboxReply):
    def __init__(self, package_name, version, use_flags):
        self.package_name = package_name
        self.version = version
        self.use_flags = use_flags

Communication (simplified) goes something like this:
Tinderbox
msg = GetNextPackage()
msg_pickled = pickle.dumps(msg)
sock.sendall(msg_pickled)

Matchbox
data = sock.recv()
command = pickle.loads(data)
if type(command) is GetNextPackage:
        package = get_next_package_to_emerge()
        msg = GetNextPackageReply(package)
        msg_pickled = pickle.dumps(msg)
        sock.sendall(msg_pickled)

• Basic communication between Matchbox/Tinderbox
• Compiling works with file list/emerge environment/stdout/stderr/etc being send back to Matchbox

There is still much more ahead of us:

• package selection on Matchbox side
• block resolution on Tinderbox
• rest of services (web interface, client, etc)

Few weeks ago I mentioned that I applied for GSoC 2009 as a student. Things have cleared up a bit and I can now say that I've been accepted (YAY!). Soon I'll start working to improve quality of my beloved Linux distribution. How best to do that than to scratch my own itch? I am now going to quote Eric S. Raymond:

Every good work of software starts by scratching a developer's personal itch.

This quote is from one of most interesting books written on Software engineering, specifically with Open-Source in mind. C'mon! I know you know the book! Yes you guessed right, it's "The Cathedral and the Bazaar".

Now the obvious question is...what's my itch? I've been using Gentoo happily for over 4 years now and it's getting better and better. One thing is still missing though. When emerging (that is installing) new application I never know how much space it will occupy once it's on my hard drive. I only know download size. I say that's not enough! I want to know at least a ballpark figure on size before I try to install some work of devil. However, this is not exactly focus of my project "Tree-wide collision checking and files database", but it could easily become byproduct of solution for my GSoC task. I will most probably keep blogging about my work on GSoC project. This will make it easier to sort various thoughts and make it easier to create progress reports in future. Oh..just so that I won't forget. My mentor is Andrey Kislyuk, apparently a bioinformatics PhD student interested in privacy and security. I better get to know him better, seems like and interesting person :-).

It sure is a great idea and I was always intrigued to participate. This year I finally decided to try it out. Gentoo, my distribution of choice was chosen as one of projects to mentor students. I read the ideas page and some of them seemed pretty interesting. One of them was "Tree-wide collision checking and files database". What was the idea? Basically, Gentoo is a source based distribution so noone knows what files will get installed with a certain package. This can be a problem for quality assurance team (QA). Emerge checks for file collisions before installing so you will never screw up your system, but installing some less known packages can give you a headache. Implementing this idea should help fix this situation and most probably be used for other purposes as well. One of them could be approximation of size of package to be installed. This is common in binary distributions, because they know size of package, but Gentoo has a lot of small "gotcha's" in this department. One of them is USE flags, great way to customize your distribution, but a nightmare for this sort of thing. Good thing emerge is such a great package manager :-). I will not repeat things I've said elsewhere so if you want to read more, you can read my application.

If I get accepted (I should know on April the 20th), there is a long way from where I am to making a great project for Gentoo. Hopefully I'll be able to keep up and help out a bit.

Few months back I had a rant about participation in opensource. Things have moved a bit since then. I had a few more commits to the mob branch of gstfs repository on repo.or.cz. More importantly Bob Copeland got in touch with me and one more developer who voiced his interest in the project and offered to hand over gstfs to us. Understandably he doesn't have as much free time to spend on such project as an average university student :-).

During the weekend I created project page, new code repository with my patches included, developer and user mailing lists and few issue tickets. I just hope I will be able to keep up the work on the project at least a bit better than this blog...Fingers crossed.

First of all...All hail our new overlord. And by overlord I mean year 2009. I hope you all will have a great time. I know I will :-). I didn't write for some time, because I was travelling then I was celebrating holidays with my family and friends. All in all I didn't have so much time to keep my information up to date not to mention doing anything resembling work. That's changing NOW!.

I recently bought new camera (lovely Nikon D90) and also decided I need to backup my previous photos to more than 2 places. I realized you can never have enough backups after a few failed HDDs. So what were the options I was considering?

• Google's Picasa: 20$/year for 10GB  storage space
• Flickr: 25$/year for unlimited storage and better sharing/privacy settings, presentation options etc.

I didn't consider other services because...well because I didn't.

Now the issue was...How to upload all of my photos (several gigabytes)? Flickr has client for Windows/MacOS, but not for Linux (The orignal client appears to work through wine though). Kflickr to the rescue! I started uploading photos in no time. But I wouldn't be writing this blog entry if everything went according to plan now would I?

Everything seemed to work, the photos were on the web. I could see them, organize them, tag them...you name it. Then I wanted to download original file from certain photo (for reason I don't remember). How great was my surprise when the file was <1MB in size. The originals I had were ~3 MB. Something rotten in here. The files were obviously recompressed with lower jpeg quality settings before being uploaded. Not all of them were this way though. It seemed like it has something to do with license I used for the files. Power is in the source, Luke so there I was. I wanted to investigate the problem and maybe fix it.

Unfortunately opening Kflickr project files with Kdevelop and trying to debug didn't work. For some reason the gdb was ignoring my breakpoins as if the application was compiled without debugging information. It was however compiled with -g3 (all debugging info). So far I was unable to properly diagnose the orignal bug, but I wrote to author of Kflickr asking for information. Now let's wait.