Archive for the ‘Gnome’ Category

tab = lose

Sunday, July 13th, 2008

The best thing about tabs that I can think of is that it will keep certain people from doing more harmful things like changing the gtk+ api for no good reason.

(The header line is a translation from Danish into English.)

Themes Are Evil, Part II

Saturday, February 2nd, 2008

In a previous post, I showed how a GTK+ theme engine can corrupt memory of any application unfortunate enough to be used with it.

In today’s edition, our guest star is the Qt theme engine. It does not, as far as I know, corrupt your memory or otherwise make your innocent application crash.[*] Instead it changes how your program works. For example, for Gnumeric it changes how numbers imported are handled.

If you import the number “8,5″ in a decimal-comma locale then you would hope to get eight-and-a-half, right? Well, with the Qt theme you get eight and we, the Gnumeric team, look incompetent. The problem arises because the Qt theme, quite reasonably, initializes the qt library. During that, less reasonably, the following code gets executed:

setlocale( LC_ALL, “” ); // use correct char set mapping
setlocale( LC_NUMERIC, “C” ); // make sprintf()/scanf() work

I am not kidding. The Qt library thinks it should change your locale. What on Earth have the Trolls been drinking? Impure home destilled booze in large quantities?

This problem in various disguises have had us puzzled for quite a while and only very recently was the Qt theme identified as the triggering factor. Once that happened, it was not too hard to locate, but before that we have spent maybe 40 hours looking for this bug. The workaround is to set up a one-shot idle handler that resets the locale properly when the gui comes us. (Repeat this for every GTK+ program that displays or accepts floating-point values.)

The Qt theme people never caught this. If they are mostly “theme” people I can understand, but if they are mostly “Qt” people they really should have known. In either case, it is another exhibit for the case that the GTK+ theme model is seriously flawed.

[*] Well, if you use threads it might. The Qt library calls setlocale to change locale and that’s not allowed in a threaded program.

Progress in the Printing World

Friday, January 25th, 2008

With gedit moving from gnome-print to gtk-print there is probably only one gnome-print user left, namely abiword.

This is amazing progress in the sense that instead of using gnome-print which is basically unmaintained and doesn’t work on Win32, we can now simply use gtk-print which is basically unmaintained and doesn’t work on Win32.

Murray, A Retraction is in Order

Monday, November 26th, 2007

(By blog and email.)

Murray, a retraction of that post is in order.

Here is why: I do not think, and you have certainly offered no evidence, that you are competent to diagnose the mental state and ditto ailments of other people. If you in fact do have such credentials from a respectable medical school, now would be a good time to display them. (And to inspect an inquiry from the relevant ethics committee.)

The truth or falsity of the rest of your post is utterly irrelevant. I do not know if it is true or false; I do not care. You have evinced seriously bad judgment and deep character flaws.

main-menu

Wednesday, November 14th, 2007

I have noticed that main-menu on my system is a bit of a pig. It takes up something like 30 cpu minutes per day. That is kind of crazy considering I don’t really use it much. Certainly not every day. So what does it do?

  • It reads /proc/mounts and /proc/partitions. It then stats everything mentioned in there.
  • It appears to be talking to NetworkManager via dbus.
  • It stats about 100 directories like /usr/local/share/icons

And it does all of those every few seconds.

Themes are Evil!

Sunday, May 27th, 2007

…although I am willing to entertain the idea that they are a necessary
evil.

Themes in GTK+ land are, simplified, arbitrary pieces of dynamically
loaded code that is hooked into the drawing layers of widgets. There
is no fault isolation, so when (not if) a theme does something naughty,
the application crashes. Then the user curses a few times and blames
the usual suspects: the screen/keyboard and the application.

Have a look at bug 438456. Theme code used in, for example, the industrial theme released various
kind of memory allocated by GTK+ using the wrong function, in this case g_free. Result: instant memory corruption in all GTK+ applications! Not good.

I do not think it is realistic to redesign the theming of GTK+ at
this point in time, but we really need to do something about
stability.

  • Theme authors need to be extremely careful with their coding.
  • Theme authors should use the full range of automated testing
    at our disposal: running under Valgrind and separately with G_SLICE=debug-blocks during some kind of theme torture test is a bare minimum. For every release.

I realize that I am asking other people to do some work. I do not feel too bad about that, though, because it is theme code that is causing my application to crash, causing people to lose data, and the blame is sent my way.

Ok, go ahead and tell me how wrong I am.

Scary Git Grep

Sunday, January 21st, 2007

I wanted to know when a certain identifier was introduced in goffice.
It turned out that it was fairly simple:

  git grep -w GO_FORMAT_MARKUP `git tag -l 'GOFFICE*'` -- '*.h'

That commands searches all .h files from all Goffice releases.
It is very fast: about 0.5s (cpu time) on a fairly slow machine.

How do I do that with SVN?

SVN

Tuesday, December 26th, 2006

I’ll happily add myself to the chorus: switching to SVN? Someone must
have been drinking out of the potty.

If we are going to suffer the pain of a conversion, then we have better get a lot out of it.

  • Retraining. We all know cvs’ quirks. (And my fingers like to type c-v-s.)
  • Lost history. None of the conversion tools are perfect.
  • Recoding. Custom scripts will have to be recoded.

These apply to all systems (except cvs). The trouble with SVN
is that it is hard to see it as more than a stepping stone.

Dave, if the only argument that people have against it is that “everyone knows that distributed’s better” is what you believe, then you have not been listening. Start with KeithP’s write-up saying, in part, that (1) SVN lacks corruption detection,
(2) Git is a whole lot faster than SVN, and (3) SVN is a space pig compared to Git.

By the way, why is it relevant whether most distributions include the system by default? We expect, from time to time, that developers have HEAD versions of various off-site libraries, so surely we can get the same developers to obtain a recent copy of Git (etc.), right?

So can we please have git and gitweb running somewhere on gnome.org
with access to, say, ~user/public_git/ directories? I promise that I will not complain too much about SVN if that happens.

f-spot

Tuesday, December 5th, 2006

I have been trying out f-spot recently and I must say that using
it gives me one of those rare warm fuzzy feelings inside.

It has well designed interface with relatively little clutter.
It by and large does what I want it to.
And it does not crash or hang for me.
It does not even spew a lot of scary warnings in my session log file.

I can find nits, sure I can. In fact I just filed a pile of them, but we are talking the would-be-nice department here.

Nice job on this, guys!

Gnome Terminal

Tuesday, November 14th, 2006

Until recently I have been using xterm and twm. Call me a stone-age
throw-back if you like, but those two are fast and lean.

But I am giving gnome-terminal and metacity a spin now. Metacity
suffers somewhat from click-to-focus, even if you set
it to focus-follows-mouse, but that is a story for another day.

Today it is gnome-terminal gripe time. Ok, so it is actually not
too bad, but it feels slow. Starting the first terminal window,
for example, takes a few seconds. Seconds! I want my window to
show up in less than .2 seconds.

A bit of stracing reveals the cause. It is dlopen-ing a zillion modules related to character support.
That is used to populate a, I estimate, rarely used menu. In my humble opinion, the penalty for this kind of thing should not be taken on startup, but when the rarely-used feature is activated. Or in the background while I type away happily. Luckily this does not seem
too hard to fix.

On top of this, Fontconfig is doing a whole lot of work on startup.
It does that for other GTK+ based programs too, so I doubt the
applications are to blame. So what does it do?

  • Stats ~200 directories all over the place.
  • Feels the need to do things three times:
    access("/etc/fonts/suse-hinting.conf", R_OK) = 0
    stat64("/etc/fonts/suse-hinting.conf", {st_mode=S_IFREG|0644, st_size=6575, ...}) = 0
    open("/etc/fonts/suse-hinting.conf", O_RDONLY) = 18
    

    Are you there? Are you there? Please open! This kind of behaviour
    is fairly cheap on a local file system, but not necessarily so on
    a remote one. And it is wrong: the file could have changed twice between the three calls.

  • Zig-zag reading files:
    read(17, "     fd9 78563412    1    4    4"..., 255) = 255
    lseek(17, -136, SEEK_CUR)               = 158
    read(17, "/usr/X11R6/lib/X11/fonts/CID/us"..., 4109) = 3938
    lseek(17, -3909, SEEK_CUR)              = 187
    read(17, "/usr/X11R6/lib/X11/fonts/URW/us"..., 4109) = 3909
    lseek(17, -3880, SEEK_CUR)              = 216
    read(17, "/usr/X11R6/lib/X11/fonts/uni/us"..., 4109) = 3880
    lseek(17, -3851, SEEK_CUR)              = 245
    

    Back-and-forth over the same area again and again. Short of timing
    system call overhead I do not see what it is doing.

I am also having problems with focus in the terminal. I am not entirely sure how I manage, but
somehow the focus ends up on one of the tabs where it has no business being.