so the kernel can send d-bus messages

Havoc Pennington hp at
Sun Jul 25 20:27:56 PDT 2004

On Sun, 2004-07-25 at 19:41, Maciej Katafiasz wrote:
> But I must ask - why is the default socket for session bus name
> constructed by appending random junk to /tmp/dbus, instead of
> predictable scheme like /tmp/$username/dbus-session? If it's for
> security reasons, aren't permissions enough to make sure noone's trying
> to spoof? That would eliminate need for the env variable set in 95% of
> cases (ie. all default setups).

Right, the "well known filename" approach is a different way to locate
the bus. It has a couple of problems.

1. the bus is supposed to be per-session, not per-user

2. anyone can create /tmp/$username/dbus-session, not only $username

Again, if you have a working alternate to the env variable, I'd love to
hear it. ;-) But afaik there's no other way to do it.

At some point you have to define some unique ID, or process, or
something, that defines the session. And whatever that is, the env
variable is the only way I can think of to let apps know what it is.

> That isn't exactly my point. Let's leave aside session bus and grounding
> points for a while, what I'm seeking for is a way to store and _change_
> settings currently managed with env vars, similarly to what XSETTINGS
> mechanism provides for X. That would be one part (apparently, the easy
> one) of solution for "how to change locale session-wide without logging
> out" problem (the second one is of course refactoring apps around
> changing values of LC_*, that's particularly big undertaking, but I
> digress). 

Yes, the hard part about changing locale is printf.
Apps are packed with stuff like:

 char *s = g_strdup_printf (gettext ("blah blah %s blah blah %d blah
blah %f"), mystring, myint, myfloat);
 gtk_label_set_text (label, s);

Now, to change the the text in the label dynamically, you will need to
keep around mystring, myint, and myfloat, and redo the printf when the
locale changes.

You also need to call gettext() again, that would be relatively easy:
 gtk_label_set_text_untranslated(label, "blah blah")
which could be defined to call gettext() on the untranslated text, and
keep the untranslated text around and call gettext() again on locale
change. But you need to also keep around the printf format args and that
seems kind of impossible to do with an API that's usable.

I suppose we're getting a bit off-topic. 

> One could argue GConf already provides that, but GConf is too complete,
> too high in stack, and has too many dependencies to really be feasible
> solution, and also doesn't do exactly what's needed (ie. you can't have
> possibly separate settings for some apps). Ideally, that would be
> kernel/libc-level mechanism, just like env vars are today, but that has
> some issues with portability to non-Linux (and maybe *BSD) Unices. What
> is needed is some way to get easy, light, changeable at runtime env vars
> on steroids.
> I hope I was clearer this time, and that someone indeed knows how to
> achieve that :)

I think if you apply my suggested changes to gconf you would have what
you need, more or less:

But I don't know exactly what you're looking for. Again, a bit offtopic,
xdg at freedesktop might be better.


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