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Yesterday, via the excellent Gentoo Bugzilla, I came across a reference to a tool for Gentoo I hadn’t seen before, one that would have come in handy before. It came up because I was trying to emerge a new amarok, and the build was unable to find libpcreposix.la… the new libpcre doesn’t include that file, but there was still a reference to it in something amarok needed.

The ebuild is called dev-util/lafilefixer, and to run it:

lafilefixer --justfixit

Whoever put this together has now helped me a great deal… I had literally hundreds of .la files that it updated. Plus it fixed amarok and let me complete my emerge update.

The thing I like most about Gentoo is the extraordinary flexibility that portage allows to make a system the way you want.   Every once in awhile, I find something annoying however (this happens on every operating system, you’re hearing about this one because it was just the most recent).   Today’s case in point:  I found that several things depending on libselinux.so.1 despite my having “-selinux” in my global USE flags, and selinux disabled in the kernel.   Because one of the packages that depends on that library is coreutils (which includes mv, cp, ln, and many other things you can’t afford to be without.)

How did this happen?  Because my /var/lib/portage/world file has a lot of packages in it that don’t really need to be there (they should be pulled in as dependancies of packages I do want, not in the way I have them.)   When I was migrating to the this box, instead of just looking at the few hundred packages in world, I grabbed a list of everything I’d compiled, and used that to build my new box.   One result of that is that sys-libs/libselinux got compiled.  (At least, I think that’s how it happened.)   I noticed but didn’t think it was going to be a problem.  However, for some ebuilds (coreutils being the most important to me), if the selinux header files are installed on the box, the configure script detects files like /usr/include/selinux/flask.h and proceeds to include selinux support.   Then you will find that /bin/cp and many other critical utilities are linked against libselinux.so.1, so you can’t remove the sys-libs/libselinux, and since the USE flag has no effect other than changing RDEPEND in the ebuild, you’re stuck.   Catch-22, almost.

Today I finally resolved to fix this, because I got annoyed, and because sys-libs/libselinux is hard-masked after my latest sync (as a result of the sync and having to update my profile with eselect).

The first part, fixing coreutils is pretty easy:

euse -D selinux
mv /usr/include/selinux /usr/include/selinux-save
emerge -av coreutils
emerge -C libselinux
rm -r /usr/include/selinux-save

Unfortunately, after that… you are still stuck.   The coreutils will work, but I was left with a number of packages that revdep-rebuild reports as missing libselinux.so.1… furthermore they all die when trying to link against libselinux:

/usr/lib/gcc/x86_64-pc-linux-gnu/4.1.2/../../../../x86_64-pc-linux-gnu/bin/ld: cannot find -lselinux

Ah, portage, why are you so cruel to me?    The above example is from gnome-terminal.  Good thing I still use xterm.

Note: the next part could help, but it’s far easier to use lafilefixer these days.

So, what to do?   I’m not kidding, this is basically it, in one line form:

find /usr/lib64 -name '*.la' -print | xargs grep selinux | cut -f1 -d: | sed -e 's#^./##g' | xargs equery b | awk '{print "="$1}' | sort -u | xargs emerge

Built that up once I realized that the *.la files still contained references to the libselinux (-lselinux).  Basically, it searches for all the .la files that contain references to selinux.   .la files are just text files that control the linking process, either as part of libtool or the compile-time linker. My command above just uses some rather lame shell tricks to run emerge against all the packages those files belong too.

Even after that was complete, I still had libnss3.so.12 breakage to contend with, but at least revdep-rebuild was working at that point (not breaking on every ebuild it found missing libselinux.so.1).    Frustrating.

I hope this saves someone some damn time, somewhere.

Sometimes I wake up to find that the cursor on my workstation has disappeared.   And it doesn’t seem to be simply invisible, it’s actually not interacting with the desktop in any way.   I can still see the mouse in the list of enumerated USB devices.   Generally the keyboard is still working.

One suggestion I keep running across in my normal google searches is to disable HWCursor in xorg.conf.   Messed around with that for a few days.

After a lot of tests, it turns out that killing xscreensaver fixes the problem…. no need to restart X.

Lately, the problem has stopped happening, so I am considering that an update to x11-misc/xscreensaver may have fixed the problem.

Recently, a friend contacted me about recovery of a Solaris box he had made a bit of a mistake on. The problem was, he had moved everything from / into a subdirectory of /, let’s call it /cores for our purposes here. Commands wouldn’t work. He had a running /sbin/sh shell but that was it…. so shell built-ins were all he could do e.g. “echo *”. We fixed it pretty quick, with only minor residual problems, but I thought I’d put down the method here in case it helps someone sometime.

The first problem is that libraries are no longer found along their proper paths…. libc.so is the first problem. That’s easily fixed, however.

# export LD_LIBRARY_PATH=/cores/usr/lib:/cores/lib

That’s the simple part, I’m sure most people know the LD_LIBRARY_PATH tricks to force searching for libraries in other directories. The part that I don’t think people get is… once you’ve done that “ld.so.1″ (the runtime linker) is still in the wrong place. ld.so.1 is responsible for using the LD_* variables in the first place, among the many other wonderful things it does. So running commands from, for example, /cores/usr/bin is still impossible, at least in the standard way.

The second and final trick you need to fix this is to use ld.so.1 to “run” the executable. So, this fails:

# /cores/usr/bin/mv /cores/* /
mv: Cannot find /usr/lib/ld.so.1
Killed

But this allows you to run a command like you’d expect:

/cores/usr/lib/ld.so.1 /cores/usr/bin/mv /cores/* /

Turns out, you can use “ld.so.1″ as an “interpreter” of sorts for executables on some flavors of Unix. At least Solaris and Linux, but I would not be surprised if this works elsewhere, I simply haven’t tested it. On Linux, for example, you would use something like:

/lib/ld-linux.so.2 /bin/ls

To run “ls” in this fashion.

The lesson, boys and girls, is to know your runtime linker, it may save you one day.

Just got back from Linux World in San Francisco (actually, show ended on Thursday but I hung out until the 19th to visit friends.) Good show, but 6 days is a recent record for me being away from home, and it’s good to be back.

I focused on the HPC and kernel development tracks while I was there. In particular, I have several new things to experiment on that I saw there.

For starters, it became clear that I should probably get an AMD-based system for my OpenSolaris experiments. The demo machine I saw there with OpenSolaris with a Brandz CentOS lx zone on it seemed like a really decent machine, and while I’ve always liked SPARC, maybe it would be good to have both.

For the meantime, I will actually be playing with opensolaris on VMWare. Virtualization has been a pretty big topic lately, and at the conference I talked to SuSE (who’s distributing Xen), XenSource, VMWare (which I’ve been using since it was first available, and am currently using at work and at home), SWSoft (makers of OpenVZ/Virtuozzo) (which I’d managed to never hear about before somehow.)

I’ll have more to say about what I saw there. Next time I may even take pictures.