Computer Problems

I was exploring a project concerned with reverse engineering some file formats (https://gitorious.org/re-lab/tools) and I needed to run a python script. This python script requires libgsf (the gnome structured file library: http://projects.gnome.org/libgsf/ ), however the debian/ubuntu packages for this aren't built with python support!

This led to errors such as:

frankster@linux-virtualbox:~/relab/tools/oletoy$ ./view.py
Traceback (most recent call last):
  File "./view.py", line 23, in <module>
    import Doc, cmd
  File "/home/frankster/relab/tools/oletoy/Doc.py", line 19, in <module>
    import ole,mf,svm,cdr,clp,rx2
  File "/home/frankster/relab/tools/oletoy/ole.py", line 23, in <module>
    import vsd, xls, ppt, vba, doc
  File "/home/frankster/relab/tools/oletoy/vsd.py", line 19, in <module>
    import gtk,gsf
ImportError: No module named gsf

Getting libgsf compiled was a bit of a pain so here are some tips that may be helpful. I initially attempted to modify the ubuntu package and simply enable the configuration switch for python support. However there are some problems with the paths for python includes in the debian build scripts that I didn't get to the bottom of. So instead of building a custom ubuntu package, I uninstalled the official libraries and built my own version. I was still able to use the debian package build infrastructure to automatically fetch the source code and the build-dependencies which made things a little easier!

sudo apt-get source libgsf
sudo apt-get install python-dev
sudo apt-get build-dep libgsf
cd libgsf-1.14.21
./configure --with-python
make
sudo make install

Check that you had all required python development libraries installed during the configure stage by looking for the following lines towards the end:

checking for python... /usr/bin/python
checking for python version... 2.7
checking for python platform... linux2
checking for python script directory... ${prefix}/lib/python2.7/dist-packages
checking for python extension module directory... ${exec_prefix}/lib/python2.7/dist-packages
checking for headers required to compile python extensions... found
checking for PYGTK... yes
checking for pygtk-codegen-2.0... /usr/bin/pygtk-codegen-2.0
yes

If you only saw some of these lines, then the python component won't get built!

Once you have got this far, your python script should now detect the gsf module. As your manual install of libgsf will have gone into the /usr/local/ tree, your python script may not be able to locate the library it needs to link to. If this happens you will see an error like the following:

Traceback (most recent call last):
  File "./view.py", line 23, in <module>
    import Doc, cmd
  File "/home/frankster/relab/tools/oletoy/Doc.py", line 19, in <module>
    import ole,mf,svm,cdr,clp,rx2
  File "/home/frankster/relab/tools/oletoy/ole.py", line 23, in <module>
    import vsd, xls, ppt, vba, doc
  File "/home/frankster/relab/tools/oletoy/vsd.py", line 19, in <module>
    import gtk,gsf
  File "/usr/local/lib/python2.7/dist-packages/gsf/__init__.py", line 8, in <module>
    from _gsf import *
ImportError: libgsf-1.so.114: cannot open shared object file: No such file or directory

If this happens you can solve it by telling the linker where it needs to look to find the library:

$ LD_LIBRARY_PATH=/usr/local/lib ./view.py

You can of course make this permanent in your .profile or .bashrc or whatever.

I have an installation of Ubuntu 11.04 running as a virtual machine under VirtualBox. It recently ran out of space, so I needed to expand the partition.

First I made a new partition that was larger than my existing partition (i.e. I created a new disc image in VirtualBox).

I then added the Ubuntu 11.04 DVD image to my VM as a new DVD device. I also needed to remove the VBoxGuestAdditions.iso, as it turns out that the VirtualBox bios only lets you boot off the first CD/DVD it finds.

That done, I fired up my VM and pressed F12 to get into the boot device menu, then chose to boot from CD. When this booted up I chose the option to run the live cd rather than install Ubuntu.

Once I hit the gnome2 desktop, I fired up a terminal and ran

$ sudo gparted

gparted showed two discs - sda and sdb. sda1 was my linux partition, and there was an extended partition containing a swap partition on sda5. sdb was empty as expected. I performed the following actions:

• select and copy the sda1 partition.
• switch to sdb and create a partition table.
• paste the sda1 partition into sdb, and change its size so it fills the entire disc minus 500MB or whatever you want for the swap partition.
• create an extended partition on sdb
• create a new swap partition inside the extended partition.
• I set the partition flag bootable on sdb1 although I don't think this was necessary.

Having done this I now needed to install grub. To get grub to work, I had to chroot into the new partition before installing it.

$ sudo mkdir /mnt/sdb1
$ sudo mount /dev/sdb1 /mnt/sdb1 -t ext2
$ sudo mount --bind /dev /mnt/sdb1/dev
$ sudo mount --bind /proc /mnt/sdb1/proc
$ sudo mount --bind /sys /mnt/sdb1/sys
$ sudo chroot /mnt/sdb1
$ sudo grub-install
$ sudo update-grub

At this stage I shutdown, and removed the old linux partition from my VM. When I started up again, it succesfully booted into my VM, from where I am writing this article!

I have a Lenovo laptop which has for a while had problems with the onboard wireless card, so I have been using a usb wireless device instead. I don't use wifi very often as I mostly have it connected to an ethernet cable, so although a bit annoying its not too much hardship having to use the usb device.

I recently put Ubuntu 11.04 on the laptop because the performance I was getting from Windows XP was deteriorating rapidly. I don't like the new Unity interface, chiefly because it forces you to have the panel on the left hand side, which is fine unless you use two monitors and you want your default monitor on the right, then you get the panel in the middle of your two screens instead of on one side. Unfortunately Mark Shuttleworth has insisted that It Must Be This Way so I can't see it changing any time soon, thus I'm sticking with the traditional Gnome2 interface.

Anyway, for whatever reason the network manager applet gets confused by the two network adaptors I have, and won't let me connect to a network on the usb adaptor, stating that its disabled in hardware. This is incorrect, its only the onboard network adaptor that has its wifi switch disabled (and in fact changing the switch doesn't make any difference to whether or not network manager thinks its disabled or not).

Running "rfkill list" confirms that the onboard adaptor is disabled in hardware, but the usb adaptor is not. The solution I found was to blacklist the modules used by the onboard adaptor. So I ran:

$ sudo vim /etc/modprobe.d/blacklist.conf

and I added the following lines:

blacklist iwlcore
blacklist iwlagn

I was finally able to connect to wifi using the usb adaptor after also running:

$ sudo rmmod iwlcore iwlagn