system-config-printer crashes when assigning a downloadable non-free Epson driver to a detected printer

Attached patch adds the code needed (~10 lines) to download the license text from a URL linked in the driver record from OpenPrinting. The download is a text file and treated as such, so no security risk by the extra download. This patch fixes this bug.

Attached is a patch which is an additional crash guard in the driver record display code for the case that the licensetext field of the driver record is None.

This bug was fixed in the package system-config-printer - 1.5.4+20141212-0ubuntu2

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system-config-printer (1.5.4+20141212-0ubuntu2) vivid; urgency=medium

  * debian/patches/35_fix-driver-package-installation-with-install-printerdriver.patch:
    Simplified communication between system-config-printer and
    install-printerdriver helper script (LP: #1412722).
  * debian/patches/37_do-not-crash-on-licensetext-being-none.patch: Crash
    guard for displaying OpenPrinting driver record where the licensetext
    field is None (LP: #1412729).
  * debian/patches/40_support-licensetext-in-separate-url.patch: Added support
    for OpenPrinting driver records with license text linked from separate
    download URL (LP: #1412729).
 -- Till Kamppeter <email address hidden> Tue, 20 Jan 2015 11:56:08 +0100

Uploaded a package fixing bug 1412729 and bug 1412722 to utopic-proposed.

Uploaded a package fixing bug 1412729 and bug 1412722 to trusty-proposed.

Hello Till, or anyone else affected,

Accepted system-config-printer into utopic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/system-config-printer/1.5.1+20141010-0ubuntu2.3 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Updated my Utopic system and got the proposed package. Now the Epson drivers install correctly. The package description/confirmation screen appears with the correct license text and after confirming the package gets installed.

This bug was fixed in the package system-config-printer - 1.5.1+20141010-0ubuntu2.3

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system-config-printer (1.5.1+20141010-0ubuntu2.3) utopic-proposed; urgency=medium

  * debian/patches/75_fix-driver-package-installation-with-install-printerdriver.patch:
    Simplified communication between system-config-printer and
    install-printerdriver helper script (LP: #1412722).
  * debian/patches/77_do-not-crash-on-licensetext-being-none.patch: Crash
    guard for displaying OpenPrinting driver record where the licensetext
    field is None (LP: #1412729).
  * debian/patches/80_support-licensetext-in-separate-url.patch: Added support
    for OpenPrinting driver records with license text linked from separate
    download URL (LP: #1412729).
  * debian/patches/83_fix-crash-in-nextnptab-if-driver-is-zero.patch: Trivial
    patch to avoid crashes when installing downloadable printer driver
    packages via OpenPrinting. These crashes were observed via the Ubuntu
    error reporting system.
 -- Till Kamppeter <email address hidden> Tue, 20 Jan 2015 13:40:08 +0100

The verification of the Stable Release Update for system-config-printer has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

Hello Till, or anyone else affected,

Accepted system-config-printer into trusty-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/system-config-printer/1.4.3+20140219-0ubuntu2.6 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance!

Updated my Trusty VM with the proposed package and all works correctly now.

I confirm it works.

I already had my wireless Epson printer setup in Ubuntu, so I removed it from the settings, uninstalled the driver package and removed the Epson repository.
Then I upgraded the 4 packages built by system-config-printer to the version in trusty-proposed and tried to add the printer. It worked correctly and the printer is working (again).
But, since the printer was already installed, the result may not have been accurate (even though I uninstalled it before testing).

Bruno thank you for testing. Your test is perfectly OK, you have removed the print queue, the driver package, and the repo, so your system is absolutely neutral. There is nothing more you can remove.

I just tested this in a VirtualBox VM (which contains a very "vanilla" 14.04 install with very few extra packages installed), and it didn't work.
I tried several times. The Epson repository is added successfully, but it hangs while it's installing the driver package (epson-inkjet-printer-nx420). The package is not installed.

The last output of "system-config-printer --debug" is:
  pk.refresh_cache succeeded
  pk.resolve
  pk.resolve succeeded
  package_id: epson-inkjet-printer-nx420;1.0.0-1lsb3.2;amd64;printdriver
  package not installed
  pk.install_packages
  Signature key supplied

After this, when I try to install the package manually, it fails because /var/cache/debconf/config.dat (and other files there) is locked by another process.
Here are the relevant lines (I think) of "ps aux":
  root 3331 0.0 0.0 0 0 pts/0 ZN+ 16:57 0:00 [dpkg] <defunct>
  root 3332 0.0 0.0 4444 648 pts/0 SN+ 16:57 0:00 /bin/sh -c /usr/sbin/dpkg-preconfigure --apt || true
  root 3333 0.0 1.0 64128 15628 pts/0 SN+ 16:57 0:00 /usr/bin/perl -w /usr/sbin/dpkg-preconfigure --apt
  root 3335 0.0 0.0 0 0 pts/0 ZN+ 16:57 0:00 [dpkg-preconfigu] <defunct>

However, if I install the packages "alien", "build-essential" and "lsb" before installing the printer through system-config-printer, the installation completes successfully.
Also, there was one time when apt failed to install the driver package (manually) because one of the dependencies, which was "lsb", was not properly configured.
So, is sytem-config-printer failing to configure a package (i.e. debconf), or is this a quirk with Virtualbox?

Another note. The driver installation window is too large to fit in my 1366x768 monitor, so the buttons in the bottom are not visible.

The "lsb" or at least the "lsb-printing" package should be in the dependencies of the printer driver package and this way get automatically installed along with it.

The dpkg processes running on yout VM and blocking the installation of the driver is more a problem of your individual system (or perhaps the VM?). Installing apt alien build-essential, ... gives perhaps some kick to these processes making them terminating.

Note that the printer driver packages do not use debconf (they are converted from RPMs).

@Till, before installing the "alien", "build-essential" and "lsb" packages, I reverted the VM to a previous snapshot (which is "clean"). I did this before every attempt at installing the printer.
In the attempt where I installed these packages manually (and their dependencies), system-config-printer succeeded in installing the driver. In the other attempts it hanged.
There was also one attempt where I installed "alien" and "build-essential", but not "lsb", and it didn't work.

Was the VM that you used for testing in a "after installation" state?
If not, could you, or anybody, else test this fix right after installing Ubuntu in a VM or an actual machine?
This way we would know if this is really an issue or if it's just a problem with VirtualBox (which it may be).
(Sorry, I can't test this in a real computer because I have only one working computer right now, and I don't want to reinstall the system).

Relative to THIS bug ("system-config-printer crashes..."), it's fixed! It doesn't crash anymore with the fix.
The issue I reported would be a new bug (if confirmed).

This bug was fixed in the package system-config-printer - 1.4.3+20140219-0ubuntu2.6

---------------
system-config-printer (1.4.3+20140219-0ubuntu2.6) trusty-proposed; urgency=medium

  * debian/patches/43_fix-driver-package-installation-with-install-printerdriver.patch:
    Simplified communication between system-config-printer and
    install-printerdriver helper script (LP: #1412722).
  * debian/patches/45_do-not-crash-on-licensetext-being-none.patch: Crash
    guard for displaying OpenPrinting driver record where the licensetext
    field is None (LP: #1412729).
  * debian/patches/47_support-licensetext-in-separate-url.patch: Added support
    for OpenPrinting driver records with license text linked from separate
    download URL (LP: #1412729).
  * debian/patches/50_fix-crash-in-nextnptab-if-driver-is-zero.patch: Trivial
    patch to avoid crashes when installing downloadable printer driver
    packages via OpenPrinting. These crashes were observed via the Ubuntu
    error reporting system.
 -- Till Kamppeter <email address hidden> Tue, 20 Jan 2015 14:59:59 +0100