ubiquity crashed in ubi-partman.py : ValueError: I/O operation on closed file

[Jean-Baptiste Lallement]

TEST CASE:
1. Boot to a live session and start Ubiquity
2. at partitioning step select "something else" (manual partitioning)
3. Click on the 'Quit' button

EXPECTED RESULT:
Quit

ACTUAL RESULT:
Feb 27 17:21:50 ubuntu ubiquity[17177]: Exception in GTK frontend (invoking crash handler):
Feb 27 17:21:50 ubuntu ubiquity[17177]: Traceback (most recent call last):
Feb 27 17:21:50 ubuntu ubiquity[17177]: File "/usr/lib/ubiquity/ubiquity/frontend/gtk_ui.py", line 1350, in watch_debconf_fd_helper
Feb 27 17:21:50 ubuntu ubiquity[17177]: return callback(source, debconf_condition)
Feb 27 17:21:50 ubuntu ubiquity[17177]: File "/usr/lib/ubiquity/ubiquity/filteredcommand.py", line 252, in process_input
Feb 27 17:21:50 ubuntu ubiquity[17177]: self.exit_ui_loops()
Feb 27 17:21:50 ubuntu ubiquity[17177]: File "/usr/lib/ubiquity/plugins/ubi-partman.py", line 2794, in exit_ui_loops
Feb 27 17:21:50 ubuntu ubiquity[17177]: bootloader_seen = self.db.fget('grub-installer/bootdev', 'seen')
Feb 27 17:21:50 ubuntu ubiquity[17177]: File "/usr/lib/python2.7/dist-packages/debconf.py", line 60, in <lambda>
Feb 27 17:21:50 ubuntu ubiquity[17177]: lambda *args, **kw: self.command(command, *args, **kw))
Feb 27 17:21:50 ubuntu ubiquity[17177]: File "/usr/lib/python2.7/dist-packages/debconf.py", line 64, in command
Feb 27 17:21:50 ubuntu ubiquity[17177]: self.write.write("%s %s\n" % (command, ' '.join(map(str, params))))
Feb 27 17:21:50 ubuntu ubiquity[17177]: ValueError: I/O operation on closed file

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: ubiquity 2.9.21
ProcVersionSignature: Ubuntu 3.2.0-17.27-generic-pae 3.2.6
Uname: Linux 3.2.0-17-generic-pae i686
ApportVersion: 1.93-0ubuntu2
Architecture: i386
CasperVersion: 1.304
Date: Mon Feb 27 17:24:00 2012
InstallCmdLine: noprompt cdrom-detect/try-usb=true persistent file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha i386 (20120226)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Ubuntu QA Website (ubuntuqa)]

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/942111

[Brian Murray (brian-murray)]

Does 3 mean click the quit button or rather that it quits after step 2?

[Brian Murray (brian-murray)]

I tried recreating this bug with a fresh disk using kvm and was unable to.

[Jean-Baptiste Lallement (jibel)]

I can reproduce it reliabliy on bare-metal with Wifi, if I quit while wifi is setting up

[Barry Warsaw (barry)]

I've tried various scenarios to reproduce in a VM since I don't have physical hardware to test this on. I'm not able to reproduce it. In bug 792652 Colin says:

"I believe that this is ultimately a regression caused by the fix for bug 756920 (ubiquity r4693). In order to try to ensure that the boot loader choice was recorded in debconf in every possible code path, this was done in exit_ui_loops as a sort of "finally" handler. However, exit_ui_loops is only supposed to do frontend interaction, and (as this bug demonstrates) it isn't safe for it to attempt to talk to debconf. I think a correct fix would move this out of exit_ui_loops again and try to find a safer way to fix the original bug."

but I'm quite reluctant to change this code unless I can reproduce it and/or provide a test case for the failure. Do you have any other suggestions for triggering this bug while under, say a vm install?