[Bug 1898026] Re: interruption of dist-upgrade can leave you next release in sources.list

Fri May 14 19:10:34 UTC 2021

Hello udippel, or anyone else affected,

Accepted ubuntu-release-upgrader into focal-proposed. The package will
build now and be available at https://launchpad.net/ubuntu/+source
/ubuntu-release-upgrader/1:20.04.33 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 on 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, what testing has been
performed on the package and change the tag from verification-needed-
focal to verification-done-focal. If it does not fix the bug for you,
please add a comment stating that, and change the tag to verification-
failed-focal. In either case, without details of your testing we will
not be able to proceed.

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

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: ubuntu-release-upgrader (Ubuntu Focal)
       Status: In Progress => Fix Committed

** Tags removed: verification-done
** Tags added: verification-needed verification-needed-focal

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https://bugs.launchpad.net/bugs/1898026

Title:
  interruption of dist-upgrade can leave you next release in
  sources.list

Status in apt package in Ubuntu:
  Fix Released
Status in ubuntu-release-upgrader package in Ubuntu:
  Fix Released
Status in apt source package in Bionic:
  New
Status in ubuntu-release-upgrader source package in Bionic:
  New
Status in apt source package in Focal:
  New
Status in ubuntu-release-upgrader source package in Focal:
  Fix Committed
Status in apt source package in Groovy:
  Fix Released
Status in ubuntu-release-upgrader source package in Groovy:
  In Progress
Status in apt source package in Hirsute:
  Fix Released
Status in ubuntu-release-upgrader source package in Hirsute:
  Fix Released

Bug description:
  [Impact]
  Calling update() or installing packages from apt clients resets their SIGINT and SIGQUIT handlers to SIG_DFL, overriding any signal handlers they might have set for them.

  In case of ubuntu-release-upgrader, this results in the release
  upgrader being unable to handle interrupts after it did the initial
  update - the default libc handler will run and the program exits.

  [Test plan]

  [[apt]]
  As a standalone test for apt, we can test the following script:

  import apt
  import time

  apt.Cache().update()
  print("WAITING")
  try:
      time.sleep(10000)
  except BaseException as e:
      print("Seen", repr(e))
  print("END")

  Pressing Ctrl+C while WAITING is printed should print Seen
  KeyboardInterrupt, and importantly, also the END line.

  [[ubuntu-release-upgrader]]
  1) On an Ubuntu 18.04 system run do-release-upgrade in a terminal.
  2) At the "Do you want to start the upgrade?" question say Y.
  3) When you see the "Lock screen disabled" message you will also see "Inhibiting until Ctrl+C is pressed".
  4) Press "Ctrl+C"

  Your /etc/apt/sources.list file will now have focal in it instead of
  bionic although the upgrade has quit. With the version of ubuntu-
  release-upgrader in -proposed you will not see the "Ctrl+C" message.
  For your sources.list file to be restored you'll need the version of
  apt from bionic-proposed installed before starting the upgrade.

  [Where problems could occur]
  apt: This specific change removes the two lines that SIG_DFL the signal handlers after running scripts. AFAWCT those lines are unnecessary - the code that calls it temporarily sets the handlers to SIG_IGN but restores previous handlers at the end; it was wrongly refactored decades ago. A regression could occur in that those signals will now continue to be ignored if we missed a spot.

  ubuntu-release-upgrader: The change is wrapping a bunch of code in a
  try: except: block so if the indentation was off the pyflakes /
  pycodestyle tests would fail but autopkgtest will catch that.

  [Original bug report]
  As a long-time-user of ?ubuntu, with apt-get as tool of choice for updates/upgrades I wrote a daily script for updates, with 'dist-upgrade'.
  In all earlier years, it wouldn't actually do an upgrade of a ?ubuntu version; just all packages including new ones. Version updates had to be initiated manually, and I was always asked if I really wanted the new ?ubuntu version. Sounds appropriate.

  Last night when it (dist-upgrade), it just gave me 20.04. No questions asked. I for one consider this kind of intrusive, though.
  It *might* have to make with me trying 'sudo do-release-upgrade -m desktop' a number of times earlier; just to *check* if the upgrade was on offer; but this is only a guess.

  In *any* case, a pop-up asking "Are you sure? Are you connected
  through an adequate pipe? Are you sitting with full batteries; better
  a power supply?" would be convenient; since I am using my PC for
  urgent duties, and didn't want to fiddle with unexpected upgrade bugs.

  ProblemType: BugDistroRelease: Ubuntu 20.04
  Package: ubuntu-release-upgrader-core 1:20.04.25
  ProcVersionSignature: Ubuntu 5.4.0-48.52-generic 5.4.60
  Uname: Linux 5.4.0-48-generic x86_64
  ApportVersion: 2.20.11-0ubuntu27.9
  Architecture: amd64
  CasperMD5CheckResult: skip
  CrashDB: ubuntu
  CurrentDesktop: KDE
  Date: Thu Oct  1 11:48:39 2020
  InstallationDate: Installed on 2019-03-14 (566 days ago)
  InstallationMedia: Kubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
  PackageArchitecture: allSourcePackage: ubuntu-release-upgrader
  Symptom: ubuntu-release-upgrader
  UpgradeStatus: Upgraded to focal on 2020-09-29 (1 days ago)
  VarLogDistupgradeAptlog:
   Log time: 2020-09-29 19:44:28.696289
   Log time: 2020-09-29 19:44:33.573481

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