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

[Launchpad Bug Tracker]

This bug was fixed in the package ubuntu-release-upgrader - 1:20.04.33

---------------
ubuntu-release-upgrader (1:20.04.33) focal; urgency=medium

  * DistUpgrade/DistUpgradeController.py: restore sources.list where possible
    if a KeyboardInterrupt event is received and redirect the output of
    gnome-session-inhibit to devnull so a message regarding Ctrl-C is not
    displayed. (LP: #1898026)
  * DistUpgrade/DistUpgradeQuirks.py: Restore code which ensured the python
    package was maked for removal. (LP: #1928397)
  * Update mirrors and translations.

 -- Brian Murray <brian at ubuntu.com>  Thu, 13 May 2021 16:38:41 -0700

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

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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 Released
Status in apt source package in Groovy:
  Fix Released
Status in ubuntu-release-upgrader source package in Groovy:
  Fix Committed
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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