group.of.nepali.translators team mailing list archive

[Eric Desrochers <eric.desrochers@xxxxxxxxxxxxx>]

I will be more favourable to do the other way around by adding a
"Depends:" in cups-filters package for ghostscript version "X" ?
Especially if cups-filters always needs ghostscript ?

It will force ghostscript to get updated instead of making the package
install to fails/breaks.

At least it's worth testing IMHO that avenue before considering the
current "Breaks:" approach.

- Eric


** Also affects: cups-filters (Ubuntu)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1848210

Title:
  ghostscript: ensure update of cups-filter

Status in cups-filters package in Ubuntu:
  New
Status in ghostscript package in Ubuntu:
  Invalid
Status in cups-filters source package in Xenial:
  New
Status in ghostscript source package in Xenial:
  In Progress
Status in cups-filters source package in Bionic:
  New
Status in ghostscript source package in Bionic:
  In Progress

Bug description:
  [Impact]

   * After an update of ghostscript but not cups-filters
     (which is possible; eg unattended-upgrade/landscape)
     users may hit errors printing PDF files (LP#1828401).

   * Landscape and unattended-upgrade allows packages
     updates to security updates / USN-only, thus
     ghostscript is updated for CVE-2019-3839-1 and -2
     (version 9.26~dfsg+0-0ubuntu0.18.04.9 and 16.04.9)
     which may break printing PDF files on cups-filters.

   * So, to ensure that ghostscript and cups-filters are
     both updated, add a versioned 'Breaks:' relationship
     to ghostscript for older cups-filters versions which
     are not yet fixed.

     Per Debian Policy [1]:

       """
       Normally a Breaks entry will have an “earlier than” version clause;
       such a Breaks is introduced in the version ... [that] reveals a bug
       in earlier versions of the broken package ...

       This use of Breaks will inform higher-level package management tools
       that the broken package must be upgraded before the new one.
       """

   * A versioned 'Depends:' relationship is not possible
     as ghostscript doesn't depend on cups-filters, thus
     it's possible to have ghostscript installed without
     cups-filters at all.

  [Test Case]

   * Install cups-filters version without fix for LP#1828401:
     1.20.2-0ubuntu3 in Bionic, and 1.8.3-2ubuntu3.4 in Xenial.

   * Update ghostscript to/later than fix for CVE-2019-3839-1/-2
     9.26~dfsg+0-0ubuntu0.18.04.9 in Bionic / .16.04.9 in Xenial.

   * Notice it does _not_ update cups-filters to version with fix:
     1.20.2-0ubuntu3.1 in Bionic, and 1.8.3-2ubuntu3.5 in Xenial.

   * $ wget -O ppd-with-pdf-support.ppd \
       'http://www.openprinting.org/ppd-o-matic.php?driver=hl7x0&printer=Brother-HL-1020&show=1'

   * $ wget -O dummy.pdf \
       https://www.w3.org/WAI/ER/tests/xhtml/testfiles/resources/pdf/dummy.pdf

   * $ foomatic-rip -v --ppd ppd-with-pdf-support.ppd dummy.pdf
     ...
     Filetype: PDF
     GPL Ghostscript 9.26: Unrecoverable error, exit code 1
     Process is dying with "Unable to determine number of pages, page count: -1
     ", exit stat 3
     ...

   * Note it's broken.

   * Install ghostscript (test) packages with the relationships
     'Breaks: cups-filters (<< 1.20.2-0ubuntu3.1)' in Bionic or
     'Breaks: ..., cups-filters (<< 1.8.3-2ubuntu3.5)' in Xenial.

   * Note it _does_ update cups-filters to version with fix.

   * $ foomatic-rip -v --ppd ppd-with-pdf-support.ppd dummy.pdf
     ...
     Filetype: PDF
     File contains 1 pages
     Starting renderer with command: <...>
     ...

   * Note it's now working.

  [Regression Potential]

   * Low.  This only causes an update to cups-filters to a version
     that fixes an already identified/resolved problem (LP#1828401),
     which is available in bionic- & xenial-updates since May 2019.

  [Other Info]

   * This is only required in Xenial and Bionic.

   * Trusty doesn't have the ghostscript update that causes the problem.

   * Disco/Eoan have the cups-filters fix that it requires (1.22.5+).

  [1] https://www.debian.org/doc/debian-policy/ch-relationships.html
  #packages-which-break-other-packages-breaks

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