[Bug 2037595] Autopkgtest regression report (gpgme1.0/1.13.1-7ubuntu2.2)

[Ubuntu SRU Bot]

All autopkgtests for the newly accepted gpgme1.0 (1.13.1-7ubuntu2.2) for focal have finished running.
The following regressions have been reported in tests triggered by the package:

samba/2:4.15.13+dfsg-0ubuntu0.20.04.7 (ppc64el)


Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-
migration/focal/update_excuses.html#gpgme1.0

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

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https://bugs.launchpad.net/bugs/2037595

Title:
  _gpgme_io_select breaks when more than 1024 file descriptors are open

Status in gpgme1.0 package in Ubuntu:
  Fix Released
Status in gpgme1.0 source package in Focal:
  Fix Committed
Status in gpgme1.0 source package in Jammy:
  Fix Committed

Bug description:
  [Impact]

  Launchpad's buildd-manager is a complex event-driven daemon that
  manages several hundred builders on production.  As such, it can often
  end up with more than 1024 file descriptors open.  It also uses gpgme
  from time to time to fetch signing keys for PPAs when dispatching
  builds that involve PPAs.

  On focal (and also on jammy), this breaks because `_gpgme_io_select`
  is implemented using select(2), whose manual page says: "WARNING:
  select() can monitor only file descriptors numbers that are less than
  FD_SETSIZE (1024)—an unreasonably low limit for many modern
  applications—and this limitation will not change.  All modern
  applications should instead use poll(2) or epoll(7), which do not
  suffer this limitation."  This is exactly the limitation we're running
  into, resulting in mysterious "Too many open files" errors despite
  resource limits being set to more than comfortable values.

  Fortunately, this was fixed upstream in https://git.gnupg.org/cgi-
  bin/gitweb.cgi?p=gpgme.git;a=commitdiff;h=8148237cb4ae20755c06a44d71761c7030973c3d,
  and lunar has that fix.  focal and jammy do not (there may be a
  similar problem with older LTSes too, but I only care about it back to
  focal).  buildd-manager currently runs on focal.

  We've been running buildd-manager with a cherry-picked fix from
  upstream for a few weeks now, and I'd like to get that SRUed back into
  Ubuntu so that we don't accidentally lose this patch in the event of a
  security update or similar.

  [Test Plan]

  William Grant provided this minimal reproducer:

  ```
  root at tmp:~# python3
  Python 3.8.10 (default, May 26 2023, 14:05:08)
  [GCC 9.4.0] on linux
  Type "help", "copyright", "credits" or "license" for more information.
  >>> import gpg
  >>> c = gpg.Context()
  >>> list(c.keylist())
  []
  >>> fs = []
  >>> for i in range(1024):
  ...     fs.append(open('/dev/null'))
  ...
  >>> list(c.keylist())
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    File "/usr/lib/python3/dist-packages/gpg/core.py", line 751, in keylist
      key = self.op_keylist_next()
    File "/usr/lib/python3/dist-packages/gpg/core.py", line 1195, in op_keylist_next
      raise excp
    File "/usr/lib/python3/dist-packages/gpg/core.py", line 1190, in op_keylist_next
      errorcheck(gpgme.gpgme_op_keylist_next(self.wrapped, ptr))
    File "/usr/lib/python3/dist-packages/gpg/errors.py", line 129, in errorcheck
      raise GPGMEError(retval, extradata)
  gpg.errors.GPGMEError: GPGME: Too many open files
  ```

  [Where problems could occur]

  `_gpgme_io_select` is pretty central to gpgme, so if something is
  wrong the package will be pretty broken.  On the other hand, that also
  means any glaring problems are likely to be caught by the package's
  test suite.

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