[Bug 1306543] [NEW] python3.4 breaks installing deb files

[Kiwinote]

Public bug reported:

[If you're facing this issue, please use bug 1290228 , so that we can
use this bug for the implementation of the fix - thanks!]

Steps to reproduce:
- run trusty (updated sometime in the last ~month)
- open ?any? deb file with an aptdaemon client (software-center, appgrid, etc)
- installation will fail (bug 1290228 etc)

After trailing through aptdaemon and python-apt code it seems that there might be multiple manifestations of this bug
python-apt: progress/base.py: InstallProgress.run()
>>> os._exit(os.spawnlp(os.P_WAIT, "dpkg", "dpkg", "--status-fd", str(self.write_stream.fileno()), "-i", obj))
aptdaemon: progress.py: DaemonDpkgInstallProgress._child()
>>> args = [apt_pkg.config["Dir::Bin::DPkg"], "--status-fd", str(self.status_child_fd)] #(...)
>>> os.execlp(apt_pkg.config["Dir::Bin::DPkg"], *args)
I think there are likely to be other points of failure too.

Noteworthy is the following:
pgg at four:~$ sudo python3.4 -c "import os; (statusfd, writefd) = os.pipe(); write_stream = os.fdopen(writefd, 'w'); print(write_stream.fileno()); r = os.execlp('/usr/bin/dpkg', '/usr/bin/dpkg', '--status-fd', str(write_stream.fileno()), '-i', '/home/pgg/Downloads/appgrid_0.1.100~trusty_all.deb'); print(r)"
4
dpkg: error: unable to read filedescriptor flags for <package status and progress file descriptor>: Bad file descriptor

pgg at four:~$ sudo python3.3 -c "import os; (statusfd, writefd) = os.pipe(); write_stream = os.fdopen(writefd, 'w'); print(write_stream.fileno()); r = os.execlp('/usr/bin/dpkg', '/usr/bin/dpkg', '--status-fd', str(write_stream.fileno()), '-i', '/home/pgg/Downloads/appgrid_0.1.100~trusty_all.deb'); print(r)"
4
(Reading database ... 227994 files and directories currently installed.)
Preparing to unpack .../appgrid_0.1.100~trusty_all.deb (etc, installs properly)

This lead me to http://legacy.python.org/dev/peps/pep-0446/ which means
that file descriptors can't be inherited in python 3.4.

My knowledge of python-apt and aptdaemon isn't really good enough to
know what the best way forward is to resolve this in the least
disruptive and safest way, but it would be nice if people could install
deb files in 14.04. I've subscribed a few people who might have ideas.

** Affects: appgrid
     Importance: Undecided
         Status: New

** Affects: aptdaemon
     Importance: Undecided
         Status: New

** Affects: python-apt (Ubuntu)
     Importance: Undecided
         Status: New

** Affects: software-center (Ubuntu)
     Importance: Critical
         Status: Triaged

** Also affects: appgrid
   Importance: Undecided
       Status: New

** Also affects: aptdaemon
   Importance: Undecided
       Status: New

** Also affects: python-apt (Ubuntu)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1306543

Title:
  python3.4 breaks installing deb files

Status in App Grid:
  New
Status in Aptdaemon:
  New
Status in “python-apt” package in Ubuntu:
  New
Status in “software-center” package in Ubuntu:
  Triaged

Bug description:
  [If you're facing this issue, please use bug 1290228 , so that we can
  use this bug for the implementation of the fix - thanks!]

  Steps to reproduce:
  - run trusty (updated sometime in the last ~month)
  - open ?any? deb file with an aptdaemon client (software-center, appgrid, etc)
  - installation will fail (bug 1290228 etc)

  After trailing through aptdaemon and python-apt code it seems that there might be multiple manifestations of this bug
  python-apt: progress/base.py: InstallProgress.run()
  >>> os._exit(os.spawnlp(os.P_WAIT, "dpkg", "dpkg", "--status-fd", str(self.write_stream.fileno()), "-i", obj))
  aptdaemon: progress.py: DaemonDpkgInstallProgress._child()
  >>> args = [apt_pkg.config["Dir::Bin::DPkg"], "--status-fd", str(self.status_child_fd)] #(...)
  >>> os.execlp(apt_pkg.config["Dir::Bin::DPkg"], *args)
  I think there are likely to be other points of failure too.

  Noteworthy is the following:
  pgg at four:~$ sudo python3.4 -c "import os; (statusfd, writefd) = os.pipe(); write_stream = os.fdopen(writefd, 'w'); print(write_stream.fileno()); r = os.execlp('/usr/bin/dpkg', '/usr/bin/dpkg', '--status-fd', str(write_stream.fileno()), '-i', '/home/pgg/Downloads/appgrid_0.1.100~trusty_all.deb'); print(r)"
  4
  dpkg: error: unable to read filedescriptor flags for <package status and progress file descriptor>: Bad file descriptor

  pgg at four:~$ sudo python3.3 -c "import os; (statusfd, writefd) = os.pipe(); write_stream = os.fdopen(writefd, 'w'); print(write_stream.fileno()); r = os.execlp('/usr/bin/dpkg', '/usr/bin/dpkg', '--status-fd', str(write_stream.fileno()), '-i', '/home/pgg/Downloads/appgrid_0.1.100~trusty_all.deb'); print(r)"
  4
  (Reading database ... 227994 files and directories currently installed.)
  Preparing to unpack .../appgrid_0.1.100~trusty_all.deb (etc, installs properly)

  This lead me to http://legacy.python.org/dev/peps/pep-0446/ which
  means that file descriptors can't be inherited in python 3.4.

  My knowledge of python-apt and aptdaemon isn't really good enough to
  know what the best way forward is to resolve this in the least
  disruptive and safest way, but it would be nice if people could
  install deb files in 14.04. I've subscribed a few people who might
  have ideas.

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