[Bug 1326854] Re: ambiguous error message "sh: echo: I/O error"

[Launchpad Bug Tracker]

** Branch linked: lp:ubuntu/trusty-proposed/ifenslave

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https://bugs.launchpad.net/bugs/1326854

Title:
  ambiguous error message "sh: echo: I/O error"

Status in ifenslave-2.6 package in Ubuntu:
  Fix Released
Status in ifenslave-2.6 source package in Trusty:
  In Progress

Bug description:
  [SRU justification]

  [Impact]

  Without this patch, trying to add a bond when this one is already
  defined leads to the following error :

  Example :

  # ifenslave bond0 eth1 eth2
  sh: echo: I/O error
  eth1: could not add interface

  [Test Case]

  For info, the ambiguous message only appears when using ifenslave on a
  bond that is already configured :

  # ifconfig eth1 up
  # ifconfig eth2 up
  # ifconfig bond0 up
  # ifenslave bond0 eth1 eth2 <<<< No error on the first execution
  # ifenslave bond0 eth1 eth2
  sh: echo: I/O error
  eth1: could not add interface

  [Regression Potential]

  None expected as the same commit is already in use in the ifenslave
  package for Wily and in the upstream debian package.

  [Original description of the problem]

  adding an interface to a bonding interface can result in the error
  message "sh: echo: I/O error" which is highly ambiguous (did the I/O
  error occur in sh, echo or is it an I/O error realted to the
  command/driver? - at least change this to "I/O error occured" which is
  still not helpful ("I/O occured in the kernel driver, please make sure
  it supports XY, check with <Z>" would be nice), but at least not
  confusing.

  reproduction:
  /etc/wpa_supplicant/wpa_supplicant.conf
  <code>
  network={
      ssid="assid"
      key_mgmt=WPA-EAP
      eap=TTLS
      proto=WPA RSN
      identity="anidentity at adomain.com"
      anonymous_identity="anonymous at adomain.de"
      ca_cert="/etc/wpa_supplicant/deutsche-telekom-root-ca-2.crt"
      phase2="auth=PAP"
  }
  </code>
  /etc/network/interfaces
  <code>
  iface main inet dhcp
      wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf

  iface bond0 inet manual
      down ifenslave -d bond0 wlan0 wlan1
      bond-mode active-backup
      bond-miimon 100
      bond-slaves wlan0 wlan1

  allow-bond0 wlan0
  iface wlan0 inet manual
      wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
      bond-master bond0

  allow-bond0 wlan1
  iface wlan1 inet manual
      wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
      bond-master bond0

  iface eth1 inet dhcp
  </code>
  my commands
  <code>
  sudo modprobe bonding
  sudo ifup wlan0
  sudo ifup wlan1
  sudo ifconfig bond0 # no DHCP example, so I've not idea how to get this running :( just providing a way to reproduce the error message (which should in no case be shown with its current content)
  sudo ifenslave bond0 wlan0 wlan1
  </code>

  I'm not requesting support here, just to fix the bug which should make
  the former unnecessary anyway :)

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