[lxc-devel] [lxc/lxc] 5d113f: start: do not unconditionally dup std{in, out, err}

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/lxc/lxc
  Commit: 5d113f650c398eca1464084d8c42b00211265403
      https://github.com/lxc/lxc/commit/5d113f650c398eca1464084d8c42b00211265403
  Author: Christian Brauner <christian.brauner at ubuntu.com>
  Date:   2017-12-12 (Tue, 12 Dec 2017)

  Changed paths:
    M src/lxc/start.c

  Log Message:
  -----------
  start: do not unconditionally dup std{in,out,err}

Starting with commit

    commit c5b93afba1d79c6861a6f45db2943b6f3cfbdab4
    Author: Li Feng <lifeng68 at huawei.com>
    Date:   Mon Jul 10 17:19:52 2017 +0800
   start: dup std{in,out,err} to pty slave
   In the case the container has a console with a valid slave pty file descriptor
  we duplicate std{in,out,err} to the slave file descriptor so console logging
  works correctly. When the container does not have a valid slave pty file
  descriptor for its console and is started daemonized we should dup to
  /dev/null.
   Closes #1646.
   Signed-off-by: Li Feng <lifeng68 at huawei.com>
  Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>

we made std{err,in,out} a duplicate of the slave file descriptor of the console
if it existed. This meant we also duplicated all of them when we executed
application containers in the foreground even if some std{err,in,out} file
descriptor did not refer to a {p,t}ty. This blocked use cases such as:

    echo foo | lxc-execute -n -- cat

which are very valid and common with application containers but less common
with system containers where we don't have to care about this. So my suggestion
is to unconditionally duplicate std{err,in,out} to the console file descriptor
if we are either running daemonized - this ensures that daemonized application
containers with a single bash shell keep on working - or when we are not
running an application container. In other cases we only duplicate those file
descriptors that actually refer to a {p,t}ty. This logic is similar to what we
do for lxc-attach already.

Refers to #1690.
Closes #2028.

Reported-by: Felix Abecassis <fabecassis at nvidia.com>
Signed-off-by: Christian Brauner <christian.brauner at ubuntu.com>


  Commit: 5875fa24a439b6036fff4f04e5e7043b3f015d10
      https://github.com/lxc/lxc/commit/5875fa24a439b6036fff4f04e5e7043b3f015d10
  Author: Stéphane Graber <stgraber at stgraber.org>
  Date:   2017-12-13 (Wed, 13 Dec 2017)

  Changed paths:
    M src/lxc/start.c

  Log Message:
  -----------
  Merge pull request #2029 from brauner/2017-12-12/do_not_unconditionally_dup_stdfds_for_execute

start: do not unconditionally dup std{in,out,err}


Compare: https://github.com/lxc/lxc/compare/547dfee335f9...5875fa24a439