Re: [PATCH] KVM Test: add -w parameter in nc command in kvm_utils.py

[Michael Goldish <mgoldish@redhat.com>]

On 10/20/2010 08:55 AM, Feng Yang wrote:
> If a connection and stdin are idle for more than timeout seconds,
> then the connection is silently closed. withou this paramter,
> nc will listen forever for a connection. This may cause our test
> hang. redmine issue:
> http://redmine.englab.nay.redhat.com/issues/show/6947
> Add -w parameter should fix this issue.
> 
> Signed-off-by: Feng Yang <fyang@redhat.com>
> ---
>  client/tests/kvm/kvm_utils.py |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/client/tests/kvm/kvm_utils.py b/client/tests/kvm/kvm_utils.py
> index a51c857..526d38d 100644
> --- a/client/tests/kvm/kvm_utils.py
> +++ b/client/tests/kvm/kvm_utils.py
> @@ -733,7 +733,7 @@ def remote_login(client, host, port, username, password, prompt, linesep="\n",
>      elif client == "telnet":
>          cmd = "telnet -l %s %s %s" % (username, host, port)
>      elif client == "nc":
> -        cmd = "nc %s %s" % (host, port)
> +        cmd = "nc %s %s -w %s" % (host, port, timeout)
>      else:
>          logging.error("Unknown remote shell client: %s" % client)
>          return

I don't understand how remote_login() can stall here.
kvm_utils._remote_login() doesn't rely on nc's self-termination.  If no
shell prompt is available after 10 seconds, nc is forcefully terminated
and _remote_login() fails.  If it somehow stalls this might indicate a
bug somewhere.