[libvirt] [libvirt-test-API][PATCH] Fix utils.exec_cmd output problem

[Guannan Ren]

On 2013年11月26日 17:17, Jincheng Miao wrote:
> Thanks for review,
> yes, I missed this situation: stdout is not the subprocess.PIPE.
>
> Since the stderr is always subprocess.PIPE, my another way is err after Popen.communicate().
>
> The patch looks like:
> ---
>   utils/utils.py | 2 ++---
>   1 file changed, 2 insertions(+)
>
> diff --git a/utils/utils.py b/utils/utils.py
> index 147c1ef..d107cbd 100644
> --- a/utils/utils.py
> +++ b/utils/utils.py
> @@ -412,6 +412,8 @@ def exec_cmd(command, sudo=False, cwd=None, infile=None, outfile=None, shell=Fal
>       p = subprocess.Popen(command, shell=shell, close_fds=True, cwd=cwd,
>                       stdin=infile, stdout=outfile, stderr=subprocess.PIPE)
>       (out, err) = p.communicate(data)
>       if out == None:
>           # Prevent splitlines() from barfing later on
>           out = ""
> +    if err != "":
> +        out += err
>       return (p.returncode, out.splitlines())
>   
>   def remote_exec_pexpect(hostname, username, password, cmd):

Why to append standard error to standard output. It is not right in 
semantics.
In order to get the standard error if executing command failed,  the 
following change is enough:

      if out == None:
          # Prevent splitlines() from barfing later on
          out = ""
+    if p.returncode:
+        out = err
      return (p.returncode, out.splitlines())


Guannan