[Piglit] [PATCH] xz: Use --help when detecting xz presence

[Jordan Justen]

On 2015-08-02 09:57:00, Dylan Baker wrote:
>    On Aug 2, 2015 00:45, "Jordan Justen" <jordan.l.justen at intel.com> wrote:
>    >
>    > If xz is present, and the piglit command's output is redirected, then
>    > xz will think its output is redirected. This will cause xz to try to
>    > read data from stdin to compress.
>    >
>    > Instead we can run xz with --help to cause it to print help
>    > information if the xz executable is present, and prevent xz from
>    > trying to compress data from stdin.
>    >
>    > Since we don't want to see 'xz --help' output from piglit, we now need
>    > to redirect both stdout and stderr to /dev/null.
>    >
>    > Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
>    > Cc: Dylan Baker <baker.dylan.c at gmail.com>
>    > ---
>    >  framework/backends/compression.py | 2 +-
>    >  1 file changed, 1 insertion(+), 1 deletion(-)
>    >
>    > diff --git a/framework/backends/compression.py
>    b/framework/backends/compression.py
>    > index 88bde2a..97b0f32 100644
>    > --- a/framework/backends/compression.py
>    > +++ b/framework/backends/compression.py
>    > @@ -95,7 +95,7 @@ try:
>    >  except ImportError:
>    >      try:
>    >          with open(os.devnull, 'w') as d:
>    > -            subprocess.check_call(['xz'], stderr=d)
>    > +            subprocess.check_call(['xz', '--help'], stdout=d,
>    stderr=subprocess.STDOUT)
> 
>    Based on you're commit message I don't think this sides what you want. I
>    think you should set stderr=d to hide both stderr and stdout.

stderr=subprocess.STDOUT should send stderr to the same file as
stdout, and stdout is sent to /dev/null.

-Jordan

> 
>    >      except subprocess.CalledProcessError as e:
>    >          if e.returncode == 1:
>    >              import contextlib
>    > --
>    > 2.1.4
>    >