Re: [Qemu-devel] [PATCH v3 17/18] trace: pass trace-events to tracetool as a positional param

["Daniel P. Berrange" <berrange@redhat.com>]

On Mon, Sep 19, 2016 at 08:18:51PM +0200, Lluís Vilanova wrote:
> Daniel P Berrange writes:
> 
> > Instead of reading the contents of 'trace-events' from stdin,
> > accept the filename as a positional parameter. This also
> > allows for reading from multiple files, though this facility
> > is not used at this time.
> 
> > Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> > ---
> >  Makefile.target      |  6 +++---
> >  scripts/tracetool.py |  5 ++++-
> >  trace/Makefile.objs  | 18 +++++++++---------
> >  3 files changed, 16 insertions(+), 13 deletions(-)
> 
> > diff --git a/scripts/tracetool.py b/scripts/tracetool.py
> > index 6accbbf..f66e767 100755
> > --- a/scripts/tracetool.py
> > +++ b/scripts/tracetool.py
> > @@ -129,7 +129,10 @@ def main(args):
> >          if probe_prefix is None:
> >              probe_prefix = ".".join(["qemu", target_type, target_name])
>  
> > -    events = tracetool.read_events(sys.stdin)
> > +    if len(args) != 1:
> > +        error_opt("missing trace-events filepath")
> > +    with open(args[0], "r") as fh:
> > +        events = tracetool.read_events(fh)
>  
> I'm not sure that's the proper way to check for a positional argument in getopt
> (iff it accepts optional args mingled with positional ones).

'args' comes from the return value of getopt.getopt(sys.argv)
which is documented as:

  "The return value consists of two elements: the first is a
   list of (option, value) pairs; the second is the list of
   program arguments left after the option list was stripped
   (this is a trailing slice of args"


Regards,
Daniel
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