linux-kernel - Re: [PATCH 10/10] perf script python: Fix string vs byte array resolving

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Date:	Tue, 12 Jul 2016 09:48:36 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Jiri Olsa <jolsa@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [PATCH 10/10] perf script python: Fix string vs byte array
 resolving

On Tue, 12 Jul 2016 15:35:52 +0200
Jiri Olsa <jolsa@...hat.com> wrote:

> On Tue, Jul 12, 2016 at 09:00:01AM -0400, Steven Rostedt wrote:
> > On Tue, 12 Jul 2016 14:52:45 +0200
> > Jiri Olsa <jolsa@...hat.com> wrote:
> > 
> >   
> > > hum, so string is not passed to trace buffer with 0 at the end?  
> > 
> > strlen() returns only the length of the string (minus the \0 at the
> > end).  
> 
> yea, is_printable_array is called here on tracepoint
> data that's why I asked.. is 0 part of the string data
> when stored within tracepoint?

Good question. It may or may not (haven't looked at the code), but we
probably want to make sure that the function is robust enough for
either case.

> 
> >   
> > > 
> > > I'll check the option of passing everything as PyByteArray.
> > > If it's the same for user, we'll have simpler code in here.
> > >   
> > > > 
> > > > because the last byte wont be 0. What about:
> > > > 
> > > > 	for (i = 0; i < len; i++)
> > > > 		if (!isprint(p[i]) && !isspace(p[i]))
> > > > 			break;
> > > > 
> > > > 	return i == len ||
> > > > 		(i == len - 1 && p[i] == 0);    
> > 
> > Or you can do:
> > 
> > 	if (p[len - 1] == 0)
> > 		len--;
> > 
> > 	for (i = 0; i < len; i++)
> > 		if (!isprint(p[i]) && !isspace(p[i]))
> > 			return 0;
> > 	return 1;  
> 
> yep, seems good.. thanks
> 

OK, great!

-- Steve