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

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Date:	Tue, 12 Jul 2016 16:27:16 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Jiri Olsa <jolsa@...hat.com>, Jiri Olsa <jolsa@...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

Em Tue, Jul 12, 2016 at 09:48:36AM -0400, Steven Rostedt escreveu:
> 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.

Ok, applied and tested up to patch 9, waiting for this discussion to
come to an end to consider 10.

- Arnaldo
 
> > 
> > >   
> > > > 
> > > > 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