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

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Date:	Tue, 12 Jul 2016 08:37:28 -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 10:11:56 +0200
Jiri Olsa <jolsa@...hat.com> wrote:


> ---
> diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
> index 75e9790ebb96..9f810e6c739a 100644
> --- a/tools/perf/util/scripting-engines/trace-event-python.c
> +++ b/tools/perf/util/scripting-engines/trace-event-python.c
> @@ -390,11 +390,13 @@ static int is_printable_array(char *p, unsigned int len)
>  {
>  	unsigned int i;
>  
> -	for (i = 0; i < len; i++)
> +	/* Exclude the last zero byte of string.. */
> +	for (i = 0; i < len - 1; i++)
>  		if (!isprint(p[i]) && !isspace(p[i]))
>  			return 0;
>  
> -	return 1;
> +	/* ... and check its presence in the last byte. */
> +	return p[i] == 0;
>  }
>  

Of course this fails on:

	is_printable_array(a, strlen(a));

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);

-- Steve