linux-kernel - Re: [PATCH] perf target: Ignore return value of strerror

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Date:	Tue, 03 Jul 2012 09:28:26 +0900
From:	Namhyung Kim <namhyung.kim@....com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
CC:	Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Markus Trippelsdorf <markus@...ppelsdorf.de>
Subject: Re: [PATCH] perf target: Ignore return value of strerror_r() explicitly

2012-07-03 12:34 AM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Jul 02, 2012 at 03:20:14PM +0900, Namhyung Kim escreveu:
>> Since glibc 2.16 added the warn_unused_result (wur) attribute
>> to the function, we should check the return value or ignore it
>> explicitly.
>>
>> Reported-by: Markus Trippelsdorf <markus@...ppelsdorf.de>
>> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
>
>> +++ b/tools/perf/util/target.c
>> @@ -111,7 +111,8 @@ int perf_target__strerror(struct perf_target *target, int errnum,
>>   	const char *msg;
>>
>>   	if (errnum >= 0) {
>> -		strerror_r(errnum, buf, buflen);
>> +		/* make glibc (>= 2.16) happy */
>> +		(void)strerror_r(errnum, buf, buflen);
>
> Is this really the best way to handle this?
>
> What if some perf tool is buggy and passes an invalid errnum?  Shouldn't
> we catch that?
>

$ man strerror_r
...
RETURN VALUE
        The  strerror()  and  the  GNU-specific strerror_r() functions
        return the appropriate error description string, or an
        "Unknown error nnn" message if the error number is unknown.

Isn't it sufficient? Or we can reset the @buf at the beginning for the case of 
a invalid negative @errnum.

Thanks,
Namhyung

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