[PATCH] perf target: Ignore return value of strerror_r() explicitly

[PATCH] perf target: Ignore return value of strerror_r() explicitly

[Namhyung Kim]

From: Namhyung Kim <namhyung.kim@lge.com>

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@trippelsdorf.de>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/target.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/target.c b/tools/perf/util/target.c
index 1064d5b148ad..18080ca9ceec 100644
--- a/tools/perf/util/target.c
+++ 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);
 		return 0;
 	}
 
-- 
1.7.10.2

Re: [PATCH] perf target: Ignore return value of strerror_r() explicitly

[Arnaldo Carvalho de Melo]

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@trippelsdorf.de>
> Signed-off-by: Namhyung Kim <namhyung@kernel.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?

- Arnaldo

Re: [PATCH] perf target: Ignore return value of strerror_r() explicitly

[Namhyung Kim]

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@trippelsdorf.de>
>> Signed-off-by: Namhyung Kim <namhyung@kernel.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