[FFmpeg-devel] Fwd: [PATCH 2/2] ffmpeg: silence unused return value warnings

[Ganesh Ajjanagadde]

Apologies.

---------- Forwarded message ----------
From: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
Date: Mon, Jul 27, 2015 at 8:31 AM
Subject: Re: [FFmpeg-devel] [PATCH 2/2] ffmpeg: silence unused return
value warnings
To: Nicolas George <george at nsup.org>


On Mon, Jul 27, 2015 at 4:42 AM, Nicolas George <george at nsup.org> wrote:
> L'octidi 8 thermidor, an CCXXIII, Ganesh Ajjanagadde a écrit :
>> GCC throws a -Wunused-result for not checking return value
>> of write(); silence it
>>
>> Signed-off-by: Ganesh Ajjanagadde <gajjanagadde at gmail.com>
>> ---
>>  ffmpeg.c | 16 ++++++++--------
>>  1 file changed, 8 insertions(+), 8 deletions(-)
>>
>> diff --git a/ffmpeg.c b/ffmpeg.c
>> index 8b5a705..6f18ab8 100644
>> --- a/ffmpeg.c
>> +++ b/ffmpeg.c
>> @@ -329,16 +329,16 @@ sigterm_handler(int sig)
>>      switch (sig) {
>>          /* 2 = STDERR_FILENO */
>>          case SIGSEGV:
>> -            write(2, "Segmentation fault, hard exiting\n",
>> -              strlen("Segmentation fault, hard exiting\n"));
>> +            if(write(2, "Segmentation fault, hard exiting\n",
>> +              strlen("Segmentation fault, hard exiting\n"))){};
>
> (void)write(...) should be enough, and IMHO more readable.

Not with latest GCC, see e.g discussion
http://stackoverflow.com/questions/7271939/declared-with-attribute-warn-unused-result
and GCC bugzilla link therein
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=25509

Attached updated patch to reflect changes made.
>
>>              abort();
>>          case SIGILL:
>> -            write(2, "Invalid instruction, hard exiting\n",
>> -              strlen("Invalid instruction, hard exiting\n"));
>> +            if(write(2, "Invalid instruction, hard exiting\n",
>> +              strlen("Invalid instruction, hard exiting\n"))){};
>>              abort();
>>          case SIGFPE:
>> -            write(2, "Arithmetic exception, hard exiting\n",
>> -              strlen("Arithmetic exception, hard exiting\n"));
>> +            if(write(2, "Arithmetic exception, hard exiting\n",
>> +              strlen("Arithmetic exception, hard exiting\n"))){};
>>              abort();
>>              break;
>>          default:
>> @@ -346,8 +346,8 @@ sigterm_handler(int sig)
>>      }
>>
>>      if(received_nb_signals > 3) {
>> -        write(2, "Received > 3 system signals, hard exiting\n",
>> -          strlen("Received > 3 system signals, hard exiting\n"));
>> +        if(write(2, "Received > 3 system signals, hard exiting\n",
>> +          strlen("Received > 3 system signals, hard exiting\n"))){};
>>          exit(123);
>
> Regards,
>
> --
>   Nicolas George
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