[FFmpeg-devel] [PATCH] ffmpeg: avoid scanf in keyboard command parsing

[Hendrik Leppkes]

On Mon, Aug 3, 2015 at 10:12 PM, Nicolas George <george at nsup.org> wrote:
> Le sextidi 16 thermidor, an CCXXIII, Hendrik Leppkes a écrit :
>> Mixing stdio and low-level IO on stdin is not safe.
>> ---
>>  ffmpeg.c | 12 ++++++++++--
>>  1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/ffmpeg.c b/ffmpeg.c
>> index 5575e2f..206b3dc 100644
>> --- a/ffmpeg.c
>> +++ b/ffmpeg.c
>> @@ -3428,9 +3428,17 @@ static int check_keyboard_interaction(int64_t cur_time)
>>              if(!debug) debug = 1;
>>              while(debug & (FF_DEBUG_DCT_COEFF|FF_DEBUG_VIS_QP|FF_DEBUG_VIS_MB_TYPE)) //unsupported, would just crash
>>                  debug += debug;
>> -        }else
>> -            if(scanf("%d", &debug)!=1)
>> +        }else{
>> +            char buf[32];
>
>> +            int k = 0;
>> +            i = 0;
>> +            while ((k = read_key()) != '\n' && k != '\r' && i < sizeof(buf)-1)
>> +                if (k > 0)
>> +                    buf[i++] = k;
>> +            buf[i] = 0;
>
> This part could have been factored withe the previous code as read_line(),
> but that is not very important.
>
>> +            if (k <= 0 || sscanf(buf, "%d", &debug)!=1)
>>                  fprintf(stderr,"error parsing debug value\n");
>> +        }
>>          for(i=0;i<nb_input_streams;i++) {
>>              input_streams[i]->st->codec->debug = debug;
>>          }
>
> This is exactly what I had in mind. I suppose it fixes the 'd0\n?' case you
> tested?
>

I figured, it wasn't hard to find out, and since you said you wouldn't
have time... Yes, it works now.

- Hendrik