[FFmpeg-devel] [FFmpeg-cvslog] cbs_mpeg2: Fix type for marker_bit reading

[Hendrik Leppkes]

On Wed, Oct 25, 2017 at 12:42 AM, Mark Thompson <sw at jkqxz.net> wrote:
> On 24/10/17 23:34, Carl Eugen Hoyos wrote:
>> 2017-10-25 0:29 GMT+02:00 Mark Thompson <sw at jkqxz.net>:
>>> On 24/10/17 23:14, Carl Eugen Hoyos wrote:
>>>> 2017-10-25 0:09 GMT+02:00 Mark Thompson <git at videolan.org>:
>>>>> ffmpeg | branch: master | Mark Thompson <sw at jkqxz.net> | Tue Oct 24 22:56:48 2017 +0100| [5b2c71bb94d7cab23ee81b5c29388f5fadbcaf22] | committer: Mark Thompson
>>>>>
>>>>> cbs_mpeg2: Fix type for marker_bit reading
>>>>>
>>>>>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5b2c71bb94d7cab23ee81b5c29388f5fadbcaf22
>>>>> ---
>>>>>
>>>>>  libavcodec/cbs_mpeg2.c | 2 +-
>>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
>>>>> index d137762227..0cac29733e 100644
>>>>> --- a/libavcodec/cbs_mpeg2.c
>>>>> +++ b/libavcodec/cbs_mpeg2.c
>>>>> @@ -54,7 +54,7 @@
>>>>>          xui(width, name, current->name)
>>>>>
>>>>>  #define marker_bit() do { \
>>>>> -        av_unused int one = 1; \
>>>>> +        av_unused uint32_t one; \
>>>>>          CHECK(ff_cbs_read_unsigned(ctx, rw, 1, "marker_bit", &one, 1, 1)); \
>>>>
>>>> The commit message doesn't match the change / is this defined behaviour?
>>>
>>> It's only written and never read, so the initialisation isn't doing anything.
>>
>> I asked because I believe it was reported once that a static analyzer protested
>> on passing uninitialized stuff - that was never going to be used - as
>> a parameter.
>> (But that may have been an uninitialized variable that was never used,
>> not a pointer.)
>
> I don't think pointers in general can be complained about in C without knowledge of the target function - consider that there are destination pointers all over the standard library which need not be initialised, like memcpy() or scanf().
>

As if static analyzers always care what you can and cannot do. :p

- Hendrik