[FFmpeg-devel] [PATCH] avfilter/vf_stack: Don't modify const strings

[Gyan]

On 14-05-2019 06:11 PM, Paul B Mahol wrote:
> On 5/14/19, Gyan <ffmpeg at gyani.pro> wrote:
>>
>> On 14-05-2019 09:45 AM, Andreas Rheinhardt wrote:
>>> b3b7ba62 introduced undefined behaviour: A (non-modifiable) string
>>> literal has been assigned to a modifiable string; said string was indeed
>>> modified later via av_strtok.
>>> This of course caused compiler warnings because of the discarded
>>> qualifier; these are in particular fixed by this commit.
>>>
>>> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
>>> ---
>>>    libavfilter/vf_stack.c | 8 +++++---
>>>    1 file changed, 5 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/libavfilter/vf_stack.c b/libavfilter/vf_stack.c
>>> index 1455f196a7..4d254e0013 100644
>>> --- a/libavfilter/vf_stack.c
>>> +++ b/libavfilter/vf_stack.c
>>> @@ -84,9 +84,11 @@ static av_cold int init(AVFilterContext *ctx)
>>>
>>>        if (!strcmp(ctx->filter->name, "xstack")) {
>>>            if (!s->layout) {
>>> -            if (s->nb_inputs == 2)
>>> -                s->layout = "0_0|w0_0";
>>> -            else {
>>> +            if (s->nb_inputs == 2) {
>>> +                s->layout = av_strdup("0_0|w0_0");
>>> +                if (!s->layout)
>>> +                    return AVERROR(ENOMEM);
>>> +            } else {
>>>                    av_log(ctx, AV_LOG_ERROR, "No layout specified.\n");
>>>                    return AVERROR(EINVAL);
>>>                }
>> Sorry, I missed what was being done with the string later on.
>>
> Why you pushed something else that what was reviewed?
The code I pushed was exactly the same as what you reviewed; only the 
commit msg was changed to what you suggested.

See

http://www.ffmpeg.org/pipermail/ffmpeg-devel/2019-May/243664.html

vs

http://git.videolan.org/?p=ffmpeg.git;a=blobdiff;f=libavfilter/vf_stack.c;h=1455f196a7cb3124f7a7931f6b56ed985848d75b;hp=b836d96bf09a70d943f28b4424da0af3bf62ecea;hb=b3b7ba623f95224557bd67a060adf4ca7ee94dde;hpb=e25bddf5fce88f95be8bf3cbc8adf4a74bc28fb5

Your review:
http://www.ffmpeg.org/pipermail/ffmpeg-devel/2019-May/243665.html


Gyan