Steven Liu: > > >> 在 2019年11月29日，13:57，Andreas Rheinhardt <andreas.rheinha...@gmail.com> 写道： >> >> Steven Liu: >>> >>> >>>> 在 2019年11月29日，13:40，Andreas Rheinhardt <andreas.rheinha...@gmail.com> 写道： >>>> >>>> Jeyapal, Karthick: >>>>> >>>>> On 11/29/19 10:45 AM, Steven Liu wrote: >>>>>> Signed-off-by: Steven Liu <l...@chinaffmpeg.org> >>>>>> --- >>>>>> libavformat/dashenc.c | 3 +-- >>>>>> 1 file changed, 1 insertion(+), 2 deletions(-) >>>>>> >>>>>> diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c >>>>>> index a462876c13..8c28fb6b6e 100644 >>>>>> --- a/libavformat/dashenc.c >>>>>> +++ b/libavformat/dashenc.c >>>>>> @@ -588,8 +588,7 @@ static void dash_free(AVFormatContext *s) >>>>>> avio_close(os->ctx->pb); >>>>>> } >>>>>> ff_format_io_close(s, &os->out); >>>>>> - if (os->ctx) >>>>>> - avformat_free_context(os->ctx); >>>>>> + avformat_free_context(os->ctx); >>>>> This 'if' condition is a safety net against double frees caused due to >>>>> any corner case and/or wrong usage. >>>>> Unless this is absolutely required for some reason, this 'if' condition >>>>> should not be removed. >>>> >>>> This 'if' doesn't help against double-frees at all: >>>> avformat_free_context() itself checks against its argument being NULL >>>> and returns immediately if it is. (But double frees are still possible >>>> given that avformat_free_context can't reset the pointer to NULL due >>>> to its signature. Resetting is something the callers have to do for >>>> themselves.) >>> What about add reset pointer to NULL into the avformat_free_context? >> >> This is pointless, because it will just reset the functions copy of >> the pointer to NULL, not the callers pointer to the AVFormatContext. >> In order to reset the latter, the parameter would have to be of type >> AVFormatContext ** (and the call here would be >> avformat_free_context(&os->ctx)). > AVFormatContext **? Isn’t that too complex for user of the API caller?
I don't see anything complex in such a parameter. And this is actually a quite common scenario (just think of av_freep() or avio_context_free() which both need **-arguments to do their job). - Andreas _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
