[FFmpeg-devel] [PATCH 1/2] avformat/demux: use io_close2 when closing avfromat

[Michael Niedermayer]

On Fri, May 30, 2025 at 10:48:29PM +0200, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > On Sat, May 17, 2025 at 03:03:19PM +0200, Andreas Rheinhardt wrote:
> >> Andreas Rheinhardt:
> >>> Kacper Michajłow:
> >>>> It's not valid to call avio_close() on context that has not been open
> >>>> with avio_open().
> >>>>
> >>>> This fixes use of custom IO. (io_open / io_close2 callbacks)
> >>>>
> >>>> Note that by default io_close2 is set to io_close2_default() which calls
> >>>> avio_close(), so default case will work the same as before.
> >>>>
> >>>> Signed-off-by: Kacper Michajłow <kasper93 at gmail.com>
> >>>> ---
> >>>>  libavformat/demux.c | 3 +--
> >>>>  1 file changed, 1 insertion(+), 2 deletions(-)
> >>>>
> >>>> diff --git a/libavformat/demux.c b/libavformat/demux.c
> >>>> index 2795863567..ecd4f40da9 100644
> >>>> --- a/libavformat/demux.c
> >>>> +++ b/libavformat/demux.c
> >>>> @@ -383,11 +383,10 @@ void avformat_close_input(AVFormatContext **ps)
> >>>>          if (ffifmt(s->iformat)->read_close)
> >>>>              ffifmt(s->iformat)->read_close(s);
> >>>>  
> >>>> +    ff_format_io_close(s, &pb);
> >>>>      avformat_free_context(s);
> >>>>  
> >>>>      *ps = NULL;
> >>>> -
> >>>> -    avio_close(pb);
> >>>>  }
> >>>>  
> >>>>  static void force_codec_ids(AVFormatContext *s, AVStream *st)
> >>>
> >>> avformat_open_input() sets AVFMT_FLAG_CUSTOM_IO when using custom IO and
> >>> avformat_close_input() checks for this and does not free the
> >>> AVFormatContext's AVIOContext in this case (but does avio_close(NULL) in
> >>> this case).
> >>> Your patch furthermore presumes that the custom IO context is compatible
> >>> with io_close2, which need not be true at all (one can use custom IO
> >>> without ever touching io_open/io_close2 pointers; I expect users that
> >>> use custom IO, but not formats that open new AVIOContexts to do so).
> >>
> >> On reading a bit further, init_input() uses io_open to open the
> >> AVIOContext in case no AVIOContext was supplied (and one is needed).
> >> This means that the AVFMT_FLAG_CUSTOM_IO flag is misleading, as it is
> >> possible to use custom IO even with this flag unset.
> > 
> >> It also means that
> >> your patch is likely correct.
> > 
> > does any reason remain against applying it ?
> > 
> 
> I don't see any.

ok, will apply it then

thx

[...]
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