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| author | Michael Niedermayer <michael@niedermayer.cc> | 2016-04-07 17:26:56 +0200 |
|---|---|---|
| committer | Michael Niedermayer <michael@niedermayer.cc> | 2016-08-13 13:08:57 +0200 |
| commit | 811d560378f34f9bca5d7bf1216e5e9bb650927a (patch) | |
| tree | 8c10410853484cd00c18b5d5b3b3b8c3ccde7c2e | |
| parent | c34f0616d9c7c2e903a026182cf4630c75cdeee8 (diff) | |
| download | ffmpeg-811d560378f34f9bca5d7bf1216e5e9bb650927a.tar.gz | |
avformat/format: Fix registering a format more than once and related races
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 4cc896ea5f06f8b1ebcde6d876d9c5b59ef9a016)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
| -rw-r--r-- | libavformat/format.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/libavformat/format.c b/libavformat/format.c index 15fe167fb2..f0abb5deeb 100644 --- a/libavformat/format.c +++ b/libavformat/format.c @@ -62,20 +62,24 @@ void av_register_input_format(AVInputFormat *format) { AVInputFormat **p = last_iformat; - format->next = NULL; - while(*p || avpriv_atomic_ptr_cas((void * volatile *)p, NULL, format)) + // Note, format could be added after the first 2 checks but that implies that *p is no longer NULL + while(p != &format->next && !format->next && avpriv_atomic_ptr_cas((void * volatile *)p, NULL, format)) p = &(*p)->next; - last_iformat = &format->next; + + if (!format->next) + last_iformat = &format->next; } void av_register_output_format(AVOutputFormat *format) { AVOutputFormat **p = last_oformat; - format->next = NULL; - while(*p || avpriv_atomic_ptr_cas((void * volatile *)p, NULL, format)) + // Note, format could be added after the first 2 checks but that implies that *p is no longer NULL + while(p != &format->next && !format->next && avpriv_atomic_ptr_cas((void * volatile *)p, NULL, format)) p = &(*p)->next; - last_oformat = &format->next; + + if (!format->next) + last_oformat = &format->next; } int av_match_ext(const char *filename, const char *extensions) |