On 4/24/2021 9:53 AM, Andreas Rheinhardt wrote:
James Almer:
On 4/24/2021 9:29 AM, Andreas Rheinhardt wrote:
Despite the documentation saying that it is not freed by libavcodec
for a decoder, avcodec_free_context() does so and has been doing so
since this function has been added more than seven years ago.
Honouring the current documentation in avcodec_free_context() would
add memleaks to all users of it that don't free their extradata
manually; given how long this behaviour has been around we can safely
assume that these are many (i.e. the fftools are among them, as is
libavformat as well as parts of libavcodec itself).
Therefore adapt the documentation to match actual behaviour.
This fixes ticket #5027.
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com>
---
libavcodec/avcodec.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index b9b487be41..4596d12647 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -633,6 +633,8 @@ typedef struct AVCodecContext {
* Must be allocated with the av_malloc() family of functions.
* - encoding: Set/allocated/freed by libavcodec.
* - decoding: Set/allocated/freed by user.
+ * Additionally, avcodec_free_context() frees it regardless of
whether
+ * the context is used for encoding or not.
I'd prefer to instead change the decoding line to
* - decoding: Set/allocated by user, freed by libavcodec.
This would be wrong as avcodec_close() does not free it for decoders.
Changing the behaviour would be a breaking change.
avcodec_free_context() needs to be called to free any AVCodecContext.
doing avcodec_close(avctx) + av_free(avctx) (Or worse, reusing the avctx
after avcodec_close()) is not only heavily discouraged by the doxy, but
already leads to leaks if you don't free a bunch of things, like
extradata, intra_matrix and inter_matrix.
Maybe also (or instead) change the
* Must be allocated with the av_malloc() family of functions.
line with
* Must be allocated with the av_malloc() family of functions, and will
be freed in avcodec_free_context().
Which puts the extradata doxy in line with the other two fields, both of
which are handled in a similar way.
Leaving the line about freed by user is IMO pointless, considering you
even mentioned in the patch message how nobody ever bothers to free it.
Honestly? avcodec_close() should have been deprecated alongside
avcodec_get_context_defaults3() and avcodec_copy_context(), so maybe we
should do it now. Having a function with its doxy saying "Do not use
this function" is pretty silly.
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