ff_aac_coder_init_mips() modifies a static const structure of
function pointers. This will crash if the binary uses relro
and is a data race in any case.
Furthermore it points to a maintainability issue: The
AACCoefficientsEncoder structures have been constified
in commit fd9212f2edfe9b107c3c08ba2df5fd2cba5ab9e3,
a Libav commit merged in 318778de9ebec276cb9dfc65509231ca56590d13.
Libav did not have the MIPS-specific AAC code and so this was
fine for them; yet FFmpeg had them, but this was not recognized.
Commit 75a099fc734a4ee2b1347d0a3d8c53d883b95174 points to another
maintainability issue: Contrary to ordinary DSP code, this code
here is way more complex and needs to be constantly kept in sync
with the ordinary code which it mimicks and replaces. Said commit
is the only commit actually changing aaccoder.c in the last few
years and the same change has not been performed for the MIPS
clone; before that, it even happened several times that the mips
code was broken due to changes of the generic code (see commits
97437bd17a8c5d4135b2f3b1b299bd7bb72ce02c and
de262d018d7d7d9c967af1dfd1b861c4b9eb2a60 or
860dbe0275e57cbf4228f3f653f872ff66ca596b or
933309a6ca0f18bf1d40e917fff455221f57fb4b or
b65ffa316e377213c29736929beba584d0d80d7c). This might even lead
to scenarios where someone changing non-dsp aacenc code would
have to modify mips inline asm in order to keep them in sync.
This is obviously a significant burden (if the AAC encoder were
actively developed).
Finally, the code does not even compile here due to errors like
"Error: float register should be even, was 1".
Reviewed-by: Lynne <dev@lynne.ee>
Reviewed-by: Jean-Baptiste Kempf <jb@videolan.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Andreas Rheinhardt