Bug#1001236: libopencv-dnn4.5 lacks stable ABI

[Steve Langasek]

Control: reassign -1 src:opencv
Control: forcemerge 998140 -1

Sorry, I see that this has already been fixed in a subsequent Debian upload
and Ubuntu is just behind.


On Mon, Dec 06, 2021 at 12:13:57PM -0800, Steve Langasek wrote:
> Package:libopencv-dnn4.5
> Version: 4.5.4+dfsg-1
> Severity: serious
> User: ubuntu-devel at lists.ubuntu.com
> Usertags: origin-ubuntu jammy
> 
> libopencv-dnn is provided as a shared library in Debian, but it evidently
> does not have a stable ABI.
> 
> This shows up in the gyoto autopkgtests, which, miserably, don't exit
> non-zero on these errors:
> 
> $ ./debian/tests/gyoto-mk-video 
> WARNING: PatternDisk: not tested for repeat_phi_>1; check your results
> Traceback (most recent call last):
>   File "<string>", line 2, in <module>
>   File "/usr/lib/python3/dist-packages/gyoto/animate.py", line 823, in main
>     mk_video(**args.__dict__)
>   File "/usr/lib/python3/dist-packages/gyoto/animate.py", line 655, in mk_video
>     video=backend(output, fps, width, height)
>   File "/usr/lib/python3/dist-packages/gyoto/animate.py", line 125, in __init__
>     import cv2
> ImportError: /usr/lib/python3/dist-packages/cv2.cpython-39-x86_64-linux-gnu.so: undefined symbol: _ZTIN2cv3dnn14dnn4_v202106085LayerE
> $
> 
> This symbol was present in opencv 4.5.3 but is not present in 4.5.4:
> 
> $ apt download libopencv-dnn4.5=4.5.3+dfsg-1ubuntu1
> Get:1 http://archive.ubuntu.com/ubuntu jammy/universe amd64 libopencv-dnn4.5 amd64 4.5.3+dfsg-1ubuntu1 [972 kB]
> Fetched 972 kB in 3s (307 kB/s)           
> $ dpkg-deb -R libopencv-dnn4.5_4.5.3+dfsg-1ubuntu1_amd64.deb dnn-4.5.3
> $ objdump -T dnn-4.5.3/usr/lib/x86_64-linux-gnu/libopencv_dnn.so.4.5|grep _ZTIN2cv3dnn14dnn4_v202106085LayerE
> 00000000002fd448 g    DO .data.rel.ro	0000000000000018  Base        _ZTIN2cv3dnn14dnn4_v202106085LayerE
> $ apt download libopencv-dnn4.5
> Get:1 http://archive.ubuntu.com/ubuntu jammy-proposed/universe amd64 libopencv-dnn4.5 amd64 4.5.4+dfsg-1ubuntu2 [1102 kB]
> Fetched 1102 kB in 2s (550 kB/s)
> $ dpkg-deb -R libopencv-dnn4.5_4.5.4+dfsg-1ubuntu2_amd64.deb dnn-4.5.4 
> $ objdump -T dnn-4.5.4/usr/lib/x86_64-linux-gnu/libopencv_dnn.so.4.5|grep _ZTIN2cv3dnn14dnn4_v202106085LayerE
> $
> 
> opencv uses no symbols files to prevent ABI skew; and from the type name
> (dnn4_v20210608) it appears this is not a stable interface.  But it is
> exported, and it is used.
> 
> This is also not a one-off symbol change.
> 
> $ diff -u <(objdump -T dnn-4.5.3/usr/lib/x86_64-linux-gnu/libopencv_dnn.so.4.5 | grep '\.text' | cut -b50- |sort) <(objdump -T dnn-4.5.4/usr/lib/x86_64-linux-gnu/libopencv_dnn.so.4.5 | grep '\.text' | cut -b50- |sort) | grep -c ^- 
> 256
> $
> 
> Since upstream doesn't ship a stable ABI here, there are basically two
> choices:
> 
>  - change the binary package name and conflict with older versions of the
>    library (libopencv-dnn4.5debian1 Conflicts: libopencv-dnn4.5)
>  - ship this as a static library only.
> 
> -- 
> Steve Langasek                   Give me a lever long enough and a Free OS
> Debian Developer                   to set it on, and I can move the world.
> Ubuntu Developer                                   https://www.debian.org/
> slangasek at ubuntu.com                                     vorlon at debian.org

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                   https://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org
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