fix find zlib.so instead of zlib.a when NDK >= 19#19522
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alalek merged 2 commits intoopencv:3.4from Feb 14, 2021
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On Android platform, `libopencv_imgcodecs.a` is built, expected to depend on `libz.so`. However, since Android NDK r19, NDK's `libz.a` is found instead of `libz.so`, leading to link error (not found libz.a) on machines without same NDK version & direcotry. Since Android NDK-r19, toolchain pieces are installed to `$NDK/toolchains/llvm/prebuilt/<host-tag>/...`, including `libz.so`. Also installed to old paths (`<NDK>/platforms` and `<NDK>/sysroot`) in NDK r19, r20, r21, but since NDK 22, old paths are removed. - https://github.com/android/ndk/wiki/Changelog-r19 - https://github.com/android/ndk/wiki/Changelog-r22 With this commit, `libz.so` can be correctly found in NDK<19 and NDK>=19. `ZLIB_LIBRARIES` is also simplified as `z`, by appending match (regex) patterns for new toolchain installation directory's libz.so's paths.
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Note: this commit tested locally, with cmake 3.19.4, without modification of |
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Note: this PR should only affect android platform. Android arm64 platform may fail, #19521 fix that failure and should be merged first. |
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alalek
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Feb 13, 2021
cmake/OpenCVFindLibsGrfmt.cmake
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| if(ZLIB_LIBRARIES MATCHES "/usr/(lib|lib32|lib64)/libz.so$") | ||
| if(ZLIB_LIBRARIES MATCHES "/usr/(lib|lib32|lib64)/libz.so$" | ||
| OR ZLIB_LIBRARIES MATCHES "/usr/lib/(aarch64-linux-android|x86_64-linux-android)/(2[1-9]|3[0-9])/libz.so" | ||
| OR ZLIB_LIBRARIES MATCHES "/usr/lib/(arm-linux-androideabi|i686-linux-android)/(1[6-9]|(2|3)[0-9])/libz.so" |
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I believe we can use here generic pattern here:
"/usr/lib.*/libz.so$"
and add two control variables:
if((OPENCV_FORCE_ANDROID_ZLIB_Z
OR ZLIB_LIBRARIES MATCHES "/usr/lib.*/libz.so")
AND NOT OPENCV_SKIP_ANDROID_ZLIB_Z
)
set(ZLIB_LIBRARIES z)
endif()
(checked locally with NDK 18, 20, 21)
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The mentioned generic pattern is simple. It's OK to use that.
For the mentioned two control variables, on android platform:
- I think there are only two origins for zlib: build from source(libz.a), or use NDK diretories(libz.so), thus :
OPENCV_FORCE_ANDROID_ZLIB_Z: is same asNOT BUILD_ZLIBOPENCV_SKIP_ANDROID_ZLIB_Z: is same asBUILD_ZLIB
So I would like to use:
if(ZLIB_LIBRARIES MATCHES "/usr/lib.*/libz.so$")
set(ZLIB_LIBRARIES z)
endif()
alalek
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Feb 14, 2021
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On Android platform,
libopencv_imgcodecs.ais built, expected todepend on
libz.so. However, since Android NDK r19, NDK'slibz.ais found instead of
libz.so, leading to link error(not found libz.a) on machines without same NDK version & direcotry.
Since Android NDK-r19, toolchain pieces are installed to
$NDK/toolchains/llvm/prebuilt/<host-tag>/..., includinglibz.so.Also installed to old paths (
<NDK>/platformsand<NDK>/sysroot)in NDK r19, r20, r21, but since NDK 22, old paths are removed.
With this commit,
libz.socan be correctly found in NDK<19 and NDK>=19.ZLIB_LIBRARIESis also simplified asz, by appending match (regex)patterns for new toolchain installation directory's libz.so's paths.
Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
Patch to opencv_extra has the same branch name.