opencv

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Hardware Address Sanitizer or HWASan is an ARM64 processor feature that simplifies detection of potential memory problems such as stack/buffer overflow, double free and so on. To use it with OpenCV, the library should be build with HWASan support enabled. In this instruction we'll describe how to build it, run tests on a device and get actual stack traces when memory error is detected.

Build OpenCV for Android:
- Clone the code from this branch: #25746 (or from 4.x branch if this PR is already merged)
- Open this instruction
- Add --hwasan and --debug flags to build_sdk.py script call
- Use NDK with version not less than 25
- Optionally you can speed up build process by commenting out all configurations except arm64-v8a in a file $YOUR_OPENCV_REPO/platforms/android/ndk-18-api-level-21.config.py
- Do first 6 steps of the instruction (before building AAR archive)
- From here on we use variable names given in the script from the instruction
Check if your Android device is ready to run tests:
- Connect the device
- Go to a directory containing ADB tool in terminal: cd $ANDROID_SDK/platform-tools
- Run ADB: ./adb devices You should see your connected device
- On Linux you may get an error telling that you do not have enough permissions. It can be fixed by:
  - adding your user to plugdev group: sudo usermod -aG plugdev $USER
  - logging out then back in
  - plugin out and then back in your Android device
Upload test application, test data and C++ STL shared library onto your device:
- ./adb push $YOUR_OPENCV_BUILD_FOLDER/o4a/bin/opencv_test_core /data/local/tmp
- ./adb push $YOUR_OPENCV_EXTRA_REPO/testdata /sdcard
- ./adb push $YOUR_OPENCV_BUILD_FOLDER/o4a/opencv_android/opencv/build/intermediates/stripped_native_libs/debug/out/lib/arm64-v8a/libc++_shared.so /data/local/tmp

Open ADB shell ./adb shell and run tests on a device:

export OPENCV_TEST_DATA_PATH=/sdcard/testdata
cd /data/local/tmp
LD_HWASAN=1 LD_PRELOAD=/data/local/tmp/libc++_shared.so ./opencv_test_core 2> out.txt

Extract logs from device: ./adb pull /data/local/tmp/out.txt $YOUR_LOGS_FILE (do not forget to set YOUR_LOGS_FILE variable)
HWAsan logs contain stack traces with return addresses expressed in hexadecimal. We’d like to get source files and line numbers instead as we expect that from typical stack trace for a debug build. To get them, we post process these logs by hwasan_symbolize script:

$ANDROID_NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/lib64/clang/14.0.6/bin/hwasan_symbolize  --symbols $YOUR_OPENCV_BUILD_FOLDER/o4a/bin/  < $YOUR_LOGS_FILE