Fix tempfile race condition on Windows (issue #19648) #28087
Fix tempfile race condition on Windows
Addresses issue #19648
Problem
The cv::tempfile() function on Windows used GetTempFileNameA() followed by an immediate DeleteFileA() call. This created a race condition where multiple OpenCV processes running simultaneously could receive the same temporary filename, leading to name collisions.
Root Cause
The previous implementation:
Called GetTempFileNameA() to generate a temp filename
Immediately deleted the file to free the name
Returned just the filename string
Between steps 2 and 3, another process could call GetTempFileNameA() and receive the same filename, causing a collision.
Solution
Replaced GetTempFileNameA() with GUID-based filename generation using CoCreateGuid(), following the same approach already used in GetTempFileNameWinRT() and Microsoft's recommendations for scenarios requiring many temp files.
Changes
modules/core/src/system.cpp:
Removed GetTempFileNameA() and DeleteFileA() calls
Added CoCreateGuid() to generate unique GUID-based filenames
Format: "ocv{GUID}" where GUID ensures uniqueness across processes
Benefits
Eliminates race condition in multi-process scenarios
No file I/O overhead from creating and deleting placeholder files
Consistent with WinRT implementation approach
Follows Microsoft best practices
Testing
Standard OpenCV test suite. The change only affects Windows temp file naming and maintains the same String return type and usage pattern.
make cuda::GpuMatND compatible with InputArray/OutputArray #23913
continuation of [PR#19259](https://github.com/opencv/opencv/pull/19259)
Make cuda::GpuMatND wrappable in InputArray/OutputArray
The goal for now is just wrapping, some functions are not supported (InputArray::size(), InputArray::convertTo(), InputArray::assign()...)
No new feature for cuda::GpuMatND
- [X] I agree to contribute to the project under Apache 2 License.
- [X] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
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Patch to opencv_extra has the same branch name.
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core: add copyAt() for ROI operation #27318
Close https://github.com/opencv/opencv/issues/27320
Close https://github.com/opencv/opencv/issues/27298
### Pull Request Readiness Checklist
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Fix missing vec_cvfo on IBM POWER9 due to unavailable VSX float64 conversion #27990
Replaces https://github.com/opencv/opencv/pull/27633
Closes https://github.com/opencv/opencv/issues/27635
### Pull Request Readiness Checklist
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Force empty output type where it's defined in API #27972
The PR replaces:
- https://github.com/opencv/opencv/pull/27936
- https://github.com/opencv/opencv/pull/21059
Empty matrix has undefined type, so user code should not relay on the output type, if it's empty. The PR introduces some exceptions:
- copyTo documentation defines, that the method re-create output buffer and set it's type.
- convertTo has output type as parameter and output type is defined and expected.
Clarified supported types in cv::patchNaNs() documentation #27959
### Pull Request Readiness Checklist
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Updated the docs for cv::patchNaNs() to specify that both CV_32F and CV_64F types are supported. Fixes incomplete information.
core: support 16 bit LUT #27890
Close https://github.com/opencv/opencv/issues/26899
### Pull Request Readiness Checklist
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core: ARM64 loop unrolling in kmeans to improve Weighted Filter performance #27596
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- This PR improves the performance of the Weighted Filter function from the ximgproc module on Windows on ARM64.
- The optimization is achieved by unrolling two performance-critical loops in the generateCentersPP function in modules/core/src/kmeans.cpp, which is internally used by the Weighted Filter function.
- The unrolling is enabled only for ARM64 builds using #if defined(_M_ARM64) guards to preserve compatibility and maintain performance on other architectures.
**Performance Improvements:**
- Improves execution time for Weighted Filter performance tests on ARM64 without affecting other platforms.
<img width="772" height="558" alt="image" src="https://github.com/user-attachments/assets/ae28c0af-97d3-460b-ad5a-207d3fc6936f" />
- Added vector_vector_Mat to gen_dict.json
- Implemented Mat_to_vector_vector_Mat and vector_vector_Mat_to_Mat conversion functions in converters.h/cpp and Converters.java
- Added DnnForwardAndRetrieve.java test to verify List<List<Mat>> conversion : Reference: C++ test in modules/dnn/test/test_misc.cpp - TEST(Net, forwardAndRetrieve)
Enable Java wrapper generation for Vec4i #27567
Fixes an issue where Java wrapper generation skips methods using Vec4i.
Related PR in opencv_contrib: https://github.com/opencv/opencv_contrib/pull/3988
The root cause was the absence of Vec4i in gen_java.json, which led to important methods such as aruco.drawCharucoDiamond() and ximgproc.HoughPoint2Line() being omitted from the Java bindings.
This PR includes the following changes:
- Added Vec4i definition to gen_java.json
- Updated gen_java.py to handle jintArray-based types properly
- ~~Also adjusted jn_args and jni_var for Vec2d and Vec3d to ensure correct JNI behavior~~
The modified Java wrapper generator successfully builds and includes the expected methods using Vec4i.
### Pull Request Readiness Checklist
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### Pull Request Readiness Checklist
resolves#16295
```
docker run --gpus 0 -v ~/opencv:/opencv -v ~/opencv_contrib:/opencv_contrib -it nvidia/cuda:12.8.1-cudnn-devel-ubuntu22.04
apt-get update && apt-get install -y cmake python3-dev python3-pip python3-venv &&
python3 -m venv .venv &&
source .venv/bin/activate &&
pip install -U pip &&
pip install -U numpy &&
pip install torch --index-url https://download.pytorch.org/whl/cu128 &&
cmake \
-DWITH_OPENCL=OFF \
-DCMAKE_BUILD_TYPE=Release \
-DBUILD_DOCS=OFF \
-DWITH_CUDA=ON \
-DOPENCV_DNN_CUDA=ON \
-DOPENCV_EXTRA_MODULES_PATH=/opencv_contrib/modules \
-DBUILD_LIST=ts,cudev,python3 \
-S /opencv -B /opencv_build &&
cmake --build /opencv_build -j16
export PYTHONPATH=/opencv_build/lib/python3/:$PYTHONPATH
```
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
- [x] I agree to contribute to the project under Apache 2 License.
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Patch to opencv_extra has the same branch name.
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Cuda 13.0 compatibility #27636
### Pull Request Readiness Checklist
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### Issue
CUDA 13 deprecated some fields, resulting in build failures with CUDA 13. This updates to use the replacement API.
The reference to the deprecated features is here: https://docs.nvidia.com/cuda/cuda-toolkit-release-notes/index.html#id6
### Testing
This was testing by building on the following configurations:
OS: Ubuntu 24.04
CUDA: 12.9, 13.0
core: support parsing back slash \ in parseKey in FileStorage (JSON) #27587Fixes#27585
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core: support parsing null in json parser in FileStorage #27579
Fixes https://github.com/opencv/opencv/issues/27578
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cuda: Fix GpuMat::convertTo issues described in 27373 #27379
Fix https://github.com/opencv/opencv/issues/27373.
1. `GpuMat::convertTo` uses `convertToScale` due to incorrect overload.
2. There are no runtime checks to prevent the use of `CV_16U` data types in Release builds.
### Pull Request Readiness Checklist
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Close https://github.com/opencv/opencv/issues/27413
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