BUG: Avoid Py_buffer memory leaks, using unique_ptr as scope guard

The original implementations of `PyBuffer::_GetImageViewFromArray`,
`PyVectorContainer::_vector_container_from_array`,
`PyVnl::_GetVnlVectorFromArray`, and `PyVnl<TElement>::_GetVnlMatrixFromArray`
might leak memory from `Py_buffer` in case of an exception.

This commit avoids such leaks by replacing the manual
`PyBuffer_Release(&pyBuffer)` calls in those member functions with scope guards.

Modules/Bridge/NumPy/include/itkPyBuffer.hxx

@@ -20,6 +20,7 @@
 
 
 #include "itkImportImageContainer.h"
+#include <memory> // For unique_ptr.
 
 namespace itk
 {
@@ -81,11 +82,12 @@ PyBuffer<TImage>::_GetImageViewFromArray(PyObject * arr, PyObject * shape, PyObj
     return nullptr;
   }
 
+  [[maybe_unused]] const std::unique_ptr<Py_buffer, decltype(&PyBuffer_Release)> bufferScopeGuard(&pyBuffer,
+                                                                                                  &PyBuffer_Release);
+
   const Py_ssize_t bufferLength = pyBuffer.len;
   void * const     buffer = pyBuffer.buf;
 
-  PyBuffer_Release(&pyBuffer);
-
   PyObject * const   shapeseq = PySequence_Fast(shape, "expected sequence");
   const unsigned int dimension = PySequence_Size(shape);
 
@@ -109,7 +111,6 @@ PyBuffer<TImage>::_GetImageViewFromArray(PyObject * arr, PyObject * shape, PyObj
   if (bufferLength < 0 || static_cast<size_t>(bufferLength) != len)
   {
     PyErr_SetString(PyExc_RuntimeError, "Size mismatch of image and Buffer.");
-    PyBuffer_Release(&pyBuffer);
     SWIG_Py_DECREF(shapeseq);
     return nullptr;
   }
@@ -150,7 +151,6 @@ PyBuffer<TImage>::_GetImageViewFromArray(PyObject * arr, PyObject * shape, PyObj
   output->SetNumberOfComponentsPerPixel(numberOfComponents);
 
   SWIG_Py_DECREF(shapeseq);
-  PyBuffer_Release(&pyBuffer);
 
   return output;
 }

Modules/Bridge/NumPy/include/itkPyVectorContainer.hxx

@@ -18,6 +18,7 @@
 #ifndef itkPyVectorContainer_hxx
 #define itkPyVectorContainer_hxx
 
+#include <memory> // For unique_ptr.
 #include <stdexcept>
 
 namespace itk
@@ -61,6 +62,9 @@ PyVectorContainer<TElementIdentifier, TElement>::_vector_container_from_array(Py
     return nullptr;
   }
 
+  [[maybe_unused]] const std::unique_ptr<Py_buffer, decltype(&PyBuffer_Release)> bufferScopeGuard(&pyBuffer,
+                                                                                                  &PyBuffer_Release);
+
   const Py_ssize_t   bufferLength = pyBuffer.len;
   const void * const buffer = pyBuffer.buf;
 
@@ -75,7 +79,6 @@ PyVectorContainer<TElementIdentifier, TElement>::_vector_container_from_array(Py
   if (bufferLength < 0 || static_cast<size_t>(bufferLength) != len)
   {
     PyErr_SetString(PyExc_RuntimeError, "Size mismatch of vector and Buffer.");
-    PyBuffer_Release(&pyBuffer);
     return nullptr;
   }
   const auto * const data = static_cast<const DataType *>(buffer);
@@ -85,7 +88,6 @@ PyVectorContainer<TElementIdentifier, TElement>::_vector_container_from_array(Py
   {
     output->SetElement(ii, data[ii]);
   }
-  PyBuffer_Release(&pyBuffer);
 
   return output;
 }

Modules/Bridge/NumPy/include/itkPyVnl.hxx

@@ -18,6 +18,7 @@
 #ifndef itkPyVnl_hxx
 #define itkPyVnl_hxx
 
+#include <memory> // For unique_ptr.
 #include <stdexcept>
 
 namespace itk
@@ -60,6 +61,9 @@ PyVnl<TElement>::_GetVnlVectorFromArray(PyObject * arr, PyObject * shape) -> con
     return VectorType();
   }
 
+  [[maybe_unused]] const std::unique_ptr<Py_buffer, decltype(&PyBuffer_Release)> bufferScopeGuard(&pyBuffer,
+                                                                                                  &PyBuffer_Release);
+
   const Py_ssize_t   bufferLength = pyBuffer.len;
   const void * const buffer = pyBuffer.buf;
 
@@ -74,12 +78,10 @@ PyVnl<TElement>::_GetVnlVectorFromArray(PyObject * arr, PyObject * shape) -> con
   if (bufferLength < 0 || static_cast<size_t>(bufferLength) != len)
   {
     PyErr_SetString(PyExc_RuntimeError, "Size mismatch of vector and Buffer.");
-    PyBuffer_Release(&pyBuffer);
     return VectorType();
   }
   const auto * const data = static_cast<const DataType *>(buffer);
   VectorType         output(data, numberOfElements);
-  PyBuffer_Release(&pyBuffer);
 
   return output;
 }
@@ -127,6 +129,9 @@ PyVnl<TElement>::_GetVnlMatrixFromArray(PyObject * arr, PyObject * shape) -> con
     return MatrixType();
   }
 
+  [[maybe_unused]] const std::unique_ptr<Py_buffer, decltype(&PyBuffer_Release)> bufferScopeGuard(&pyBuffer,
+                                                                                                  &PyBuffer_Release);
+
   const Py_ssize_t   bufferLength = pyBuffer.len;
   const void * const buffer = pyBuffer.buf;
 
@@ -145,13 +150,11 @@ PyVnl<TElement>::_GetVnlMatrixFromArray(PyObject * arr, PyObject * shape) -> con
   if (bufferLength < 0 || static_cast<size_t>(bufferLength) != len)
   {
     PyErr_SetString(PyExc_RuntimeError, "Size mismatch of matrix and Buffer.");
-    PyBuffer_Release(&pyBuffer);
     return MatrixType();
   }
 
   const auto * const data = static_cast<const DataType *>(buffer);
   MatrixType         output(data, size[0], size[1]);
-  PyBuffer_Release(&pyBuffer);
 
   return output;
 }