Saxon » SaxonC

In the C++ code to avoid the dangling pointer issue we introduced some new logic to relinquish items from the XdmValue to the caller once they have been accessed. If we do not assign to a variable the calls to methods such as getHead() PHP may call the GC therefore calling the getHead() method again will cause a segmentation fault because the XdmItem object has been deleted.

The workaroun is to assign the above example to a variable:

        $head1 =  $result->getHead();
        if ($head1 != NULL) {
            $this->assertStringContainsString("[]", $head1->getStringValue());
        }

It is possible this affects Python too.

Confirmed that this issue affect python. I have pushed a similar fix in the Python code. Fix available in the maintenance release.

Added some pytest tests.

Discovered similar problem when creating a PyXdmValue from items:

from saxoncee import *

saxonproc = PySaxonProcessor(license=True)

xdm_value = PyXdmValue()

xdm_value.add_xdm_item(saxonproc.make_string_value('foo'))

print(xdm_value)
xdm_value.add_xdm_item(saxonproc.make_string_value('bar'))

print(xdm_value)

This issue has been resolved. The next problem is when we assign the created PyXdmAtomicValue to a variable before we add it to PyXdmValue the ref count does not go to zero and therefore does not get garbage collected:

xdm_value = PyXdmValue()

item1 = saxonproc.make_string_value('foo')
xdm_value.add_xdm_item(item1)


print(xdm_value)

Bug now fixed.

Bug fix applied in the Saxon 12.5 Maintenance release.