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Binary package hint: python-apt
This bug report references code from python/acquire.cc and
python/generic.h. I think it applies to *all* versions of python-apt.
As far as I can tell, every single use of the CppPyObject<T> template
with a pointer type for the template parameter T results in a memory
leak. To give a concrete example, consider the use of the template in
python/acquire.cc:
pkgAcqFile *af = new pkgAcqFile(/* ... */);
CppPyObject<pkgAcqFile*> *AcqFileObj =
CppPyObject_NEW<pkgAcqFile*>(&PkgAcquireFileType);
AcqFileObj->Object = af;
The function registered to deallocate the CppPyObject<pkgAcqFile*> is
CppDealloc<>(). Here is its existing implementation:
template <class T>
void CppDealloc(PyObject *Obj)
{
GetCpp<T>(Obj).~T();
PyMem_DEL(Obj);
}
Notice that it calls the destructor for the contained object. That
works when T is a non-pointer type. However, when T is a pointer type,
the deconstructor being called is *that of the pointer, not what it
points to*. I.e. the destructor call resembles this:
typedef char* T;
T a = new char;
a.~T();
Which of course doesn't really make sense. Calling a.~T() doesn't free
the memory pointed to by a. So, when CppDealloc<>() is called with a
pointer type, you probably want this:
template <class T>
void CppDealloc(PyObject *Obj)
{
delete GetCpp<T>(Obj)
PyMem_DEL(Obj);
}
I see several ways to fix this:
1) don't use pointers with CppPyObject<>
2) add a template specialization like CppPyObject<T*> that uses delete
instead of calling the destructor directly
3) use smart pointers (std::auto_ptr, or better, boost::shared_ptr) instead
of naked pointers
The second option would be easy to implement, but what if you wanted a
CppPyObject to contain a pointer without deleting it? The first option
is too restrictive. Probably, the third option makes the most sense.
** Affects: python-apt (Ubuntu)
Importance: Undecided
Assignee: Ubuntu Foundations Team (ubuntu-foundations)
Status: New
--
Multiple memory leak in ALL versions of python-apt
https://bugs.edge.launchpad.net/bugs/370149
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