Memory leak in surflock.c

[illume]

Originally reported by: René Dudfield (Bitbucket: illume, GitHub: illume)

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== , 2009-04-14 12:31:07 -0700

This issue is in the surflock.c, not surface.c. I diagnosed it in 1.8.1, but a quick look at subversion shows that the relevant code has not changed.

The PySurface_LockBy function is leaking a weakref.ref each time a surface is locked. The weak reference is created on line 82 of surflock.c, and then is appended to the list on line 90. PyList_Append does not steal the reference, and so the reference count remains incremented even when PySurface_LockBy returns, causing a memory leak.

The solution is to add Py_DECREF(ref) as line 91 of surflock.c, making the function read:

static int
PySurface_LockBy (PyObject* surfobj, PyObject* lockobj)
{
    PyObject *ref;
    PySurfaceObject* surf = (PySurfaceObject*) surfobj;

    if (!surf->locklist)
    {
        surf->locklist = PyList_New (0);
        if (!surf->locklist)
            return 0;
    }
    ref = PyWeakref_NewRef (lockobj, NULL);
    if (!ref)
        return 0;
    if (ref == Py_None)
    {
        Py_DECREF (ref);
        return 0;
    }
    PyList_Append (surf->locklist, ref);
    Py_DECREF(ref);
    
    if (surf->subsurface)
        PySurface_Prep (surfobj);
    if (SDL_LockSurface (surf->surf) == -1)
    {
        PyErr_SetString (PyExc_RuntimeError, "error locking surface");
        return 0;
    }
    return 1;
}

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== illume, 2009-05-26 01:55:25 -0700

Thanks Tom!

Committed revision 2259.

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• Bitbucket: https://bitbucket.org/pygame/pygame/issue/30

[illume]

Original comment by Thomas Kluyver (Bitbucket: takluyver, GitHub: takluyver):

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Removing version: unspecified (automated comment)