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python: Fix object deallocation.

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Handing a reference to the wrapper object created a non-trivial
circular reference that Pythons garbage collector is unable to break.
Explicitly break it by using a weak reference.

* lang/python/helpers.c (pygpgme_stash_callback_exception): Retrieve
object from weak reference.
* lang/python/pyme/core.py (Context.__del__): Free status callback.
(Context.set_passphrase_cb): Use a weak reference.
(Context.set_progress_cb): Likewise.
(Context.set_status_cb): Likewise.
(Context.op_edit): Likewise.

Signed-off-by: Justus Winter <justus@gnupg.org>
This commit is contained in:
Justus Winter 2016-05-27 12:25:59 +02:00
parent e74cd9fb80
commit ebfe2300c3
2 changed files with 29 additions and 14 deletions
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20
lang/python/helpers.c
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@ -64,9 +64,9 @@ void pygpgme_clear_generic_cb(PyObject **cb) {
/* Exception support for callbacks. */
#define EXCINFO "_callback_excinfo"
static void pygpgme_stash_callback_exception(PyObject *self)
static void pygpgme_stash_callback_exception(PyObject *weak_self)
{
PyObject *ptype, *pvalue, *ptraceback, *excinfo;
PyObject *self, *ptype, *pvalue, *ptraceback, *excinfo;
PyErr_Fetch(&ptype, &pvalue, &ptraceback);
excinfo = PyTuple_New(3);
@ -86,6 +86,22 @@ static void pygpgme_stash_callback_exception(PyObject *self)
PyTuple_SetItem(excinfo, 2, Py_None);
}
self = PyWeakref_GetObject(weak_self);
/* self only has a borrowed reference. */
if (self == Py_None) {
/* This should not happen, as even if we're called from the data
release callback triggered from the wrappers destructor, the
object is still alive and hence the weak reference still refers
to the object. However, in case this ever changes, not seeing
any exceptions is worse than having a little extra code, so
here we go. */
fprintf(stderr,
"Error occurred in callback, but the wrapper object "
"has been deallocated.\n");
PyErr_Restore(ptype, pvalue, ptraceback);
PyErr_Print();
}
else
PyObject_SetAttrString(self, EXCINFO, excinfo);
}

21
lang/python/pyme/core.py
View File

@ -16,9 +16,7 @@
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
# import generators for portability with python2.2
import weakref
from . import pygpgme
from .errors import errorcheck, GPGMEError
from . import errors
@ -149,6 +147,7 @@ class Context(GpgmeWrapper):
self._free_passcb()
self._free_progresscb()
self._free_statuscb()
if self.own and pygpgme.gpgme_release:
pygpgme.gpgme_release(self.wrapped)
@ -252,9 +251,9 @@ class Context(GpgmeWrapper):
else:
self.last_passcb = pygpgme.new_PyObject_p_p()
if hook == None:
hookdata = (self, func)
hookdata = (weakref.ref(self), func)
else:
hookdata = (self, func, hook)
hookdata = (weakref.ref(self), func, hook)
pygpgme.pygpgme_set_passphrase_cb(self.wrapped, hookdata, self.last_passcb)
def set_progress_cb(self, func, hook=None):
@ -275,9 +274,9 @@ class Context(GpgmeWrapper):
else:
self.last_progresscb = pygpgme.new_PyObject_p_p()
if hook == None:
hookdata = (self, func)
hookdata = (weakref.ref(self), func)
else:
hookdata = (self, func, hook)
hookdata = (weakref.ref(self), func, hook)
pygpgme.pygpgme_set_progress_cb(self.wrapped, hookdata, self.last_progresscb)
def set_status_cb(self, func, hook=None):
@ -297,9 +296,9 @@ class Context(GpgmeWrapper):
else:
self.last_statuscb = pygpgme.new_PyObject_p_p()
if hook == None:
hookdata = (self, func)
hookdata = (weakref.ref(self), func)
else:
hookdata = (self, func, hook)
hookdata = (weakref.ref(self), func, hook)
pygpgme.pygpgme_set_status_cb(self.wrapped, hookdata,
self.last_statuscb)
@ -333,9 +332,9 @@ class Context(GpgmeWrapper):
if key == None:
raise ValueError("op_edit: First argument cannot be None")
if fnc_value:
opaquedata = (self, func, fnc_value)
opaquedata = (weakref.ref(self), func, fnc_value)
else:
opaquedata = (self, func)
opaquedata = (weakref.ref(self), func)
result = pygpgme.gpgme_op_edit(self.wrapped, key, opaquedata, out)
if self._callback_excinfo: