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Make gdk_event_apply_filters safe against changes in filter list

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An event filter may add or remove filters itself.  This patch does
two things to address this case.  The first is to take a temporary
reference to the filter while it is being used.  The second is
to wait until after the filter function is run before determining
the next node in the list to process.  This guards against
changes to the next node.  It also does not run functions
that have been marked as removed.  Though I'm not sure if this
case can arise.

https://bugzilla.gnome.org/show_bug.cgi?id=635380
This commit is contained in:
William Jon McCann
2010-11-20 17:58:50 -05:00
parent abe20a7c97
commit 323df2b280
5 changed files with 96 additions and 18 deletions
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33
gdk/win32/gdkevents-win32.c
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@ -1025,7 +1025,7 @@ fill_key_event_string (GdkEvent *event)
static GdkFilterReturn
apply_event_filters (GdkWindow *window,
MSG *msg,
GList *filters)
GList **filters)
{
GdkFilterReturn result = GDK_FILTER_CONTINUE;
GdkEvent *event;
@ -1043,13 +1043,34 @@ apply_event_filters (GdkWindow *window,
*/
node = _gdk_event_queue_append (_gdk_display, event);
tmp_list = filters;
tmp_list = *filters;
while (tmp_list)
{
GdkEventFilter *filter = (GdkEventFilter *) tmp_list->data;
tmp_list = tmp_list->next;
GList *node;
if ((filter->flags & GDK_EVENT_FILTER_REMOVED) != 0)
{
tmp_list = tmp_list->next;
continue;
}
filter->ref_count++;
result = filter->function (msg, event, filter->data);
/* get the next node after running the function since the
function may add or remove a next node */
node = tmp_list;
tmp_list = tmp_list->next;
filter->ref_count--;
if (filter->ref_count == 0)
{
*filters = g_list_remove_link (*filters, node);
g_list_free_1 (node);
g_free (filter);
}
if (result != GDK_FILTER_CONTINUE)
break;
}
@ -1756,7 +1777,7 @@ gdk_event_translate (MSG *msg,
{
/* Apply global filters */
GdkFilterReturn result = apply_event_filters (NULL, msg, _gdk_default_filters);
GdkFilterReturn result = apply_event_filters (NULL, msg, &_gdk_default_filters);
/* If result is GDK_FILTER_CONTINUE, we continue as if nothing
* happened. If it is GDK_FILTER_REMOVE or GDK_FILTER_TRANSLATE,
@ -1822,7 +1843,7 @@ gdk_event_translate (MSG *msg,
{
/* Apply per-window filters */
GdkFilterReturn result = apply_event_filters (window, msg, ((GdkWindowObject *) window)->filters);
GdkFilterReturn result = apply_event_filters (window, msg, &((GdkWindowObject *) window)->filters);
if (result == GDK_FILTER_REMOVE || result == GDK_FILTER_TRANSLATE)
{