If the library extension thinks there's more events to an extension than the
server actually has, the event_vec for the overlapping range can get
overwritten. This depends on the initialization order of the libraries.
Reported-by: Nathan Kidd
Signed-off-by: Peter Hutterer peter.hutte...@who-t.net
---
Changes to previous version:
- whitespaces fixed
- loop now removes all excessive extension handlers (as Julien suggested)
src/extutil.c | 47 ++-
1 files changed, 46 insertions(+), 1 deletions(-)
diff --git a/src/extutil.c b/src/extutil.c
index ac861ea..800971b 100644
--- a/src/extutil.c
+++ b/src/extutil.c
@@ -103,6 +103,7 @@ XExtDisplayInfo *XextAddDisplay (
int nevents,
XPointer data)
{
+static unsigned char ext_handlers[64] = {0};
XExtDisplayInfo *dpyinfo;
dpyinfo = (XExtDisplayInfo *) Xmalloc (sizeof (XExtDisplayInfo));
@@ -117,10 +118,54 @@ XExtDisplayInfo *XextAddDisplay (
*/
if (dpyinfo-codes) {
int i, j;
+ int idx = dpyinfo-codes-first_event 0x3f;
+
+
+ /* Xlib extensions use compiled in event numbers. A new library
+* against an older server may thus expect a different (higher)
+* number of events than the server will send. We have no way of
+* knowing the number of events for an extension, the server won't
+* tell us.
+*
+* Depending on the extension initialization order, this smashes the
+* event_vec[type] for anything after the extension with the
+* different number of events.
+*
+* e.g. server with inputproto 1.3 expects 15 events, libXi with
+* inputproto 2.0 expects 17 events.
+* base code is 80, events [80,96] are handled by libXi. events [95,
+* 96] belong to the next extension already though.
+* This requires XI to be initialized after the extension occupying
+* the next range of event codes.
+*
+* To avoid this, we have a zeroed out array of extension handlers.
+* If an extension handler for an event type is already set, and the
+* previous event code (before base_code) is the same extension, we
+* have the nevents conflict. Unset all those handlers and allow
+* overwriting them with the new handlers.
+*
+* If a handler for a (base + n) event is already set, stop
+* registering this extension for the event codes.
+*
+* event_codes are subtracted by 64 since we don't need to worry
+* about core.
+*/
+
+ if (idx ext_handlers[idx - 1] == ext_handlers[idx]) {
+ for (i = idx; i 64; i++) {
+ if (ext_handlers[idx - 1] == ext_handlers[i])
+ ext_handlers[i] = 0;
+ else
+ break;
+ }
+ }
- for (i = 0, j = dpyinfo-codes-first_event; i nevents; i++, j++) {
+ for (i = 0, j = dpyinfo-codes-first_event; i nevents; i++, j++,
idx++) {
+ if (ext_handlers[idx]) /* don't smash the following extension */
+ break;
XESetWireToEvent (dpy, j, hooks-wire_to_event);
XESetEventToWire (dpy, j, hooks-event_to_wire);
+ ext_handlers[idx] = dpyinfo-codes-first_event 0x3f;
}
/* register extension for XGE */
--
1.6.5.2
___
xorg mailing list
xorg@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/xorg
