[patch] x11/fvwm2 and libX11 1.8.1

Hi,

I've received a report that fvwm2 is abort(2)ing under -current, since
the import of libX11 1.8.1. The backtrace associated with this report
shows that it's the same issue that I fixed in xfce4-settings
earlier.

Unfortunatly, I can't reproduce the crash with the default fvwm2
configuration on my machines so I can't confirm if the patch below is
enough to completely fix the issue. I'm still waiting for a report
from the original reporter.

(There is also a NetBSD report that's probably caused by the same
issue: https://marc.infœ?l=netbsd-current-users&m=165902977815467&w=2)

Did anyone else here stumble on fvwm2 aborting since libX11 1.8.2 was
imported (approxymatly july 25 snapshots) ? if so can you try the
patch below ?

PS: x11/fvwm3 will need a very similar change. If you see the issue
with fvwm3, please try to adapt the patch and report.

Index: Makefile
===================================================================
RCS file: /cvs/OpenBSD/ports/x11/fvwm2/Makefile,v
retrieving revision 1.73
diff -u -p -u -r1.73 Makefile
--- Makefile 29 Jul 2022 07:45:04 -0000 1.73
+++ Makefile 7 Aug 2022 13:11:02 -0000
@@ -1,7 +1,7 @@
COMMENT= multiple virtual desktop window manager

VERSION= 2.6.9
-REVISION= 1
+REVISION= 2
DISTNAME= fvwm-${VERSION}
PKGNAME= fvwm2-${VERSION}

Index: patches/patch-fvwm_events_c
===================================================================
RCS file: patches/patch-fvwm_events_c
diff -N patches/patch-fvwm_events_c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-fvwm_events_c 7 Aug 2022 13:21:18 -0000
@@ -0,0 +1,28 @@
+Fix for XCheckIfEvent() callback lock recursion
+
+Index: fvwm/events.c
+--- fvwm/events.c.orig
++++ fvwm/events.c
+@@ -258,6 +258,12 @@ static int _pred_weed_accumulate_expose(
+ return 1;
+ }
+
++static int _pred_weed_is_expose(
++ Display *display, XEvent *event, XPointer arg)
++{
++ return (event->type == Expose);
++}
++
+ static int _pred_weed_handle_expose(
+ Display *display, XEvent *event, XPointer arg)
+ {
+@@ -4542,7 +4548,8 @@ void handle_all_expose(void)
+
+ saved_event = fev_save_event();
+ FPending(dpy);
+- FWeedIfEvents(dpy, _pred_weed_handle_expose, NULL);
++ FWeedAndHandleIfEvents(dpy, _pred_weed_is_expose,
++ _pred_weed_handle_expose, NULL);
+ fev_restore_event(saved_event);
+
+ return;
Index: patches/patch-libs_FEvent_c
===================================================================
RCS file: patches/patch-libs_FEvent_c
diff -N patches/patch-libs_FEvent_c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-libs_FEvent_c 7 Aug 2022 13:21:18 -0000
@@ -0,0 +1,34 @@
+Fix for XCheckIfEvent() callback lock recursion
+
+Index: libs/FEvent.c
+--- libs/FEvent.c.orig
++++ libs/FEvent.c
+@@ -532,6 +532,28 @@ int FWeedIfEvents(
+ return weed_args.count;
+ }
+
++int FWeedAndHandleIfEvents(
++ Display *display,
++ int (*weed_predicate) (Display *display, XEvent *event, XPointer arg),
++ int (*handler) (Display *display, XEvent *event, XPointer arg),
++ XPointer arg)
++{
++ _fev_weed_args weed_args;
++ XEvent e;
++
++ assert(fev_is_invalid_event_type_set);
++ memset(&weed_args, 0, sizeof(weed_args));
++ weed_args.weed_predicate = weed_predicate;
++ weed_args.arg = arg;
++ if (FCheckPeekIfEvent(display, &e, _fev_pred_weed_if,
++ (XPointer)&weed_args)) {
++ handler(display, &e, arg);
++ }
++ _fev_pred_weed_if_finish(&weed_args);
++
++ return weed_args.count;
++}
++
+ int FWeedIfWindowEvents(
+ Display *display, Window window,
+ int (*weed_predicate) (
Index: patches/patch-libs_FEvent_h
===================================================================
RCS file: patches/patch-libs_FEvent_h
diff -N patches/patch-libs_FEvent_h
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-libs_FEvent_h 7 Aug 2022 13:11:02 -0000
@@ -0,0 +1,20 @@
+Fix for XCheckIfEvent() callback lock recursion
+
+Index: libs/FEvent.h
+--- libs/FEvent.h.orig
++++ libs/FEvent.h
+@@ -113,6 +113,14 @@ int FWeedIfEvents(
+ Display *display, XEvent *current_event, XPointer arg),
+ XPointer arg);
+
++/* Same as FWeedIfEvents but with a second callback out of XLockDisplay()
++ * to handle events in a lock-safe manner */
++int FWeedAndHandleIfEvents(
++ Display *display,
++ int (*weed_predicate) (Display *display, XEvent *event, XPointer arg),
++ int (*handler) (Display *display, XEvent *event, XPointer arg),
++ XPointer arg);
++
+ /* Same as FWeedIfEvents but weeds only events for the given window. The
+ * weed_predicate is only called for events with a matching window. */
+ int FWeedIfWindowEvents(

--
Matthieu Herrb