From b3157722535db692d54b8fe7d26d07f94d49daf3 Mon Sep 17 00:00:00 2001
From: Takao Fujiwara <tfujiwar@redhat.com>
Date: Fri, 26 Apr 2024 01:29:26 +0900
Subject: [PATCH libX11 5/7] Accept anon windows in XFilterEvent to update XIM
 state

When input focuses are switched quickly with shortcut keys in a Java
window, the focus is sometimes lost and the Window=0 is assigned in
XFilterEvent() but the XKeyEvent was forwarded by a XIM serer(IBus)
with XIM_FORWARD_EVENT -> XNextEvent() -> XFilterEvent() and the event
needs to be forwarded to the XIM XKeyEvent press and release filters
to update the XIM state with Window=0 likes _XimPendingFilter() and
_XimUnfabricateSerial().

Closes: #205, #206
Fixes: 024d229f ("ximcp: Unmark to fabricate key events with XKeyEvent serial")
Part-of: <https://gitlab.freedesktop.org/xorg/lib/libx11/-/merge_requests/246>
(cherry picked from commit 5a1e62d77b65ba148b1c6d1d22a81dc2b07e7d9e)
---
 modules/im/ximcp/imDefFlt.c | 34 ++++++++++++++++++++++++++++++----
 src/FilterEv.c              | 25 +++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/modules/im/ximcp/imDefFlt.c b/modules/im/ximcp/imDefFlt.c
index ad8a272b..76d63e88 100644
--- a/modules/im/ximcp/imDefFlt.c
+++ b/modules/im/ximcp/imDefFlt.c
@@ -138,7 +138,8 @@ _XimPendingFilter(
 static Bool
 _XimProtoKeypressFilter(
     Xic		 ic,
-    XKeyEvent	*ev)
+    XKeyEvent	*ev,
+    Window	 w)
 {
     Xim		im = (Xim)ic->core.im;
 
@@ -147,6 +148,9 @@ _XimProtoKeypressFilter(
 	_XimUnfabricateSerial(im, ev);
 	return NOTFILTERD;
     }
+    /* w=0 is used for _XimIsFabricatedSerial() only */
+    if (!w)
+	return NOTFILTERD;
 
     if (IS_NEGLECT_EVENT(ic, KeyPressMask))
 	return FILTERD;
@@ -193,13 +197,14 @@ _XimFilterKeypress(
     XEvent		*ev,
     XPointer		 client_data)
 {
-    return _XimProtoKeypressFilter((Xic)client_data, (XKeyEvent *)ev );
+    return _XimProtoKeypressFilter((Xic)client_data, (XKeyEvent *)ev, w);
 }
 
 static Bool
 _XimProtoKeyreleaseFilter(
     Xic		 ic,
-    XKeyEvent	*ev)
+    XKeyEvent	*ev,
+    Window	 w)
 {
     Xim		im = (Xim)ic->core.im;
 
@@ -208,6 +213,9 @@ _XimProtoKeyreleaseFilter(
 	_XimUnfabricateSerial(im, ev);
 	return NOTFILTERD;
     }
+    /* w=0 is used for _XimIsFabricatedSerial() only */
+    if (!w)
+	return NOTFILTERD;
 
     if (IS_NEGLECT_EVENT(ic, KeyReleaseMask))
 	return FILTERD;
@@ -254,7 +262,7 @@ _XimFilterKeyrelease(
     XEvent		*ev,
     XPointer		 client_data)
 {
-    return _XimProtoKeyreleaseFilter((Xic)client_data, (XKeyEvent *)ev);
+    return _XimProtoKeyreleaseFilter((Xic)client_data, (XKeyEvent *)ev, w);
 }
 
 static void
@@ -263,6 +271,11 @@ _XimRegisterKeyPressFilter(
 {
     if (ic->core.focus_window) {
 	if (!(ic->private.proto.registed_filter_event & KEYPRESS_MASK)) {
+	    _XRegisterFilterByType (ic->core.im->core.display,
+				    0,
+				    KeyPress, KeyPress,
+				    _XimFilterKeypress,
+				    (XPointer)ic);
 	    _XRegisterFilterByType (ic->core.im->core.display,
 				    ic->core.focus_window,
 				    KeyPress, KeyPress,
@@ -280,6 +293,11 @@ _XimRegisterKeyReleaseFilter(
 {
     if (ic->core.focus_window) {
 	if (!(ic->private.proto.registed_filter_event & KEYRELEASE_MASK)) {
+	    _XRegisterFilterByType (ic->core.im->core.display,
+				    0,
+				    KeyRelease, KeyRelease,
+				    _XimFilterKeyrelease,
+				    (XPointer)ic);
 	    _XRegisterFilterByType (ic->core.im->core.display,
 				    ic->core.focus_window,
 				    KeyRelease, KeyRelease,
@@ -301,6 +319,10 @@ _XimUnregisterKeyPressFilter(
 				ic->core.focus_window,
 				_XimFilterKeypress,
 				(XPointer)ic);
+	    _XUnregisterFilter (ic->core.im->core.display,
+				0,
+				_XimFilterKeypress,
+				(XPointer)ic);
 	    ic->private.proto.registed_filter_event &= ~KEYPRESS_MASK;
 	}
     }
@@ -317,6 +339,10 @@ _XimUnregisterKeyReleaseFilter(
 				ic->core.focus_window,
 				_XimFilterKeyrelease,
 				(XPointer)ic);
+	    _XUnregisterFilter (ic->core.im->core.display,
+				0,
+				_XimFilterKeyrelease,
+				(XPointer)ic);
 	    ic->private.proto.registed_filter_event &= ~KEYRELEASE_MASK;
 	}
     }
diff --git a/src/FilterEv.c b/src/FilterEv.c
index 0a48e548..07845bcc 100644
--- a/src/FilterEv.c
+++ b/src/FilterEv.c
@@ -100,6 +100,31 @@ XFilterEvent(
 	    }
 	}
     }
+    for (p = ev->xany.display->im_filters; p != NULL; p = p->next) {
+	/* Java sometimes calls XFilterEvent() with window=0 and ev come from
+	 * XNextEvent() when users type some keys quickly and switch multiple
+	 * input focuses in a Java window with the keys.
+	 * But XKeyEvent filters need to receive the event with window=0 for
+	 * _XimPendingFilter() and _XimUnfabricateSerial() to clear the
+	 * fowarded XKeyEvent with XIM_FORWARD_EVENT.
+	 *
+	 * The case of p->window == 0 is checkekd after all cases of p->window
+	 * != 0 are checked because all input contexts share
+	 * Display->im_filters but each input context has
+	 * Xic->private.proto.registed_filter_event for the filters
+	 * and same p->filter could be registerd to Display->im_filters twice
+	 * with different p->window.
+	 */
+	if (p->window == 0 && window == 0) {
+	    if ((mask & p->event_mask) ||
+		(ev->type >= p->start_type && ev->type <= p->end_type)) {
+		UnlockDisplay(ev->xany.display);
+		ret = (*(p->filter))(ev->xany.display, p->window, ev,
+				      p->client_data);
+		return(ret);
+	    }
+	}
+    }
     UnlockDisplay(ev->xany.display);
 #endif
     return(False);
-- 
2.47.1