From 15910e5da34a084fe01e0fd96ecf394cb1030e25 Mon Sep 17 00:00:00 2001
From: Po Lu <luangruo@yahoo.com>
Date: Sun, 20 Feb 2022 10:03:28 +0800
Subject: [PATCH] Ignore modifier keys early when handling X key press events

* src/xterm.c (handle_one_xevent): Ignore modifier keys earlier
without going through the usual key lookup.
(x_delete_terminal): Free recorded modifier map.
(x_find_modifier_meanings): Record modifier map.

* src/xterm.h (struct x_display_info): New field `modmap'.
---
 src/xterm.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/xterm.h |  3 +++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/src/xterm.c b/src/xterm.c
index 64bee110227..4c1c4312172 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -6162,7 +6162,10 @@ x_find_modifier_meanings (struct x_display_info *dpyinfo)
     dpyinfo->hyper_mod_mask &= ~dpyinfo->super_mod_mask;
 
   XFree (syms);
-  XFreeModifiermap (mods);
+
+  if (dpyinfo->modmap)
+    XFreeModifiermap (dpyinfo->modmap);
+  dpyinfo->modmap = mods;
 }
 
 /* Convert between the modifier bits X uses and the modifier bits
@@ -9893,6 +9896,7 @@ handle_one_xevent (struct x_display_info *dpyinfo,
 	  /* `xkey' will be modified, but it's not important to modify
 	     `event' itself.  */
 	  XKeyEvent xkey = event->xkey;
+	  int i;
 
 #ifdef USE_GTK
           /* Don't pass keys to GTK.  A Tab will shift focus to the
@@ -9924,6 +9928,27 @@ handle_one_xevent (struct x_display_info *dpyinfo,
           if (modifiers & dpyinfo->meta_mod_mask)
             memset (&compose_status, 0, sizeof (compose_status));
 
+#ifdef HAVE_XKB
+	  if (FRAME_DISPLAY_INFO (f)->xkb_desc)
+	    {
+	      XkbDescRec *rec = FRAME_DISPLAY_INFO (f)->xkb_desc;
+
+	      if (rec->map->modmap && rec->map->modmap[xkey.keycode])
+		goto done_keysym;
+	    }
+	  else
+#endif
+	    {
+	      if (dpyinfo->modmap)
+		{
+		  for (i = 0; i < 8 * dpyinfo->modmap->max_keypermod; i++)
+		    {
+		      if (xkey.keycode == dpyinfo->modmap->modifiermap[i])
+			  goto done_keysym;
+		    }
+		}
+	    }
+
 #ifdef HAVE_X_I18N
           if (FRAME_XIC (f))
             {
@@ -11545,6 +11570,27 @@ handle_one_xevent (struct x_display_info *dpyinfo,
 		}
 #endif
 
+#ifdef HAVE_XKB
+	      if (FRAME_DISPLAY_INFO (f)->xkb_desc)
+		{
+		  XkbDescRec *rec = FRAME_DISPLAY_INFO (f)->xkb_desc;
+
+		  if (rec->map->modmap && rec->map->modmap[xev->detail])
+		    goto done_keysym;
+		}
+	      else
+#endif
+		{
+		  if (dpyinfo->modmap)
+		    {
+		      for (i = 0; i < 8 * dpyinfo->modmap->max_keypermod; i++)
+			{
+			  if (xkey.keycode == dpyinfo->modmap->modifiermap[xev->detail])
+			    goto done_keysym;
+			}
+		    }
+		}
+
 #ifdef HAVE_XKB
 	      if (dpyinfo->xkb_desc)
 		{
@@ -16743,6 +16789,9 @@ x_delete_terminal (struct terminal *terminal)
       XCloseDisplay (dpyinfo->display);
 #endif
 #endif /* ! USE_GTK */
+
+      if (dpyinfo->modmap)
+	XFreeModifiermap (dpyinfo->modmap);
       /* Do not close the connection here because it's already closed
 	 by X(t)CloseDisplay (Bug#18403).  */
       dpyinfo->display = NULL;
diff --git a/src/xterm.h b/src/xterm.h
index f58fa0fe54d..14457b32cc2 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -526,6 +526,9 @@ struct x_display_info
   Atom Xatom_Meta, Xatom_Super, Xatom_Hyper, Xatom_ShiftLock, Xatom_Alt;
 #endif
 
+  /* Core modifier map when XKB is not present.  */
+  XModifierKeymap *modmap;
+
 #ifdef HAVE_XRANDR
   int xrandr_major_version;
   int xrandr_minor_version;
-- 
2.39.5