x11/libxfce4menu: Fix leaked keygrabs when layout changes

As diagnosed by Jethro Nederhof, xfce-shortcuts-grabber.c attempts to update
grabbed key shortcuts when xkeyboard layout changes. Unfortunately, it had no
memory of which keycodes it has actually grabbed. Instead, it attempted to
ungrab the *new* keycode, which obviously doesn't actually ungrab those codes.

This went unnoticed for some time, probably because nothing collided with
important keys. Recently, a default PrintScreen shortcut was added to Xfce,
which for whatever reason seems to collide with Up in initial layout. When the
kbd layout changes, the shortcut ungrabs the *new* Printscreen keycode and then
re-grabs the same keycode, leaving the Up keycode grabbed.

Fix this by giving xfce-shortcuts-grabber some memory of which keycodes it has
grabbed. When it grabs a key, it remembers the keycode it grabbed in the
XfceKey object. When it ungrabs a key, it ungrabs the keycodes in the XfceKey
object, rather than those for the new keyboard layout.

PR:		244290
Reported by:	Aryeh Friedman <aryeh.friedman AT gmail.com>, many others
Approved by:	madpilot
Differential Revision:	https://reviews.freebsd.org/D24338

2 files changed, 100 insertions, 0 deletions

diff --git a/x11/libxfce4menu/Makefile b/x11/libxfce4menu/Makefile
index 0faeb81b39cc..c880d9f0a113 100644
--- a/x11/libxfce4menu/Makefile
+++ b/x11/libxfce4menu/Makefile
@@ -3,6 +3,7 @@
 
 PORTNAME=	libxfce4menu
 PORTVERSION=	4.14.1
+PORTREVISION=	1
 CATEGORIES=	x11 xfce
 MASTER_SITES=	XFCE
 DISTNAME=	libxfce4ui-${DISTVERSIONFULL}
diff --git a/x11/libxfce4menu/files/patch-libxfce4kbd-private_xfce-shortcuts-grabber.c b/x11/libxfce4menu/files/patch-libxfce4kbd-private_xfce-shortcuts-grabber.c
new file mode 100644
index 000000000000..45a0ada41560
--- /dev/null
+++ b/x11/libxfce4menu/files/patch-libxfce4kbd-private_xfce-shortcuts-grabber.c
@@ -0,0 +1,99 @@
+--- libxfce4kbd-private/xfce-shortcuts-grabber.c.orig	2020-04-08 15:05:21 UTC
++++ libxfce4kbd-private/xfce-shortcuts-grabber.c
+@@ -74,6 +74,16 @@ struct _XfceKey
+ {
+   guint keyval;
+   guint modifiers;
++  /*
++   * Cache of old keycodes grabbed by this key.  Used to ungrab the keycodes we
++   * actually grabbed.
++   *
++   * An arbitrary number of keys may generate the same keyval.  Rather than add
++   * memory allocation to this path, I just constrained the unmapping behavior
++   * to 8 identically coded keys.  It seems unlikely?  But I am no xkeyboard
++   * expert.
++   */
++  int keycodes[8];
+ };
+ 
+ 
+@@ -269,12 +279,20 @@ xfce_shortcuts_grabber_grab (XfceShortcutsGrabber *gra
+     }
+ 
+   /* Get all keys generating keyval */
+-  if (!gdk_keymap_get_entries_for_keyval (keymap,key->keyval,
++  if (grab && !gdk_keymap_get_entries_for_keyval (keymap,key->keyval,
+                                           &keys, &n_keys))
+     {
+       TRACE ("Got no keys for keyval");
+       return;
+     }
++  if (grab)
++    {
++      if (n_keys > G_N_ELEMENTS(key->keycodes))
++        TRACE ("Got %d keys for keyval but can remember only %d", n_keys,
++          (int)G_N_ELEMENTS(key->keycodes));
++    }
++  else
++    n_keys = G_N_ELEMENTS(key->keycodes);
+ 
+   if (n_keys == 0)
+     {
+@@ -290,9 +308,9 @@ xfce_shortcuts_grabber_grab (XfceShortcutsGrabber *gra
+   for (i = 0; i < n_keys; i ++)
+     {
+       /* Grab all hardware keys generating keyval */
++      if (grab)
++        TRACE ("New Keycode: %d", keys[i].keycode);
+ 
+-      TRACE ("Keycode: %d", keys[i].keycode);
+-
+       for (j = 0; j < screens; j++)
+         {
+           /* Do the grab on all screens */
+@@ -338,11 +356,14 @@ xfce_shortcuts_grabber_grab (XfceShortcutsGrabber *gra
+                           False,
+                           GrabModeAsync,
+                           GrabModeAsync);
+-              else
++              else {
++                if (key->keycodes[i] == -1)
++                  break;
+                 XUngrabKey (GDK_DISPLAY_XDISPLAY (display),
+-                            keys[i].keycode,
++                            key->keycodes[i],
+                             modifiers | mod_masks [k],
+                             root_window);
++              }
+             }
+ 
+           gdk_flush ();
+@@ -355,9 +376,18 @@ xfce_shortcuts_grabber_grab (XfceShortcutsGrabber *gra
+                 TRACE ("Failed to ungrab");
+             }
+         }
++      /* Remember the old keycode, as we need it to ungrab. */
++      if (grab && i < G_N_ELEMENTS (key->keycodes))
++        key->keycodes[i] = keys[i].keycode;
++      else if (!grab)
++        key->keycodes[i] = -1;
+     }
+ 
+-  g_free (keys);
++  if (grab) {
++    g_free (keys);
++    for (; i < G_N_ELEMENTS (key->keycodes); i++)
++      key->keycodes[i] = -1;
++  }
+ }
+ 
+ 
+@@ -514,6 +544,8 @@ xfce_shortcuts_grabber_add (XfceShortcutsGrabber *grab
+   g_return_if_fail (shortcut != NULL);
+ 
+   key = g_new0 (XfceKey, 1);
++  for (size_t i = 0; i < G_N_ELEMENTS (key->keycodes); i++)
++    key->keycodes[i] = -1;
+ 
+   gtk_accelerator_parse (shortcut, &key->keyval, &key->modifiers);
+