[PATCH] gtk: disable GTK Clipboard with a new option 'gtk_clipboard'

[Claudio Fontana]

The GTK Clipboard implementation may cause guest hangs.

Therefore implement a new configure switch --enable-gtk-clipboard,
disabled by default, as a meson option.

Regenerate the meson build options to include it.

The initialization of the clipboard is gtk.c, as well as the
compilation of gtk-clipboard.c are now conditional on this new option
to be set.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1150
Signed-off-by: Claudio Fontana <cfontana@suse.de>
---
 meson.build                   | 9 +++++++++
 meson_options.txt             | 7 +++++++
 scripts/meson-buildoptions.sh | 3 +++
 ui/gtk.c                      | 2 ++
 ui/meson.build                | 5 ++++-
 5 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/meson.build b/meson.build
index 1d448272ab..8bb96e5e8c 100644
--- a/meson.build
+++ b/meson.build
@@ -1243,6 +1243,8 @@ if nettle.found() and gmp.found()
 endif
 
 
+have_gtk_clipboard = false
+
 gtk = not_found
 gtkx11 = not_found
 vte = not_found
@@ -1258,12 +1260,18 @@ if not get_option('gtk').auto() or have_system
                         kwargs: static_kwargs)
     gtk = declare_dependency(dependencies: [gtk, gtkx11])
 
+    have_gtk_clipboard = get_option('gtk_clipboard').enabled()
+
     if not get_option('vte').auto() or have_system
       vte = dependency('vte-2.91',
                        method: 'pkg-config',
                        required: get_option('vte'),
                        kwargs: static_kwargs)
     endif
+  else
+    if get_option('gtk_clipboard').enabled()
+      error('GTK clipboard requested, but GTK not found')
+    endif
   endif
 endif
 
@@ -1842,6 +1850,7 @@ if glusterfs.found()
 endif
 config_host_data.set('CONFIG_GTK', gtk.found())
 config_host_data.set('CONFIG_VTE', vte.found())
+config_host_data.set('CONFIG_GTK_CLIPBOARD', have_gtk_clipboard)
 config_host_data.set('CONFIG_LIBATTR', have_old_libattr)
 config_host_data.set('CONFIG_LIBCAP_NG', libcap_ng.found())
 config_host_data.set('CONFIG_EBPF', libbpf.found())
diff --git a/meson_options.txt b/meson_options.txt
index 66128178bf..4b749ca549 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -219,6 +219,13 @@ option('vnc_sasl', type : 'feature', value : 'auto',
        description: 'SASL authentication for VNC server')
 option('vte', type : 'feature', value : 'auto',
        description: 'vte support for the gtk UI')
+
+# GTK Clipboard implementation is disabled by default, since it may cause hangs
+# of the guest VCPUs. See gitlab issue 1150:
+# https://gitlab.com/qemu-project/qemu/-/issues/1150
+
+option('gtk_clipboard', type: 'feature', value : 'disabled',
+       description: 'clipboard support for the gtk UI (EXPERIMENTAL, MAY 
HANG)')
 option('xkbcommon', type : 'feature', value : 'auto',
        description: 'xkbcommon support')
 option('zstd', type : 'feature', value : 'auto',
diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
index 2cb0de5601..a542853bfd 100644
--- a/scripts/meson-buildoptions.sh
+++ b/scripts/meson-buildoptions.sh
@@ -93,6 +93,7 @@ meson_options_help() {
   printf "%s\n" '  glusterfs       Glusterfs block device driver'
   printf "%s\n" '  gnutls          GNUTLS cryptography support'
   printf "%s\n" '  gtk             GTK+ user interface'
+  printf "%s\n" '  gtk-clipboard   clipboard support for the gtk UI 
(EXPERIMENTAL, MAY HANG)'
   printf "%s\n" '  guest-agent     Build QEMU Guest Agent'
   printf "%s\n" '  guest-agent-msi Build MSI package for the QEMU Guest Agent'
   printf "%s\n" '  hax             HAX acceleration support'
@@ -274,6 +275,8 @@ _meson_option_parse() {
     --disable-gprof) printf "%s" -Dgprof=false ;;
     --enable-gtk) printf "%s" -Dgtk=enabled ;;
     --disable-gtk) printf "%s" -Dgtk=disabled ;;
+    --enable-gtk-clipboard) printf "%s" -Dgtk_clipboard=enabled ;;
+    --disable-gtk-clipboard) printf "%s" -Dgtk_clipboard=disabled ;;
     --enable-guest-agent) printf "%s" -Dguest_agent=enabled ;;
     --disable-guest-agent) printf "%s" -Dguest_agent=disabled ;;
     --enable-guest-agent-msi) printf "%s" -Dguest_agent_msi=enabled ;;
diff --git a/ui/gtk.c b/ui/gtk.c
index 7ec21f7798..4817623c8f 100644
--- a/ui/gtk.c
+++ b/ui/gtk.c
@@ -2403,7 +2403,9 @@ static void gtk_display_init(DisplayState *ds, 
DisplayOptions *opts)
         opts->u.gtk.show_tabs) {
         gtk_menu_item_activate(GTK_MENU_ITEM(s->show_tabs_item));
     }
+#ifdef CONFIG_GTK_CLIPBOARD
     gd_clipboard_init(s);
+#endif /* CONFIG_GTK_CLIPBOARD */
 }
 
 static void early_gtk_display_init(DisplayOptions *opts)
diff --git a/ui/meson.build b/ui/meson.build
index ec13949776..c1b137bf33 100644
--- a/ui/meson.build
+++ b/ui/meson.build
@@ -97,7 +97,10 @@ if gtk.found()
   softmmu_ss.add(when: 'CONFIG_WIN32', if_true: files('win32-kbd-hook.c'))
 
   gtk_ss = ss.source_set()
-  gtk_ss.add(gtk, vte, pixman, files('gtk.c', 'gtk-clipboard.c'))
+  gtk_ss.add(gtk, vte, pixman, files('gtk.c'))
+  if have_gtk_clipboard
+    gtk_ss.add(files('gtk-clipboard.c'))
+  endif
   gtk_ss.add(when: x11, if_true: files('x_keymap.c'))
   gtk_ss.add(when: opengl, if_true: files('gtk-gl-area.c'))
   gtk_ss.add(when: [x11, opengl], if_true: files('gtk-egl.c'))
-- 
2.26.2