fix: handle X11 connection loss gracefully

Use XSetIOErrorExitHandler on X11 to detect connection loss and
disable GTK features (tray, clipboard, notifications).

Signed-off-by: Michael Vetter <jubalh@iodoru.org>
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Co-authored-by: Paul Fertser <fercerpav@gmail.com>

meson.build

@@ -188,9 +188,18 @@ if get_option('notifications').enabled()
 endif
 
 # GTK (for icons and clipboard)
+x11_extra_dep = []
 if get_option('icons-and-clipboard').enabled()
   gtk_dep = dependency('gtk+-3.0', version: '>= 3.24.0', required: true)
   conf_data.set('HAVE_GTK', 1)
+
+  x11_dep = dependency('x11', required: false)
+  if x11_dep.found()
+    if cc.has_function('XSetIOErrorExitHandler', dependencies: x11_dep)
+      conf_data.set('HAVE_XEXITHANDLER', 1)
+      x11_extra_dep = [x11_dep]
+    endif
+  endif
 endif
 
 # XScreenSaver
@@ -330,6 +339,10 @@ if xscrnsaver_dep.length() > 0
   profanity_deps += xscrnsaver_dep
 endif
 
+if x11_extra_dep.length() > 0
+  profanity_deps += x11_extra_dep
+endif
+
 if python_dep.found()
   profanity_deps += python_dep
 endif

src/command/cmd_funcs.c

@@ -6477,6 +6477,10 @@ gboolean
 cmd_tray(ProfWin* window, const char* const command, gchar** args)
 {
 #ifdef HAVE_GTK
+    if (!tray_gtk_ready()) {
+        log_warning("GTK is not ready. Tray functionality is disabled.");
+        return TRUE;
+    }
     if (g_strcmp0(args[0], "timer") == 0) {
         if (args[1] == NULL) {
             cons_bad_cmd_usage(command);
@@ -8975,6 +8979,10 @@ gboolean
 cmd_paste(ProfWin* window, const char* const command, gchar** args)
 {
 #ifdef HAVE_GTK
+    if (!tray_gtk_ready()) {
+        log_warning("GTK is not ready. Paste from clipboard is disabled.");
+        return TRUE;
+    }
     auto_char char* clipboard_buffer = clipboard_get();
 
     if (clipboard_buffer) {

src/tools/clipboard.c

@@ -15,6 +15,7 @@
 #include <stdlib.h>
 
 #include "log.h"
+#include "ui/tray.h"
 
 /*
 For now we rely on tray_init(void)
@@ -27,6 +28,9 @@ void clipboard_init(int argc, char **argv) {
 char*
 clipboard_get(void)
 {
+    if (!tray_gtk_ready()) {
+        return NULL;
+    }
     gchar* clip;
 
     GtkClipboard* cl = gtk_clipboard_get(GDK_SELECTION_CLIPBOARD);

src/ui/notifier.c

@@ -26,6 +26,9 @@
 #include "config/preferences.h"
 #include "ui/ui.h"
 #include "ui/window_list.h"
+#ifdef HAVE_GTK
+#include "ui/tray.h"
+#endif
 #include "xmpp/xmpp.h"
 #include "xmpp/muc.h"
 
@@ -54,6 +57,11 @@ _notifier_uninit(void)
 static void
 _notify(const char* const message, int timeout, const char* const category)
 {
+#ifdef HAVE_GTK
+    if (!tray_gtk_ready()) {
+        return;
+    }
+#endif
     log_debug("Attempting notification: %s", message);
     if (notify_is_initted()) {
         log_debug("Reinitialising libnotify");

src/ui/tray.c

@@ -21,6 +21,11 @@
 #include "ui/tray.h"
 #include "ui/window_list.h"
 
+#if defined(GDK_WINDOWING_X11) && defined(HAVE_XEXITHANDLER)
+#include <gdk/gdkx.h>
+#include <X11/Xlib.h>
+#endif
+
 static gboolean gtk_ready = FALSE;
 static GtkStatusIcon* prof_tray = NULL;
 static GString* icon_filename = NULL;
@@ -29,6 +34,21 @@ static gint unread_messages;
 static gboolean shutting_down;
 static guint timer;
 
+#if defined(GDK_WINDOWING_X11) && defined(HAVE_XEXITHANDLER)
+static void
+_x_io_error_handler(Display* display, void* user_data)
+{
+    log_warning("Error: X Server connection lost.");
+    gtk_ready = FALSE;
+}
+
+static int
+_x_io_handler(Display* display)
+{
+    return 0;
+}
+#endif
+
 /*
  * Get icons from installation share folder or (if defined) .locale user's folder
  *
@@ -98,7 +118,7 @@ _get_icons(void)
 gboolean
 _tray_change_icon(gpointer data)
 {
-    if (shutting_down) {
+    if (shutting_down || !gtk_ready) {
         return FALSE;
     }
 
@@ -151,6 +171,14 @@ tray_init(void)
         return;
     }
 
+#if defined(GDK_WINDOWING_X11) && defined(HAVE_XEXITHANDLER)
+    GdkDisplay* display = gdk_display_get_default();
+    if (GDK_IS_X11_DISPLAY(display)) {
+        XSetIOErrorExitHandler(GDK_DISPLAY_XDISPLAY(display), _x_io_error_handler, NULL);
+        XSetIOErrorHandler(_x_io_handler);
+    }
+#endif
+
     if (prefs_get_boolean(PREF_TRAY)) {
         log_debug("Building GTK icon");
         tray_enable();
@@ -167,9 +195,18 @@ tray_update(void)
     }
 }
 
+gboolean
+tray_gtk_ready(void)
+{
+    return gtk_ready;
+}
+
 void
 tray_set_timer(int interval)
 {
+    if (!gtk_ready) {
+        return;
+    }
     if (timer) {
         g_source_remove(timer);
     }
@@ -186,6 +223,9 @@ tray_set_timer(int interval)
 void
 tray_enable(void)
 {
+    if (!gtk_ready) {
+        return;
+    }
     prof_tray = gtk_status_icon_new_from_file(icon_filename->str);
     shutting_down = FALSE;
     _tray_change_icon(NULL);

src/ui/tray.h

@@ -11,8 +11,10 @@
 #define UI_TRAY_H
 
 #ifdef HAVE_GTK
+#include <glib.h>
 void tray_init(void);
 void tray_update(void);
+gboolean tray_gtk_ready(void);
 
 void tray_enable(void);
 void tray_disable(void);