Bug 1759785 - Intercept crashy GTK messages that we don't have visibility into. r=stransky

This should get us crash reports for Wayland errors that otherwise we're
blind to, see comments.

Some of those might be expected / not our fault (if the Wayland
compositor crashes altogether for example), but in that case we're
unlikely to even be able to pop up the crash reporter window.

Worst case we can always revert this I guess.

Differential Revision: https://phabricator.services.mozilla.com/D141173

Author: emilio

toolkit/xre/nsSigHandlers.cpp

@@ -18,6 +18,7 @@
 #  include "prthread.h"
 #  include "prenv.h"
 #  include "nsDebug.h"
+#  include "nsString.h"
 #  include "nsXULAppAPI.h"
 
 #  if defined(LINUX)
@@ -123,13 +124,40 @@ MOZ_NEVER_INLINE void child_ah_crap_handler(int signum) {
 static GLogFunc orig_log_func = nullptr;
 
 extern "C" {
-static void my_glib_log_func(const gchar* log_domain, GLogLevelFlags log_level,
-                             const gchar* message, gpointer user_data);
+static void glib_log_func(const gchar* log_domain, GLogLevelFlags log_level,
+                          const gchar* message, gpointer user_data);
 }
 
-/* static */ void my_glib_log_func(const gchar* log_domain,
-                                   GLogLevelFlags log_level,
-                                   const gchar* message, gpointer user_data) {
+// GDK sometimes avoids calling exit handlers, but we still want to know when we
+// crash, see https://gitlab.gnome.org/GNOME/gtk/-/issues/4514 and bug 1743144.
+static bool IsCrashyGtkMessage(const nsACString& aMessage) {
+  if (aMessage.EqualsLiteral("Lost connection to Wayland compositor.")) {
+    // https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gdk/wayland/gdkeventsource.c#L210
+    return true;
+  }
+  if (StringBeginsWith(aMessage, "Error flushing display: "_ns)) {
+    // https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gdk/wayland/gdkeventsource.c#L68
+    return true;
+  }
+  if (StringBeginsWith(aMessage, "Error reading events from display: "_ns)) {
+    // https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gdk/wayland/gdkeventsource.c#L97
+    return true;
+  }
+  if (StringBeginsWith(aMessage, "Error "_ns) &&
+      StringEndsWith(aMessage, " dispatching to Wayland display."_ns)) {
+    // https://gitlab.gnome.org/GNOME/gtk/-/blob/gtk-3-24/gdk/wayland/gdkeventsource.c#L205
+    return true;
+  }
+  return false;
+}
+
+/* static */ void glib_log_func(const gchar* log_domain,
+                                GLogLevelFlags log_level, const gchar* message,
+                                gpointer user_data) {
+  if (MOZ_UNLIKELY(IsCrashyGtkMessage(nsDependentCString(message)))) {
+    MOZ_CRASH_UNSAFE(strdup(message));
+  }
+
   if (log_level &
       (G_LOG_LEVEL_ERROR | G_LOG_FLAG_FATAL | G_LOG_FLAG_RECURSION)) {
     NS_DebugBreak(NS_DEBUG_ASSERTION, message, "glib assertion", __FILE__,
@@ -291,14 +319,11 @@ void InstallSignalHandlers(const char* aProgname) {
 #  if defined(MOZ_WIDGET_GTK) && \
       (GLIB_MAJOR_VERSION > 2 || \
        (GLIB_MAJOR_VERSION == 2 && GLIB_MINOR_VERSION >= 6))
-  const char* assertString = PR_GetEnv("XPCOM_DEBUG_BREAK");
-  if (assertString &&
-      (!strcmp(assertString, "suspend") || !strcmp(assertString, "stack") ||
-       !strcmp(assertString, "abort") || !strcmp(assertString, "trap") ||
-       !strcmp(assertString, "break"))) {
-    // Override the default glib logging function so we get stacks for it too.
-    orig_log_func = g_log_set_default_handler(my_glib_log_func, nullptr);
-  }
+  // Override the default glib logging function to intercept some crashes that
+  // are uninterceptable otherwise.
+  // Also, when XPCOM_DEBUG_BREAK is set, we can also get stacks for them.
+  // so we get stacks for it too.
+  orig_log_func = g_log_set_default_handler(glib_log_func, nullptr);
 #  endif
 }