From 1bd9076590013e0c327f2517ac536a02ddf8e13e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marco=20Trevisan=20=28Trevi=C3=B1o=29?= <mail@3v1n0.net>
Date: Mon, 2 Sep 2019 17:05:27 +0200
Subject: [PATCH] main: Define a custom log writer to dump on structured
 messages

Even though GNOME Shell is not explicitly using structured logging via
G_LOG_USE_STRUCTURED, GLib uses it as default since 2016 [1], and so
we're de facto using it.

As per this, if backtrace on warnings is enabled, it is ignored since the
log handler isn't used anymore, and no dump is printed.

Thus, replace the default log handlers with writer functions instead, honoring
backtrace-warnings debug string.

[1] https://gitlab.gnome.org/GNOME/glib/-/commit/fce7cfaf40b6e1e50c9140aa0397f5

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/697>
---
 src/main.c | 56 +++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 36 insertions(+), 20 deletions(-)

diff --git a/src/main.c b/src/main.c
index 03708fc8f..29275cda0 100644
--- a/src/main.c
+++ b/src/main.c
@@ -287,39 +287,55 @@ shell_init_debug (const char *debug_env)
                                        G_N_ELEMENTS (keys));
 }
 
-static void
-default_log_handler (const char     *log_domain,
-                     GLogLevelFlags  log_level,
-                     const char     *message,
-                     gpointer        data)
+static GLogWriterOutput
+default_log_writer (GLogLevelFlags   log_level,
+                    const GLogField *fields,
+                    gsize            n_fields,
+                    gpointer         user_data)
 {
-  if (!log_domain || !g_str_has_prefix (log_domain, "tp-glib"))
-    g_log_default_handler (log_domain, log_level, message, data);
+  GLogWriterOutput output;
+  int i;
 
-  /* Filter out Gjs logs, those already have the stack */
-  if (log_domain && strcmp (log_domain, "Gjs") == 0)
-    return;
+  output = g_log_writer_default (log_level, fields, n_fields, user_data);
 
   if ((_shell_debug & SHELL_DEBUG_BACKTRACE_WARNINGS) &&
       ((log_level & G_LOG_LEVEL_CRITICAL) ||
        (log_level & G_LOG_LEVEL_WARNING)))
-    gjs_dumpstack ();
+    {
+      const char *log_domain = NULL;
+
+      for (i = 0; i < n_fields; i++)
+        {
+          if (g_strcmp0 (fields[i].key, "GLIB_DOMAIN") == 0)
+            {
+              log_domain = fields[i].value;
+              break;
+            }
+        }
+
+      /* Filter out Gjs logs, those already have the stack */
+      if (g_strcmp0 (log_domain, "Gjs") != 0)
+        gjs_dumpstack ();
+    }
+
+  return output;
 }
 
-static void
-shut_up (const char     *domain,
-         GLogLevelFlags  level,
-         const char     *message,
-         gpointer        user_data)
+static GLogWriterOutput
+shut_up (GLogLevelFlags   log_level,
+         const GLogField *fields,
+         gsize            n_fields,
+         gpointer         user_data)
 {
+  return (GLogWriterOutput) {0};
 }
 
 static void
 dump_gjs_stack_alarm_sigaction (int signo)
 {
-  g_log_set_default_handler (g_log_default_handler, NULL);
+  g_log_set_writer_func (g_log_writer_default, NULL, NULL);
   g_warning ("Failed to dump Javascript stack, got stuck");
-  g_log_set_default_handler (default_log_handler, NULL);
+  g_log_set_writer_func (default_log_writer, NULL, NULL);
 
   raise (caught_signal);
 }
@@ -384,7 +400,7 @@ list_modes (const char  *option_name,
    * ShellGlobal has some GTK+ dependencies, so initialize GTK+; we
    * don't really care if it fails though (e.g. when running from a tty),
    * so we mute all warnings */
-  g_log_set_default_handler (shut_up, NULL);
+  g_log_set_writer_func (shut_up, NULL, NULL);
   gtk_init_check (NULL, NULL);
 
   _shell_global_init (NULL);
@@ -533,7 +549,7 @@ main (int argc, char **argv)
   shell_introspection_init ();
   shell_fonts_init ();
 
-  g_log_set_default_handler (default_log_handler, NULL);
+  g_log_set_writer_func (default_log_writer, NULL, NULL);
 
   /* Initialize the global object */
   if (session_mode == NULL)