[glib/mcatanzaro/kfsb] gkeyfilesettingsbackend: check for errors when creating file monitors

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 26f6e3db9e896521af4bbd25d4f971ed25bf2e15
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Tue Feb 23 16:31:26 2021 -0600

    gkeyfilesettingsbackend: check for errors when creating file monitors
    
    File monitor creation may fail. We should check for this, rather than
    ignoring it and then spewing criticals upon improperly assuming that we
    have a valid GFileMonitor rather than NULL.
    
    In practice, creating the GFileMonitors here fail when opening a large
    number of tabs in Epiphany. I'm still investigating to see why, but it
    doesn't matter for the purposes of this commit.

 gio/gkeyfilesettingsbackend.c | 48 +++++++++++++++++++++++++++++++------------
 1 file changed, 35 insertions(+), 13 deletions(-)
---
diff --git a/gio/gkeyfilesettingsbackend.c b/gio/gkeyfilesettingsbackend.c
index 485a25a14..094be3f91 100644
--- a/gio/gkeyfilesettingsbackend.c
+++ b/gio/gkeyfilesettingsbackend.c
@@ -605,19 +605,24 @@ g_keyfile_settings_backend_finalize (GObject *object)
   g_hash_table_unref (kfsb->system_locks);
   g_free (kfsb->defaults_dir);
 
-  g_file_monitor_cancel (kfsb->file_monitor);
-  g_object_unref (kfsb->file_monitor);
+  if (kfsb->file_monitor)
+    {
+      g_file_monitor_cancel (kfsb->file_monitor);
+      g_object_unref (kfsb->file_monitor);
+    }
   g_object_unref (kfsb->file);
 
-  g_file_monitor_cancel (kfsb->dir_monitor);
-  g_object_unref (kfsb->dir_monitor);
+  if (kfsb->dir_monitor)
+    {
+      g_file_monitor_cancel (kfsb->dir_monitor);
+      g_object_unref (kfsb->dir_monitor);
+    }
   g_object_unref (kfsb->dir);
 
   g_free (kfsb->root_group);
   g_free (kfsb->prefix);
 
-  G_OBJECT_CLASS (g_keyfile_settings_backend_parent_class)
-    ->finalize (object);
+  G_OBJECT_CLASS (g_keyfile_settings_backend_parent_class)->finalize (object);
 }
 
 static void
@@ -724,6 +729,7 @@ static void
 g_keyfile_settings_backend_constructed (GObject *object)
 {
   GKeyfileSettingsBackend *kfsb = G_KEYFILE_SETTINGS_BACKEND (object);
+  GError *error = NULL;
   const char *path;
 
   if (kfsb->file == NULL)
@@ -749,15 +755,31 @@ g_keyfile_settings_backend_constructed (GObject *object)
   if (g_mkdir_with_parents (path, 0700) == -1)
     g_warning ("Failed to create %s: %s", path, g_strerror (errno));
 
-  kfsb->file_monitor = g_file_monitor (kfsb->file, G_FILE_MONITOR_NONE, NULL, NULL);
-  kfsb->dir_monitor = g_file_monitor (kfsb->dir, G_FILE_MONITOR_NONE, NULL, NULL);
+  kfsb->file_monitor = g_file_monitor (kfsb->file, G_FILE_MONITOR_NONE, NULL, &error);
+  if (!kfsb->file_monitor)
+    {
+      g_warning ("Failed to create file monitor for %s: %s", g_file_peek_path (kfsb->file), error->message);
+      g_clear_error (&error);
+    }
+  else
+    {
+      g_signal_connect (kfsb->file_monitor, "changed",
+                        G_CALLBACK (file_changed), kfsb);
+    }
 
-  compute_checksum (kfsb->digest, NULL, 0);
+  kfsb->dir_monitor = g_file_monitor (kfsb->dir, G_FILE_MONITOR_NONE, NULL, &error);
+  if (!kfsb->dir_monitor)
+    {
+      g_warning ("Failed to create file monitor for %s: %s", g_file_peek_path (kfsb->file), error->message);
+      g_clear_error (&error);
+    }
+  else
+    {
+      g_signal_connect (kfsb->dir_monitor, "changed",
+                        G_CALLBACK (dir_changed), kfsb);
+    }
 
-  g_signal_connect (kfsb->file_monitor, "changed",
-                    G_CALLBACK (file_changed), kfsb);
-  g_signal_connect (kfsb->dir_monitor, "changed",
-                    G_CALLBACK (dir_changed), kfsb);
+  compute_checksum (kfsb->digest, NULL, 0);
 
   g_keyfile_settings_backend_keyfile_writable (kfsb);
   g_keyfile_settings_backend_keyfile_reload (kfsb);