Sends a dbus signal for generating thumbnails.

glib-thumbnailer.patch

From 01ce72fb8086fb6984e4409739a821408045612e Mon Sep 17 00:00:00 2001
From: Dudemanguy <[email protected]>
Date: Sat, 24 Feb 2024 15:07:31 -0600
Subject: [PATCH] glocalfileinfo: add a dbus thumbnail generator

---
 gio/glocalfileinfo.c | 186 +++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 179 insertions(+), 7 deletions(-)

diff --git a/gio/glocalfileinfo.c b/gio/glocalfileinfo.c
index 4f51427f5..5e1698da0 100644
--- a/gio/glocalfileinfo.c
+++ b/gio/glocalfileinfo.c
@@ -68,6 +68,12 @@
 #include "glib-private.h"
 
 #include "thumbnail-verify.h"
+#ifdef HAVE_DBUS1
+#define FREEDESKTOP_THUMBNAILER
+#include <gio/gio.h>
+#include <gio/gdbusproxy.h>
+#include <glib-object.h>
+#endif /* HAVE_DBUS1 */
 
 #ifdef G_OS_WIN32
 #include <windows.h>
@@ -109,6 +115,16 @@ struct ThumbMD5Context {
 	unsigned char in[64];
 };
 
+#ifdef FREEDESKTOP_THUMBNAILER
+typedef struct
+{
+  GMainLoop *mainloop;
+  guint32 handle;
+  gboolean success;
+  const char *error_message;
+} ThumbnailerState;
+#endif /* FREEDESKTOP_THUMBNAILER */
+
 #ifndef G_OS_WIN32
 
 typedef struct {
@@ -1419,18 +1435,137 @@ get_thumbnail_dirname_from_size (ThumbnailSize size)
   g_return_val_if_reached (NULL);
 }
 
+#ifdef FREEDESKTOP_THUMBNAILER
+static void
+thumbnailer_signal_cb (GDBusProxy *proxy,
+                       gchar      *sender_name,
+                       gchar      *signal_name,
+                       GVariant   *parameters,
+                       gpointer    thumbnailer_state)
+{
+  ThumbnailerState *state = (ThumbnailerState *) thumbnailer_state;
+  guint32 signal_handle;
+  const gchar **uris;
+
+
+  if (g_strcmp0 (signal_name, "Error") == 0)
+    {
+      g_variant_get (parameters, "(uasis)", &signal_handle, NULL, NULL, &state->error_message);
+      state->success = FALSE;
+    }
+  else if (g_strcmp0 (signal_name, "Ready") == 0)
+    {
+      g_variant_get (parameters, "(u^as)", &signal_handle, &uris);
+      state->success = TRUE;
+    }
+  else if (g_strcmp0 (signal_name, "Finished") == 0)
+    {
+      g_main_loop_quit (state->mainloop);
+    }
+
+}
+
+static gboolean
+generate_thumbnail(const char *uri, const char *mime_type)
+{
+  GMainContext *thread_context;
+  GDBusConnection *connection;
+  GDBusProxy *proxy;
+  GVariant *result = NULL;
+  GError *error = NULL;
+  ThumbnailerState state;
+  const gchar *uris[2] = { uri, NULL };
+  const gchar *mime_types[2] = { mime_type, NULL };
+
+  thread_context = g_main_context_new ();
+  state.mainloop = g_main_loop_new (thread_context, FALSE);
+  state.success = FALSE;
+
+  connection = g_dbus_connection_new_for_address_sync (
+      g_dbus_address_get_for_bus_sync (G_BUS_TYPE_SESSION, NULL, NULL),
+      G_DBUS_CONNECTION_FLAGS_MESSAGE_BUS_CONNECTION | G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_CLIENT,
+      NULL,
+      NULL,
+      &error);
+
+  g_main_context_push_thread_default (thread_context);
+  proxy = g_dbus_proxy_new_sync (connection,
+                                 G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES,
+                                 NULL,
+                                 "org.freedesktop.thumbnails.Thumbnailer1",
+                                 "/org/freedesktop/thumbnails/Thumbnailer1",
+                                 "org.freedesktop.thumbnails.Thumbnailer1",
+                                 NULL, /* TODO: cancellable */
+                                 &error);
+  if (!proxy)
+    {
+      g_warning ("generate_thumbnail (): g_dbus_proxy_new_sync failed");
+      goto done;
+    }
+  else
+    g_debug("generate_thumbnail (): connected to D-Bus");
+
+  g_signal_connect (G_OBJECT (proxy), "g-signal",
+                    G_CALLBACK (thumbnailer_signal_cb), &state);
+
+  result = g_dbus_proxy_call_sync (proxy,
+                                  "Queue",
+                                   g_variant_new("(^as^asssu)",
+                                                 uris,
+                                                 mime_types,
+                                                 "normal",
+                                                 "default",
+                                                 0),
+                                   G_DBUS_CALL_FLAGS_NONE,
+                                   -1,
+                                   NULL,
+                                   &error);
+  if (!result || error)
+    {
+      g_warning ("generate_thumbnail (): g_dbus_proxy_call_sync() failed: %s", error->message);
+      goto done;
+    }
+  g_variant_get (result, "(u)", &(state.handle));
+  g_variant_unref (result);
+  // block until the loop is terminated in thumbnailer_signal_cb ()
+  g_main_loop_run (state.mainloop);
+
+done:
+  if (proxy)
+    g_object_unref (proxy);
+
+  if (connection)
+    g_object_unref (connection);
+
+  g_main_loop_unref (state.mainloop);
+  g_main_context_pop_thread_default (thread_context);
+  g_main_context_unref (thread_context);
+
+  if (state.success)
+    {
+      g_debug ("generate_thumbnail (): Thumbnail generated for %s", uris[0]);
+      return TRUE;
+    }
+  else
+    return FALSE;
+}
+#endif /* FREEDESKTOP_THUMBNAILER */
+
+
 /* @stat_buf is the pre-calculated result of stat(path), or %NULL if that failed. */
 static void
 get_thumbnail_attributes (const char     *path,
                           GFileInfo      *info,
                           const GLocalFileStat *stat_buf,
-                          ThumbnailSize   size)
+                          ThumbnailSize   size,
+                          gboolean        generate)
 {
   GChecksum *checksum;
   const char *dirname;
   char *uri;
   char *filename = NULL;
   char *basename;
+  const char *content_type;
   guint32 failed_attr_id;
   guint32 is_valid_attr_id;
   guint32 path_attr_id;
@@ -1507,6 +1642,7 @@ get_thumbnail_attributes (const char     *path,
       _g_file_info_set_attribute_byte_string_by_id (info, path_attr_id, filename);
       _g_file_info_set_attribute_boolean_by_id (info, is_valid_attr_id,
                                                 thumbnail_verify (filename, uri, stat_buf));
+      generate = FALSE;
     }
   else
     {
@@ -1521,9 +1657,31 @@ get_thumbnail_attributes (const char     *path,
           _g_file_info_set_attribute_boolean_by_id (info, failed_attr_id, TRUE);
           _g_file_info_set_attribute_boolean_by_id (info, is_valid_attr_id,
                                                     thumbnail_verify (filename, uri, stat_buf));
+          generate = FALSE;
         }
     }
 
+  if (generate)
+    {
+#ifdef FREEDESKTOP_THUMBNAILER
+      content_type = g_file_info_get_content_type (info);
+      if (content_type)
+        {
+          g_debug ("invoking Freedesktop Thumbnailer for %s (%s)", uri, content_type);
+          if (generate_thumbnail (uri, content_type))
+            {
+              /* Now that the thumbnail is generated, find it. */
+              get_thumbnail_attributes (path, info, stat_buf, size, FALSE);
+            }
+          /*else
+            {
+              _g_file_info_set_attribute_boolean_by_id (info, G_FILE_ATTRIBUTE_ID_THUMBNAILING_FAILED, TRUE);
+              _g_file_info_set_attribute_boolean_by_id (info, G_FILE_ATTRIBUTE_ID_THUMBNAIL_IS_VALID, FALSE);
+            }*/
+         }
+#endif /* FREEDESKTOP_THUMBNAILER */
+    }
+
   g_free (basename);
   g_free (filename);
   g_free (uri);
@@ -1914,6 +2072,18 @@ _g_local_file_info_get (const char             *basename,
 
   info = g_file_info_new ();
 
+  /* Thumbnail generation requires a content-type.
+   * TODO: implement g_file_attribute_matcher_add () in gfileinfo.c */
+  if (_g_file_attribute_matcher_matches_id (attribute_matcher, G_FILE_ATTRIBUTE_ID_THUMBNAIL_PATH)
+      && !_g_file_attribute_matcher_matches_id (attribute_matcher, G_FILE_ATTRIBUTE_ID_STANDARD_CONTENT_TYPE))
+    {
+      char *attributes = g_file_attribute_matcher_to_string (attribute_matcher);
+      char *_attributes = g_strdup_printf ("%s,standard::content-type", attributes);
+      attribute_matcher = g_file_attribute_matcher_new (_attributes);
+      g_free (attributes);
+      g_free (_attributes);
+    }
+
   /* Make sure we don't set any unwanted attributes */
   g_file_info_set_attribute_mask (info, attribute_matcher);
   
@@ -2049,7 +2219,9 @@ _g_local_file_info_get (const char             *basename,
       _g_file_attribute_matcher_matches_id (attribute_matcher,
 					    G_FILE_ATTRIBUTE_ID_STANDARD_ICON) ||
       _g_file_attribute_matcher_matches_id (attribute_matcher,
-					    G_FILE_ATTRIBUTE_ID_STANDARD_SYMBOLIC_ICON))
+					    G_FILE_ATTRIBUTE_ID_STANDARD_SYMBOLIC_ICON) ||
+      _g_file_attribute_matcher_matches_id (attribute_matcher,
+              G_FILE_ATTRIBUTE_ID_THUMBNAIL_PATH))
     {
       char *content_type = get_content_type (basename, path, stat_ok ? &statbuf : NULL, is_symlink, symlink_broken, flags, FALSE);
 
@@ -2165,7 +2337,7 @@ _g_local_file_info_get (const char             *basename,
       _g_file_attribute_matcher_matches_id (attribute_matcher,
                                             G_FILE_ATTRIBUTE_ID_THUMBNAILING_FAILED))
     {
-      get_thumbnail_attributes (path, info, stat_ok ? &statbuf : NULL, THUMBNAIL_SIZE_AUTO);
+      get_thumbnail_attributes (path, info, stat_ok ? &statbuf : NULL, THUMBNAIL_SIZE_AUTO, TRUE);
     }
 
   if (_g_file_attribute_matcher_matches_id (attribute_matcher,
@@ -2175,7 +2347,7 @@ _g_local_file_info_get (const char             *basename,
       _g_file_attribute_matcher_matches_id (attribute_matcher,
                                             G_FILE_ATTRIBUTE_ID_THUMBNAILING_FAILED_NORMAL))
     {
-      get_thumbnail_attributes (path, info, stat_ok ? &statbuf : NULL, THUMBNAIL_SIZE_NORMAL);
+      get_thumbnail_attributes (path, info, stat_ok ? &statbuf : NULL, THUMBNAIL_SIZE_NORMAL, TRUE);
     }
 
   if (_g_file_attribute_matcher_matches_id (attribute_matcher,
@@ -2185,7 +2357,7 @@ _g_local_file_info_get (const char             *basename,
       _g_file_attribute_matcher_matches_id (attribute_matcher,
                                             G_FILE_ATTRIBUTE_ID_THUMBNAILING_FAILED_LARGE))
     {
-      get_thumbnail_attributes (path, info, stat_ok ? &statbuf : NULL, THUMBNAIL_SIZE_LARGE);
+      get_thumbnail_attributes (path, info, stat_ok ? &statbuf : NULL, THUMBNAIL_SIZE_LARGE, TRUE);
     }
 
   if (_g_file_attribute_matcher_matches_id (attribute_matcher,
@@ -2195,7 +2367,7 @@ _g_local_file_info_get (const char             *basename,
       _g_file_attribute_matcher_matches_id (attribute_matcher,
                                             G_FILE_ATTRIBUTE_ID_THUMBNAILING_FAILED_XLARGE))
     {
-      get_thumbnail_attributes (path, info, stat_ok ? &statbuf : NULL, THUMBNAIL_SIZE_XLARGE);
+      get_thumbnail_attributes (path, info, stat_ok ? &statbuf : NULL, THUMBNAIL_SIZE_XLARGE, TRUE);
     }
 
   if (_g_file_attribute_matcher_matches_id (attribute_matcher,
@@ -2205,7 +2377,7 @@ _g_local_file_info_get (const char             *basename,
       _g_file_attribute_matcher_matches_id (attribute_matcher,
                                             G_FILE_ATTRIBUTE_ID_THUMBNAILING_FAILED_XXLARGE))
     {
-      get_thumbnail_attributes (path, info, stat_ok ? &statbuf : NULL, THUMBNAIL_SIZE_XXLARGE);
+      get_thumbnail_attributes (path, info, stat_ok ? &statbuf : NULL, THUMBNAIL_SIZE_XXLARGE, TRUE);
     }
 
   vfs = g_vfs_get_default ();
-- 
2.43.2

On a clean rebuild of the AUR package glib2-patched-thumbnailer, I do not have major issues with xdg-portals starting anymore.
One noticeable thing is there is a small delay (1-2 seconds) with the first app that starts that makes uses of portals, in my case, waybar.

Thanks for fixing the issue!

Hmm still not really sure how this even affects portals but not being stuck in an infinite loop is definitely an improvement.