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

Could you explain how to use/apply this patch? Thanks!

You need to check out the glib2 source code, apply this patch, and then compile it yourself.

fyi this fails to apply on glib past commit e7a68531 (which has been cherry-picked by ubuntu kinetic and debian sid)

Finally got around to updating it for glib 2.74.1. Should be fine now.

i should probably bring this up in here https://bbs.archlinux.org/viewtopic.php?pid=2152437#p2152437

I have no idea why this would affect portals.

Me neither

Just a hunch:

+ g_main_context_push_thread_default (thread_context);
…
+  if (!result || error)
+    {
+      g_warning ("generate_thumbnail (): g_dbus_proxy_call_sync() failed: %s", error->message);
+      return FALSE;
+    }
…
+  g_main_context_pop_thread_default (thread_context);

If g_dbus_proxy_call_sync fails it leaves quite some stuff behind, incl. a thread on some stack (I guess, I've no real experience w/ gtk code at all)
Some of the unrefs should™ probably be in the early exit as well?

While that should probably be cleaned up, that should just be a memory leak at the worst. I think the problem is likely that it is stuck running the main loop because the callback from the signal isn't working as expected for some reason.

thread_context never gets destroyed and remains the default context because it's also no popped.
If the main loop was stuck or waiting for a dbus timeout, I'd understood a delay, but not the interference w/ xdg-desktop-portal.

Should be easy enough for Kyuunex to test, though.

give the updated patch and i can test

In gio/glocalfileinfo.c, copy

+  g_object_unref (proxy);
+  g_object_unref (connection);
+  g_main_loop_unref (state.mainloop);
+  g_main_context_pop_thread_default (thread_context);
+  g_main_context_unref (thread_context);

into the if (!result || error)block

If the main loop was stuck or waiting for a dbus timeout, I'd understood a delay

I thought that was exactly the issue though?

@Kyuunex: If you need it, try this. I'll clean it up later but I don't think it will solve your issue (wouldn't mind being wrong though).

i tried lue's solution and was unable to build. i'll test later

There's a delay but

1. afaiu the client stll starts
2. what's more weird is that xdg-desktop-portal doesn't event attempt to launch any implementation w/ the patch in place.

And the failing xdg-desktop-portal backend alone can explain the delay.

Good news, I possibly may have fixed it and bumped the AUR package with the update. Well I don't use portals so I can't say for sure but there was a very longstanding problem with this patch that I finally solved. Also thanks to @luebking for pointing out the incomplete cleanup.

testing

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.