medialibrary: Allow an event to be unregistered from its callback

include/vlc_media_library.h

@@ -719,6 +719,16 @@ vlc_ml_event_register_callback( vlc_medialibrary_t* p_ml, vlc_ml_callback_t cb,
  */
 VLC_API void vlc_ml_event_unregister_callback( vlc_medialibrary_t* p_ml,
                                                vlc_ml_event_callback_t* p_callback );
+/**
+ * \brief Unregisters a medialibrary callback from the said callback.
+ * \param p_callback The handle returned by vlc_ml_register_callback
+ *
+ * This must only be called synchronously from the callback function provided to
+ * vlc_ml_event_register_callback
+ * The p_callback handle must be considered invalid when this function returns
+ */
+VLC_API void vlc_ml_event_unregister_from_callback( vlc_medialibrary_t* p_ml,
+                                                    vlc_ml_event_callback_t* p_callback );
 
 
 VLC_API void vlc_ml_show_release( vlc_ml_show_t* p_show );

src/libvlccore.sym

@@ -599,6 +599,7 @@ vlc_ml_control
 vlc_ml_list
 vlc_ml_event_register_callback
 vlc_ml_event_unregister_callback
+vlc_ml_event_unregister_from_callback
 vlc_ml_show_release
 vlc_ml_artist_release
 vlc_ml_genre_release

src/misc/medialibrary.c

@@ -87,6 +87,14 @@ void vlc_ml_event_unregister_callback( vlc_medialibrary_t* p_ml,
     free( p_cb );
 }
 
+void vlc_ml_event_unregister_from_callback( vlc_medialibrary_t* p_ml,
+                                            vlc_ml_event_callback_t* p_cb )
+{
+    vlc_mutex_assert( &p_ml->lock );
+    vlc_list_remove( &p_cb->node );
+    free( p_cb );
+}
+
 static const vlc_medialibrary_callbacks_t callbacks = {
     .pf_send_event = &vlc_ml_event_send
 };