[fixed] NRE in ISO/Zip-ResourceAccessor (1 Viewer)

[morpheus_xx]

Accessing properties of an ISO/ZIP-ResourceAccessor can throw a NRE, because the underlying proxy object is disposed/set to null:

[2012-11-18 15:22:56,555] [2733063] [FanArt Downloader 0] [DEBUG] - MovieTheMovieDbMatcher Download: Finished saving banners for ID 4982
[2012-11-18 15:22:57,740] [2734249] [Importer ] [ERROR] - MediaAccessor: Error extracting metadata from metadata extractor 'Movies thumbnail extractor' (Id: 'fb0aa0ed-97b2-4721-be74-ac67e77a17b2')
System.NullReferenceException: Der Objektverweis wurde nicht auf eine Objektinstanz festgelegt.
  bei MediaPortal.Extensions.ResourceProviders.IsoResourceProvider.IsoResourceAccessor.get_CanonicalLocalResourcePath()
  bei MediaPortal.Extensions.MetadataExtractors.MovieThumbnailer.MovieThumbnailer.TryExtractMetadata(IResourceAccessor mediaItemAccessor, IDictionary`2 extractedAspectData, Boolean forceQuickMode)
  bei MediaPortal.Common.Services.MediaManagement.MediaAccessor.ExtractMetadata(IResourceAccessor mediaItemAccessor, IEnumerable`1 metadataExtractors, Boolean forceQuickMode)

    public bool TryExtractMetadata(IResourceAccessor mediaItemAccessor, IDictionary<Guid, MediaItemAspect> extractedAspectData, bool forceQuickMode)
    {
      try
      {
        if (forceQuickMode)
          return false;
 
        if (!(mediaItemAccessor is IFileSystemResourceAccessor))
          return false;
        using (IFileSystemResourceAccessor fsra = (IFileSystemResourceAccessor) mediaItemAccessor.Clone())
        using (ILocalFsResourceAccessor lfsra = StreamedResourceToLocalFsAccessBridge.GetLocalFsResourceAccessor(fsra))
          return ExtractThumbnail(lfsra, extractedAspectData);
      }
      catch (Exception e)
      {
        // Only log at the info level here - And simply return false. This lets the caller know that we
        // couldn't perform our task here.
        ServiceRegistration.Get<ILogger>().Info("MovieThumbnailer: Exception reading resource '{0}' (Text: '{1}')", mediaItemAccessor.CanonicalLocalResourcePath, e.Message);
      }
      return false;
    }

The NRE occures when accessing properties like:

    public ResourcePath CanonicalLocalResourcePath
    {
      get { return _isoProxy.IsoFileResourceAccessor.CanonicalLocalResourcePath.ChainUp(IsoResourceProvider.ISO_RESOURCE_PROVIDER_ID, _pathToDirOrFile); }
    }

where _isoProxy is null already.

This problem also occure from other places of Importer, not only from the MovieThumbnailerMDE above

 

[morpheus_xx]

Fixed by Albert, thanks!