Gzip is unusable on zip-compression-method

epician · September 26, 2017, 2:38am

I’m using Duplicati - 2.0.2.8_canary_2017-09-20.
On the zip-compression-method option, I can’t use the Gzip.
Am I misconfigured something? It makes an error like below.

Fatal error
SharpCompress.Common.InvalidFormatException: Invalid compression method: GZip

at SharpCompress.Writers.Zip.ZipWriter.ToZipCompressionMethod(CompressionType compressionType)

at SharpCompress.Writers.Zip.ZipWriter.WriteToStream(String entryPath, ZipWriterEntryOptions options)

at Duplicati.Library.Compression.FileArchiveZip.CreateFile(String file, CompressionHint hint, DateTime lastWrite)

at Duplicati.Library.Main.Volumes.VolumeWriterBase.AddManifestfile()

at Duplicati.Library.Main.Volumes.VolumeWriterBase…ctor(Options options, DateTime timestamp)

at Duplicati.Library.Main.Volumes.FilesetVolumeWriter…ctor(Options options, DateTime timestamp)

at Duplicati.Library.Main.Operation.BackupHandler.Run(String[] sources, IFilter filter)

kenkendk · September 26, 2017, 11:58am

It seems that SharpCompress does not support all the possible compression methods:

github.com

adamhathcock/sharpcompress/blob/master/src/SharpCompress/Writers/Zip/ZipWriter.cs#L69


        ulong size = 0;
        foreach (ZipCentralDirectoryEntry entry in entries)
        {
            size += entry.Write(OutputStream);
        }
        WriteEndRecord(size);
    }
    base.Dispose(isDisposing);
}


private static ZipCompressionMethod ToZipCompressionMethod(CompressionType compressionType)
{
    switch (compressionType)
    {
        case CompressionType.None:
            {
                return ZipCompressionMethod.None;
            }
        case CompressionType.Deflate:
            {
                return ZipCompressionMethod.Deflate;

kenkendk · September 26, 2017, 12:06pm

I have updated the code to only report the supported methods; it will be part of the next canary build.

epician · September 27, 2017, 10:35am

Thanks for your great work and support!