decompress files on google storage on the fly using c#

Question

I have a very interesting problem that I hope I can solve using.Net, simply I have a zip file in google storage which I want to decompress and move to a different bucket, but I don't have enough memory nor storage to save the whole file and decompress. To solve this issue I have to read the central directory part of the zip file at the end of the file and then do streaming decompress. Did anyone work on a similar issue?

So far I figured to get the last 1024 bytes from the file using the following code:

  var fileInfo = _storage.GetObject(BucketName, fileName, new GetObjectOptions { Projection = Projection.Full });

var stream = new MemoryStream();
_storage.DownloadObject(BucketName, fileName, stream, new DownloadObjectOptions { Range = new System.Net.Http.Headers.RangeHeaderValue((long)(fileInfo.Size - 1024), (long)(fileInfo.Size)) });

The problem is I can't read the central directory from this stream:

ZipArchive z = new ZipArchive(stream);

Answer 1

You can try to adapt sunzip to your needs. It reads a zip file as a stream and decompresses it.