有没有办法用另一个库解压缩 DynaZip Max 文件？ F.E. DotNetZip

Question

我有一个数据库，我们使用以下代码存储了使用 DynaZip Max Secure 压缩的 pdf 文件：

MemoryStream msIN = new System.IO.MemoryStream();   //Input MemoryStream
MemoryStream msZip = new System.IO.MemoryStream();  //Compressed MemoryStream
BinaryReader objBinaryReader;
BinaryWriter objBinaryWriter;


public MemoryStream CompressStream(byte[] vbuf)
{
    System.IO.BinaryWriter bw = new System.IO.BinaryWriter(msIN);
    bw.Write(vbuf);
    CDZipSNET dz1 = new CDZipSNET();
    dz1.ZipMemToMemCallback += new CDZipSNET.OnZipMemToMemCallback(this.ZipMemToMemCallback_event);
    dz1.ActionDZ = CDZipSNET.DZACTION.ZIP_MEMTOMEM;
    return msZip;
}

这是 ZipMemToMemCallback_event 代码：

public void ZipMemToMemCallback_event(CDZipSNET.MEMTOMEMACTION lAction,ref byte[] lpMemBuf,ref uint pdwSize,uint dwTotalReadL,uint dwTotalReadH,uint dwTotalWrittenL,uint dwTotalWrittenH,ref CDZipSNET.MEMTOMEMRESPONSE plRet)
{
    int bytesToRead;

    switch(lAction)
    {
        case CDZipSNET.MEMTOMEMACTION.MEM_READ_DATA:
            if((dwTotalReadL == 0) && (dwTotalReadH == 0))
            {
                msIN.Seek(0, System.IO.SeekOrigin.Begin);
                objBinaryReader = new System.IO.BinaryReader(msIN);
            }
            try
            {
                bytesToRead = (int)(objBinaryReader.BaseStream.Length - dwTotalReadL);
                if(bytesToRead > pdwSize)
                {
                    bytesToRead = (int)pdwSize;
                    plRet = CDZipSNET.MEMTOMEMRESPONSE.MEM_CONTINUE;
                }
                else
                { 
                    plRet = CDZipSNET.MEMTOMEMRESPONSE.MEM_DONE; 
                }
                pdwSize = (uint)bytesToRead;
                if(bytesToRead > 0)
                { 
                    objBinaryReader.Read(lpMemBuf, 0, bytesToRead); 
                }
            }
            catch 
            { 
                plRet = CDZipSNET.MEMTOMEMRESPONSE.MEM_ERROR; 
            }
            break;

        case CDZipSNET.MEMTOMEMACTION.MEM_WRITE_DATA:
            if((dwTotalWrittenL == 0) && (dwTotalWrittenH == 0))
            { 
                objBinaryWriter = new System.IO.BinaryWriter(msZip); 
            }
            try
            {
                objBinaryWriter.Write(lpMemBuf, 0, (int)pdwSize);
                plRet = CDZipSNET.MEMTOMEMRESPONSE.MEM_CONTINUE;
            }
            catch (System.Exception)
            { 
                plRet = CDZipSNET.MEMTOMEMRESPONSE.MEM_ERROR; 
            }
            break;

        default: plRet = CDZipSNET.MEMTOMEMRESPONSE.MEM_ERROR;
            break;
    }
}

我会提供任何其他必要的东西来解答这个谜题，我尝试过常规的 Zip 解压缩、Zlib、Gzip 都无济于事。我将不胜感激。谢谢。

编辑： 问题在于 DinaZip 是一个专有的、已停产的库，发布它的公司没有提供任何帮助或故障排除，我被委托解压缩一堆以前压缩过的文件使用这个库（使用代码 avobe）并且我不再有可用于解压缩的库，我想知道是否有人知道任何方法可以使用其他库或方法来解压这些文件。

Answer 1

此代码来自https://zlibnet.codeplex.com，它可以解压未加密的DynaZip流：

public static class DynazipCompressor
{
    const int DZ_DEFLATE_POS = 46;

    public static bool IsDynazip(byte[] source)
    {
        return source.Length >= 4 && BitConverter.ToInt32(source, 0) == 0x02014b50;
    }

    public static byte[] DeCompress(byte[] source)
    {
        if (!IsDynazip(source))
            throw new InvalidDataException("not dynazip header");
        using (MemoryStream srcStream = new MemoryStream(source, DZ_DEFLATE_POS, source.Length - DZ_DEFLATE_POS))
        using (MemoryStream dstStream = DeCompress(srcStream))
            return dstStream.ToArray();
    }

    private static MemoryStream DeCompress(Stream source)
    {
        MemoryStream dest = new MemoryStream();
        DeCompress(source, dest);
        dest.Position = 0;
        return dest;
    }

    private static void DeCompress(Stream source, Stream dest)
    {
        using (DeflateStream zsSource = new DeflateStream(source, CompressionMode.Decompress, true))
        {
            zsSource.CopyTo(dest);
        }
    }
}

DynaZip 流只是带有 PKZIP 标头的 DeflateStream，因此此代码只是跳过标头。