Question

我正在使用mono来充气/缩小字节。这是代码：

public static byte[] Inflate(byte[] data)
    {
        using (MemoryStream inStream = new MemoryStream(data))
        {
            using (MemoryStream outStream = new MemoryStream())
            {
                using (DeflateStream decompressStream = new DeflateStream(inStream, CompressionMode.Decompress))
                {
                    decompressStream.CopyTo(outStream);
                }
                return outStream.ToArray();
            }
        }
    }

输入数据是：＆lt; 789c3dca b9110020 0c04b196 bc9c3f7a 73f11030 281652d1 88b04195 1e742987 2f86258f acdec63d 6dcf0184 560cde＆gt; 47bytes。该算法是DEFLATE。

我在其他平台上成功地膨胀了相同的数据，但是通过上面的代码，它引发了以下异常：

System.IO.IOException: Corrupted data ReadInternal
  at System.IO.Compression.DeflateStreamNative.CheckResult (Int32 result, System.String where) [0x00000] in <filename unknown>:0 
  at System.IO.Compression.DeflateStreamNative.ReadZStream (IntPtr buffer, Int32 length) [0x00000] in <filename unknown>:0 
  at System.IO.Compression.DeflateStream.ReadInternal (System.Byte[] array, Int32 offset, Int32 count) [0x00000] in <filename unknown>:0 
  at System.IO.Compression.DeflateStream.Read (System.Byte[] dest, Int32 dest_offset, Int32 count) [0x00000] in <filename unknown>:0 
  at System.IO.Stream.CopyTo (System.IO.Stream destination, Int32 bufferSize) [0x00000] in <filename unknown>:0 
  at System.IO.Stream.CopyTo (System.IO.Stream destination) [0x00000] in <filename unknown>:0

Answer 1

最后我使用DotNetZip：http://dotnetzip.codeplex.com来解决问题。

public static byte[] Inflate(byte[] data)
    {
        int outputSize = 1024;
        byte[] output = new Byte[ outputSize ];
        bool expectRfc1950Header = true;
        using ( MemoryStream ms = new MemoryStream())
        {
            ZlibCodec compressor = new ZlibCodec();
            compressor.InitializeInflate(expectRfc1950Header);

            compressor.InputBuffer = data;
            compressor.AvailableBytesIn = data.Length;
            compressor.NextIn = 0;
            compressor.OutputBuffer = output;

            foreach (var f in new FlushType[] { FlushType.None, FlushType.Finish } )
            {
                int bytesToWrite = 0;
                do
                {
                    compressor.AvailableBytesOut = outputSize;
                    compressor.NextOut = 0;
                    compressor.Inflate(f);

                    bytesToWrite = outputSize - compressor.AvailableBytesOut ;
                    if (bytesToWrite > 0)
                        ms.Write(output, 0, bytesToWrite);
                }
                while (( f == FlushType.None && (compressor.AvailableBytesIn != 0 || compressor.AvailableBytesOut == 0)) ||
                    ( f == FlushType.Finish && bytesToWrite != 0));
            }

            compressor.EndInflate();

            return ms.ToArray();
        }
    }

    public static byte[] Deflate(byte[] data)
    {
        int outputSize = 1024;
        byte[] output = new Byte[ outputSize ];
        int lengthToCompress = data.Length;

        // If you want a ZLIB stream, set this to true.  If you want
        // a bare DEFLATE stream, set this to false.
        bool wantRfc1950Header = true;

        using ( MemoryStream ms = new MemoryStream())
        {
            ZlibCodec compressor = new ZlibCodec();
            compressor.InitializeDeflate(CompressionLevel.BestCompression, wantRfc1950Header);  

            compressor.InputBuffer = data;
            compressor.AvailableBytesIn = lengthToCompress;
            compressor.NextIn = 0;
            compressor.OutputBuffer = output;

            foreach (var f in new FlushType[] { FlushType.None, FlushType.Finish } )
            {
                int bytesToWrite = 0;
                do
                {
                    compressor.AvailableBytesOut = outputSize;
                    compressor.NextOut = 0;
                    compressor.Deflate(f);

                    bytesToWrite = outputSize - compressor.AvailableBytesOut ;
                    if (bytesToWrite > 0)
                        ms.Write(output, 0, bytesToWrite);
                }
                while (( f == FlushType.None && (compressor.AvailableBytesIn != 0 || compressor.AvailableBytesOut == 0)) ||
                    ( f == FlushType.Finish && bytesToWrite != 0));
            }

            compressor.EndDeflate();

            ms.Flush();
            return ms.ToArray();
        }
    }

Answer 2

如果您阅读我的评论，您会发现我在18个小时前遇到了此问题，尽管问题的答案就在您的答案中，但并不直接可见。在您的答案中有一个变量集wantRfc1950Header = true，在您的输入流中，前两个字节是RFC 1950魔术字节78 9c。 System.IO.Compression.DeflateStream需要一个原始的RFC 1951流，其中省略了这两个字节。我想如果将前两个字节切碎后再送入充气机，您应该可以使用最初的示例。

不利的一面是，我花了18个小时才发现我需要删除两个字节的数据。从好的方面来说，我更加熟悉zlib和Huffman编码的内部。

Answer 3

是的，您只能+2个字节，但是我不确定这是否可以使损坏的数据通过或在所有情况下都可以工作？

   // Note: Caller must Dispose/Close.
    public DataReader ReadCompressedData()
    {
        // TODO: Optimize when using MemoryStream to use GetBuffer?
        var uncompressedSize = ReadInt32();
        var compressedSize = ReadInt32();

        // Consuming 2 bytes for the 78 9C (Sometimes other like 78 DA)
        // Unity / .Net Deflate Stream expects the data to not have this header.
        // I could use the SharpZlib project to get around this or the DotNetZip.
        // https://stackoverflow.com/questions/762614/how-do-you-use-a-deflatestream-on-part-of-a-file
        // http://www.faqs.org/rfcs/rfc1950.html
        // https://stackoverflow.com/questions/20850703/cant-inflate-with-c-sharp-using-deflatestream
        //stream.Position += 2;
        byte[] magic = ReadBytes(2);
        compressedSize -= 2;
        // I wonder if I should check these?

        var compressedData = ReadBytes(compressedSize);
        if (compressedData.Length != compressedSize)
        {
            Debug.LogError("Data read from underlying stream does not match specified size.");
        }

        // Decompress the data in the stream leaving it open.
        // Note: Not sure how to stop DeflateStream gobbling up all data in the stream.
        // using (var ds = new DeflateStream(BaseStream, CompressionMode.Decompress, true))
        // {
        //
        // }

        // Note: We are trusting that the decompressed data will fit completely into uncompressedSize.
        var os = new MemoryStream(uncompressedSize);
        using (var inputStream = new MemoryStream(compressedData))
        {
            using (var ds = new DeflateStream(inputStream, CompressionMode.Decompress))
            {
                ds.CopyTo(os);
            }
        }

        // Reset the stream to the beginning for reading.
        os.Position = 0;
        return new DataReader(os);
    }

不能使用DeflateStream用C＃充气

3 个答案: