/// <summary>
/// Decompressed (inflates) a compressed byte array using the Inflate algorithm.
/// </summary>
/// <param name="compressedData">The deflate-compressed data</param>
/// <param name="dictionary">The dictionary originally used to compress the data, or null if no dictionary was used.</param>
/// <returns>The uncompressed data</returns>
internal static byte[] ZlibDecompressWithDictionary(byte[] compressedData, byte[] dictionary)
{
using (var ms = new MemoryStream())
{
const int bufferSize = 256;
var buffer = new byte[bufferSize];
var codec = new ZlibCodec
{
InputBuffer = compressedData,
NextIn = 0,
AvailableBytesIn = compressedData.Length
};
codec.AssertOk("InitializeInflate", codec.InitializeInflate(false));
if (dictionary != null)
{
codec.AssertOk("SetDictionary", codec.SetDictionaryUnconditionally(dictionary));
}
codec.OutputBuffer = buffer;
while (true)
{
codec.NextOut = 0;
codec.AvailableBytesOut = bufferSize;
var inflateReturnCode = codec.Inflate(FlushType.None);
var bytesToWrite = bufferSize - codec.AvailableBytesOut;
ms.Write(buffer, 0, bytesToWrite);
if (inflateReturnCode == ZlibConstants.Z_STREAM_END)
{
break;
}
else if (inflateReturnCode == ZlibConstants.Z_NEED_DICT && dictionary != null)
{
//implies bytesToWrite was 0
var dictionaryAdler32 = ((int)Adler.Adler32(1u, dictionary, 0, dictionary.Length));
if (codec.Adler32 != dictionaryAdler32)
{
throw new InvalidOperationException("Compressed data is requesting a dictionary with adler32 " + codec.Adler32 + ", but the dictionary is actually " + dictionaryAdler32);
}
codec.AssertOk("SetDictionary", codec.SetDictionary(dictionary));
}
else
{
codec.AssertOk("Inflate", inflateReturnCode);
}
}
codec.AssertOk("EndInflate", codec.EndInflate());
return(ms.ToArray());
}
}
