/// <summary>
/// Read data from the stream into the specified buffer and increment the stream position.
/// </summary>
/// <param name="buffer">Byte array to use as a buffer.</param>
/// <param name="offset">The offset within the buffer indicating where to copy the read data.</param>
/// <param name="count">The number of bytes to populate within the buffer.</param>
/// <returns>An integer representing the number of bytes read.</returns>
public override int Read(byte[] buffer, int offset, int count)
{
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}
if (offset < 0)
{
throw new ArgumentOutOfRangeException("Offset must be zero or greater.");
}
if (count < 0)
{
throw new ArgumentOutOfRangeException("Count must be zero or greater.");
}
if ((offset + count) > buffer.Length)
{
throw new ArgumentOutOfRangeException("Offset and count combined must not exceed buffer length.");
}
if (offset >= Length)
{
return(0);
}
DedupeObjectMap map = _Database.GetObjectMapForPosition(_Metadata.Key, _Position);
if (map == null)
{
return(0);
}
if (map.ChunkAddress > Position)
{
throw new IOException("Data error while reading chunks from object.");
}
byte[] chunkData = _Callbacks.ReadChunk(map.ChunkKey);
int chunkDataReadStart = 0;
if (map.ChunkAddress < Position)
{
chunkDataReadStart += (int)(Position - map.ChunkAddress);
}
int bytesAvailInChunk = (int)(map.ChunkLength - chunkDataReadStart);
if (count >= bytesAvailInChunk)
{
Buffer.BlockCopy(chunkData, chunkDataReadStart, buffer, offset, bytesAvailInChunk);
_Position += bytesAvailInChunk;
return(bytesAvailInChunk);
}
else
{
Buffer.BlockCopy(chunkData, chunkDataReadStart, buffer, offset, count);
_Position += count;
return(count);
}
}
private List <DedupeChunk> ChunkStream(string key, long contentLength, Stream stream, Action <DedupeChunk, DedupeObjectMap> processChunk)
{
if (String.IsNullOrEmpty(key))
{
throw new ArgumentNullException(nameof(key));
}
if (contentLength < 1)
{
throw new ArgumentException("Content length must be greater than zero.");
}
if (stream == null)
{
throw new ArgumentNullException(nameof(stream));
}
if (!stream.CanRead)
{
throw new ArgumentException("Cannot read from supplied stream.");
}
if (processChunk == null)
{
throw new ArgumentNullException(nameof(processChunk));
}
#region Initialize
List <DedupeChunk> chunks = new List <DedupeChunk>();
DedupeObjectMap map = null;
DedupeChunk chunk = null;
long bytesRead = 0;
string chunkKey = null;
#endregion
if (contentLength <= _Settings.MinChunkSize)
{
#region Single-Chunk
byte[] chunkData = DedupeCommon.ReadBytesFromStream(stream, contentLength, out bytesRead);
chunkKey = DedupeCommon.BytesToBase64(DedupeCommon.Sha256(chunkData));
chunk = new DedupeChunk(chunkKey, chunkData.Length, 1, chunkData);
chunks.Add(chunk);
map = new DedupeObjectMap(key, chunkKey, chunk.Length, 0, 0);
processChunk(chunk, map);
return(chunks);
#endregion
}
else
{
#region Sliding-Window
Streams streamWindow = new Streams(stream, contentLength, _Settings.MinChunkSize, _Settings.ShiftCount);
byte[] chunkData = null;
long chunkAddress = 0; // should only be set at the beginning of a new chunk
while (true)
{
byte[] newData = null;
bool finalChunk = false;
long tempPosition = 0;
byte[] window = streamWindow.GetNextChunk(out tempPosition, out newData, out finalChunk);
if (window == null)
{
return(chunks);
}
if (chunkData == null)
{
chunkAddress = tempPosition;
}
if (chunkData == null)
{
// starting a new chunk
chunkData = new byte[window.Length];
Buffer.BlockCopy(window, 0, chunkData, 0, window.Length);
}
else
{
// append new data
chunkData = DedupeCommon.AppendBytes(chunkData, newData);
}
byte[] md5Hash = DedupeCommon.Md5(window);
if (DedupeCommon.IsZeroBytes(md5Hash, _Settings.BoundaryCheckBytes) ||
chunkData.Length >= _Settings.MaxChunkSize)
{
#region Chunk-Boundary
chunkKey = DedupeCommon.BytesToBase64(DedupeCommon.Sha256(chunkData));
chunk = new DedupeChunk(chunkKey, chunkData.Length, 1, chunkData);
map = new DedupeObjectMap(key, chunk.Key, chunkData.Length, chunks.Count, chunkAddress);
processChunk(chunk, map);
chunk.Data = null;
chunks.Add(chunk);
chunk = null;
chunkData = null;
streamWindow.AdvanceToNewChunk();
#endregion
}
else
{
// do nothing, continue;
}
if (finalChunk)
{
#region Final-Chunk
if (chunkData != null)
{
chunkKey = DedupeCommon.BytesToBase64(DedupeCommon.Sha256(chunkData));
chunk = new DedupeChunk(chunkKey, chunkData.Length, 1, chunkData);
map = new DedupeObjectMap(key, chunk.Key, chunk.Length, chunks.Count, chunkAddress);
processChunk(chunk, map);
chunk.Data = null;
chunks.Add(chunk);
break;
}
#endregion
}
}
#endregion
}
return(chunks);
}
