/// <summary>
/// Reads data from the buffer or the underlying stream.
/// </summary>
/// <param name="userBuffer">The buffer to read the data to.</param>
/// <param name="offset">The offset in the buffer to write to.</param>
/// <param name="count">The number of bytes to read.</param>
/// <returns>The number of bytes actually read.</returns>
public override int Read(byte[] userBuffer, int offset, int count)
{
ExceptionUtils.CheckArgumentNotNull(userBuffer, "userBuffer");
ExceptionUtils.CheckIntegerNotNegative(offset, "offset");
ExceptionUtils.CheckIntegerPositive(count, "count");
int bytesRead = 0;
// See whether we still have buffered data and read from it if we have;
// NOTE When not reading from the buffer the currentReadNode must be null.
while (this.currentReadNode != null && count > 0)
{
byte[] currentBytes = this.currentReadNode.Value;
int bytesInCurrentBuffer = currentBytes.Length - this.positionInCurrentBuffer;
if (bytesInCurrentBuffer == count)
{
// Copy all the remaining bytes of the current buffer to the user buffer
// and move to the next buffer
Buffer.BlockCopy(currentBytes, this.positionInCurrentBuffer, userBuffer, offset, count);
bytesRead += count;
this.MoveToNextBuffer();
return(bytesRead);
}
if (bytesInCurrentBuffer > count)
{
// Copy the requested number of bytes to the user buffer
// and update the position in the current buffer
Buffer.BlockCopy(currentBytes, this.positionInCurrentBuffer, userBuffer, offset, count);
bytesRead += count;
this.positionInCurrentBuffer += count;
return(bytesRead);
}
// Copy the remaining bytes of the current buffer to the user buffer and
// move to the next buffer
Buffer.BlockCopy(currentBytes, this.positionInCurrentBuffer, userBuffer, offset, bytesInCurrentBuffer);
bytesRead += bytesInCurrentBuffer;
offset += bytesInCurrentBuffer;
count -= bytesInCurrentBuffer;
this.MoveToNextBuffer();
}
// When we get here we either could not satisfy the requested number of bytes
// from the buffers or are in buffering mode.
Debug.Assert(this.currentReadNode == null, "No current read node should exist if we are not working off the buffers.");
int bytesReadFromInnerStream = this.innerStream.Read(userBuffer, offset, count);
// If we are in buffering mode, store the read bytes in our buffer
if (!this.bufferingModeDisabled && bytesReadFromInnerStream > 0)
{
byte[] newDataBuffer = new byte[bytesReadFromInnerStream];
Buffer.BlockCopy(userBuffer, offset, newDataBuffer, 0, bytesReadFromInnerStream);
this.buffers.AddLast(newDataBuffer);
}
return(bytesRead + bytesReadFromInnerStream);
}