/// <summary>
/// Reads in a block from a file.
/// </summary>
/// <param name="a_block">Contains parameters to the blocks location.</param>
/// <param name="a_torrent">The torrent file that contains save directory,
/// the file name, and the piece length needed to read the block.
/// </param>
/// <returns>Returns a byte array containing the block requested.</returns>
/// <remarks>
/// ReadBlock()
///
/// SYNOPSIS
///
/// byte[] ReadBlock(OutgoingBlock a_block, Torrent a_torrent);
///
/// DESCRIPTION
///
/// This function will read in the block at the specified piece index,
/// beginning offset. It will return a byte array with the block to
/// be used when sending a piece to a peer.
///
/// </remarks>
public static byte[] ReadBlock(OutgoingBlock a_block, Torrent a_torrent)
{
string file = a_torrent.SaveDirectory + "\\" + a_torrent.Name;
var block = new byte[a_torrent.ComputePieceLength(a_block.Index)];
using (var filestream = new FileStream(file, FileMode.Open, FileAccess.Read))
{
filestream.Position = a_block.Index * a_torrent.PieceLength + a_block.Begin;
filestream.Read(block, 0, (int)a_block.Length);
}
return(block);
}
