/// <summary>
/// Reads the specified number of bytes from the current position.
/// </summary>
public override int Read(byte[] buffer, int offset, int count)
{
if (count <= 0)
{
return(0);
}
try
{
var rangeToRead = IndexRange.FromLength(this.position, count);
int writtenCount = 0;
if (fileDataRange.Intersection(rangeToRead) == null)
{
int readCountFromFooter;
if (TryReadFromFooter(rangeToRead, buffer, offset, out readCountFromFooter))
{
writtenCount += readCountFromFooter;
}
return(writtenCount);
}
rangeToRead = fileDataRange.Intersection(rangeToRead);
var startingBlock = ByteToBlock(rangeToRead.StartIndex);
var endingBlock = ByteToBlock(rangeToRead.EndIndex);
for (var blockIndex = startingBlock; blockIndex <= endingBlock; blockIndex++)
{
var currentBlock = blockFactory.Create(blockIndex);
var rangeToReadInBlock = currentBlock.LogicalRange.Intersection(rangeToRead);
var copyStartIndex = rangeToReadInBlock.StartIndex % blockFactory.GetBlockSize();
Buffer.BlockCopy(currentBlock.Data, (int)copyStartIndex, buffer, offset + writtenCount, (int)rangeToReadInBlock.Length);
writtenCount += (int)rangeToReadInBlock.Length;
}
this.position += writtenCount;
return(writtenCount);
}
catch (Exception e)
{
throw new VhdParsingException("Invalid or Corrupted VHD file", e);
}
}