private IList<Segment> ReadSegments(Stream stream, Page page)
{
IList<Segment> result = new List<Segment>(page.PageSegments);
int offsetFromSegmentsTable = 0;
for (int i = 0; i < page.PageSegments; i++)
{
int read = stream.ReadByte();
if (read == -1)
throw new PrematureEndOfFileException("Could not read sufficient number of segment sizes");
var s = new Segment();
s.Size = read;
//we must include the size of segments table
s.FileOffset = m_offset + offsetFromSegmentsTable + page.PageSegments;
offsetFromSegmentsTable += read;
result.Add(s);
}
if (page.PageSegments > 0)
{
var last = result.Last();
m_offset = last.FileOffset + last.Size;
//offset from segments' table contains the first packet of net page
stream.Seek(offsetFromSegmentsTable, SeekOrigin.Current);
}
return result;
}
private Page ReadPage(Stream stream)
{
var readBytes = stream.Read(m_headerBuffer, 0, HeaderInfo.HeaderSize);
//EOF
if (readBytes == 0)
return null;
if (readBytes != HeaderInfo.HeaderSize)
throw new PrematureEndOfFileException();
var p = new Page();
p.MagicString = Encoding.ASCII.GetString(m_headerBuffer, HeaderInfo.MagicPattern, HeaderInfo.MagicPatternSize);
if (p.MagicString != HeaderInfo.MagicPatternString)
throw new InvalidMagicNumberException(p.MagicString);
p.PageType = (PageType) m_headerBuffer[HeaderInfo.HeaderType];
p.Version = m_headerBuffer[HeaderInfo.StreamStructureVersion];
p.GranulePosition = BitConverter.ToUInt64(m_headerBuffer, HeaderInfo.GranulePosition);
p.StreamSerialNumber = BitConverter.ToUInt32(m_headerBuffer, HeaderInfo.StreamSerialNumber);
p.PageNumber = BitConverter.ToUInt32(m_headerBuffer, HeaderInfo.PageNumber);
p.Checksum = BitConverter.ToUInt32(m_headerBuffer, HeaderInfo.PageChecksum);
p.PageSegments = m_headerBuffer[HeaderInfo.PageSegments];
m_offset += HeaderInfo.HeaderSize;
return p;
}
