/// <summary>
/// ctor: Create class from data returned by the Reader
/// </summary>
/// <param name="reader">A binary data reader for this type of data - positioned at last page</param>
public p4kEndOfCentralDirRecord(p4kRecReader reader)
{
// sanity check only
System.Diagnostics.Trace.Assert(Marshal.SizeOf(typeof(MyRecord)) == RecordLength,
"Record size does not match!(" + Marshal.SizeOf(typeof(MyRecord)).ToString( ) + ")");
if (reader.IsOpen( ))
{
try {
long thisPos = 0;
// 20180804BM- fix when the last page is barely used and the sig is one or more pages before
// - backup one or more pages to find end of dir (max 10 times)
int tries = 10;
while (!m_itemValid && (tries > 0))
{
thisPos = reader.Position;
long cPos = p4kSignatures.FindSignatureInPage(reader, p4kSignatures.EndOfCentralDirRecord);
if (cPos >= 0)
{
m_recordOffset = cPos;
reader.Seek(cPos);
m_item = p4kRecReader.ByteToType <MyRecord>(reader.TheReader);
m_itemValid = true;
}
else
{
// backup one page again
reader.Seek(thisPos);
reader.BackwardPage( );
tries--;
}
}
}
catch {
m_itemValid = false;
m_recordOffset = -1;
}
finally {
if (!m_itemValid)
{
throw new OperationCanceledException(string.Format("EOF - cannot find EndOfCentralDirRecord"));
}
}
}
}
