public IndexFileNTX(Stream stream, DbfTable dbfTable, bool?skipDeleted = null, int indexPageCacheSize = 0)
: base(stream, dbfTable, skipDeleted, indexPageCacheSize) // 'stream', 'dbfTable' and 'skipDeleted' already stored by base class constructor
{
this.header = GetHeader(stream); // fill 'header' & IsStreamValid/Exception if error
Top();
}
public static NtxHeader GetHeader(Stream stream)
{
if (stream.Length < (pageSize * 2))
{
throw ExceptionFactory.CreateArgumentOutOfRangeException("stream", "NTX index stream length '{0}' < '{1}'!", stream.Length, (pageSize * 2));
}
if ((stream.Length % pageSize) != 0)
{
throw ExceptionFactory.CreateArgumentOutOfRangeException("stream", "NTX index stream length ({0}) isn't a multiple of '{1}'!", stream.Length, pageSize);
}
//
NtxHeader header = new NtxHeader();
stream.Position = 0;
BinaryReader reader = new BinaryReader(stream); // don't use 'using (BinaryReader reader...' because 'using' dispose 'stream' too!
header.signature = reader.ReadUInt16();
header.version = reader.ReadUInt16();
header.root = reader.ReadInt32();
header.unused = reader.ReadInt32();
header.itemSize = reader.ReadUInt16();
header.keySize = reader.ReadUInt16();
header.keyDec = reader.ReadUInt16();
header.maxItem = reader.ReadUInt16();
header.halfPage = reader.ReadUInt16();
header.keyExpr = reader.ReadBytes(maxKeyLen);
byte uniqueFlag = reader.ReadByte();
header.unique = (uniqueFlag != 0);
Debug.Assert(reader.BaseStream.Position == 279);
//
byte sign1Byte = (byte)(header.signature >> 8); // get first byte
if (!Array.Exists(validSignatures, s => (s == sign1Byte)))
{
throw ExceptionFactory.CreateArgumentOutOfRangeException("stream", "Signature byte of NTX index stream is invalid! '{0}'", sign1Byte);
}
byte sign2Byte = (byte)(header.signature); // cut off first byte
if (sign2Byte != 0)
{
throw ExceptionFactory.CreateArgumentOutOfRangeException("stream", "Second signature byte in NTX index stream header is invalid!'{0}'", sign2Byte);
}
if ((header.keySize < 1) || (header.keySize > 250))
{
throw ExceptionFactory.CreateArgumentOutOfRangeException("stream", "Key size in NTX index stream header is invalid!");
}
if ((header.keySize + 8) != header.itemSize)
{
throw ExceptionFactory.CreateArgumentOutOfRangeException("stream", "Key size (+8) in NTX index stream header is invalid!");
}
if (ProcessKeyExpressionBuffer(header.keyExpr) == null)
{
throw ExceptionFactory.CreateNotSupportedException("Content of key expression bytes is envalid!");
}
if (!((uniqueFlag == 0) || (uniqueFlag == 1)))
{
throw ExceptionFactory.CreateArgumentOutOfRangeException("stream", "Unique flag in NTX index stream header is invalid!");
}
//
return(header);
}
