public static NdxHeader GetHeader(Stream stream)
{
if (stream.Length < (pageSize * 2))
{
throw ExceptionFactory.CreateArgumentOutOfRangeException("stream", "NDX index stream length '{0}' < '{1}'!", stream.Length, (pageSize * 2));
}
if ((stream.Length % pageSize) != 0)
{
throw ExceptionFactory.CreateArgumentOutOfRangeException("stream", "NDX index stream length ({0}) isn't a multiple of '{1}'!", stream.Length, pageSize);
}
//
NdxHeader header = new NdxHeader();
stream.Position = 0;
BinaryReader reader = new BinaryReader(stream); // don't use 'using (BinaryReader reader...' because 'using' dispose 'stream' too!
header.rootPage = reader.ReadInt32();
header.totalPages = reader.ReadInt32();
reader.ReadInt32(); // reserved space
header.keyLen = reader.ReadUInt16();
header.keyPages = reader.ReadUInt16();
header.keyType = reader.ReadUInt16();
header.keyRecSize = reader.ReadInt32(); // Size of key record is a multiplum of 4. Record size is 4 (Pointer to next page) + 4 (record number i dbf) + key size ( as a multiplum of 4 ). i.e. if the key size is 10, the record size is 20 (4+4+12)
{
int extraSpace = header.keyLen % 4;
if (extraSpace != 0)
{
extraSpace += (4 - extraSpace);
}
header.keyRecSize = 4 + 4 + header.keyLen + extraSpace; // rewrite readed value because it was a not valid value
}
reader.ReadByte(); // reserved space
header.unique = reader.ReadBoolean();
header.keyExpr = reader.ReadBytes(maxKeyLen);
if (ProcessKeyExpressionBuffer(header.keyExpr) == null)
{
throw ExceptionFactory.CreateNotSupportedException("Content of NDX key expression bytes is envalid!");
}
return(header);
}
public IndexFileNDX(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
//
#if DEBUG
List <string> list = new List <string>();
for (int i = 1; (i < this.header.totalPages); i++)
{
list.Add(String.Empty);
list.Add(String.Format("*** Page {0} *** {1}", i, (i == this.header.rootPage) ? "[ROOT]" : ""));
var keyPages = KeyPageRead(i);
foreach (var kp in keyPages)
{
string line = String.Empty;
if (kp.leftPage > 0)
{
line = String.Format(">>page {0}: '", kp.leftPage);
}
else if (kp.recNo > 0)
{
line = String.Format("{0,5} rec: '", kp.recNo);
}
line += _dbfTable.parametersReadOnly.encoding.GetString(kp.key) + "'";
list.Add(line);
}
}
File.WriteAllLines(@".\IndexPages.txt", list, _dbfTable.parametersReadOnly.encoding);
#endif
}
