/// <summary>Reads and returns the header page (page 0) from the given pageChannel.</summary>
/// <remarks>Reads and returns the header page (page 0) from the given pageChannel.</remarks>
/// <exception cref="System.IO.IOException"></exception>
protected internal static ByteBuffer ReadHeaderPage(PageChannel pageChannel)
{
ByteBuffer buffer = pageChannel.CreatePageBuffer();
pageChannel.ReadPage(buffer, 0);
return(buffer);
}
/// <summary>
/// <inheritDoc></inheritDoc>
/// <p>
/// This implementation returns DUMMY_HANDLER for databases with no encoding
/// and UNSUPPORTED_HANDLER for databases with any encoding.
/// </summary>
/// <exception cref="System.IO.IOException"></exception>
public virtual CodecHandler CreateHandler(PageChannel channel, Encoding charset)
{
JetFormat format = channel.GetFormat();
switch (format.CODEC_TYPE)
{
case JetFormat.CodecType.NONE:
{
// no encoding, all good
return(DUMMY_HANDLER);
}
case JetFormat.CodecType.JET:
{
// check for an encode key. if 0, not encoded
ByteBuffer bb = channel.CreatePageBuffer();
channel.ReadPage(bb, 0);
int codecKey = bb.GetInt(format.OFFSET_ENCODING_KEY);
return((codecKey == 0) ? DUMMY_HANDLER : UNSUPPORTED_HANDLER);
}
case JetFormat.CodecType.MSISAM:
{
// always encoded, we don't handle it
return(UNSUPPORTED_HANDLER);
}
default:
{
throw new RuntimeException("Unknown codec type " + format.CODEC_TYPE);
}
}
}
/// <param name="database">database that contains this usage map</param>
/// <param name="pageNum">Page number that this usage map is contained in</param>
/// <param name="rowNum">Number of the row on the page that contains this usage map</param>
/// <returns>
/// Either an InlineUsageMap or a ReferenceUsageMap, depending on
/// which type of map is found
/// </returns>
/// <exception cref="System.IO.IOException"></exception>
public static HealthMarketScience.Jackcess.UsageMap Read(Database database, int pageNum
, int rowNum, bool assumeOutOfRangeBitsOn)
{
JetFormat format = database.GetFormat();
PageChannel pageChannel = database.GetPageChannel();
ByteBuffer tableBuffer = pageChannel.CreatePageBuffer();
pageChannel.ReadPage(tableBuffer, pageNum);
short rowStart = Table.FindRowStart(tableBuffer, rowNum, format);
int rowEnd = Table.FindRowEnd(tableBuffer, rowNum, format);
tableBuffer.Limit(rowEnd);
byte mapType = tableBuffer.Get(rowStart);
HealthMarketScience.Jackcess.UsageMap rtn = new HealthMarketScience.Jackcess.UsageMap
(database, tableBuffer, pageNum, rowStart);
rtn.InitHandler(mapType, assumeOutOfRangeBitsOn);
return(rtn);
}