public override void SetLength(long value)
{
long desiredNumClusters = (value + _reader.ClusterSize - 1) / _reader.ClusterSize;
long actualNumClusters = (_length + _reader.ClusterSize - 1) / _reader.ClusterSize;
if (desiredNumClusters < actualNumClusters)
{
uint cluster;
if (!TryGetClusterByPosition(value, out cluster))
{
throw new IOException("Internal state corrupt - unable to find cluster");
}
uint firstToFree = _fat.GetNext(cluster);
_fat.SetEndOfChain(cluster);
_fat.FreeChain(firstToFree);
while (_knownClusters.Count > desiredNumClusters)
{
_knownClusters.RemoveAt(_knownClusters.Count - 1);
}
_knownClusters.Add(FatBuffer.EndOfChain);
if (desiredNumClusters == 0)
{
FireFirstClusterAllocated(0);
}
}
else if (desiredNumClusters > actualNumClusters)
{
uint cluster;
while (!TryGetClusterByPosition(value, out cluster))
{
cluster = ExtendChain();
_reader.WipeCluster(cluster);
}
}
if (_length != value)
{
_length = (uint)value;
if (_position > _length)
{
_position = _length;
}
}
}
