@Override
public void reposition(long id)
{
if ( allocBlock != null )
throw new StorageException("In the middle of an alloc-write") ;
int newSize = (int)id ;
if ( newSize < 0 || newSize > buffers.size() )
// Can reposition to the end of the file.
throw new StorageException() ;
if ( newSize == buffers.size() )
return ;
List<ByteBuffer> buffers2 = new ArrayList<ByteBuffer>(newSize) ;
for ( int i = 0 ; i < id ; i++ )