/// <summary>
/// Inserts the entry into list.
/// Tries to resurrect deleted entry if possible.
/// Adds new entry if not possible. Updates data in storage.
/// Tries to do optimization on every 100 items added.
/// </summary>
private void InsertEntryIntoList([NotNull] string name, bool directory, [NotNull] Address nodeAddress)
{
uint currentBlockIndex = 0;
uint currentBlockSpace = Constants.BlockSizeBytes;
foreach (var currentEntry in _list)
{
if (currentEntry.IsDeleted && currentEntry.Name.Length >= name.Length)
{
currentEntry.Resurrect(name, directory, nodeAddress);
currentEntry.Save(DiskAccess);
return;
}
if (currentEntry.EntrySizeBytes > currentBlockSpace)
{
currentBlockIndex++;
currentBlockSpace = Constants.BlockSizeBytes;
}
currentBlockSpace -= currentEntry.EntrySizeBytes;
}
var newEntry = new DirectoryEntry { Name = name, IsDirectory = directory, NodeAddress = nodeAddress };
if (currentBlockSpace < newEntry.EntrySizeBytes)
{
currentBlockIndex++;
currentBlockSpace = Constants.BlockSizeBytes;
}
if (currentBlockIndex >= Storage.NumBlocksAllocated)
{
// should never need to allocate more than 1 block
Storage.AddBlocks(1);
}
var offset = Constants.BlockSizeBytes - currentBlockSpace;
var addr = Storage.GetBlockStartAddress(currentBlockIndex);
newEntry.EntrySelfAddress = new Address(addr.Value + offset);
newEntry.Save(DiskAccess);
var lastItem = _list.LastOrDefault();
if (lastItem != null)
{
lastItem.Next = newEntry.EntrySelfAddress;
lastItem.Save(DiskAccess);
}
_list.Add(newEntry);
UpdateSize((ulong)_list.Count); // size holds total number of entries, including deleted ones.
if (_list.Count % 100 == 0)
{
// do space optimization on every 100 files,
// to prevent attack like adding files with increasing name length.
Save();
}
}
/// <summary>
/// Overload of base load, used to load directory entries from storage.
/// </summary>
/// <exception cref="Exception">Directory entry list corrupted.</exception>
public override void Load()
{
base.Load();
// now load directory list, after loading base node info.
_list.Clear();
var address = Storage.GetBlockStartAddress(0);
var dataOffset = address.Value;
for (int i = 0; i < NumberOfEntries; ++i)
{
var entry = new DirectoryEntry();
entry.Load(dataOffset, DiskAccess);
_list.Add(entry);
dataOffset = entry.Next == null ? 0 : entry.Next.Value;
}
if (NumberOfEntries > 0 && dataOffset != 0)
{
throw new Exception("Directory entry list corrupted.");
}
}