/// <inheritdoc />
/// <summary>
/// Sets the next cluster.
/// </summary>
/// <param name="cluster">The cluster.</param>
/// <param name="nextCluster">The next cluster.</param>
public void SetNextCluster(Cluster cluster, Cluster nextCluster)
{
lock (_fatLock)
{
// the only point is to avoid writing to virtual hard disk, which may be sparse and handle sparseness more or less efficiently...
var fatPage = GetFatPage(cluster);
var clusterIndex = (int)(cluster.Value % ClustersPerFatPage);
var b = LittleEndian.GetBytes((UInt32)nextCluster.Value);
var fatPageOffset = clusterIndex * sizeof(UInt32);
if (b[0] == fatPage[fatPageOffset] && b[1] == fatPage[fatPageOffset + 1] && b[2] == fatPage[fatPageOffset + 2] && b[3] == fatPage[fatPageOffset + 3])
{
return;
}
Buffer.BlockCopy(b, 0, fatPage, fatPageOffset, sizeof(Int32));
_fatPageDirty = true;
if (!_options.HasAny(ExFatOptions.DelayWrite))
{
FlushFatPage();
}
}
}
private void UpdateEntry(ExFatFilesystemEntry entry, FileAccess fileAccess, DataDescriptor dataDescriptor)
{
if (entry?.MetaEntry == null)
{
return;
}
DateTimeOffset?now = null;
var file = (FileExFatDirectoryEntry)entry.MetaEntry.Primary;
// if file was open for reading and the flag is set, the entry is updated
if (fileAccess.HasAny(FileAccess.Read) && _options.HasAny(ExFatOptions.UpdateLastAccessTime))
{
now = DateTimeOffset.Now;
file.LastAccessDateTimeOffset.Value = now.Value;
}
// when it was open for writing, its characteristics may have changed, so we update them
if (fileAccess.HasAny(FileAccess.Write))
{
now = now ?? DateTimeOffset.Now;
file.FileAttributes.Value |= ExFatFileAttributes.Archive;
file.LastWriteDateTimeOffset.Value = now.Value;
var stream = entry.MetaEntry.SecondaryStreamExtension;
if (dataDescriptor.Contiguous)
{
stream.GeneralSecondaryFlags.Value |= ExFatGeneralSecondaryFlags.NoFatChain;
}
else
{
stream.GeneralSecondaryFlags.Value &= ~ExFatGeneralSecondaryFlags.NoFatChain;
}
stream.FirstCluster.Value = (UInt32)dataDescriptor.FirstCluster.Value;
stream.ValidDataLength.Value = dataDescriptor.LogicalLength;
stream.DataLength.Value = dataDescriptor.PhysicalLength;
}
// now has value only if it was used before, so we spare a flag :)
if (now.HasValue)
{
Update(entry);
}
}
