public VirtualNode CreateFileNode(string name)
{
if (!IsDirectory)
{
throw new Exception("Must be a directory to create children!");
}
// read current list of children
LoadChildren();
// Find the first two FREE_SECTORs on the disk
int[] freeSectors = drive.GetNextFreeSectors(2);
// allocate a new FILE_NODE and DATA_SECTOR on the disk
//FILE_NODE
FILE_NODE fileSector = new FILE_NODE(drive.Disk.BytesPerSector, freeSectors[1], name, 0);
drive.Disk.WriteSector(freeSectors[0], fileSector.RawBytes);
//DATA_SECTOR
DATA_SECTOR dataSector = new DATA_SECTOR(drive.Disk.BytesPerSector, 0, new byte[] { 0 });
drive.Disk.WriteSector(freeSectors[1], dataSector.RawBytes);
// Create a new virtual node
VirtualNode newNode = new VirtualNode(drive, freeSectors[0], fileSector, this);
// Add it to its parent
children.Add(name, newNode);
CommitChildren();
return(newNode);
}
public VirtualNode CreateFileNode(string name)
{
LoadChildren(); //insure child cached is full
if (children.ContainsKey(name))
{
throw new Exception("Another child with that name already exists");
}
//where do we store new file? which sector?
//find 2 free sectors
int[] sectors = drive.GetNextFreeSectors(2);
int newFileNodeSectorAt = sectors[0];
int newFileDataSectorAt = sectors[1];
//creat new on disk
FILE_NODE newFileNodeSector = new FILE_NODE(drive.Disk.BytesPerSector, newFileDataSectorAt, name, 0);
drive.Disk.WriteSector(newFileNodeSectorAt, newFileNodeSector.RawBytes);
//creat a data sector for dir
DATA_SECTOR newFileDataSector = new DATA_SECTOR(drive.Disk.BytesPerSector, 0, null);
drive.Disk.WriteSector(newFileDataSectorAt, newFileDataSector.RawBytes);
//creat virtual node
VirtualNode newFile = new VirtualNode(drive, newFileNodeSectorAt, newFileNodeSector, this);
//add dir to parent
children.Add(name, newFile);
CommitChildren();
return(newFile);
}
public static NODE CreateFromBytes(byte[] raw)
{
switch (GetTypeFromBytes(raw))
{
case SectorType.DIR_NODE:
return(DIR_NODE.CreateFromBytes(raw));
case SectorType.FILE_NODE:
return(FILE_NODE.CreateFromBytes(raw));
}
throw new Exception("Expected a DIR_NODE or FILE_NODE!");
}
private void LoadChildren()
{
// Ensure that the children cache is correctly put in memory (i.e. reflects what's on the disk)
// Assume if the cache exsists, it is correct at the moment
// So, we need to call CommitChildren()
if (children == null)
{
// Create the cache itself
children = new Dictionary <string, VirtualNode>();
// Read the list of children for this directory from disk
// Instantiate a VirtualNode for each [child?] and add them to the children cache.
// Read the data sector for this directory
DATA_SECTOR dataSector = DATA_SECTOR.CreateFromBytes(drive.Disk.ReadSector(sector.FirstDataAt));
// Extract the list of children from the sata sector
byte[] rawList = dataSector.DataBytes;
// Foreach child in the list...
for (int i = 0; i < ChildCount; i++)
{
// Getthe child's sector address
int childSectorAt = BitConverter.ToInt32(rawList, i * 4);
// Read its sector from disk
// Check if it's a file or directory
byte[] childNodeBytes = drive.Disk.ReadSector(childSectorAt);
NODE childSector;
if (SECTOR.GetTypeFromBytes(childNodeBytes) == SECTOR.SectorType.DIR_NODE)
{
childSector = DIR_NODE.CreateFromBytes(drive.Disk.ReadSector(childSectorAt));
}
else if (SECTOR.GetTypeFromBytes(childNodeBytes) == SECTOR.SectorType.FILE_NODE)
{
childSector = FILE_NODE.CreateFromBytes(drive.Disk.ReadSector(childSectorAt));
}
else
{
throw new Exception("Unexpected sector type whe reading directory's children!");
}
// Construct a VirtualNode
VirtualNode childNode = new VirtualNode(drive, childSectorAt, childSector, this);
// Add the VirtualNode to the children cache
children.Add(childNode.Name, childNode);
}
}
}
