private ExtentBlock LoadExtentBlock(ExtentIndex idxEntry)
{
uint blockSize = _context.SuperBlock.BlockSize;
_context.RawStream.Position = idxEntry.LeafPhysicalBlock * blockSize;
byte[] buffer = Utilities.ReadFully(_context.RawStream, (int)blockSize);
ExtentBlock subBlock = Utilities.ToStruct <ExtentBlock>(buffer, 0);
return(subBlock);
}
public int ReadFrom(byte[] buffer, int offset)
{
Mode = Utilities.ToUInt16LittleEndian(buffer, offset + 0);
UserIdLow = Utilities.ToUInt16LittleEndian(buffer, offset + 2);
FileSize = Utilities.ToUInt32LittleEndian(buffer, offset + 4);
AccessTime = Utilities.ToUInt32LittleEndian(buffer, offset + 8);
CreationTime = Utilities.ToUInt32LittleEndian(buffer, offset + 12);
ModificationTime = Utilities.ToUInt32LittleEndian(buffer, offset + 16);
DeletionTime = Utilities.ToUInt32LittleEndian(buffer, offset + 20);
GroupIdLow = Utilities.ToUInt16LittleEndian(buffer, offset + 24);
LinksCount = Utilities.ToUInt16LittleEndian(buffer, offset + 26);
BlocksCount = Utilities.ToUInt32LittleEndian(buffer, offset + 28);
Flags = (InodeFlags)Utilities.ToUInt32LittleEndian(buffer, offset + 32);
FastSymlink = null;
Extents = null;
DirectBlocks = null;
if (FileType == UnixFileType.Link && BlocksCount == 0)
{
FastSymlink = new byte[60];
Array.Copy(buffer, offset + 40, FastSymlink, 0, 60);
}
else if ((Flags & InodeFlags.ExtentsUsed) != 0)
{
Extents = Utilities.ToStruct <ExtentBlock>(buffer, offset + 40);
}
else
{
DirectBlocks = new uint[12];
for (int i = 0; i < 12; ++i)
{
DirectBlocks[i] = Utilities.ToUInt32LittleEndian(buffer, offset + 40 + (i * 4));
}
IndirectBlock = Utilities.ToUInt32LittleEndian(buffer, offset + 88);
DoubleIndirectBlock = Utilities.ToUInt32LittleEndian(buffer, offset + 92);
TripleIndirectBlock = Utilities.ToUInt32LittleEndian(buffer, offset + 96);
}
FileVersion = Utilities.ToUInt32LittleEndian(buffer, offset + 100);
FileAcl = Utilities.ToUInt32LittleEndian(buffer, offset + 104);
DirAcl = Utilities.ToUInt32LittleEndian(buffer, offset + 108);
FragAddress = Utilities.ToUInt32LittleEndian(buffer, offset + 112);
Fragment = buffer[offset + 116];
FragmentSize = buffer[offset + 117];
UserIdHigh = Utilities.ToUInt16LittleEndian(buffer, offset + 120);
GroupIdHigh = Utilities.ToUInt16LittleEndian(buffer, offset + 122);
return(128);
}
public override int Read(long pos, byte[] buffer, int offset, int count)
{
if (pos > _inode.FileSize)
{
return(0);
}
long blockSize = _context.SuperBlock.BlockSize;
int totalRead = 0;
int totalBytesRemaining = (int)Math.Min(count, _inode.FileSize - pos);
ExtentBlock extents = _inode.Extents;
while (totalBytesRemaining > 0)
{
uint logicalBlock = (uint)((pos + totalRead) / blockSize);
int blockOffset = (int)((pos + totalRead) - (logicalBlock * blockSize));
int numRead = 0;
Extent extent = FindExtent(extents, logicalBlock);
if (extent == null)
{
throw new IOException("Unable to find extent for block " + logicalBlock);
}
else if (extent.FirstLogicalBlock > logicalBlock)
{
numRead = (int)Math.Min(totalBytesRemaining, ((extent.FirstLogicalBlock - logicalBlock) * blockSize) - blockOffset);
Array.Clear(buffer, offset + totalRead, numRead);
}
else
{
long physicalBlock = (logicalBlock - extent.FirstLogicalBlock) + (long)extent.FirstPhysicalBlock;
int toRead = (int)Math.Min(totalBytesRemaining, ((extent.NumBlocks - (logicalBlock - extent.FirstLogicalBlock)) * blockSize) - blockOffset);
_context.RawStream.Position = (physicalBlock * blockSize) + blockOffset;
numRead = _context.RawStream.Read(buffer, offset + totalRead, toRead);
}
totalBytesRemaining -= numRead;
totalRead += numRead;
}
return(totalRead);
}
private Extent FindExtent(ExtentBlock node, uint logicalBlock)
{
if (node.Index != null)
{
ExtentIndex idxEntry = null;
if (node.Index.Length == 0)
{
return(null);
}
else if (node.Index[0].FirstLogicalBlock >= logicalBlock)
{
idxEntry = node.Index[0];
}
else
{
for (int i = 0; i < node.Index.Length; ++i)
{
if (node.Index[i].FirstLogicalBlock > logicalBlock)
{
idxEntry = node.Index[i - 1];
break;
}
}
}
if (idxEntry == null)
{
idxEntry = node.Index[node.Index.Length - 1];
}
ExtentBlock subBlock = LoadExtentBlock(idxEntry);
return(FindExtent(subBlock, logicalBlock));
}
else if (node.Extents != null)
{
Extent entry = null;
if (node.Extents.Length == 0)
{
return(null);
}
else if (node.Extents[0].FirstLogicalBlock >= logicalBlock)
{
return(node.Extents[0]);
}
else
{
for (int i = 0; i < node.Extents.Length; ++i)
{
if (node.Extents[i].FirstLogicalBlock > logicalBlock)
{
entry = node.Extents[i - 1];
break;
}
}
}
if (entry == null)
{
entry = node.Extents[node.Extents.Length - 1];
}
return(entry);
}
else
{
return(null);
}
}