public static async Task <IEnumerable <LoadSegBlock> > Read(
RigidDiskBlock rigidDiskBlock, FileSystemHeaderBlock fileSystemHeaderBlock, Stream stream)
{
var loadSegBlocks = new List <LoadSegBlock>();
var segListBlock = fileSystemHeaderBlock.SegListBlocks;
do
{
// calculate seg list block offset
var segListBlockOffset = rigidDiskBlock.BlockSize * segListBlock;
// seek partition block offset
stream.Seek(segListBlockOffset, SeekOrigin.Begin);
// read block
var block = await BlockHelper.ReadBlock(stream);
// parse file system header block
var loadSegBlock = await Parse(block);
loadSegBlocks.Add(loadSegBlock);
// get next partition list block and increase partition number
segListBlock = loadSegBlock.NextLoadSegBlock;
} while (segListBlock > 0);
return(loadSegBlocks);
}
public static void ResetFileSystemHeaderBlockPointers(FileSystemHeaderBlock fileSystemHeaderBlock)
{
fileSystemHeaderBlock.NextFileSysHeaderBlock = 0;
fileSystemHeaderBlock.SegListBlocks = 0;
foreach (var loadSegBlock in fileSystemHeaderBlock.LoadSegBlocks)
{
ResetLoadSegBlockPointers(loadSegBlock);
}
}
public static async Task <byte[]> BuildBlock(FileSystemHeaderBlock fileSystemHeaderBlock)
{
var blockStream =
new MemoryStream(
fileSystemHeaderBlock.BlockBytes == null || fileSystemHeaderBlock.BlockBytes.Length == 0
? new byte[BlockSize.FileSystemHeaderBlock * 4]
: fileSystemHeaderBlock.BlockBytes);
await blockStream.WriteAsciiString(BlockIdentifiers.FileSystemHeaderBlock);
await blockStream.WriteLittleEndianUInt32(BlockSize.FileSystemHeaderBlock); // size
// skip checksum, calculated when block is built
blockStream.Seek(4, SeekOrigin.Current);
await blockStream.WriteLittleEndianUInt32(fileSystemHeaderBlock
.HostId); // SCSI Target ID of host, not really used
await blockStream.WriteLittleEndianUInt32(fileSystemHeaderBlock
.NextFileSysHeaderBlock); // Block number of the next FileSysHeaderBlock
await blockStream.WriteLittleEndianUInt32(fileSystemHeaderBlock.Flags); // Flags
// skip reserved
blockStream.Seek(4 * 2, SeekOrigin.Current);
await blockStream
.WriteBytes(fileSystemHeaderBlock
.DosType); // # Dostype of the file system, file system description: match this with partition environment's DE_DOSTYPE entry
await blockStream.WriteLittleEndianUInt32(fileSystemHeaderBlock
.Version); // filesystem version 0x0027001b == 39.27
await blockStream.WriteLittleEndianUInt32(fileSystemHeaderBlock.PatchFlags);
await blockStream.WriteLittleEndianUInt32(fileSystemHeaderBlock.Type);
await blockStream.WriteLittleEndianUInt32(fileSystemHeaderBlock.Task);
await blockStream.WriteLittleEndianUInt32(fileSystemHeaderBlock.Lock);
await blockStream.WriteLittleEndianUInt32(fileSystemHeaderBlock.Handler);
await blockStream.WriteLittleEndianUInt32(fileSystemHeaderBlock.StackSize);
await blockStream.WriteLittleEndianInt32(fileSystemHeaderBlock.Priority);
await blockStream.WriteLittleEndianInt32(fileSystemHeaderBlock.Startup);
await blockStream.WriteLittleEndianInt32(fileSystemHeaderBlock
.SegListBlocks); // first of linked list of LoadSegBlocks
await blockStream.WriteLittleEndianInt32(fileSystemHeaderBlock.GlobalVec);
// skip reserved
blockStream.Seek((23 + 21) * 4, SeekOrigin.Current);
// calculate and update checksum
var blockBytes = blockStream.ToArray();
fileSystemHeaderBlock.Checksum = await BlockHelper.UpdateChecksum(blockBytes, 8);
fileSystemHeaderBlock.BlockBytes = blockBytes;
return(blockBytes);
}
