public static DiskImage Create(DiskImage hdd)
{
byte[] headBytes = hdd.ReadBytes(hdd.Length - 512, 512);
VhdHeader head = Program.ToStructFromBigEndian <VhdHeader>(headBytes);
if (head.CookieStr != "conectix")
{
throw new Exception("missing magic string");
}
if (head.FileFormatVersion != 0x00010000)
{
throw new Exception("upsupported version");
}
//TODO: validate checksum
if (head.DiskType == DiskType.Fixed)
{
return(new FixedVhd(hdd, in head));
}
else if (head.DiskType == DiskType.Dynamic)
{
return(new DynamicVhd(hdd, in head));
}
else
{
throw new Exception("Only fixed size VHDs are supported.");
}
}
void readBlock(Span <byte> array, long blockOffset, int blockStartNdx)
{
if (blockOffset == -1)
{
array.Fill(0);
}
else
{
mHdd.ReadBytes(array, blockOffset + blockStartNdx);
}
}
unsafe public VdiDiskImage(DiskImage hdd)
: base(hdd)
{
var headBytes = hdd.ReadBytes(0, sizeof(VdiHeader));
VdiHeader head = Program.ToStruct <VdiHeader>(headBytes);
if (head.ImageSig != VdiMagic)
{
throw new Exception("Wrong magic.");
}
if (head.Version != VdiVersion)
{
throw new Exception("Wrong version.");
}
if (head.SizeOfHeader != VdiHeadSize)
{
throw new Exception("Wrong size.");
}
if (head.ImageType != ImageType.Dynamic)
{
throw new NotImplementedException("Only dynamic is supported.");
}
var dataOffset = head.OffsetData;
mBlockOffsets = new long[head.BlocksInHdd];
mBlockSize = (int)head.BlockSize;
for (long i = 0; i < head.BlocksInHdd; i++)
{
uint blockLoc;
hdd.Get <uint>(head.OffsetBlocks + i * 4, out blockLoc);
if (blockLoc == ~0u)
{
mBlockOffsets[i] = -1;
}
else
{
mBlockOffsets[i] = dataOffset + blockLoc * mBlockSize;
}
}
}
public override void ReadBytes(Span <byte> dest, long offset)
{
CheckOffsets(offset, dest.Length);
mHdd.ReadBytes(dest, mOffset + offset);
}