public unsafe zio_cksum_t Calculate(ArraySegment <byte> input)
{
if (input.Count % 4 != 0)
{
throw new ArgumentException("Input must have a length that is a multiple of 4.");
}
ulong a, b, c, d;
a = b = c = d = 0;
fixed(byte *ptr = input.Array)
{
int size = input.Count / 4;
uint *intPtr = (uint *)(ptr + input.Offset);
for (int i = 0; i < size; i++)
{
a += intPtr[i];
b += a;
c += b;
d += c;
}
}
zio_cksum_t ret = new zio_cksum_t()
{
word1 = a,
word2 = b,
word3 = c,
word4 = d
};
return(ret);
}
public unsafe static bool IsEmbeddedChecksumValid(ArraySegment <byte> bytes, zio_cksum_t verifier)
{
int embeddedChecksumSize = sizeof(zio_eck_t);
if (bytes.Count <= embeddedChecksumSize)
{
throw new ArgumentOutOfRangeException(nameof(bytes), "Not enough space for an embedded checksum.");
fixed(byte *bytePtr = bytes.Array)
{
zio_eck_t *pzec = (zio_eck_t *)(bytePtr + bytes.Offset + bytes.Count - embeddedChecksumSize);
if (!pzec->IsMagicValid)
{
return(false);
}
var expectedChecksum = pzec->zec_cksum;
pzec->zec_cksum = verifier;
var actualChecksum = sEmbeddedChecksum.Calculate(bytes);
pzec->zec_cksum = expectedChecksum;
return(actualChecksum.Equals(expectedChecksum));
}
}
const int SPA_MINBLOCKSHIFT = 9;
private static zio_cksum_t CalculateGangChecksumVerifier(ref blkptr_t blkptr)
{
var ret = new zio_cksum_t();
ret.word1 = (ulong)blkptr.dva1.VDev;
ret.word2 = (ulong)(blkptr.dva1.Offset << SPA_MINBLOCKSHIFT);
ret.word3 = (ulong)blkptr.PhysBirth;
ret.word4 = 0;
return(ret);
}
/// <summary>
/// Reads and verifies data from a label.
/// </summary>
/// <param name="offset"></param>
/// <param name="count"></param>
/// <returns>true if the checksum is valid, false otherwise</returns>
public bool ReadLabelBytes(ArraySegment <byte> dest, long offset)
{
ReadBytes(dest, offset);
var verifier = new zio_cksum_t()
{
word1 = (ulong)offset,
word2 = 0,
word3 = 0,
word4 = 0,
};
return(Zio.IsEmbeddedChecksumValid(dest, verifier));
}