blockSize := aes.BlockSize
	paddingSize := blockSize - (len(data) % blockSize)
	result := make([]byte, blockSize+len(data)+paddingSize)
	iv := result[:blockSize]
	if _, err := io.ReadFull(rand.Reader, iv); err != nil {
		return nil, errors.New("unable to read sufficient random bytes")
	}
	copy(result[blockSize:], data)

	// add PKCS#7 padding for CBC

	hkey := bytes.Clone(key)
	hmac := &boringHMAC{
		md:        md,
		size:      ch.Size(),
		blockSize: ch.BlockSize(),
		key:       hkey,
	}
	hmac.Reset()
	return hmac
}

type boringHMAC struct {
	md          *C.GO_EVP_MD
	ctx         C.GO_HMAC_CTX
	ctx2        C.GO_HMAC_CTX
	size        int
	blockSize   int
	key         []byte
	sum         []byte
	needCleanup bool
}

		numBlocks := (len(src) + blockSize - 1) / blockSize
		buf := s.buf[bufSize-numBlocks*blockSize:]
		copy(buf, src)
		s.xorKeyStreamBlocksGeneric(buf, buf)
		s.len = len(buf) - copy(dst, buf)
		return
	}

	// If we have a partial (multi-)block, pad it for xorKeyStreamBlocks, and
	// keep the leftover keystream for the next XORKeyStream invocation.
	if len(src) > 0 {
		s.buf = [bufSize]byte{}
		copy(s.buf[:], src)

// using a given key. It provides the capability to encrypt
// or decrypt individual blocks. The mode implementations
// extend that capability to streams of blocks.
type Block interface {
	// BlockSize returns the cipher's block size.
	BlockSize() int

	// Encrypt encrypts the first block in src into dst.
	// Dst and src must overlap entirely or not at all.
	Encrypt(dst, src []byte)

	// Decrypt decrypts the first block in src into dst.

					testReadFrom{fileOps{
						int64(1e10 - blockSize),
						strings.Repeat("\x00", blockSize-100) + strings.Repeat("0123456789", 10),
						int64(1e10 - blockSize),
						strings.Repeat("\x00", blockSize-100) + strings.Repeat("0123456789", 10),
						int64(1e10 - blockSize),
						strings.Repeat("\x00", blockSize-100) + strings.Repeat("0123456789", 10),
						int64(1e10 - blockSize),

			unique = false
		}
	}()
	if !unique {
		panic("crypto/hmac: hash generation function does not produce unique values")
	}
	blocksize := hm.inner.BlockSize()
	hm.ipad = make([]byte, blocksize)
	hm.opad = make([]byte, blocksize)
	if len(key) > blocksize {
		// If key is too big, hash it.
		hm.outer.Write(key)
		key = hm.outer.Sum(nil)
	}
	copy(hm.ipad, key)
	copy(hm.opad, key)

			blockLength = e.blockSize - blockOffset
		case block == endBlock:
			blockOffset = 0
			blockLength = (offset + length) % e.blockSize
		default:
			blockOffset = 0
			blockLength = e.blockSize
		}
		if blockLength == 0 {
			break
		}

		var err error
		bufs, err = reader.Read(bufs)
		if len(bufs) > 0 {
			// Set only if there are be enough data for reconstruction.

		values[2], values[3] = scaleHeapSample(r.InUseObjects(), r.InUseBytes(), rate)
		var blockSize int64
		if r.AllocObjects > 0 {
			blockSize = r.AllocBytes / r.AllocObjects
		}
		b.pbSample(values, locs, func() {
			if blockSize != 0 {
				b.pbLabel(tagSample_Label, "bytes", "", blockSize)
			}
		})
	}
	b.build()
	return nil
}

// scaleHeapSample adjusts the data from a heap Sample to

// column and first row.
var zigzag = [blockSize]int{
	0, 1, 5, 6, 14, 15, 27, 28,
	2, 4, 7, 13, 16, 26, 29, 42,
	3, 8, 12, 17, 25, 30, 41, 43,
	9, 11, 18, 24, 31, 40, 44, 53,
	10, 19, 23, 32, 39, 45, 52, 54,
	20, 22, 33, 38, 46, 51, 55, 60,
	21, 34, 37, 47, 50, 56, 59, 61,
	35, 36, 48, 49, 57, 58, 62, 63,
}

func TestZigUnzig(t *testing.T) {
	for i := 0; i < blockSize; i++ {
		if unzig[zigzag[i]] != i {

	fd := f.Fd()
	_, err := unix.FcntlInt(fd, unix.F_NOCACHE, 0)
	return err
}

// AlignedBlock - pass through to directio implementation.
func AlignedBlock(blockSize int) []byte {
	return directio.AlignedBlock(blockSize)