Implement Alibaba Cloud OSS gateway support (#5103)

vendor/github.com/aliyun/aliyun-oss-go-sdk/oss/crc.go

@@ -0,0 +1,123 @@
+package oss
+
+import (
+	"hash"
+	"hash/crc64"
+)
+
+// digest represents the partial evaluation of a checksum.
+type digest struct {
+	crc uint64
+	tab *crc64.Table
+}
+
+// NewCRC creates a new hash.Hash64 computing the CRC-64 checksum
+// using the polynomial represented by the Table.
+func NewCRC(tab *crc64.Table, init uint64) hash.Hash64 { return &digest{init, tab} }
+
+// Size returns the number of bytes Sum will return.
+func (d *digest) Size() int { return crc64.Size }
+
+// BlockSize returns the hash's underlying block size.
+// The Write method must be able to accept any amount
+// of data, but it may operate more efficiently if all writes
+// are a multiple of the block size.
+func (d *digest) BlockSize() int { return 1 }
+
+// Reset resets the Hash to its initial state.
+func (d *digest) Reset() { d.crc = 0 }
+
+// Write (via the embedded io.Writer interface) adds more data to the running hash.
+// It never returns an error.
+func (d *digest) Write(p []byte) (n int, err error) {
+	d.crc = crc64.Update(d.crc, d.tab, p)
+	return len(p), nil
+}
+
+// Sum64 returns crc64 value.
+func (d *digest) Sum64() uint64 { return d.crc }
+
+// Sum returns hash value.
+func (d *digest) Sum(in []byte) []byte {
+	s := d.Sum64()
+	return append(in, byte(s>>56), byte(s>>48), byte(s>>40), byte(s>>32), byte(s>>24), byte(s>>16), byte(s>>8), byte(s))
+}
+
+// gf2Dim dimension of GF(2) vectors (length of CRC)
+const gf2Dim int = 64
+
+func gf2MatrixTimes(mat []uint64, vec uint64) uint64 {
+	var sum uint64
+	for i := 0; vec != 0; i++ {
+		if vec&1 != 0 {
+			sum ^= mat[i]
+		}
+
+		vec >>= 1
+	}
+	return sum
+}
+
+func gf2MatrixSquare(square []uint64, mat []uint64) {
+	for n := 0; n < gf2Dim; n++ {
+		square[n] = gf2MatrixTimes(mat, mat[n])
+	}
+}
+
+// CRC64Combine combine crc64
+func CRC64Combine(crc1 uint64, crc2 uint64, len2 uint64) uint64 {
+	var even [gf2Dim]uint64 // even-power-of-two zeros operator
+	var odd [gf2Dim]uint64  // odd-power-of-two zeros operator
+
+	// Degenerate case
+	if len2 == 0 {
+		return crc1
+	}
+
+	// Put operator for one zero bit in odd
+	odd[0] = crc64.ECMA // CRC64 polynomial
+	var row uint64 = 1
+	for n := 1; n < gf2Dim; n++ {
+		odd[n] = row
+		row <<= 1
+	}
+
+	// Put operator for two zero bits in even
+	gf2MatrixSquare(even[:], odd[:])
+
+	// Put operator for four zero bits in odd
+	gf2MatrixSquare(odd[:], even[:])
+
+	// Apply len2 zeros to crc1, first square will put the operator for one zero byte, eight zero bits, in even
+	for {
+		// Apply zeros operator for this bit of len2
+		gf2MatrixSquare(even[:], odd[:])
+
+		if len2&1 != 0 {
+			crc1 = gf2MatrixTimes(even[:], crc1)
+		}
+
+		len2 >>= 1
+
+		// If no more bits set, then done
+		if len2 == 0 {
+			break
+		}
+
+		// Another iteration of the loop with odd and even swapped
+		gf2MatrixSquare(odd[:], even[:])
+		if len2&1 != 0 {
+			crc1 = gf2MatrixTimes(odd[:], crc1)
+		}
+		len2 >>= 1
+
+		// If no more bits set, then done
+		if len2 == 0 {
+			break
+		}
+	}
+
+	// Return combined crc
+	crc1 ^= crc2
+	return crc1
+}