Update oci library

1, update go-digest to v1.0.0-rc1
2, update image-spec to v1.0.1

Signed-off-by: wang yan <wangyan@vmware.com>

vendor/github.com/opencontainers/go-digest/digest.go

@@ -1,3 +1,17 @@
+// Copyright 2017 Docker, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package digest
 
 import (
@@ -31,16 +45,21 @@ func NewDigest(alg Algorithm, h hash.Hash) Digest {
 // functions. This is also useful for rebuilding digests from binary
 // serializations.
 func NewDigestFromBytes(alg Algorithm, p []byte) Digest {
-	return Digest(fmt.Sprintf("%s:%x", alg, p))
+	return NewDigestFromEncoded(alg, alg.Encode(p))
 }
 
-// NewDigestFromHex returns a Digest from alg and a the hex encoded digest.
+// NewDigestFromHex is deprecated. Please use NewDigestFromEncoded.
 func NewDigestFromHex(alg, hex string) Digest {
-	return Digest(fmt.Sprintf("%s:%s", alg, hex))
+	return NewDigestFromEncoded(Algorithm(alg), hex)
+}
+
+// NewDigestFromEncoded returns a Digest from alg and the encoded digest.
+func NewDigestFromEncoded(alg Algorithm, encoded string) Digest {
+	return Digest(fmt.Sprintf("%s:%s", alg, encoded))
 }
 
 // DigestRegexp matches valid digest types.
-var DigestRegexp = regexp.MustCompile(`[a-zA-Z0-9-_+.]+:[a-fA-F0-9]+`)
+var DigestRegexp = regexp.MustCompile(`[a-z0-9]+(?:[.+_-][a-z0-9]+)*:[a-zA-Z0-9=_-]+`)
 
 // DigestRegexpAnchored matches valid digest types, anchored to the start and end of the match.
 var DigestRegexpAnchored = regexp.MustCompile(`^` + DigestRegexp.String() + `$`)
@@ -82,26 +101,18 @@ func FromString(s string) Digest {
 // error if not.
 func (d Digest) Validate() error {
 	s := string(d)
-
 	i := strings.Index(s, ":")
-
-	// validate i then run through regexp
-	if i < 0 || i+1 == len(s) || !DigestRegexpAnchored.MatchString(s) {
+	if i <= 0 || i+1 == len(s) {
 		return ErrDigestInvalidFormat
 	}
-
-	algorithm := Algorithm(s[:i])
+	algorithm, encoded := Algorithm(s[:i]), s[i+1:]
 	if !algorithm.Available() {
+		if !DigestRegexpAnchored.MatchString(s) {
+			return ErrDigestInvalidFormat
+		}
 		return ErrDigestUnsupported
 	}
-
-	// Digests much always be hex-encoded, ensuring that their hex portion will
-	// always be size*2
-	if algorithm.Size()*2 != len(s[i+1:]) {
-		return ErrDigestInvalidLength
-	}
-
-	return nil
+	return algorithm.Validate(encoded)
 }
 
 // Algorithm returns the algorithm portion of the digest. This will panic if
@@ -119,12 +130,17 @@ func (d Digest) Verifier() Verifier {
 	}
 }
 
-// Hex returns the hex digest portion of the digest. This will panic if the
+// Encoded returns the encoded portion of the digest. This will panic if the
 // underlying digest is not in a valid format.
-func (d Digest) Hex() string {
+func (d Digest) Encoded() string {
 	return string(d[d.sepIndex()+1:])
 }
 
+// Hex is deprecated. Please use Digest.Encoded.
+func (d Digest) Hex() string {
+	return d.Encoded()
+}
+
 func (d Digest) String() string {
 	return string(d)
 }