Update vendor

vendor/github.com/google/go-containerregistry/pkg/v1/v1util/verify.go

@@ -0,0 +1,61 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// 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
+//
+//    http://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 v1util
+
+import (
+	"encoding/hex"
+	"fmt"
+	"hash"
+	"io"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+)
+
+type verifyReader struct {
+	inner    io.Reader
+	hasher   hash.Hash
+	expected v1.Hash
+}
+
+// Read implements io.Reader
+func (vc *verifyReader) Read(b []byte) (int, error) {
+	n, err := vc.inner.Read(b)
+	if err == io.EOF {
+		got := hex.EncodeToString(vc.hasher.Sum(make([]byte, 0, vc.hasher.Size())))
+		if want := vc.expected.Hex; got != want {
+			return n, fmt.Errorf("error verifying %s checksum; got %q, want %q",
+				vc.expected.Algorithm, got, want)
+		}
+	}
+	return n, err
+}
+
+// VerifyReadCloser wraps the given io.ReadCloser to verify that its contents match
+// the provided v1.Hash before io.EOF is returned.
+func VerifyReadCloser(r io.ReadCloser, h v1.Hash) (io.ReadCloser, error) {
+	w, err := v1.Hasher(h.Algorithm)
+	if err != nil {
+		return nil, err
+	}
+	r2 := io.TeeReader(r, w)
+	return &readAndCloser{
+		Reader: &verifyReader{
+			inner:    r2,
+			hasher:   w,
+			expected: h,
+		},
+		CloseFunc: r.Close,
+	}, nil
+}