Vendor in c/image with sigstore support

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

vendor/github.com/google/go-containerregistry/pkg/name/ref.go

@@ -0,0 +1,75 @@
+// 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 name
+
+import (
+	"fmt"
+)
+
+// Reference defines the interface that consumers use when they can
+// take either a tag or a digest.
+type Reference interface {
+	fmt.Stringer
+
+	// Context accesses the Repository context of the reference.
+	Context() Repository
+
+	// Identifier accesses the type-specific portion of the reference.
+	Identifier() string
+
+	// Name is the fully-qualified reference name.
+	Name() string
+
+	// Scope is the scope needed to access this reference.
+	Scope(string) string
+}
+
+// ParseReference parses the string as a reference, either by tag or digest.
+func ParseReference(s string, opts ...Option) (Reference, error) {
+	if t, err := NewTag(s, opts...); err == nil {
+		return t, nil
+	}
+	if d, err := NewDigest(s, opts...); err == nil {
+		return d, nil
+	}
+	return nil, newErrBadName("could not parse reference: " + s)
+}
+
+type stringConst string
+
+// MustParseReference behaves like ParseReference, but panics instead of
+// returning an error. It's intended for use in tests, or when a value is
+// expected to be valid at code authoring time.
+//
+// To discourage its use in scenarios where the value is not known at code
+// authoring time, it must be passed a string constant:
+//
+//    const str = "valid/string"
+//    MustParseReference(str)
+//    MustParseReference("another/valid/string")
+//    MustParseReference(str + "/and/more")
+//
+// These will not compile:
+//
+//    var str = "valid/string"
+//    MustParseReference(str)
+//    MustParseReference(strings.Join([]string{"valid", "string"}, "/"))
+func MustParseReference(s stringConst, opts ...Option) Reference {
+	ref, err := ParseReference(string(s), opts...)
+	if err != nil {
+		panic(err)
+	}
+	return ref
+}