pull in containers/image deps

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

vendor/github.com/containers/image/docker/policyconfiguration/naming.go

@@ -0,0 +1,57 @@
+package policyconfiguration
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/docker/docker/reference"
+)
+
+// DockerReferenceIdentity returns a string representation of the reference, suitable for policy lookup,
+// as a backend for ImageReference.PolicyConfigurationIdentity.
+// The reference must satisfy !reference.IsNameOnly().
+func DockerReferenceIdentity(ref reference.Named) (string, error) {
+	res := ref.FullName()
+	tagged, isTagged := ref.(reference.NamedTagged)
+	digested, isDigested := ref.(reference.Canonical)
+	switch {
+	case isTagged && isDigested: // This should not happen, docker/reference.ParseNamed drops the tag.
+		return "", fmt.Errorf("Unexpected Docker reference %s with both a name and a digest", ref.String())
+	case !isTagged && !isDigested: // This should not happen, the caller is expected to ensure !reference.IsNameOnly()
+		return "", fmt.Errorf("Internal inconsistency: Docker reference %s with neither a tag nor a digest", ref.String())
+	case isTagged:
+		res = res + ":" + tagged.Tag()
+	case isDigested:
+		res = res + "@" + digested.Digest().String()
+	default: // Coverage: The above was supposed to be exhaustive.
+		return "", errors.New("Internal inconsistency, unexpected default branch")
+	}
+	return res, nil
+}
+
+// DockerReferenceNamespaces returns a list of other policy configuration namespaces to search,
+// as a backend for ImageReference.PolicyConfigurationIdentity.
+// The reference must satisfy !reference.IsNameOnly().
+func DockerReferenceNamespaces(ref reference.Named) []string {
+	// Look for a match of the repository, and then of the possible parent
+	// namespaces. Note that this only happens on the expanded host names
+	// and repository names, i.e. "busybox" is looked up as "docker.io/library/busybox",
+	// then in its parent "docker.io/library"; in none of "busybox",
+	// un-namespaced "library" nor in "" supposedly implicitly representing "library/".
+	//
+	// ref.FullName() == ref.Hostname() + "/" + ref.RemoteName(), so the last
+	// iteration matches the host name (for any namespace).
+	res := []string{}
+	name := ref.FullName()
+	for {
+		res = append(res, name)
+
+		lastSlash := strings.LastIndex(name, "/")
+		if lastSlash == -1 {
+			break
+		}
+		name = name[:lastSlash]
+	}
+	return res
+}