ocilayout: handle Windows paths in local OCI layout refs

Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>

util/ocilayout/parse.go

@@ -34,7 +34,7 @@ func Parse(s string) (Ref, bool, error) {
 		}
 	}
 
-	if i := strings.LastIndex(localPath, ":"); i >= 0 {
+	if i := strings.LastIndex(localPath, ":"); i >= 0 && !isWindowsDrivePath(localPath, i) {
 		after := localPath[i+1:]
 		if reference.TagRegexp.MatchString(after) {
 			localPath, out.Tag = localPath[:i], after
@@ -51,10 +51,18 @@ func Parse(s string) (Ref, bool, error) {
 func (r Ref) String() string {
 	s := prefix + r.Path
 	if r.Tag != "" {
-		return s + ":" + r.Tag
+		s += ":" + r.Tag
 	}
 	if r.Digest != "" {
-		return s + "@" + r.Digest.String()
+		s += "@" + r.Digest.String()
 	}
 	return s
 }
+
+func isWindowsDrivePath(path string, colon int) bool {
+	if colon != 1 || len(path) < 2 {
+		return false
+	}
+	c := path[0]
+	return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z')
+}

util/ocilayout/parse_test.go

@@ -3,6 +3,7 @@ package ocilayout
 import (
 	"testing"
 
+	digest "github.com/opencontainers/go-digest"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -39,6 +40,27 @@ func TestParse(t *testing.T) {
 			path: "/path/to/oci/@/layout",
 			tag:  "latest",
 		},
+		{
+			s:    `oci-layout://C:\path\to\oci\layout`,
+			path: `C:\path\to\oci\layout`,
+			tag:  "latest",
+		},
+		{
+			s:    `oci-layout://C:\path\to\oci\layout:1.3`,
+			path: `C:\path\to\oci\layout`,
+			tag:  "1.3",
+		},
+		{
+			s:    `oci-layout://C:\path\to\oci\layout@sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+			path: `C:\path\to\oci\layout`,
+			dgst: "sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+		},
+		{
+			s:    `oci-layout://C:\path\to\oci\layout:1.3@sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa`,
+			path: `C:\path\to\oci\layout`,
+			tag:  "1.3",
+			dgst: "sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
+		},
 	} {
 		ref, ok, err := Parse(tt.s)
 		require.True(t, ok)
@@ -48,3 +70,13 @@ func TestParse(t *testing.T) {
 		assert.Equal(t, tt.tag, ref.Tag, "comparing tag: %s", tt.s)
 	}
 }
+
+func TestRefString(t *testing.T) {
+	ref := Ref{
+		Path:   "/path/to/oci/layout",
+		Tag:    "1.3",
+		Digest: digest.Digest("sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"),
+	}
+
+	assert.Equal(t, "oci-layout:///path/to/oci/layout:1.3@sha256:aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", ref.String())
+}