From a763b1c866fea4a3c82828fe7312f0c7fb69ac9f Mon Sep 17 00:00:00 2001
From: Francis Laniel <flaniel@linux.microsoft.com>
Date: Tue, 21 Nov 2023 19:03:09 +0100
Subject: [PATCH] Add Untag() to oci.Store.

Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
---
 content/oci/oci.go      | 27 +++++++++++++++++++++++++++
 content/oci/oci_test.go | 27 +++++++++++++++++++++++++++
 content/resolver.go     |  6 ++++++
 3 files changed, 60 insertions(+)

diff --git a/content/oci/oci.go b/content/oci/oci.go
index 5d4699a1f..94201946a 100644
--- a/content/oci/oci.go
+++ b/content/oci/oci.go
@@ -238,6 +238,33 @@ func (s *Store) Resolve(ctx context.Context, reference string) (ocispec.Descript
 	return desc, nil
 }
 
+func (s *Store) Untag(ctx context.Context, reference string) error {
+	s.sync.RLock()
+	defer s.sync.RUnlock()
+
+	if reference == "" {
+		return errdef.ErrMissingReference
+	}
+
+	desc, err := s.tagResolver.Resolve(ctx, reference)
+	if err != nil {
+		return fmt.Errorf("reference %q does not point to a descriptor: %w", reference, err)
+	}
+	if reference == desc.Digest.String() {
+		return fmt.Errorf("reference %q is a digest and not a tag", reference)
+	}
+
+	return s.untag(reference)
+}
+
+func (s *Store) untag(reference string) error {
+	s.tagResolver.Untag(reference)
+	if s.AutoSaveIndex {
+		return s.saveIndex()
+	}
+	return nil
+}
+
 // Predecessors returns the nodes directly pointing to the current node.
 // Predecessors returns nil without error if the node does not exists in the
 // store.
diff --git a/content/oci/oci_test.go b/content/oci/oci_test.go
index 01028b1a4..8f83ba058 100644
--- a/content/oci/oci_test.go
+++ b/content/oci/oci_test.go
@@ -204,6 +204,15 @@ func TestStore_Success(t *testing.T) {
 	if !bytes.Equal(got, manifest) {
 		t.Errorf("Store.Fetch() = %v, want %v", got, manifest)
 	}
+
+	// test untag
+	err = s.Untag(ctx, ref)
+	if err != nil {
+		t.Fatal("Store.Untag() error =", err)
+	}
+	if got, want := len(internalResolver.Map()), 1; got != want {
+		t.Errorf("resolver.Map() = %v, want %v", got, want)
+	}
 }
 
 func TestStore_RelativeRoot_Success(t *testing.T) {
@@ -333,6 +342,15 @@ func TestStore_RelativeRoot_Success(t *testing.T) {
 	if !bytes.Equal(got, manifest) {
 		t.Errorf("Store.Fetch() = %v, want %v", got, manifest)
 	}
+
+	// test untag
+	err = s.Untag(ctx, ref)
+	if err != nil {
+		t.Fatal("Store.Untag() error =", err)
+	}
+	if got, want := len(internalResolver.Map()), 1; got != want {
+		t.Errorf("resolver.Map() = %v, want %v", got, want)
+	}
 }
 
 func TestStore_NotExistingRoot(t *testing.T) {
@@ -654,6 +672,15 @@ func TestStore_DisableAutoSaveIndex(t *testing.T) {
 	if _, err := os.Stat(s.indexPath); err != nil {
 		t.Errorf("error: %s does not exist", s.indexPath)
 	}
+
+	// test untag
+	err = s.Untag(ctx, ref)
+	if err != nil {
+		t.Fatal("Store.Untag() error =", err)
+	}
+	if got, want := len(internalResolver.Map()), 1; got != want {
+		t.Errorf("resolver.Map() = %v, want %v", got, want)
+	}
 }
 
 func TestStore_RepeatTag(t *testing.T) {
diff --git a/content/resolver.go b/content/resolver.go
index b536b5ddc..fafaa24fb 100644
--- a/content/resolver.go
+++ b/content/resolver.go
@@ -39,3 +39,9 @@ type TagResolver interface {
 	Tagger
 	Resolver
 }
+
+// Untagger untags reference tags.
+type Untagger interface {
+	// Untag untags the given reference string.
+	Untag(ctx context.Context, reference string) error
+}
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