From f38e7c28d0737e21804e00c8ba5241d7e4695dee Mon Sep 17 00:00:00 2001
From: Viktor Kuznietsov <vkuzniet@amazon.com>
Date: Wed, 17 Aug 2022 19:55:19 +0000
Subject: [PATCH] Remove null blobs from Soci Index

Signed-off-by: Viktor Kuznietsov <vkuzniet@amazon.com>
---
 fs/artifact_fetcher.go     |  5 +----
 fs/fs.go                   |  6 ++----
 integration/create_test.go | 20 ++------------------
 soci/soci_index.go         | 11 +++++++++--
 4 files changed, 14 insertions(+), 28 deletions(-)

diff --git a/fs/artifact_fetcher.go b/fs/artifact_fetcher.go
index 7f7a445df..c39c58b9d 100644
--- a/fs/artifact_fetcher.go
+++ b/fs/artifact_fetcher.go
@@ -217,10 +217,7 @@ func FetchSociArtifacts(ctx context.Context, imageRef, indexDigest string, store
 
 	eg, ctx := errgroup.WithContext(ctx)
 	for _, blob := range index.Blobs {
-		if blob == nil {
-			continue
-		}
-		blob := *blob
+		blob := blob
 		eg.Go(func() error {
 			rc, local, err := fetcher.Fetch(ctx, blob)
 			if err != nil {
diff --git a/fs/fs.go b/fs/fs.go
index 48e9fac24..f01426709 100644
--- a/fs/fs.go
+++ b/fs/fs.go
@@ -209,10 +209,8 @@ func (fs *filesystem) fetchSociArtifacts(ctx context.Context, imageRef, indexDig
 
 func (fs *filesystem) populateImageLayerToSociMapping(sociIndex *soci.SociIndex) {
 	for _, desc := range sociIndex.Blobs {
-		if desc != nil {
-			ociDigest := desc.Annotations[soci.IndexAnnotationImageLayerDigest]
-			fs.imageLayerToSociDesc[ociDigest] = *desc
-		}
+		ociDigest := desc.Annotations[soci.IndexAnnotationImageLayerDigest]
+		fs.imageLayerToSociDesc[ociDigest] = desc
 	}
 }
 
diff --git a/integration/create_test.go b/integration/create_test.go
index b3c4530bc..34448ddd8 100644
--- a/integration/create_test.go
+++ b/integration/create_test.go
@@ -106,22 +106,11 @@ func TestSociCreateSparseIndex(t *testing.T) {
 			}
 
 			blobs := sociIndex.Blobs
-			notNilBlobCount := 0
-			for _, b := range blobs {
-				if b != nil {
-					notNilBlobCount++
-				}
-			}
-			if notNilBlobCount != len(includedLayers) {
-				t.Fatalf("unexpected blob count; expected=%v, got=%v", len(includedLayers), notNilBlobCount)
+			if len(blobs) != len(includedLayers) {
+				t.Fatalf("unexpected blob count; expected=%v, got=%v", len(includedLayers), len(blobs))
 			}
 
 			for i, blob := range blobs {
-				if blob == nil {
-					continue
-				}
-				blob := *blob
-
 				blobContent := fetchContentFromPath(sh, blobStorePath+"/"+trimSha256Prefix(blob.Digest.String()))
 				blobSize := int64(len(blobContent))
 				blobDigest := digest.FromBytes(blobContent)
@@ -205,11 +194,6 @@ func TestSociCreate(t *testing.T) {
 			blobs := sociIndex.Blobs
 
 			for _, blob := range blobs {
-				if blob == nil {
-					continue
-				}
-				blob := *blob
-
 				blobContent := fetchContentFromPath(sh, blobStorePath+"/"+trimSha256Prefix(blob.Digest.String()))
 				blobSize := int64(len(blobContent))
 				blobDigest := digest.FromBytes(blobContent)
diff --git a/soci/soci_index.go b/soci/soci_index.go
index 7c0678948..25211b567 100644
--- a/soci/soci_index.go
+++ b/soci/soci_index.go
@@ -64,7 +64,7 @@ type SociIndex struct {
 	MediaType    string `json:"mediaType"`
 	ArtifactType string `json:"artifactType"`
 	// descriptors of ztocs
-	Blobs []*ocispec.Descriptor `json:"blobs,omitempty"`
+	Blobs []ocispec.Descriptor `json:"blobs,omitempty"`
 	// descriptor of image manifest
 	Subject ocispec.Descriptor `json:"subject,omitempty"`
 
@@ -172,6 +172,13 @@ func BuildSociIndex(ctx context.Context, cs content.Store, img images.Image, spa
 		return nil, err
 	}
 
+	ztocsDesc := make([]ocispec.Descriptor, 0, len(manifest.Layers))
+	for _, desc := range sociLayersDesc {
+		if desc != nil {
+			ztocsDesc = append(ztocsDesc, *desc)
+		}
+	}
+
 	annotations := map[string]string{
 		IndexAnnotationBuildToolIdentifier: config.buildToolIdentifier,
 		IndexAnnotationBuildToolVersion:    config.buildToolVersion,
@@ -180,7 +187,7 @@ func BuildSociIndex(ctx context.Context, cs content.Store, img images.Image, spa
 	sociIndex := SociIndex{
 		MediaType:    sociIndexMediaType,
 		ArtifactType: SociIndexArtifactType,
-		Blobs:        sociLayersDesc,
+		Blobs:        ztocsDesc,
 		Subject: ocispec.Descriptor{
 			MediaType:   imgManifestDesc.MediaType,
 			Digest:      imgManifestDesc.Digest,