WIP

attest/manifest/manifest.go

@@ -42,6 +42,14 @@ func MakeDirContentsStatement(dir string, entries *types.PathCheckSummaryCollect
 	}
 }
 
+func MakeDirContentsStatementFrom(statement types.Statement) DirContents {
+	dirContents := DirContents{
+		GenericStatement: attestTypes.GenericStatement[SourceDirectory]{},
+	}
+	dirContents.ConvertFrom(statement)
+	return dirContents
+}
+
 func (a SourceDirectory) Compare(b SourceDirectory) types.Cmp {
 	if cmp := cmp.Compare(a.Path, b.Path); cmp != 0 {
 		return &cmp

attest/types/types.go

@@ -119,6 +119,30 @@ func Export(s ExportableStatement) toto.Statement {
 	}
 }
 
+func FilterByPredicateType(t string, s Statements) Statements {
+	results := Statements{}
+	for i := range s {
+		if s[i].GetType() == t {
+			results = append(results, s[i])
+		}
+	}
+	return results
+}
+
+type StamentConverter[T any] struct {
+	Statement
+}
+
+func (s *GenericStatement[T]) ConvertFrom(statement Statement) error {
+	predicate, ok := s.GetPredicate().(ComparablePredicate[T])
+	if !ok {
+		return fmt.Errorf("cannot convert statement with predicte of type %T into %T", s.GetPredicate(), GenericStatement[T]{})
+	}
+
+	*s = MakeStatement[T](s.GetType(), predicate, s.GetSubject()...)
+	return nil
+}
+
 func (s Statements) Export() []toto.Statement {
 	statements := make([]toto.Statement, len(s))
 	for i := range s {

oci/artefact.go

@@ -23,6 +23,7 @@ import (
 	"github.com/google/go-containerregistry/pkg/v1/tarball"
 	typesv1 "github.com/google/go-containerregistry/pkg/v1/types"
 
+	"github.com/docker/labs-brown-tape/attest/manifest"
 	attestTypes "github.com/docker/labs-brown-tape/attest/types"
 	manifestTypes "github.com/docker/labs-brown-tape/manifest/types"
 )
@@ -223,6 +224,10 @@ func (c *Client) PushArtefact(ctx context.Context, destinationRef, sourceDir str
 	}
 	defer os.RemoveAll(tmpDir)
 
+	_, err = SemVerFromAttestations(ctx, sourceAttestations...)
+	if err != nil {
+		return "", err
+	}
 	tmpFile := filepath.Join(tmpDir, "artefact.tgz")
 
 	outputFile, err := os.OpenFile(tmpFile, os.O_RDWR|os.O_CREATE|os.O_EXCL, regularFileMode)
@@ -348,6 +353,20 @@ func (c *Client) PushArtefact(ctx context.Context, destinationRef, sourceDir str
 	return tagAlias.String() + "@" + digest.String(), err
 }
 
+func SemVerFromAttestations(ctx context.Context, sourceAttestations ...attestTypes.Statement) (string, error) {
+	statements := attestTypes.FilterByPredicateType(manifest.ManifestDirPredicateType, sourceAttestations)
+	if len(statements) == 0 {
+		return "", fmt.Errorf("VCS provinance attestion (%q) not found", manifest.ManifestDirPredicateType)
+	}
+	if len(statements) > 1 {
+		return "", fmt.Errorf("too many attestations of type %q found, expected 1", manifest.ManifestDirPredicateType)
+	}
+
+	_ = manifest.MakeDirContentsStatementFrom(statements[0])
+
+	return "", nil
+}
+
 func makeDescriptorWithPlatform() Descriptor {
 	return Descriptor{
 		Platform: &Platform{