Fix missing manifest error processing

README.md

@@ -110,7 +110,7 @@ func main() {
     }
 
     // Sign the signature
-    signed, err := ctx.Sign(sig)
+    signed, err := ctx.SignManifest(sig)
     if err != nil {
         panic(err)
     }

main_test.go

@@ -59,7 +59,7 @@ func TestManifestExample(t *testing.T) {
 	require.NoError(t, err)
 
 	// Sign the signature
-	signed, err := ctx.Sign(sig)
+	signed, err := ctx.SignManifest(sig)
 	require.NoError(t, err)
 
 	// Validate
@@ -82,6 +82,19 @@ func TestManifestExample(t *testing.T) {
 	require.NotEmpty(t, manifest)
 }
 
+func TestMissingManifest(t *testing.T) {
+
+	// Generate a key and self-signed certificate for signing
+	randomKeyStore := RandomKeyStoreForTest()
+	ctx := NewDefaultSigningContext(randomKeyStore)
+
+	sig := ctx.CreateSignature("id1234")
+
+	// Sign the signature
+	_, err := ctx.SignManifest(sig)
+	require.Error(t, err)
+}
+
 func TestRecursiveSigning(t *testing.T) {
 
 	// Generate a key and self-signed certificate for signing
@@ -95,7 +108,7 @@ func TestRecursiveSigning(t *testing.T) {
 	require.NoError(t, err)
 
 	// Sign the signature
-	signed, err := ctx.Sign(sig)
+	signed, err := ctx.SignManifest(sig)
 	require.NoError(t, err)
 
 	list := &etree.Element{Tag: "Signatures"}

sign.go

@@ -278,7 +278,7 @@ func (ctx *SigningContext) createNamespacedElement(el *etree.Element, tag string
 	return child
 }
 
-func (ctx *SigningContext) Sign(sig *etree.Element) (*etree.Element, error) {
+func (ctx *SigningContext) SignManifest(sig *etree.Element) (*etree.Element, error) {
 
 	// First get the default context
 	rootNSCtx := etreeutils.DefaultNSContext
@@ -290,8 +290,8 @@ func (ctx *SigningContext) Sign(sig *etree.Element) (*etree.Element, error) {
 	}
 
 	man := sig.FindElementPath(ctx.manifestPath(sig))
-	if err != nil {
-		return nil, err
+	if man == nil {
+		return nil, errors.New("missing manifest element")
 	}
 
 	manifest, err := etreeutils.NSDetatch(sigNSCtx, man)

sign_test.go

@@ -147,7 +147,7 @@ func TestSignManifest(t *testing.T) {
 	id := man.SelectAttr(ctx.IdAttribute)
 	require.NotEmpty(t, id)
 
-	signed, err := ctx.Sign(sig)
+	signed, err := ctx.SignManifest(sig)
 	require.NoError(t, err)
 
 	signedInfo := signed.FindElement("//" + SignedInfoTag)