added PostCopy call

Signed-off-by: Kyle M. Tarplee <[email protected]>

copy.go

@@ -116,7 +116,7 @@ type CopyGraphOptions struct {
 // sourceReference is the repository to use for mounting (the mount point).
 // mounter is the destination for the mount (a well-known implementation of this is *registry.Repository representing the target).
 // onMounted is called (if provided) when the blob is mounted.
-// The original PreCopy hook is called only on copy, and there fore not when the blob is mounted.
+// The original PreCopy hook is called only on copy, and therefore not when the blob is mounted.
 func (opts *CopyGraphOptions) WithMount(sourceRepository string, mounter registry.Mounter, onMounted func(context.Context, ocispec.Descriptor)) {
 	preCopy := opts.PreCopy
 	opts.PreCopy = func(ctx context.Context, desc ocispec.Descriptor) error {
@@ -150,12 +150,22 @@ func (opts *CopyGraphOptions) WithMount(sourceRepository string, mounter registr
 			return err
 		}
 
-		if !mountFailed && onMounted != nil {
-			onMounted(ctx, desc)
+		if !mountFailed {
+			// mounted
+			if onMounted != nil {
+				onMounted(ctx, desc)
+			}
+			// signal that the descriptor now exists
+			return ErrSkipDesc
 		}
 
-		// Mount succeeded or we copied it
-		// either way we return ErrSkipDesc to signal that the descriptor now exists
+		// we copied it
+		if opts.PostCopy != nil {
+			if err := opts.PostCopy(ctx, desc); err != nil {
+				return err
+			}
+		}
+		// signal that the descriptor now exists
 		return ErrSkipDesc
 	}
 }