fixtures: make shred sort order natural

Sorry for the `git pull` jumpscare!

cmd/radiance/blockstore/dumpshreds/dumpshreds.go

@@ -100,7 +100,7 @@ func dumpShreds(
 		if !ok || curSlot != slot {
 			break
 		}
-		p := filepath.Join(slotPath, fmt.Sprintf("%s%03d", namePrefix, curIndex))
+		p := filepath.Join(slotPath, fmt.Sprintf("%s%04d", namePrefix, curIndex))
 		if err := os.WriteFile(p, iter.Value().Data(), 0644); err != nil {
 			return err
 		}

cmd/radiance/car/create/create.go

@@ -0,0 +1,23 @@
+package create
+
+import (
+	"github.com/certusone/radiance/pkg/blockstore"
+	"github.com/spf13/cobra"
+	"k8s.io/klog/v2"
+)
+
+var Cmd = cobra.Command{
+	Use:   "create <rocksdb...>",
+	Short: "Create CAR from RocksDB",
+	Args:  cobra.MaximumNArgs(1),
+}
+
+func run(_ *cobra.Command, args []string) {
+	rocksDB := args[0]
+
+	db, err := blockstore.OpenReadOnly(rocksDB)
+	if err != nil {
+		klog.Exitf("Failed to open blockstore: %s", err)
+	}
+	defer db.Close()
+}