stage0/image_verify: don't always render images

This avoids rendering an image that has not yet been rendered, and
skips doing the verification for it since it's a nonsensical operation.

rkt/image_verify.go

@@ -15,15 +15,18 @@
 package main
 
 import (
-	"github.com/coreos/rkt/store/imagestore"
-	"github.com/coreos/rkt/store/treestore"
+	"os"
+
+	"github.com/hashicorp/errwrap"
+	"github.com/rkt/rkt/store/imagestore"
+	"github.com/rkt/rkt/store/treestore"
 	"github.com/spf13/cobra"
 )
 
 var (
 	cmdImageVerify = &cobra.Command{
 		Use:   "verify IMAGE...",
-		Short: "Verify one or more images in the local store",
+		Short: "Verify one or more rendered images in the local store",
 		Long: `Verify is able to check that, based on the stored hash value, a rendered image on disk has not changed.
 
 This command may be used if the user suspects disk corruption might have damaged the rkt store.`,
@@ -65,6 +68,10 @@ func runVerifyImage(cmd *cobra.Command, args []string) int {
 			return 254
 		}
 		_, err = ts.Check(id)
+		if isNotRenderedErr(err) {
+			stdout.Printf("image %q not rendered; no verification needed", img)
+			continue
+		}
 		if err != nil {
 			stdout.Printf("tree cache verification failed for image %s: %v;  rebuilding...", img, err)
 			_, _, err = ts.Render(key, true)
@@ -78,3 +85,17 @@ func runVerifyImage(cmd *cobra.Command, args []string) int {
 	}
 	return 0
 }
+
+func isNotRenderedErr(err error) bool {
+	containsIsNotExist := false
+	containsReadHashErr := false
+	errwrap.Walk(err, func(e error) {
+		if os.IsNotExist(e) {
+			containsIsNotExist = true
+		}
+		if e == treestore.ErrReadHashfile {
+			containsReadHashErr = true
+		}
+	})
+	return containsIsNotExist && containsReadHashErr
+}

store/treestore/tree.go

@@ -56,6 +56,10 @@ const (
 	minlenKey  = len(hashPrefix) + 2 // at least sha512-aa
 )
 
+var (
+	ErrReadHashfile = errors.New("cannot read hash file")
+)
+
 // Store represents a store of rendered ACIs
 type Store struct {
 	dir string
@@ -362,7 +366,7 @@ func (ts *Store) check(id string) (string, error) {
 	treepath := ts.GetPath(id)
 	hash, err := ioutil.ReadFile(filepath.Join(treepath, hashfilename))
 	if err != nil {
-		return "", errwrap.Wrap(errors.New("cannot read hash file"), err)
+		return "", errwrap.Wrap(ErrReadHashfile, err)
 	}
 	curhash, err := ts.Hash(id)
 	if err != nil {