options: reject empty runroot or graphroot

make sure that the runroot and graphroot are not empty otherwise we will
end up using an empty directory as path prefix and create files in the
current directory.

Signed-off-by: Giuseppe Scrivano <[email protected]>

types/options.go

@@ -152,20 +152,24 @@ func defaultStoreOptionsIsolated(rootless bool, rootlessUID int, storageConf str
 			}
 		}
 	}
-	if storageOpts.RunRoot != "" {
-		runRoot, err := expandEnvPath(storageOpts.RunRoot, rootlessUID)
-		if err != nil {
-			return storageOpts, err
-		}
-		storageOpts.RunRoot = runRoot
+	if storageOpts.RunRoot == "" {
+		return storageOpts, fmt.Errorf("runroot must be set")
 	}
-	if storageOpts.GraphRoot != "" {
-		graphRoot, err := expandEnvPath(storageOpts.GraphRoot, rootlessUID)
-		if err != nil {
-			return storageOpts, err
-		}
-		storageOpts.GraphRoot = graphRoot
+	runRoot, err := expandEnvPath(storageOpts.RunRoot, rootlessUID)
+	if err != nil {
+		return storageOpts, err
+	}
+	storageOpts.RunRoot = runRoot
+
+	if storageOpts.GraphRoot == "" {
+		return storageOpts, fmt.Errorf("graphroot must be set")
 	}
+	graphRoot, err := expandEnvPath(storageOpts.GraphRoot, rootlessUID)
+	if err != nil {
+		return storageOpts, err
+	}
+	storageOpts.GraphRoot = graphRoot
+
 	if storageOpts.RootlessStoragePath != "" {
 		storagePath, err := expandEnvPath(storageOpts.RootlessStoragePath, rootlessUID)
 		if err != nil {