Move escape function to util and clarify name

pkg/util/escape.go

@@ -0,0 +1,36 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package util
+
+import (
+	"strings"
+)
+
+// EscapeQualifiedNameForDisk converts a plugin name, which might contain a / into a
+// string that is safe to use on-disk.  This assumes that the input has already
+// been validates as a qualified name.  we use "~" rather than ":" here in case
+// we ever use a filesystem that doesn't allow ":".
+func EscapeQualifiedNameForDisk(in string) string {
+	return strings.Replace(in, "/", "~", -1)
+}
+
+// UnescapeQualifiedNameForDisk converts an escaped plugin name (as per EscapeQualifiedNameForDisk)
+// back to its normal form.  This assumes that the input has already been
+// validates as a qualified name.
+func UnescapeQualifiedNameForDisk(in string) string {
+	return strings.Replace(in, "~", "/", -1)
+}