diff --git a/ui/build/util.go b/ui/build/util.go
new file mode 100644
index 0000000..ad084da
--- /dev/null
+++ b/ui/build/util.go
@@ -0,0 +1,79 @@
+// Copyright 2017 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 build
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// indexList finds the index of a string in a []string
+func indexList(s string, list []string) int {
+	for i, l := range list {
+		if l == s {
+			return i
+		}
+	}
+
+	return -1
+}
+
+// inList determines whether a string is in a []string
+func inList(s string, list []string) bool {
+	return indexList(s, list) != -1
+}
+
+// ensureDirectoriesExist is a shortcut to os.MkdirAll, sending errors to the ctx logger.
+func ensureDirectoriesExist(ctx Context, dirs ...string) {
+	for _, dir := range dirs {
+		err := os.MkdirAll(dir, 0777)
+		if err != nil {
+			ctx.Fatalf("Error creating %s: %q\n", dir, err)
+		}
+	}
+}
+
+// ensureEmptyFileExists ensures that the containing directory exists, and the
+// specified file exists. If it doesn't exist, it will write an empty file.
+func ensureEmptyFileExists(ctx Context, file string) {
+	ensureDirectoriesExist(ctx, filepath.Dir(file))
+	if _, err := os.Stat(file); os.IsNotExist(err) {
+		f, err := os.Create(file)
+		if err != nil {
+			ctx.Fatalf("Error creating %s: %q\n", file, err)
+		}
+		f.Close()
+	} else if err != nil {
+		ctx.Fatalf("Error checking %s: %q\n", file, err)
+	}
+}
+
+// singleUnquote is similar to strconv.Unquote, but can handle multi-character strings inside single quotes.
+func singleUnquote(str string) (string, bool) {
+	if len(str) < 2 || str[0] != '\'' || str[len(str)-1] != '\'' {
+		return "", false
+	}
+	return str[1 : len(str)-1], true
+}
+
+// decodeKeyValue decodes a key=value string
+func decodeKeyValue(str string) (string, string, bool) {
+	idx := strings.IndexRune(str, '=')
+	if idx == -1 {
+		return "", "", false
+	}
+	return str[:idx], str[idx+1:], true
+}