diff --git a/glob/glob.go b/glob/glob.go
new file mode 100644
index 0000000..45ba285
--- /dev/null
+++ b/glob/glob.go
@@ -0,0 +1,129 @@
+// Copyright 2015 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 glob
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"blueprint/deptools"
+)
+
+func IsGlob(glob string) bool {
+	return strings.IndexAny(glob, "*?[") >= 0
+}
+
+// GlobWithDepFile finds all files that match glob.  It compares the list of files
+// against the contents of fileListFile, and rewrites fileListFile if it has changed.  It also
+// writes all of the the directories it traversed as a depenencies on fileListFile to depFile.
+//
+// The format of glob is either path/*.ext for a single directory glob, or path/**/*.ext
+// for a recursive glob.
+//
+// Returns a list of file paths, and an error.
+func GlobWithDepFile(glob, fileListFile, depFile string) (files []string, err error) {
+	globPattern := filepath.Base(glob)
+	globDir := filepath.Dir(glob)
+	recursive := false
+
+	if filepath.Base(globDir) == "**" {
+		recursive = true
+		globDir = filepath.Dir(globDir)
+	}
+
+	var dirs []string
+
+	err = filepath.Walk(globDir,
+		func(path string, info os.FileInfo, err error) error {
+			if err != nil {
+				return err
+			}
+
+			if info.Mode().IsDir() {
+				dirs = append(dirs, path)
+				if !recursive && path != globDir {
+					return filepath.SkipDir
+				}
+			} else if info.Mode().IsRegular() {
+				match, err := filepath.Match(globPattern, info.Name())
+				if err != nil {
+					return err
+				}
+				if match {
+					files = append(files, path)
+				}
+			}
+
+			return nil
+		})
+
+	fileList := strings.Join(files, "\n")
+
+	writeFileIfChanged(fileListFile, []byte(fileList), 0666)
+	deptools.WriteDepFile(depFile, fileListFile, dirs)
+
+	return
+}
+
+func writeFileIfChanged(filename string, data []byte, perm os.FileMode) error {
+	var isChanged bool
+
+	dir := filepath.Dir(filename)
+	err := os.MkdirAll(dir, 0777)
+	if err != nil {
+		return err
+	}
+
+	info, err := os.Stat(filename)
+	if err != nil {
+		if os.IsNotExist(err) {
+			// The file does not exist yet.
+			isChanged = true
+		} else {
+			return err
+		}
+	} else {
+		if info.Size() != int64(len(data)) {
+			isChanged = true
+		} else {
+			oldData, err := ioutil.ReadFile(filename)
+			if err != nil {
+				return err
+			}
+
+			if len(oldData) != len(data) {
+				isChanged = true
+			} else {
+				for i := range data {
+					if oldData[i] != data[i] {
+						isChanged = true
+						break
+					}
+				}
+			}
+		}
+	}
+
+	if isChanged {
+		err = ioutil.WriteFile(filename, data, perm)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}