luci-go/common/dirwalk: Code for walking a directory tree efficiently

common/dirwalk/walk_basic.go

+// Copyright 2016 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package dirwalk
+
+import (
+        "os"
+        "path/filepath"
+        "strings"
+)
+
+// WalkBasic is the trivial implementation of a directory tree walker using
+// built in filepath.Walk function.
+func WalkBasic(root string, callback WalkFunc) {
+        dirs := newStringStack()
+        dirs.push("")
+        filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
+                if err != nil {
+                        callback(path, -1, nil, err)
+                        return nil
+                }
+
+                for true {
+                        if strings.HasPrefix(path, dirs.peek()) {
+                                break
+                        }
+                        callback(dirs.pop(), -1, nil, nil)
+                }
+
+                if info.IsDir() {
+                        dirs.push(path)
+                } else {
+                        f, err := os.Open(path)
+                        if err != nil {
+                                callback(path, -1, nil, err)
+                                return nil
+                        }
+                        callback(path, info.Size(), f, nil)
+                }
+                return nil
+        })
+        for true {
+                if dirs.peek() == "" {
+                        break
+                }
+                callback(dirs.pop(), -1, nil, nil)
+        }
+}