From 5db7572ddfd431e14febbf5f006e0408c5f1ae1b Mon Sep 17 00:00:00 2001
From: Wei Congrui <crvv.mail@gmail.com>
Date: Fri, 15 Sep 2017 15:36:16 +0800
Subject: [PATCH] path/filepath: ensure Walk report unreadable directories once

Before this change, if Walk encounters an unreadable directory,
it will call walkFn with this directory twice. Argument err in
the first call is nil, and the second is the permission error.

This change removes the former call and makes Walk call walkFn
with permission error.

Fixes #21758

Change-Id: I21e57c67f3c5a8370fc80a43db3c8009fbce6439
Reviewed-on: https://go-review.googlesource.com/63994
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
---
 src/path/filepath/path.go      | 24 ++++++++++++------------
 src/path/filepath/path_test.go | 12 ++++++------
 2 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/src/path/filepath/path.go b/src/path/filepath/path.go
index c242143c7a..87f8faf21a 100644
--- a/src/path/filepath/path.go
+++ b/src/path/filepath/path.go
@@ -351,23 +351,23 @@ type WalkFunc func(path string, info os.FileInfo, err error) error
 
 var lstat = os.Lstat // for testing
 
-// walk recursively descends path, calling w.
+// walk recursively descends path, calling walkFn.
 func walk(path string, info os.FileInfo, walkFn WalkFunc) error {
-	err := walkFn(path, info, nil)
-	if err != nil {
-		if info.IsDir() && err == SkipDir {
-			return nil
-		}
-		return err
-	}
-
 	if !info.IsDir() {
-		return nil
+		return walkFn(path, info, nil)
 	}
 
 	names, err := readDirNames(path)
-	if err != nil {
-		return walkFn(path, info, err)
+	err1 := walkFn(path, info, err)
+	// If err != nil, walk can't walk into this directory.
+	// err1 != nil means walkFn want walk to skip this directory or stop walking.
+	// Therefore, if one of err and err1 isn't nil, walk will return.
+	if err != nil || err1 != nil {
+		// The caller's behavior is controlled by the return value, which is decided
+		// by walkFn. walkFn may ignore err and return nil.
+		// If walkFn returns SkipDir, it will be handled by the caller.
+		// So walk should return whatever walkFn returns.
+		return err1
 	}
 
 	for _, name := range names {
diff --git a/src/path/filepath/path_test.go b/src/path/filepath/path_test.go
index e1c801b659..3ebd3fbd2d 100644
--- a/src/path/filepath/path_test.go
+++ b/src/path/filepath/path_test.go
@@ -389,6 +389,12 @@ func checkMarks(t *testing.T, report bool) {
 // If clear is true, any incoming error is cleared before return. The errors
 // are always accumulated, though.
 func mark(info os.FileInfo, err error, errors *[]error, clear bool) error {
+	name := info.Name()
+	walkTree(tree, tree.name, func(path string, n *Node) {
+		if n.name == name {
+			n.mark++
+		}
+	})
 	if err != nil {
 		*errors = append(*errors, err)
 		if clear {
@@ -396,12 +402,6 @@ func mark(info os.FileInfo, err error, errors *[]error, clear bool) error {
 		}
 		return err
 	}
-	name := info.Name()
-	walkTree(tree, tree.name, func(path string, n *Node) {
-		if n.name == name {
-			n.mark++
-		}
-	})
 	return nil
 }