io/fs, path/filepath: honor SkipDir on second WalkDirFunc error call

Fixes golang#51617

Change-Id: I03e9e575d9bad1481e7e4f051b50a077ba5f2fe0
Reviewed-on: https://go-review.googlesource.com/c/go/+/392154
Trust: Ian Lance Taylor <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Emmanuel Odeke <[email protected]>

src/io/fs/walk.go

@@ -76,6 +76,9 @@ func walkDir(fsys FS, name string, d DirEntry, walkDirFn WalkDirFunc) error {
  // Second call, to report ReadDir error.
  err = walkDirFn(name, d, err)
  if err != nil {
+ if err == SkipDir && d.IsDir() {
+ err = nil
+ }
  return err
  }
  }

src/io/fs/walk_test.go

@@ -8,6 +8,8 @@ import (
  . "io/fs"
  "os"
  pathpkg "path"
+ "path/filepath"
+ "reflect"
  "testing"
  "testing/fstest"
 )
@@ -122,3 +124,34 @@ func TestWalkDir(t *testing.T) {
  }
  checkMarks(t, true)
 }
+
+func TestIssue51617(t *testing.T) {
+ dir := t.TempDir()
+ for _, sub := range []string{"a", filepath.Join("a", "bad"), filepath.Join("a", "next")} {
+ if err := os.Mkdir(filepath.Join(dir, sub), 0755); err != nil {
+ t.Fatal(err)
+ }
+ }
+ bad := filepath.Join(dir, "a", "bad")
+ if err := os.Chmod(bad, 0); err != nil {
+ t.Fatal(err)
+ }
+ defer os.Chmod(bad, 0700) // avoid errors on cleanup
+ var saw []string
+ err := WalkDir(os.DirFS(dir), ".", func(path string, d DirEntry, err error) error {
+ if err != nil {
+ return filepath.SkipDir
+ }
+ if d.IsDir() {
+ saw = append(saw, path)
+ }
+ return nil
+ })
+ if err != nil {
+ t.Fatal(err)
+ }
+ want := []string{".", "a", "a/bad", "a/next"}
+ if !reflect.DeepEqual(saw, want) {
+ t.Errorf("got directories %v, want %v", saw, want)
+ }
+}

src/path/filepath/path.go

@@ -396,6 +396,9 @@ func walkDir(path string, d fs.DirEntry, walkDirFn fs.WalkDirFunc) error {
  // Second call, to report ReadDir error.
  err = walkDirFn(path, d, err)
  if err != nil {
+ if err == SkipDir && d.IsDir() {
+ err = nil
+ }
  return err
  }
  }

src/path/filepath/path_test.go

@@ -1526,3 +1526,38 @@ func TestEvalSymlinksAboveRootChdir(t *testing.T) {
  t.Logf("EvalSymlinks(%q) = %q", check, resolved)
  }
 }
+
+func TestIssue51617(t *testing.T) {
+ dir := t.TempDir()
+ for _, sub := range []string{"a", filepath.Join("a", "bad"), filepath.Join("a", "next")} {
+ if err := os.Mkdir(filepath.Join(dir, sub), 0755); err != nil {
+ t.Fatal(err)
+ }
+ }
+ bad := filepath.Join(dir, "a", "bad")
+ if err := os.Chmod(bad, 0); err != nil {
+ t.Fatal(err)
+ }
+ defer os.Chmod(bad, 0700) // avoid errors on cleanup
+ var saw []string
+ err := filepath.WalkDir(dir, func(path string, d fs.DirEntry, err error) error {
+ if err != nil {
+ return filepath.SkipDir
+ }
+ if d.IsDir() {
+ rel, err := filepath.Rel(dir, path)
+ if err != nil {
+ t.Fatal(err)
+ }
+ saw = append(saw, rel)
+ }
+ return nil
+ })
+ if err != nil {
+ t.Fatal(err)
+ }
+ want := []string{".", "a", filepath.Join("a", "bad"), filepath.Join("a", "next")}
+ if !reflect.DeepEqual(saw, want) {
+ t.Errorf("got directories %v, want %v", saw, want)
+ }
+}