Resolve one layer of symlinks in directory impl

go/runfiles/directory.go

@@ -15,6 +15,7 @@
 package runfiles
 
 import (
+	"errors"
 	"io/fs"
 	"os"
 	"path/filepath"
@@ -43,5 +44,42 @@ func (d Directory) path(s string) (string, error) {
 }
 
 func (d Directory) open(name string) (fs.File, error) {
-	return os.DirFS(string(d)).Open(name)
+	f, err := os.DirFS(string(d)).Open(name)
+	if err != nil {
+		return nil, err
+	}
+	return &resolvedFile{f.(*os.File), func(child string) (fs.FileInfo, error) {
+		path := filepath.Join(string(d), filepath.FromSlash(name), child)
+		target, err := os.Readlink(path)
+		if err != nil {
+			if errors.Is(err, os.ErrInvalid) {
+				target = path
+			} else {
+				return nil, err
+			}
+		}
+		return os.Lstat(target)
+	}}, nil
+}
+
+type resolvedFile struct {
+	fs.ReadDirFile
+	lstatChildAfterReadlink func(string) (fs.FileInfo, error)
+}
+
+func (f *resolvedFile) ReadDir(n int) ([]fs.DirEntry, error) {
+	entries, err := f.ReadDirFile.ReadDir(n)
+	if err != nil {
+		return nil, err
+	}
+	for i, entry := range entries {
+		if entry.Type()&fs.ModeSymlink != 0 {
+			info, err := f.lstatChildAfterReadlink(entry.Name())
+			if err != nil {
+				return nil, err
+			}
+			entries[i] = renamedDirEntry{fs.FileInfoToDirEntry(info), entry.Name()}
+		}
+	}
+	return entries, nil
 }

tests/runfiles/fs_test.go

@@ -21,6 +21,7 @@ import (
 	"path"
 	"path/filepath"
 	"runtime"
+	"slices"
 	"strings"
 	"testing"
 
@@ -165,6 +166,9 @@ func testFS(t *testing.T, r *runfiles.Runfiles) {
 	testFile(t, r, "link_test.txt", "hi!\n")
 	testFile(t, r, "link_test_dir/file.txt", "file\n")
 	testFile(t, r, "link_test_dir/subdir/other_file.txt", "other_file\n")
+
+	testGlob(t, r)
+	testWalkDir(t, r)
 }
 
 func testFile(t *testing.T, r *runfiles.Runfiles, name, content string) {
@@ -198,6 +202,51 @@ func testFile(t *testing.T, r *runfiles.Runfiles, name, content string) {
 	}
 }
 
+func testGlob(t *testing.T, r *runfiles.Runfiles) {
+	matches, err := fs.Glob(r, "*/subdir/*.txt")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := []string{
+		"link_test_dir/subdir/other_file.txt",
+	}
+	if !slices.Equal(matches, expected) {
+		t.Errorf("got %v, want %v", matches, expected)
+	}
+}
+
+func testWalkDir(t *testing.T, r *runfiles.Runfiles) {
+	var found []string
+	err := fs.WalkDir(r, "io_bazel_rules_go/tests/runfiles", func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if !d.IsDir() {
+			found = append(found, path)
+		}
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	exeSuffix := ""
+	if runtime.GOOS == "windows" {
+		exeSuffix = ".exe"
+	}
+	expected := []string{
+		"io_bazel_rules_go/tests/runfiles/runfiles_test_/runfiles_test" + exeSuffix,
+		"io_bazel_rules_go/tests/runfiles/test.txt",
+		"io_bazel_rules_go/tests/runfiles/test_dir/file.txt",
+		"io_bazel_rules_go/tests/runfiles/test_dir/subdir/other_file.txt",
+		"io_bazel_rules_go/tests/runfiles/testprog/testprog_/testprog" + exeSuffix,
+	}
+	if !slices.Equal(found, expected) {
+		t.Errorf("got %v, want %v", found, expected)
+	}
+}
+
 func TestFS_empty(t *testing.T) {
 	dir := t.TempDir()
 	manifest := filepath.Join(dir, "manifest")